class II (comments).pdf

ContentsOriginal articles89 Cranial base and airway morphology in adult Malays with obstructive sleep apnoea

Saeed M. Banabilh, A.H. Suzina, Sidek Dinsuhaimi and G.D. Singh96 Accuracy of bracket placement by orthodontists and inexperienced dental students

David Armstrong, Gang Shen, Peter Petocz and M. Ali Darendeliler104 Fracture characteristics of fibre reinforced composite bars used to provide rigid orthodontic dental segments

Soodeh Tahmasbi, Farzin Heravi and Saied Mostafa Moazzami109 Assessment of palatal bone thickness in adults with cone beam computerised tomography

Antonio Gracco, Lombardo Luca, Mauro Cozzani and Giuseppe Siciliani114 Vertical changes in treated and untreated Class II division 1 malocclusions

Craig Sharp, Michael Harkness and Peter HerbisonReview121 The relationships between malocclusion, fixed orthodontic appliances and periodontal disease.

A review of the literatureJan van Gastel, Marc Quirynen, Wim Teughels and Carine Carels

Case reports130 Treatment of a Class I deep bite malocclusion in a periodontally compromised adult

Marcelo do Amaral Ferreira and Rogério do Amaral Ferreira137 Use of miniscrews as temporary anchorage devices in orthodontic practice. II – Case reports

George Anka147 Molar distalisation with skeletal anchorage

Antonio Gracco, Lombardo Luca and Giuseppe SicilianiEditorial153 What is a minimal clinically important difference?

Michael HarknessLetter155 Force and tooth movement

Brian LeeComment156 Why would anyone be interested in measurement error?

Peter Herbison157 When should we finish with a Class I molar relationship?

Hussam M. Abdel-Kader

Obituary160 Thomas Graber (1917-2007)

General161 Book reviews169 Interview177 Recent publications180 In appreciation182 New products183 Calendar185 Index

AustralianOrthodontic JournalVolume 23 Number 2, November 2007

Australian Orthodontic Journal Volume 23 No. 2 November 2007

Introduction

Obstructive sleep apnoea (OSA) has come to theforefront in the last 30 years, and has been describedas a public health problem comparable to smoking inits effects upon society.1 The Wisconsin Sleep Cohortstudy suggested that the prevalence of OSA amongmiddle-aged women and men is 9 per cent and 24 percent respectively (regardless of the presence of symptoms), while the prevalence of OSAS (OSA pluspresence of excessive daytime sleepiness) is 2 per centin women and 4 per cent in men.2 It is thought thatthe pathophysiology of OSA involves factors thatrelate to the anatomical dimensions of the upper air-way, upper airway resistance and upper airway muscleactivity during sleep.3 Therefore, upper airway

morphology is often measured in investigations ofupper airway mechanics and OSA pathophysiology.The upper airway has been categorised into threeanatomical regions: the nasopharynx (the area behindthe nose and above the soft palate); the oropharynx(the area from soft palate to upper border of theepiglottis), which is subdivided into the retropalatalarea (behind the palate) and the retroglossal area(behind the tongue); and the hypopharynx (laryngo-pharynx), which is the area from the upper border of epiglottis to the inferior border of the cricoid cartilage.4

Many techniques have been used to measure upperairway morphology, including nasopharyngoscopy,5acoustic reflectance,6 computerised tomography7 and

© Australian Society of Orthodontists Inc. 2007 Australian Orthodontic Journal Volume 23 No. 2 November 2007 89

Cranial base and airway morphology in adultMalays with obstructive sleep apnoea

Saeed M. Banabilh,* A.H. Suzina,* Sidek Dinsuhaimi* and G.D. Singh†

Department of ORL-HNS, School of Medical Sciences, Universiti Sains Malaysia, Kelantan, Malaysia* and Department of Speech and HearingSciences, Portland State University, Portland, USA†

Background: Obstructive sleep apnoea (OSA) has been described as a public health problem comparable to smoking in itsimpacts upon society. Objective: To compare the differences in cranial base and airway morphology in Malay adults with and without OSA usingfinite element analysis (FEM). Method: Lateral skull radiographs of 38 adult Malays aged 18–60 years were divided into two groups of 19 (13 male, 6 female). The first group consisted of 19 patients with OSA, defined as an apnoea-hypopnea index > 5/hr of sleep, diagnosed with overnight polysomnography. The second group consisted of 19 healthy, non-OSA control subjects. For each lateral skull radiograph 27 homologous landmarks, which encompassed the naso-oropharyngeal airway, were digitised usingMorphoStudio software. The mean OSA and control 2D airway configurations were computed and subjected to t-tests andFEM. Results: The mean 2D OSA airway was statistically different from the mean control airway (p < 0.01). Inter-landmark analysisrevealed that the cranial base saddle angle was more acute in the OSA group (153.9 degrees ± 3.4) compared to the control group (158.3 degrees ± 2.5; p < 0.01). In addition, using pseudo-coloured FEM a relative 58 per cent decrease innasopharyngeal airway area was found above and behind the soft palate. As well, a 32 per cent decrease in oropharyngealairway area was located behind the base of the tongue, with a 23 per cent decrease in hypopharyngeal area near the levelof the hyoid bone. In contrast, a 96 per cent increase in area associated with downward displacement of the hyoid bone wasdetected. Conclusion: Functional airway impairments associated with OSA can be quantified and localised in Malay patients, and arepredominantly associated with the morphology of the posterior regions of the cranial base.(Aust Orthod J 2007; 23: 89–95)

Received for publication: March 2007Accepted: May 2007

BANABILH ET AL


magnetic resonance imaging.8 Although all thesetechniques can be used to accurately measure upperairway morphology, the invasive nature of some ofthem is disadvantageous. As well, while most previousstudies compared OSA airway morphology usingconventional techniques,9–10 only a few studies haveused robust geometric morphometric methods suchas finite element morphometry (FEM). For example,FEM was used to model the upper airway and to create anatomically correct sagittal pharyngeal air-ways, as well as to assess the collapsibility of the upperairway.11 Similarly, pharyngeal cross-sectional areaswere assessed using FEM.5 Recently, Singh et al.12

used FEM to quantify changes in the upper airway in children undergoing functional orthodontic treatments.

Using FEM, change in morphology is viewed as adeformation of an initial geometric configuration,whose boundaries are formed by edges that connectanatomical landmarks into a final form.13 Indeed,this technique has been employed previously in astudy of craniofacial growth,14 facial soft tissuechanges15–17 and dental arch features.18 It is thoughtthat FEM allows a better understanding and visual-isation of the magnitude and direction of morpho-logic change.19 Hence, this study was undertaken todetermine whether any morphologic differences canbe identified in the upper airway of adult Malays withand without OSA, using FEM. The aim of this studyis to test the null hypothesis that no morphologic dif-ferences in terms of upper airway size and shape areidentifiable in the two groups. Rejection of the nullhypothesis might indicate how OSA might be bettermanaged in patients of diverse ethnicity.

Materials and methods

This multidisciplinary study took place in theDepartment of Otorhinolaryngology, HospitalUniversiti Sains Malaysia (HUSM). After obtainingappropriate consent, lateral skull radiographs weretaken for a total of 38 adult Malays aged 18–60 years.The first group consisted of 19 patients (13 males, 6females) with OSA, defined as an Apnoea-HypopneaIndex (AHI) > 5/hr of sleep, diagnosed with limitedovernight polysomnography (PSG). The secondgroup consisted of 19 (13 males, 6 females) healthy,non-OSA control subjects who did not have anyapnoeic symptoms as evaluated by the attendingphysician and limited channel PSG, but the Epworth

sleepiness scale was not used in this comparative,cross-sectional study. Exclusion criteria for sampleselection were any subjects with psychiatric illness,sedative and/or alcohol intake, patient-specific dis-orders (such as neuromuscular disorders) and anycraniofacial deformity, such as cleft lip and/or palate.An overnight hospital type III sleep study with PSGmonitoring was performed on each subject between2200 hours and 0600 hours. All variables wererecorded simultaneously and continuously on a limit-ed standard 8 channel PSG (Somnologica, lceland) atHUSM Sleep Science Laboratory. Occurrence ofOSA was scored when there was cessation of breath-ing for >10 seconds or associated with evidence ofpersistent respiratory effort. Hypopnea was scoredwhen there was >50 per cent decrease in the airflowsignal with >3 per cent decrease in arterial oxygen saturation.20 Therefore, the severity of OSA was eval-uated by the AHI, defined as the total number ofapnoeas and hypopneas divided by the total sleeptime in minutes.

On the lateral skull radiographs, 27 homologous land-marks, which encompassed the upper airway, weredigitised using MorphoStudio software to obtain thex, y coordinates (Figure 1). All data were subjected toduplicate digitisation by the same investigator (SMB)on two different occasions. Next, Procrustes super-imposition was implemented to obtain a generalisedrotational fit, that is, all configurations were scaled toan equivalent size and registered with respect to oneanother. Thus, mean 2D nasopharyngeal airway morphologies were determined for both groups, andFEM was used to compare the mean OSA airwaywith the mean control airway. For statistical testing,the Procrustes means were subjected to Student’s t-tests to identify elements showing significantchanges. In addition, MorphoStudio software wasused to perform an inter-landmark analysis to detectchanges in length, and the statistical behaviour of the2D linear distance between specific landmarks on themandible (gonion) and the body of the hyoid bone inthe Procrustes means. Finally, the cranial base ‘saddle’angle (nasion-sella-basion, N-S-PPW1) was alsomeasured and subjected to Student’s t-tests. No othercephalometric parameters were utilised in this partic-ular study, which was largely based on geometricmorphometric techniques.

To demonstrate sources of cranial base heterogeneity,FEM was undertaken that incorporated a spline

interpolation function on a personal computer. FEMcan be used to depict transformations in terms ofallometry (size-related shape change) and anisotropy(directionality of shape change).21 Based on thisapproach, differences can be described graphically asa size-change, shape-change or both. Change in formbetween the reference configuration and the finalconfiguration is viewed as a continuous deformation,which can be quantified based on major and minorstrains (principal strains). If the two strains are equal,the form change is characterised by a simple increaseor decrease in size, but if one of the principal strainschanges in a greater proportion, transformationoccurs in both size and shape. The product of thestrains indicates a change in size if the result is notequal to 1. A product greater than 1 represents anincrease in size equal to the remainder, for example,1.30 indicates a 30 per cent increase. On the otherhand, a result of 0.80 indicates a 20 per cent decreasein size. Changes in shape are determined by the ratioof the principal extensions, where a value not equal to1 represents an observable change in shape. Theproducts and ratios can be resolved for individuallandmarks within the configuration, and these can belinearised using a log-linear scale and pseudo-colourcoded to provide a graphic display of size- and shape-change.

Results

The control group included subjects whose AHIranged from 0–4.20 For the OSA group, patients withmild OSA presented with an AHI of 5–15. Patientswith moderate OSA demonstrated an AHI of 15–30.Patients with severe OSA had an AHI >30. In thisstudy, 6 patients had mild OSA, 4 had moderate OSAand 9 had severe OSA. The mean AHI for the OSAgroup was 37.6 ± 24.3 per hour while the mean AHIfor the control group was 1.6 ±2.1 per hour (p < 0.001). The mean oxygen saturation of the OSAgroup was 94.2 per cent ± 3.8 while the mean oxygensaturation for the control group was 98 per cent ± 0.9per hour (p < 0.001). The mean BMI for the controlgroup was 20.5 ± 2.6 and the BMI for the OSA groupwas 33.8 ± 7.4 (p < 0.001).

On duplicate digitisation of the landmarks, no signif-icant differences were found (p > 0.05) using amethod equivalent to Dahlberg’s formula, and there-fore the study digitisation error was assumed to haveno effect on the findings. The inter-landmark

CRANIAL BASE IN OSA

Australian Orthodontic Journal Volume 23 No. 2 November 2007 91

Figure 1. Homologous landmarks employed for airway space evaluation.0. Sella: centre of sella turcica.1. Nasion.2. Posterior cranial base: point directly below sella in the vertical plane

that intersects with the inferior surface of the posterior cranial base.3. Posterior nasal spine.4. Superior pterygomaxillare: superior point where pterygoid process of

sphenoid bone and pterygoid process of the maxilla form the pterygomaxillary fissure.

5. Inferior pterygomaxillare: lowest point of the opening of the pterygomaxillary fissure as defined above.

6. Atlas: anterior-most point on anterior process of the atlas.7. Atlas soft: anterior-most point on posterior pharyngeal wall in the

horizontal plane directly opposing atlas.8. Uvula: most inferior point on the tip of the uvula.9. Uvula dorsum: point of maximum convexity on the dorsum of the uvula.

10. Posterior pharyngeal wall 1 (PPW1): point directly opposing PNS in thehorizontal plane on the posterior pharyngeal wall.

11. Gonion: lowest and most posterior point on the angle of the mandible.12. Base of tongue: most posterior point on the posterior surface of the

dorsum of the tongue.13. Second cervical vertebra lower: lowest point of the C2 intervertebral

disc.14. Soft second cervical vertebra: point on the surface of the posterior

pharyngeal wall in the horizontal plane directly opposite point 13.15. Third cervical vertebra: highest point of the intervertebral disc of C3.16. Soft third cervical vertebra: point on the surface of the posterior

pharyngeal wall in the horizontal plane directly opposite point 15.17. Third cervical vertebra lower: lowest point of the C3 intervertebral disc.18. Soft third cervical vertebra lower: point on the surface of the posterior

pharyngeal wall in the horizontal plane directly opposite point 17.19. Fourth cervical vertebra: highest point of the intervertebral disc of C4.20. Soft fourth cervical vertebra: point on the surface of the posterior

pharyngeal wall in the horizontal plane directly opposite point 19.21. Fourth cervical vertebra lower: lowest point of the intervertebral disc

of C4.22. Soft fourth cervical vertebra lower: point on the surface of the posterior

pharyngeal wall in the horizontal plane directly opposite point 21.23. Epiglottis: superior tip of epiglottis.24. Hyoid: anterior-most point on body of hyoid bone.25. Anterior nasal spine.26. Gnathion: most antero-inferior point on mandibular profile.

5

6 7

8

9 3

24

0

1

10

26

25

12

2324

11

22212019

1617 18

151413

BANABILH ET AL


analysis on the Procrustes means revealed that the linear distance from gonion (angle of the mandible)to the body of the hyoid bone increased in length byapproximately 47 per cent (p < 0.01) for the OSAgroup, and the cranial base saddle angle was moreacute in the OSA group (153.9 degrees ± 3.4) com-pared to the control group (158.3 degrees ± 2.5; p < 0.01). In addition, the results of the t-tests indi-cated that the normalised mean OSA airway was statistically different from the mean control airway (p < 0.01).

Comparison of the nasopharyngeal region indicatedthat striking changes were detected using FEM, as theOSA configurations showed a relative 58–78 per centdecrease in area in the posterior cranial base andnasopharyngeal region above and behind the softpalate (Figure 2, vertical pseudo-colour scale).Specifically, the posterior pharyngeal wall (PPW1)was involved in the reduction in area. However,localised increases in area of 30–55 per cent werefound further anteriorly (Figure 2). In addition, shape-changes were highly anisotropic (non-uniform). Thedirectionality of these non-homogeneous shapechanges is shown in Figure 3, which indicates a 45degrees axis of narrowing with respect to the midsagittal plane (blue colour using the circular pseudo-colour scale). As well, antero-posterior nar-rowing is indicated by the green region visible inFigure 3 (using the circular colour scale).

Comparison of the oropharyngeal region indicated a28–30 per cent increase in area posteriorly, allied witha 32–45 per cent decrease in oropharyngeal airwayarea located behind the base of the tongue (Figure 2,vertical pseudo-colour scale). In addition, shape-changes were highly anisotropic. The directionality ofthe shape changes identifies antero-posterior narrow-ing, as indicated by the green region using the circular pseudo-colour scale (Figure 3).

Comparison of hypopharyngeal region indicated a 23per cent decrease in hypopharyngeal area near thelevel of the fourth cervical vertebra, C4 (blue colour,Figure 2, vertical pseudo-colour scale). Moreover, thehyoid bone moved more inferiorly with respect to theangle of the mandible (gonion), and C4 appeared tolocate posteriorly. Accordingly, a 70–96 per centincrease in area was noted in the submandibularregion associated with downward displacement of thehyoid bone. In addition, shape-changes were highlyanisotropic. The directionality of the shape changesidentifies supero-inferior elongation as indicated by the purple coloration but, antero-inferior (blue)and postero-inferior (red) deformations are alsodemonstrable in that region, using the circular pseudo-colour scale (Figure 3).

Discussion

In this study, the characteristics of the cranial baseand upper airway morphology in Malay patients with

Figure 2. Comparison of mean OSA and normal airway configurations forsize change. Overall the airway space is narrower in the posterior regionfor the OSA group. Using the entire vertical pseudo-colour scale bar, whichindicates the degree of size-change, a relative 58 per cent decrease innasopharyngeal airway area is found above and behind the soft palate indicated by the light and dark blue pseudo-colouration.

Figure 3. Comparison of mean OSA and normal airway configurations fordirectionality of change. The circular pseudo-colour scale indicates direction.The two green areas indicate narrowing of the airway in the antero-posteriorplane. The blue central zone indicates a 45 degrees axis of antero-posteriornarrowing, while the purple regions indicate vertical.

CRANIAL BASE IN OSA


obstructive sleep apnoea (OSA) were investigatedusing finite element analysis (FEM). While most pre-vious studies compared OSA cranial base and airwaymorphology using conventional techniques,9–10 onlya few studies5,11–12 have used FEM, a relatively newanalytic tool. Although the FEM method appears tobe somewhat theoretical, one advantage is that theresults are presented graphically and one can viewchanges in size or shape. Nevertheless, the currentstudy could not overcome some methodological limitations. For example, the radiographs employedfor the study were obtained during wakefulness.However, there have been clearly documented abnor-malities of upper airway anatomy and physiology insubjects with OSA during wakefulness. Therefore, webelieve that careful anatomic/physiologic assessmentduring wakefulness may provide some valuable infor-mation even though cephalometric data cannotescape the limitations of 2D imaging.

In this study the mean cranial base configuration ofthe OSA group was compared to that of a non-apnoeic control group. For the groups studied, theinter-landmark analysis on the Procrustes meansrevealed that patients with OSA had a significantlymore acute cranial base flexure angle (153.9 degrees ±3.4) when compared to the control group (158.3degrees ± 2.5). In addition, relative 58–78 per centdecreases in area of the posterior cranial base regionwere found using FEM (Figure 2). These findingssupport the view that an acute cranial base flexureangle may be responsible for a decrease in pharyngealairway dimension in patients with OSA by reducingthe distance between the anterior and the posteriorpharyngeal walls, and bringing the cervical spine andposterior pharyngeal wall further forwards.22 Both ofthese mechanisms would potentially reduce the spaceavailable for the airway.9 Indeed, the presence of anarrower than normal pharyngeal diameter in OSApatients has been previously documented using con-ventional techniques. For example, in Japanesepatients with OSA all upper airway cephalometricvariables were smaller compared with a controlgroup.23 In addition, the majority of CT and MRIstudies indicate that even during wakefulness theupper airway of patients with OSA is smaller thancontrols.24

Our results localise the anatomical regions of theupper airway affected and quantify the decrease inairway area in the OSA group compared with a

matched, non-apnoeic, control group using a FEMtechnique. In a previous study, the antero-posteriorwidth of the bony nasopharynx and oropharynx werealso significantly reduced in obese and non-obesepatients with OSA.25 The smaller width of the bony pharynx may reflect a posterior position of themaxilla secondary to cranial base morphology, andtogether with an enlarged soft palate may contributeto upper airway narrowing. In addition, narrowing ofthe oropharynx as shown in this present study maydisplace the tongue into the hypopharyngeal space,and that displacement may play an important role inthe development of OSA (Figures 2 and 3).

Another finding of our study is that the hyoid bonewas displaced more inferiorly with respect to theangle of the mandible (gonion), and the fourth cer-vical vertebra (C4) appeared to relocate posteriorly.Accordingly, a 70–96 per cent increase in area wasnoted in the submandibular region. This displace-ment occurred in the vertical plane predominantly(Figure 3). Many previous studies have shown thatpatients with OSA have inferior displacement of thehyoid bone,2,10, 25–27 which is found lower at the levelof cervical vertebrae C4-C6 compared to controls, inwhom it is typically located at the level of C3-C4.Indeed, it has been suggested that a large neck circumference is caused not only by obesity or fatdeposition, but also by inferior positioning of thehyoid bone allied with posterior positioning of C4.28

It has also been suggested that an inferiorly placedhyoid bone relocates the tongue base into thehypopharynx, and thus the patency of the hypo-pharyngeal airway is adversely affected.29 These ideasmight also explain the case in Malay patients withOSA. The lower position of the hyoid bone in thisgroup of patients might be a compensatory mecha-nism to ease the increased airway resistance caused byreduced airway space.30

Alternatively, in Asian patients with OSA other morphological abnormalities such as a ‘large’ cranialbase might be a major contributor to the pathogene-sis of OSA.31 Indeed, habitual snorers show a signifi-cant decrease in sagittal cranial base dimensions32 andfor patients with OSA, craniofacial abnormalitiesinclude a greater flexion of the cranial base.33

Similarly, compared with normal subjects, Chinesepatients with OSA exhibit a shortened cranial base.34

In Chinese-Singaporeans, a ‘narrower skull base’ hasalso been reported.35 In Chinese males with severe

OSA craniocervical extension was significantlyincreased, while differences were also found for anterior cranial base length.36 In terms of effect,Wong et al.28 suggest that craniocervical angulationand head posture correlate with airway resistanceassociated with OSA in Malaysian patients.Robertson37 also reported that while nearly all linearcranial base dimensions are smaller in patients withOSA, these failed to reach statistical significance, pre-sumably due to the lack of normalisation in thatstudy. Ono et al.38 reported that when patients withOSA changed their posture from upright to supine,significant correlations were observed between thecranial base and upper cervical column angle.Tangugsorn et al.39 also reported a shorter cranialbase dimension with counterclockwise rotation anddepression of the clivus in patients with OSA.Therefore, on the basis of the current results, we alsoconclude that an acute cranial base flexure angle isone important craniofacial factor, which may beresponsible for OSA in Malays. Consequently, exam-ination and evaluation of the cranial base and upperairway anatomy must be undertaken to confirm thediagnosis of OSA and support decision-makingamong various treatments. As the use of mandibularadvancement devices would be contraindicated inpatients presenting with Class III malocclusions secondary to cranial base morphology,40–41 we sug-gest that changing the size of the apnoeic airwaycould be achieved by non-surgical alterations of struc-tures that surround the upper airway. This notion iscurrently under investigation and remains as thepremise for future studies.

Acknowledgment

This study was funded by a short term research grant(No. 304/PPSP/6131489) from Universiti SainsMalaysia.

Corresponding author

Professor G.D. Singh Department of Speech and Hearing SciencesPortland State University85 Neuberger Hall724 SW Harrison StPortland, OR 97207-0751USAFax: (+1) 866 201 3869Email: [email protected]

References1. Phillipson EA. Sleep apnoea – a major public health

problem. N Engl J Med 1993; 328:1271–3.2. Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S.

The occurrence of sleep-disordered breathing among middle-aged adults. N Engl J Med 1993;328:1230–5.

3. Hudgel DW. The role of upper airway anatomy and physiol-ogy in obstructive sleep apnoea. Clin Chest Med 1992;13:383–98.

4. Rama AN, Tekwani SH, Kushida CA. Sites of obstruction inobstructive sleep apnoea. Chest 2002;122:1139–47.

5. Mansour KF, Rowley JA, Badr MS. Measurement of pharyn-geal cross-sectional area by finite element analysis. J ApplPhysiol 2006;100:294–303.

6. Mohsenin V. Effects of gender on upper airway collapsibilityand severity of obstructive sleep apnoea. Sleep Med 2003;4:523–9.

7. Schwab RJ, Gefter WB, Hoffman EA, Gupta KB, Pack AI.Dynamic upper airway imaging during awake respiration innormal subjects and patients with sleep disordered breath-ing. Am Rev Respir Dis 1993;148:1385–400.

8. Welch KC, Foster GD, Ritter CT, Wadden TA, Arens R,Maislin G et al. A novel volumetric magnetic resonanceimaging paradigm to study upper airway anatomy. Sleep2002;25:532–42.

9. Battagel JM, Johal A, Kotecha B. A cephalometric compari-son of subjects with snoring and obstructive sleep apnoea.Eur J Orthod 2000;22:353–65.

10. Hou HM, Sam K, Hagg U, Rabie AB, Bendeus M, Yam LYet al. Long-term dentofacial changes in Chinese obstructivesleep apnoea patients after treatment with a mandibularadvancement device. Angle Orthod 2006;76:432–40.

11. Malhotra A, Huang Y, Fogel RB, Pillar G, Edwards JK,Kikinis R et al. The male predisposition to pharyngeal col-lapse: importance of airway length. Am J Respir Crit CareMed 2002;166:1388–95.

12. Singh GD, García-Motta AV, Hang WM. Evaluation of theposterior airway space following Biobloc therapy: geometricmorphometrics. Cranio 2007;25: 84–89.

13. Singh GD, McNamara JA Jr., Lozanoff S. Morphometry ofthe cranial base in subjects with Class III malocclusion. JDent Res 1997;76:694–703.

14. Singh GD, Rivera-Robles J, de Jesus-Vinas J. Longitudinalcraniofacial growth patterns in patients with orofacial clefts:geometric morphometrics. Cleft Palate Craniofac J 2004;41:136–43.

15. Singh GD, Maldonado L, Thind BS. Changes in the soft tissue facial profile following orthodontic extractions: a geometric morphometric study. Funct Orthod 2004;22:34–8, 40.

16. Singh GD, McNamara JA Jr., Lozanoff S. Finite-elementmorphometry of soft tissues in prepubertal Korean andEuropean-Americans with Class III malocclusions. ArchOral Biol 1999;44:429–36.

17. Banabilh SM, Rajion ZA, Samsudin AR, Singh GD. Facialsoft tissue features assessed with finite element analysis. IntJ Orthod Milwaukee. 2006;17:17–20.

18. Banabilh SM, Rajion ZA, Samsudin R, Singh GD. Dentalarch shape and size in Malay schoolchildren with Class IImalocclusion. Aust Orthod J 2006;22:99–103.

19. McAlarney ME, Chiu WK. Comparison of numeric tech-niques in the analysis of cleft palate dental arch formchange. Cleft Palate Craniofac J 1997;34:281–91.

20. The report of an American Academy of Sleep Medicine Task Force. Sleep-related breathing disorders in adults:

BANABILH ET AL


recommendation for syndrome definition and measurementtechniques in clinical research. Sleep 1999;22:667–89.

21. Singh GD, McNamara JA Jr., Lozanoff S. Finite elementanalysis of the cranial base in subjects with Class III malo-cclusion. Br J Orthod 1997;24:103–12.

22. Steinberg B, Fraser B. The cranial base in obstructive sleepapnoea. J Oral Maxillofac Surg 1995;53:1150–4.

23. Endo S, Mataki S, Kurosaki N. Cephalometric evaluation ofcraniofacial and upper airway structures in Japanese patientswith obstructive sleep apnoea. J Med Dent Sci 2003;50:109–20.

24. Schwab RJ, Pasirstein M, Pierson R, Mackley A,Hachadoorian R, Arens R et al. Identification of upper air-way anatomic risk factors for obstructive sleep apnoea withvolumetric magnetic resonance imaging. Am J Respir CritCare Med 2003;168:522–30.

25. Yu X, Fujimoto K, Urushibata K, Matsuzawa Y, Kubo K.Cephalometric analysis in obese and nonobese patients withobstructive sleep apnoea syndrome. Chest 2003;124:212–18.

26. Lyberg T, Krogstad O, Djupesland G. Cephalometric analy-sis in patients with obstructive sleep apnoea syndrome. I.Skeletal morphology. J Laryngol Otol 1989;103:287–92.

27. Wong ML, Sandham A, Ang PK, Wong DC, Tan WC,Huggare J. Craniofacial morphology, head posture, andnasal respiratory resistance in obstructive sleep apnoea: aninter-ethnic comparison. Eur J Orthod 2005;27:91–7.

28. Pae EK, Lowe AA, Fleetham JA. A thin-plate spline analysisof the face and tongue in obstructive sleep apnoea patients.Clin Oral Investig 1997;1:178–84.

29. Lam B, Ooi CG, Peh WC, Lauder I, Tsang KW, Lam WK etal. Computed tomographic evaluation of the role of cranio-facial and upper airway morphology in obstructive sleepapnoea in Chinese. Respir Med 2004;98:301–7.

30. Verin E, Tardif C, Buffet X, Marie JP, Lacoume Y, Andrieu-Guitrancourt J et al. Comparison between anatomy andresistance of upper airway in normal subjects, snorers andOSAS patients. Respir Physiol 2002;129:335–43.

31. Koubayashi S, Nishida A, Nakagawa M, Shoda, Wada K,Susami R. Dentofacial morphology of obstructive sleepapnoea syndrome patients. Nippon Kyosei Shika GakkaiZasshi 1989;48:391–403. [Article in Japanese]

32. Zucconi M, Ferini-Strambi L, Palazzi S, Curci C, Cucchi E,Smirne S. Craniofacial cephalometric evaluation in habitualsnorers with and without obstructive sleep apnoea.Otolaryngol Head Neck Surg 1993;109:1007–13.

33. Cistulli PA. Craniofacial abnormalities in obstructive sleepapnoea: implications for treatment. Respirology 1996;1:167–74.

34. Tong M, Xia X, Cao E. Cephalometric analysis of the craniofacial bony structures in patients with obstructivesleep apnoea. Zhonghua Jie He He Hu Xi Za Zhi 1999;22:335–7. [Article in Chinese]

35. Hsu PP, Tan AK, Chan YH, Lu PK, Blair RL. Clinical pre-dictors in obstructive sleep apnoea patients with calibratedcephalometric analysis – a new approach. Clin Otolaryngol2005; 30:234–41.

36. Hou HM, Hagg U, Sam K, Rabie AB, Wong RW, Lam B, IpMS. Dentofacial characteristics of Chinese obstructive sleepapnoea patients in relation to obesity and severity. AngleOrthod 2006;76:962–9.

37. Robertson C. Cranial base considerations between apnoeicsand non-apnoeic snorers, and associated effects of long-termmandibular advancement on condylar and natural head position. Eur J Orthod 2002;24:353–61.

38. Ono T, Lowe AA, Ferguson KA, Fleetham JA. Associationsamong upper airway structure, body position, and obesity inskeletal Class I male patients with obstructive sleep apnoea.Am J Orthod Dentofacial Orthop 1996;109:625–34.

39. Tangugsorn V, Skatvedt O, Krogstad O, Lyberg T.Obstructive sleep apnoea: a cephalometric study. Part I.Cervico-craniofacial skeletal morphology. Eur J Orthod1995;17:45–56.

40. Singh GD, McNamara JA, Lozanoff S. Allometry of the cra-nial base in prepubertal Korean subjects with class III mal-occlusions: finite element morphometry. Angle Orthod1999;69:507–14.

41. Singh GD, McNamara JA, Lozanoff S. Craniofacial hetero-geneity of prepubertal Korean and European-American sub-jects with Class III malocclusions: Procrustes, EDMA, andcephalometric analyses. Int J Adult Orthodon OrthognathSurg 1998;13:227–40.

CRANIAL BASE IN OSA


Introduction

The developments of direct bonding and pre-adjustedappliances have allowed orthodontists to achievegood results with greater clinical efficiency. However,ideal bracket placement is often impossible due to theposition of the teeth and operator error.1 Poorly positioned brackets result in poorly positioned teeth,which can lead to multiple rebonding of brackets,longer treatment and/or a less than ideal final occlusion.2 Indirect bonding has been advocatedbecause it is more efficient, reduces chair time, maxi-mises the use of assistants and is more accurate thandirect bonding.3,4

Indirect bonding is more accurate than direct bond-ing for angular positioning of brackets on maxillaryand mandibular canines and vertical positioning ofbrackets on the maxillary canines, but it is less

accurate than direct bonding of brackets on themandibular second premolars (p < 0.01).5 Koo et al.confirmed that indirect bonding was more accuratethan direct bonding with respect to the verticaldimension, but there were no statistically significantdifferences between direct and indirect bonding ineither the angulation or the mesio-distal positions ofthe brackets.6 Recently, it has been reported that inboth methods, the mean bracket placement errorswere similar.7

Taylor and Cook8 looked at direct bracket placementon the anterior teeth in a typodont set-up, and foundthat angular judgements by the participants were lessconsistent than linear assessments. They reported thatno participant was able to reposition a bracket in thesame position: some participants could repositionbrackets within a 2 degree limit, but others had a variability of 19 degrees. This questions whether the

Australian Orthodontic Journal Volume 23 No. 2 November 2007 © Australian Society of Orthodontists Inc. 200796

Accuracy of bracket placement by orthodontistsand inexperienced dental students

David Armstrong,* Gang Shen,* Peter Petocz† and M. Ali Darendeliler*

Department of Orthodontics, Faculty of Dentistry, Sydney Dental Hospital, The University of Sydney, Sydney, Australia* and Department ofStatistics, Macquarie University, Sydney, Australia†

Background: Well-finished orthodontic treatment begins with accurate positioning of the brackets on the teeth.Aims: To compare the positions of orthodontic brackets placed by experienced clinicians and inexperienced trainees. Methods: Twenty orthodontists (13 male, 7 female) representing experienced specialists, and 20 final year dental students (10 male, 10 female) representing inexperienced trainees, were asked to bond pre-adjusted straight-wire brackets at the centresof the clinical crowns of the teeth in a Class I crowded typodont set-up. The teeth were removed from the typodont, placed in astandardised jig and photographed. The vertical, mesio-distal and angular (tip) positions of the brackets, relative to the centresof the clinical crowns, were measured with the aid of imaging software. The accuracy of bracket placement by the groups wascompared.Results: The dental students took significantly longer than orthodontists to place the brackets (50.65 ± 16.33 minutes vs 28.53± 9.51 minutes, p < 0.001), but were more accurate than the orthodontists at positioning the brackets vertically (0.90 ± 0.21mm vs 1.19 ± 0.23 mm, p < 0.001). There were no statistically significant differences between the dental students and thespecialists in either the mesio-distal or the angular/tip positions of the brackets (p > 0.05). Both groups tended to bond thebrackets with a distal tip. The students had slightly more right-left differences than the orthodontists. Mesio-distal errors in bracketplacement were associated with rotated and displaced teeth.Conclusions: Accurate direct bonding of orthodontic brackets to teeth does not appear to be related to clinical experience orspecialist training.(Aust Orthod J 2007; 23: 96–103)

Received for publication: December 2006Accepted: July 2007

ACCURACY OF BRACKET PLACEMENT


variation is due to experience or to natural ability.8Balut and coworkers9 looked at the accuracy of 10faculty members bonding brackets to teeth in fivetypodont set-ups. They reported means of 0.34 ±0.29 mm for vertical discrepancies and 5.54 ± 4.32degrees for angular discrepancies. Three faculty mem-bers had significant angular deviations and two faculty members had significant vertical deviations.These findings suggest that different operators have different abilities at placing brackets. Fowler10

reported that training and experience reduced boththe intra- and inter-clinician error, however thereductions were small. He also reported that morerecently trained clinicians were more consistent andmore accurate in identifying the long axes of clinicalcrowns than experienced clinicians.

It is uncertain whether the accuracy of bracket place-ment is related to clinical experience, recent training,natural ability or diligence.11–13 This study wasdesigned to compare the abilities of experienced clinicians and inexperienced dental students to bondorthodontic brackets in the centres of the clinicalcrowns of the teeth in a standardised typodont set-up.All participants were given the same set of instruc-tions, and a typodont set-up was used to simulate theclinical situation and avoid some of the variablesassociated with patients.

Materials and methodsParticipantsThe participants represented two groups with differ-ent levels of clinical experience and knowledge oforthodontics: group 1 consisted of 20 orthodontists(13 male, 7 female) representing the experienced clinicians, and group 2 was composed of 20 final yeardental students (10 male, 10 female) representing the dental trainees with no previous experience at

positioning orthodontic brackets. All participantswere right handed.

Typodont set-up Forty typodonts were set-up with the same Class I,crowded malocclusion. No tooth was so severely dis-placed that it prevented a bracket from being placedin the centre of the clinical crown (Figure 1). Thetypodont was then mounted on an adjustable rod toallow each operator to position the typodont as theywould position a patient’s head during bonding.Synthetic latex lips were used to prevent direct visionof the premolar teeth (Figure 2).

All participants were given a prepared handout withphotographs illustrating the position each bracketwas to be placed, and a selection of instruments (mirror, probe, periodontal probe, scaler, Hollenbach,flat plastic, rule and Unitek height gauge). They werealso asked if they required any further instruments.Prior to the placement of the brackets the teeth weresandblasted with 50 mm alumina particles for 10 seconds. A cheek retractor (Sasa, Kongivor, Norway)was then placed, and the participants were asked tobond 20 Victory series low profile MBT brackets(3M Unitek, Monrovia, CA, USA) on the typodontteeth using Transbond (3M Unitek, Monrovia, CA,USA), and remove any excess adhesive. The bracketswere then cured with the curing light available ineach surgery. The time taken to complete the bond-ing was recorded. As the bond strengths of the brackets were not tested standardisation of the curinglight was not necessary.

Figure 1. The simulated Class I malocclusion.

Figure 2. The typodont with synthetic latex lips preventing direct vision of thepremolar teeth.

Identifying the bracket placement deviation or error The teeth were removed from the typodont and theexcess wax removed. Each tooth was then placed inan individually made jig (Odontosil, Dreve-Dentamid GMBH, Germany) and two digital photo-graphs were taken (buccal and occlusal) using aNikon D1 fitted with a Nikon 110 lens (Figure 3).The digital images were opened using AnalysSIS Pro3.1 (Soft imaging system, Munich, Germany) and

magnified to the same scale using the rule attached tothe jig. The vertical position, the mesio-distal position and the angulation of the brackets weremeasured three times, and the mean of the threemeasurements used in all subsequent calculations.

The positioning errors were:

1. Vertical positioning error. Two diagonal lines weredrawn across the archwire slot to locate the centre ofthe slot. The vertical height of the bracket was thenmeasured from the incisal edge to the intersection

ARMSTRONG ET AL


Figure 3. The photographic set-up used to record bracket placement oneach tooth. A print of an upper central incisor is indicated by the arrow.

Figure 4a. Vertical positioning error. The difference between the centre ofthe bracket (dark line) and the incisal edge and the centre of the clinicalcrown and the incisal edge (light line).

Figure 4b. Mesio-distal positioning error. The difference between the mesio-distal midpoints of the bracket (dark line) and the clinical crown (light line).The outer lines indicate the mesial and distal surfaces.

Figure 4c. Angular (tip) positioning error. The angle between the long axis ofthe bracket (dark line) and the long axis of the clinical crown (light line).



of the lines (Figure 4a). The vertical positioning error was calculated by subtracting this measure-ment from the actual centre of the clinical crown(length of the clinical crown/2).14 Positive valuesindicated displacement towards the incisal edge andnegative values displacement towards the gingivalmargin.

2. Mesio-distal positioning error. This was measuredfrom the occlusal image. The midpoint of the toothwas identified, and the horizontal distance from themidpoint of the tooth to the midpoint of the bracket

measured (Figure 4b). Deviations from the midlinewere given the following sign: positive (mesial) andnegative (distal).

3. Angular/tip positioning error. This was defined asthe angle between the vertical scribe line on thebracket and the long axis of the clinical crown. Thetwo lines were highlighted and the software calcul-ated the intersecting angle (Figure 4c). If the bracketwas tipped mesially the value was recorded as posi-tive, and if it was tipped distally a negative value wasrecorded.

Table I. Errors in bracket placement by orthodontists and dental students.

Teeth* 15 14 13 12 11Mean SD Mean SD Mean SD Mean SD Mean SD

Vertical Orthod 1.31 0.31 0.66 0.44 1.34 0.55 1.26 0.36 2.24 0.44Student 1.18 0.39 0.37 0.36 0.63 0.55 0.77 0.34 1.70 0.27

Mesio-distal Orthod 0.10 0.15 -0.15 0.18 -0.12 0.22 -0.24 0.12 -0.11 0.24Student 0.11 0.30 -0.16 0.22 0.09 0.36 -0.25 0.16 -0.14 0.24

Tip Orthod -2.13 4.28 -4.57 4.74 -2.04 4.24 1.32 1.62 -2.26 3.91Student -4.84 3.92 -6.42 4.46 -5.87 3.86 -0.83 3.75 -1.66 2.73

Teeth 21 22 23 24 25Mean SD Mean SD Mean SD Mean SD Mean SD


Mesio-distal Orthod -0.13 0.26 -0.02 0.20 -0.02 0.29 -0.12 0.25 -0.23 0.29Student -0.03 0.19 -0.15 0.15 -0.01 0.377 0.04 0.35 -0.47 0.35

Tip Orthod -0.45 2.76 1.52 2.95 -2.22 5.395 -1.17 4.89 -3.34 4.49Student 0.69 2.371 2.55 2.39 0.23 4.692 -4.00 5.96 -2.78 3.50



Mesio-distal Orthod -0.06 0.43 -0.26 0.33 -0.02 0.21 -0.04 0.13 -0.23 0.16Student -0.38 0.22 0.14 0.57 0.22 0.33 -0.05 0.17 -0.05 0.15

Tip Orthod -0.27 6.24 0.33 3.92 -2.03 3.41 -4.62 2.80 -0.49 1.99Student 0.66 3.50 -1.00 4.61 0.82 3.74 -2.27 2.50 0.48 2.26



Mesio-distal Orthod 0.03 0.16 -0.02 0.14 -0.14 0.28 -0.18 0.34 0.15 0.41Student -0.11 0.18 -0.29 0.20 -0.07 0.29 -0.33 0.48 0.06 0.63

Tip Orthod -1.49 2.85 -2.10 3.55 -3.00 3.49 -4.20 3.82 1.60 5.36Student -1.94 2.14 -0.25 2.46 -2.57 3.04 -2.74 4.39 0.93 5.70

* FDI notationVertical and mesio-distal deviations in mm, tip/angular deviations in degrees

ARMSTRONG ET AL


Data statistics

The accuracy of the bracket placement was analysedusing the Statistical Package for the Social Sciences(SPSS for Windows, Release 12.0, SPSSInc, Chicago,Illinois). Since multiple and related tests were per-formed, a significance level of p = 0.01 was used in alltests. The measurement error was calculated byremeasuring the brackets in one quadrant (the lowerright) for three participants. The method error wasdetermined using the coefficient of variation (CV),which is the standard deviation divided by the mean expressed as a percentage.15 It revealed thatthere was no significant difference between repeatedmeasurements.

Results

The mean age of the orthodontists was 41 years (SD:7.61 years; Range: 29–53 years), with on average of8.88 years of experience (SD: 7.36 years; Range:1–25 years). The mean age of the students was 26.4years (SD: 4.08 years, Range: 23–42 years). The timetaken by the orthodontists to bond the 20 bracketswas significantly shorter (Mean: 28.53 minutes; SD:9.51; p < 0.001) than the time taken by the dentalstudents (Mean: 50.65 minutes; SD: 16.33).

The means and standard deviations of the three measurements (vertical, mesio-distal and tip) for eachtooth are given in Table I, and the significant findingsin Table II. The majority of the tip errors were nega-tive, which suggests that the participants tended tobond the brackets with a distal tip (Table I). This tendency was not statistically significant.

Brackets bonded by the orthodontists were placedmore incisally than the brackets bonded by the dental students (All, i.e. both upper and lower teeth:Orthodontists 1.19 ± 0.23 mm; Dental students 0.90± 0.21 mm, p < 0.001; Upper arch: Orthodontists1.37 ± 0.27 mm; Dental students 0.92 ± 0.26 mm, p < 0.001). The vertical errors were then assessed rel-ative to their mean bracket position vertically, and thedental students were slightly more accurate overall(Orthodontists: 0.56 ± 0.11; Dental students: 0.46 ±0.07 mm, p = 0.001). There were no statistically sig-nificant differences between the groups when themesio-distal and tip errors were compared (Table III).

When the side-to-side differences in placement weredetermined the orthodontists had significant (p <0.01) right-left differences for the following teeth:Vertical and mesio-distal errors: Teeth 15, 25; 12, 22;Vertical error: Teeth 13, 23; Mesio-distal error: Teeth41, 31; Tip error: Teeth 44, 34. The dental students

Table II. Comparison of the errors in bracket placement by orthodontists and students, significant findings only.

Deviation/Tooth Orthodontists Students p More accurate

Mean SD Mean SD

Vertical 13 1.34 0.55 0.63 0.55 <0.001 StudentTip 13 -2.04 4.23 -5.87 3.86 <0.001 OrthodVertical 12 1.26 0.36 0.77 0.34 <0.001 StudentVertical 11 2.24 0.44 1.70 0.27 <0.001 StudentVertical 21 2.07 0.36 1.31 0.37 <0.001 StudentVertical 22 1.47 0.29 1.02 0.39 <0.001 StudentVertical 23 1.67 0.59 1.00 0.52 <0.001 StudentVertical 24 0.77 0.41 0.38 0.37 <0.003 StudentMesio-distal 45 -0.06 0.43 -0.37 0.22 <0.005 OrthodVertical 43 1.19 0.33 0.65 0.51 <0.001 StudentTip 42 -4.62 2.80 -2.27 2.50 0.008 StudentMesio-distal 41 -0.23 0.16 -0.05 0.15 0.001 StudentVertical 31 1.23 0.37 0.87 0.37 <0.004 StudentMesio-distal 32 -0.02 0.14 -0.29 0.20 <0.001 OrthodVertical 33 1.27 0.39 0.87 0.31 0.001 Student

Vertical and mesio-distal deviations in mm, tip/angular deviations in degrees



had more significant right-left differences than theorthodontists (p < 0.01): Vertical and mesio-distalerrors: Teeth 15, 25; Vertical and tip errors: Teeth 13,23; 12, 22; 11, 21; Tip error: Teeth 41, 31; Mesio-distal and tip errors: Teeth 42, 32; 43–33; Mesio-distal error: Teeth 45, 35 (Table II).

The teeth with the greatest malpositions were assessedand there was a trend for tooth position to be assoc-iated with specific mesio-distal errors in placement ofthe brackets (Table IV).

Discussion

This study was designed to compare the ‘ability’ oftwo groups, each with a different experience of

clinical orthodontics, to bond brackets to the centresof the clinical crowns of teeth in a standardisedtypodont set-up. The groups were experienced specialists and undergraduate dental students, andboth groups were given the same instructions at thestart. The accuracy of each participant to bond brack-ets in centres of the clinical crowns was assessed bymeasuring the deviations of the bonded bracketsfrom the defined positions given to each participant.Not surprisingly, the orthodontists completed theexercise in slightly more than half the time taken bythe students, with fewer side-to-side errors, but witha small, but statistically significant, difference in vertical positioning. The orthodontists placed thebrackets more incisally than the students, althoughthe latter also placed the brackets more incisally thanrequested. Although there was a tendency for theposition of a tooth to predispose towards certainerrors in placement, for example, brackets on mesio-lingually rotated teeth tended to be placed more dis-tally, the errors in placement were small and, it couldbe argued, may not be of clinical significance.

Many orthodontists will agree that the pre-adjustedorthodontic appliances are an efficient and effectivemeans of treating most malocclusions. Patientresponse to treatment can be an important limitingfactor as well as the orthodontist’s ability to preciselyplace an appliance.16 Identification of bracket positioning errors is important, as poorly placedbrackets may result in more archwire adjustments,

Table III. The difference in error of bracket placement between the upper and lower dental arches.

Orthodontists Students

Mean SD Mean SD p

Vertical All 1.19 0.23 0.90 0.21 0.000Upper 1.37 0.27 0.92 0.26 0.000Lower 1.02 0.24 0.87 0.26 0.075

Vertical relative to the mean All 0.56 0.11 0.46 0.07 0.001Upper 0.60 0.13 0.51 0.10 0.024Lower 0.44 0.15 0.37 0.07 0.053

Mesio-distal All -0.09 0.06 -0.09 0.09 0.983Upper -0.11 0.06 -0.10 0.07 0.707Lower -0.08 0.11 -0.08 0.14 0.833

Tip All -1.61 1.02 -1.54 1.25 0.857Upper -1.59 1.41 -2.30 1.84 0.180Lower -1.63 1.25 -0.79 1.40 0.054

Paired t - test, significant values in boldVertical and mesio-distal deviations in mm, tip/angular deviations in degrees

Table IV. Comparison of the mesiodistal errors in bracket placement withthe initial tooth position (+ mesial, - distal).

Tooth Mesio-distal Initial position Error

Mean SD

15 0.10 0.23 Distal rotation Mesial12 -0.25 0.14 Palatal Distal11 -0.12 0.24 Mesio-palatal rotation Distal22 -0.08 0.18 Palatal Distal43 0.10 0.30 Distal rotation Mesial41 -0.14 0.17 Lingual Distal32 -0.15 0.22 Mesio-lingual rotation Distal35 0.11 0.53 Distal rotation Mesial

replacement of incorrectly placed brackets andincreased treatment time.2 Although the finishingstage of treatment invariably requires the archwires tobe modified because appliance prescriptions are basedon averages, accurate placement of brackets at thestart of treatment is considered to be an importantstep towards successful treatment.17

It was not surprising to find that the orthodontistsneeded less time to bond the 20 brackets than thedental students. With their greater experience of, andfamiliarity with, the materials one would expect themto perform the task more quickly and efficiently thanthe students. There was no time limit imposed on theparticipants, so the inexperienced students had ampletime to complete the task.

On average, the upper central incisor brackets bonded by the orthodontists were placed about 0.5mm more incisally than the brackets bonded to thesame teeth by the students. Other brackets hadgreater or lesser errors in placement. These findingsmay not be randomly distributed, but may be due toone or more of the following factors: the students followed the instructions more carefully than theorthodontists; the students were better than theorthodontists at identifying the centres of the clinicalcrowns; the orthodontists may have subconsciouslyplaced the brackets more incisally because this is acommon procedure in practice. All participants were asked to follow the instructions on the handoutand not to modify the positions of the brackets tocompensate for specific aspects of the malocclusion.

Both groups bonded the brackets more incisally thanrequested. This is in agreement with Koo et al.6 whoreported that directly placed brackets tended to beplaced towards the incisal edge, but in contrast toothers7 who found that directly placed brackets tend-ed to be towards the gingival margins (–0.27 ± 0.46mm). The vertical errors in this study (Orthodontists:1.19 ± 0.23 mm; Dental students: 0.9 ± 0.21 mm)appear to be greater than the errors reported by otherinvestigators (Table III). Other researchers8 studiedthe accuracy of bracket placements within or beyonda 0.5 mm range, and reported that more brackets fellwithin the range than outside it, which suggests thatbrackets can be accurately positioned vertically. In thepresent study the vertical errors relative to theirmeans (Orthodontists: 0.56 ± 0.11 mm; Dental stu-dents: 0.46 ± 0.07 mm) are similar to those obtainedby Balut et al. (0.34 ± 0.29 mm).9

Typodonts are frequently used for training in fixedappliance technique, but they are unable to exactlyrecreate the clinical situation. In particular, the teethwe used lacked a clearly demarcated cemento-enameljunction, which may have contributed to the verticalerrors.18 All teeth were set up ‘fully erupted’ so thatthe participants did not have to estimate the positionof the cemento-enamel junction.

There were no statistically significant differencesbetween the orthodontists and dental students inrelation to the mesio-distal or tip errors (Table I andII). The mesio-distal errors in this study(Orthodontists: –0.09 ± 0.06 mm; Dental students:–0.09 ± 0.09 mm) are comparable to the errorsreported in other studies (0.19 ± 0.12 mm;6 –0.11 ±0.30 mm;7 +/- 0.22 mm10). The tip errors we found(Orthodontists: –1.61 ± 1.02 degrees; Dental students:–1.54 ± 1.25 degrees) are comparable to the errorsalso reported by other investigators (2.57 ± 1.79degrees;6 5.54 ± 4.32 degrees9), but were greater than those reported by Hodge et al.,7 who reportedthe smallest angular discrepancies (0.08 ± 0.14degrees).

The initial position of the tooth may influence bracket placement. For example, when a tooth isrotated the error is likely to be in the opposite direc-tion to the direction of rotation. A bracket is morelikely to be placed mesially on a tooth with a distalrotation and, conversely, a bracket is more likely to beplaced distally on a tooth with a mesio-palatal rotation. If a tooth is palatally placed the error is like-ly to be incisal and distal. There was also a tendencyfor all participants to place the brackets with a slightdistal tip.

The right-left comparisons did not indicate a partic-ular trend in bracket placement. Other investigatorshave reported a trend for left side bonds (direct andindirect) to be more accurate in the upper arch, andright side bonds to be more accurate in the lower arch.5

It has been stated that errors in bracket placement arerelated to the skill of the operator, tooth structure,size of the clinical crowns and tooth position.9 Thisstudy demonstrated that with a prepared handouteven orthodontically inexperienced operators canperform as well as, if not better than, experiencedoperators in accuracy of bracket placement, albeit at a cost of increased time. This suggests that oper-ator experience may not be an important factor determining the accuracy of bracket positioning.

ARMSTRONG ET AL




As mentioned earlier, the present study may haveevaluated the influence of clinical experience on theerrors of bracket placement. Further studies will beneeded to identify if other factors affect the accuracyof bracket positioning.

Conclusions

1. Orthodontists and senior dental students have similar errors in direct bonding of orthodontic brackets.

2. The provision of clear instructions enabled thedental students to place brackets as accurately as experienced clinicians, although they did requiremore time to do so.

3. The initial position of a tooth may influence accur-ate bracket placement, even when there is adequatespace for the bracket.

Acknowledgments

The authors would like to thank Ken Tyler for hismanufacturing of the photographic jig and the ortho-dontists and dental students who gave up their timeto participate in this study. We would also like tothank 3M Unitek, Australia for providing the ortho-dontic brackets, and Sydney Dental Hospital and The Dental Board of New South Wales for financialassistance.


Professor M. Ali Darendeliler Department of OrthodonticsFaculty of Dentistry, Sydney Dental HospitalThe University of Sydney Level 2, 2 Chalmers StreetSurry Hills, NSW 2010Australia Tel: +61 2 9351 8314 Fax: +61 29351 8336Email: [email protected]

References1. Garino F, Garino GB. Computer-aided interactive indirect

bonding. Prog Orthod 2005;6:214–23. 2. Carlson SK, Johnson E. Bracket positioning and resets: Five

steps to align crowns and roots consistently. Am J OrthodDentofacial Orthop 2001;119:76–80.

3. Kalange JT. Ideal appliance placement with APC bracketsand indirect bonding. J Clin Orthod 1999;33:516–26.

4. Sondhi A. Bonding in the new millennium: Reliable andconsistent bracket placement with indirect bonding. World JOrthod 2001;2:106–14.

5. Aguirre MJ, King GJ, Waldron JM. Assessment of bracketplacement and bond strength when comparing direct bond-ing to indirect bonding techniques. Am J Orthod1982;82:269–76.

6. Koo BC, Chung C, Vanarsdall RL. Comparison of the accu-racy of bracket placement between direct and indirect bond-ing techniques. Am J Orthod Dentofacial Orthop1999;116:346–51.

7. Hodge TM, Dhopatkar AA, Rock WP, Spary DJ. A random-ized clinical trial comparing the accuracy of direct versusindirect bracket placement. J Orthod 2004;31:132–7.

8. Taylor NG, Cook, PA. The reliability of positioning pre-adjusted brackets: an in vitro study. Br J Orthod 1992;19:25–34.

9. Balut N, Klapper L, Sandrik J, Bowman D. Variations inbracket placement in the preadjusted orthodontic appliance.Am J Orthod Dentofacial Orthop 1992;102:62–7.

10. Fowler PV. Variations in the perception of ideal bracketlocation and its implications for the preadjusted edgewiseappliance. Br J Orthod 1990;17:305–10.

11. Cash AC, Good SA, Curtis RV, McDonald F. An evaluationof slot size in orthodontic brackets – are standards as expect-ed? Angle Orthod 2004;74:450–3.

12. Chen S, Chen YX, Li W. A study on the center height ofclinical crowns for the people with normal occlusion inChengdu area. Hua Xi Kou Qiang Yi Xue Za Zhi2004;22:138–41.

13. Muchitsch AP, Droschl H, Bantleon HP, Blumauer D, SternG. The effect of the vertical bracket position on the ortho-dontic finish. Fortschr Kieferorthop 1990;51:195–203.

14. Andrews LF. The Straight-wire appliance. Br J Orthod1979;6:125–43.

15. Bland, M. An Introduction to Medical Statistics. 3rd edn.Oxford: Oxford University Press. 2000; pp 269–272.

16. Poling R. A method of finishing the occlusion. Am J OrthodDentofacial Orthop1999;115:476–87.

17. Bai D, Luo SJ, Chen YX, Xiao LW. The clinic skill in fixedappliance based on characteristics of Chinese normalOcclusion. Hua Xi Kou Qiang Yi Xue Za Zhi 2005;23:32–4.

18. Henao SP, Kusy RP. Frictional evaluations of dentaltypodont models using four self-ligating designs and a con-ventional design. Angle Orthod 2005;75:75–85.

Introduction

Glass and carbon fibre reinforced polymethyl-metacrylate dentures were introduced to clinical dentistry in the 1960s.1,2 Previous studies havereported that FRC has an appropriate flexural modulus,3 flexural strength3,4 and fracture strength5,6

for fixed partial dentures. Fibre reinforced compositeshave been used in bonded lingual retainers,7,8 in anovel but seldom used glass fibre reinforced com-posite ‘wire’,9 to join adjacent teeth as an anchorageunit or for en masse movement10–12 and in spacemaintainers.13,14 Fibre reinforced composite is relatively straight-forward to use, it is biocompatibleand tooth-coloured, and brackets, tubes and hookscan be directly bonded to it.12 It is a material suited

to partial or adjunctive orthodontics, particularly inadult patients with advanced periodontal disease orpatients who are concerned about the appearance ofconventional fixed orthodontic appliances.

Although FRC bonded to enamel has acceptablebond strength15 and orthodontic attachments can bebonded to it,16 further information is needed on thebehaviour of FRC bars under masticatory loads.During mastication, adjacent teeth often move inde-pendently of each other and, as a result, compositebars without fibre reinforcement either fracture ordebond.17,18 The addition of fibres to composites hasbeen shown to improve the physical behaviour of thematerial to such an extent that FRCs are used inprosthodontic bridges.3,4


Fracture characteristics of fibre reinforced composite bars used to provide rigid orthodonticdental segments

Soodeh Tahmasbi,* Farzin Heravi† and Saied Mostafa Moazzami+

Dental Research Center, Shahid Beheshti University of Medical Sciences, Tehran,* Department of Orthodontics, Mashad University of MedicalSciences,† and Department of Restorative Dentistry, Mashad University of Medical Sciences,+ Mashad, Iran

Background: Fibre reinforced composites (FRC) can be used to join teeth as a rigid unit for anchorage purposes and/or fortooth movement. The utility of FRCs for these applications depends on the fracture characteristics and durability of the materialunder masticatory loads.Aims: To evaluate the effect of simulated masticatory loads on the fracture characteristics of FRC bars joining two bicuspids.Methods: Eighty extracted maxillary bicuspids were used. Pairs of bicuspids were joined with FRC bars on the buccal surfaces.The specimens were divided into two equal groups. In group A the fracture loads of the FRC bars were measured, and ingroup B the specimens were placed in a simulator and subjected to 4x105 chewing cycles, simulating a 2-year period of mastication. At the conclusion of this test the fracture loads of the FRC bars were measured in the intact specimens. All specimens were examined stereomicroscopically to determine the fracture pattern.Results: There were no bond failures in group B during the simulated masticatory forces. The mean fracture loads in groups A and B were 195.8 N and 190.6 N, respectively. Stereomicroscopic examination showed that most fractures occurred at theenamel-composite interfaces in both groups. There were no significant differences between the groups in the fracture loads andfracture patterns. Conclusions: Fibre reinforced composite bars bonded to bicuspids had sufficient durability to withstand the loads simulating a2-year period of function. The fracture loads and fracture patterns of the FRC bars were not affected by the loads exerted bythe simulator. (Aust Orthod J 2007; 23: 104–108)

Received for publication: July 2007Accepted: September 2007

FRACTURE CHARACTERISTICS OF FRC BARS


The aims of this study were to determine if FRC barsbonded to adjacent teeth will remain intact under theloads simulating a 2-year period of intra-oral func-tion, and to determine if the fracture characteristics ofFRC bars are affected by simulated masticatoryforces.

Materials and methods

In this in vitro study, 80 recently extracted intactmaxillary bicuspids with normal anatomy were collected and stored in normal saline solution until required. The teeth were removed from thesaline, allowed to dry in air and the roots coveredwith a 0.1–0.2 mm thick layer of vinyl poly-siloxane impression material (Speedex, Coltene AG,Alstatten, Switzerland). The intention was to create aflexible layer, simulating the periodontal ligament,that would allow the teeth to move independentlyunder simulated masticatory loads.19 Pairs of bicuspids were matched in shape and size and mounted in plastic cylinders (25 mm x 20 mm) withan autopolymerising resin. The bicuspids weremounted with their proximal surfaces in contact,with the marginal ridges at the same level and thecentral grooves aligned.

The buccal surfaces of the bicuspids were cleanedwith a rotating prophylaxis brush, pumice and waterand the buccal surface of each tooth masked withPVC tape. A 2.5 mm x 4 mm rectangular window inthe tape left the central area of the buccal surface clearfor etching. The teeth were etched with 35 per cent

phosphoric acid for 20 seconds, rinsed for 10 secondsand dried with air. A thin layer of bonding resin(Excite, Ivoclar-Vivadent, Schaan, Liechtenstein) wasapplied and cured with a light unit (Astralis-7,Ivoclar-Vivadent, Schaan, Liechtenstein) using thelow power program (400 mW/cm2) for 20 seconds.Tetric-Ceram composite (Ivoclar-Vivadent, Schaan,Liechtenstein) was then applied to the resin. A 3 mmx 12 mm strip of Ribbond (Ribbond Inc, Seattle,Washington) saturated with the bonding resin wasadapted to the composite. Any composite expressedoutside the strip was removed. Next, a thin layer of aflowable composite (Tetric-Flow, Ivoclar-Vivandent,Schaan, Liechtenstein) was applied to the fibre/com-posite combination and cured with the Astralis-7 unitusing the high power program (750 mW/cm2) for 40seconds. The curing unit was placed on the buccalaspect of each tooth. The procedure was repeated forall specimens.

Figure 1. Location of the crosshead on the FRC bar.

Figure 2. A specimen in the simulator.

After 24 hours storage in normal saline, the speci-mens were randomly divided into two equal groups.In group A, the fracture load (N) of each FRC barwas measured with a universal testing machine(Instron Corp, Canton, Mass) at a crosshead speed of5 mm/min. The specimens were oriented in the posi-tioning jig so that the blade of the crosshead loadedthe FRC bar vertically at the midpoint interdentally(Figure 1). The specimens in Group B were placed ina chewing simulator machine operated for 4x105

cycles at 14 N loads with a frequency of 3 Hz andduration of 0.2 seconds. This simulated two years ofmastication (Figure 2).20 At the conclusion of this testspecimens were inspected for bond failure or fracture,and the ratio of intact specimens to initial specimensreported as the survival rate. The load (N) required tofracture each intact specimen was then determinedusing the methods described for group A. The dataobtained for the groups were compared with theStudent t-test.

Each specimen was then examined with a stereomicro-scope (Olympus SZH10, Tokyo, Japan) at x10 mag-nification and the fracture pattern classified as follows:

1. Adhesive failure at the enamel surface (enamelexposed on more than 75 per cent of one of the fractured surfaces).

2. Cohesive failure in the composite material betweenFRC and enamel surface (composite exposed on morethan 75 per cent of both fractured surfaces).

3. Adhesive failure at the FRC interface (FRC exposedon more than 75 per cent of one of the fractured surfaces).

4. Cohesive failure within the FRC (FRC exposed onmore than 75 per cent of both fractured surfaces).

The fracture patterns in the groups were comparedwith the Chi-square test.

Results

As all specimens in Group B were intact at the end ofthe test simulating the forces of mastication the sur-vival rate of the FRC bars was 100 per cent. Themean loads required to fracture the specimens ingroups A and B were 195.8 N (SD: 14.34) and 190.6N (SD: 24.03) respectively (Table I). There was nosignificant difference between the mean fracture loadsof the two groups (p > 0.05).

The distributions of the fracture patterns in the twogroups are shown in Figure 3. In both groups mostfractures occurred at the enamel-composite interface.The Chi-square test revealed that the fracture patternwas independent of the groups: i.e. the fracture pattern was similar in both groups.

Discussion

Fibre-reinforced composite bars can be used to jointeeth to form rigid anchorage units or units for activetooth movement. This study was designed to deter-mine if FRC bars bonded to adjacent bicuspidswould survive the loads simulating two years of mas-tication, and to determine if the fracture characteris-tics of the FRC bars were affected by the simulatedmasticatory forces. The results indicated that FRCbars linking the bicuspids had sufficient durability towithstand the simulated masticatory forces, and theseforces did not have adverse effects on the fracture

TAHMASBI ET AL


Table I. Fracture strengths of the FRC bars linking two bicuspids.

Group Total Mean (N) SD (N) SEM (N)

A 20 195.8 14.34 3.21B 20 190.6 24.03 5.37

Student t-test, not significant

Figure 3. Pattern of failure.1. Adhesive failure at the enamel-composite interface.2. Cohesive failure in composite between enamel surface and FRC.3. Adhesive failure at the FRC interface.4. Cohesive failure in the FRC.

80

70

60

50

40

30

20

10

0

Freq

uenc

y

A B

Groups

Patternof

fracture

1

2

3

4

FRACTURE CHARACTERISTICS OF FRC BARS


characteristics of FRC bars. Although previous stud-ies have demonstrated the durability of FRC fixedpartial dentures under chewing forces,6 no similarstudy has been carried out on the survival rate of posterior teeth joined with FRC.

In our study, we attempted to reproduce the perio-dontal ligament by covering the roots of the teethwith a thin layer of vinyl polysiloxane impressionmaterial. We assume the flexible layer allowed theteeth to move independently of each other under thesimulated masticatory loads. The FRC connectingbars had sufficient strength and durability to remainintact for the entire period of the study. Fallis andKusy,9 in a short-term clinical study, found no frac-tures in fibre reinforced composite wires used forretainers, but Rose et al.8 reported that the survivaltime of FRC lingual orthodontic retainers was only11.5 months.

The FRC bars had fracture loads between 190 and195 N, which compares favourably with the range offorces (45 to 120 N) experienced during masti-cation.21,22 We consider that FRC bars may have sufficient fracture strength to tolerate normal masticatory forces but not maximum biting loads,which can be more than 500 N.23,24 Patients should be warned that FRC bars are likely to fail ifthey are subjected to heavy biting forces that may occur during bruxism and clenching. The samesituation applies to most bonded attachments and retainers.25

Stereomicroscopic examination of the fracture areasin both groups showed that the majority of fracturesoccurred at the enamel-composite interface (Figure3). The patterns of failure were estimated so one mustacknowledge that some bias may have occurred in ourjudgements of the sites of failure. Using the data wecollected we were unable to demonstrate any sig-nificant difference in fracture pattern.

It is noteworthy that in the latest generation of pre-impregnated FRC bars, the fibres and the resinousmatrix are coupled during the manufacturing process.This process results in a higher concentration offibres, more complete wetting, fewer voids andreduced chair time when placing FRC bars, as com-pared with the FRC method we used.26 Based uponthe results of the present study we suggest clinicalinvestigations are now needed to determine the valueof FRC bars bonded to two or more teeth.

Conclusions

Fibre reinforced composite bars linking bicuspids hadsufficient durability to withstand the loads simulatinga 2-year period of function. The fracture loads andfracture patterns of the FRC bars were not affectedadversely by the loads exerted by the simulator.

Acknowledgment

The authors would like to thank Dr Fazli Bazzaz,Vice-Chancellor of Research, Mashad University ofMedical Sciences, for her support and encourage-ment.


Dr S. TahmasbiDental Research CenterSchool of Dentistry Shahid Beheshti University of Medical SciencesTehranIranTel: +9821 2241 3897Fax: +9821 2242 7753Email: [email protected]

References 1. Smith DC. Recent developments and prospects in dental

polymers. J Prosthet Dent 1962;12:1066–78.2. Manley TR, Bowman AJ, Cook M. Denture bases reinforced

with carbon fibers. Br Dent J 1979;146:25–8.3. Goldberg AJ, Freilich MA, Haser KA, Audi JH. Flexure

properties and fiber architecture of commercial fiber rein-forced composites. J Dent Res 1998;77:226.

4. Freilich MA, Karmaker AC, Burstone CJ, Goldberg AJ.Flexure strength of fiber-reinforced composites designed forprosthodontic application. J Dent Res 1997;76:138.

5. Behr M, Rosentritt M, Latzel D, Kreisler T. Comparison ofthree types of fiber-reinforced composite molar crowns ontheir fracture resistance and marginal adaptation. J Dent2001;29:187–96.

6. Kolbeck C, Rosentritt M, Behr M, Lang R, Handel G. Invitro examination of the fracture strength of 3 differentfiber-reinforced composite and 1 all-ceramic posterior inlayfixed partial denture systems. J Prosthodont 2002;11:248–53.

7. Diamond M. Resin fiberglass bonded retainer. J ClinOrthod 1987;21:182–3.

8. Rose E, Frucht S, Jonas IE. Clinical comparison of a multi-stranded wire and a direct bonded polyethylene ribbon-rein-forced resin composite used for lingual retention.Quintessence Int 2002;33:579–83.

9. Fallis DW, Kusy RP. Novel esthetic bonded retainers: a blendof art and science. Clin Orthod Res 1999;2:200–8.

10. Burstone CJ, Kuhlberg AJ. Fiber-reinforced composites inorthodontics. J Clin Orthod 2000;34:271–9.

TAHMASBI ET AL


11. Cacciafesta V, Sfondrini MF. One-appointment correctionof a scissor bite with 2D lingual brackets and fiber-rein-forced composites. J Clin Orthod 2006;40:409–11.

12. Uribe F, Nanda R. Treatment of bimaxillary protrusion usingfiber-reinforced composites. J Clin Orthod 2007;41:27–32.

13. Zuccati G, de Barros e Silva Mda G, Doldo T, Savastano C.Fiber-reinforced composite space maintenance for anteriorimplant therapy. J Clin Orthod 2007;41:336–40.

14. Kargul B, Caglar E, Kabalay U. Glass fiber-reinforced com-posite resin as fixed space maintainers in children: 12-monthclinical follow-up. J Dent Child 2005;72:109–12.

15. Meiers JC, Kazemi RB, Donadio M. The influence of fiberreinforcement of composites on shear bond strengths toenamel. J Prosthet Dent 2003;89:388–93.

16. Freudenthaler JW, Tischler GK, Burstone CJ. Bond strengthof fiber-reinforced composite bars for orthodontic attach-ment. Am J Orthod Dentofacial Orthop 2001;120: 648–53.

17. Zachrisson BU. The acid etch technique in orthodontics:clinical studies. In: Silverstone LM, Dagon L, eds. Proceed-ings of an international symposium on the acid etch technique. St Paul, 265–75. Minn: North Central, 1975.

18. Rosenberg S. A new method for stabilization of periodont-ally involved teeth. J Periodontol 1980;51:469–73.

19. Pitts DL, Matheny HE, Nicholls JI. An in vitro study ofspreader loads required to cause vertical root fracture duringlateral condensation. J Endod 1983;9:544–50.

20. Outhwaite WC, Twiggs SW, Fairhurst CW, King GE. Slotsvs pins: a comparison of retention under simulated chewingstresses. J Dent Res 1982;61:400–2.

21. Mizrahi E, Smith DC. Direct attachment of orthodonticbrackets to dental enamel: A preliminary clinical report. BrDent J 1971;130:392–6.

22. Newman GV. Epoxy adhesives for orthodontic attachments:progress report. Am J Orthod 1965;51:901–12.

23. Hidaka O, Iwasaki M, Saito M, Morimoto T et al. Influenceof clenching intensity on bite force balance, occlusal contactarea, and average bite pressure. J Dent Res 1999;78:1336–44.

24. Reynolds IR. A review of direct orthodontic bonding. Br JOrthod 1975; 2:171–8.

25. Bin Abdullah MS, Rock WP. The effect of etch time anddebond interval upon the shear bond strength of metallicorthodontic brackets. Br J Orthod 1996;23:121–4.

26. Freilich MA, Meiers JC, Duncan JP, Goldberg AJ. Fiber-reinforced composites in clinical dentistry. Chicago:Quintessence, 2000:13.

Introduction

Miniscrews can be placed in many different intra-oralbony sites. Once placed they can be used immedi-ately, without having to wait for osseointegration.Several studies have been carried out to determine theideal sites for insertion of the miniscrews.1–3

In the maxilla the palate is considered a suitable sitefor miniscrews because of its structure and ease ofaccess.4–7 With the exception of the incisive canalregion, the median and paramedian areas of thepalate consist of thick, dense bone capable of sup-porting one or more miniscrews and orthopaedicloads.8 In these areas there are no anatomical struc-tures, such as nerves, blood vessels or dental roots,which may impede the insertion of miniscrews orlead to complications.9,10

The soft tissue in the midline of the palate betweenthe first and second premolars is, on average 3.06 +/-0.45 mm thick.2 The thickness and intrinsic charac-teristics of the palatal mucosa may enhance the stability of a miniscrew inserted in this area.9,10 Earlyimplants for stable anchorage required a flap oper-ation for insertion and removal, could only be placedin the anterior region of the palate and could not be

loaded until osteointegration had occurred.5,11–17

Miniscrews have successfully overcome these disad-vantages. For example, Kyung et al.10 successfullyused a miniscrew inserted into the median zone of thepalate to distalise upper molars, and Lee et al.18 usedpalatal miniscrews to intrude teeth. However, mini-screws less than 2 mm in diameter may not be stablein this site.19,20

Miniscrews have a place in facilitating other forms oforthodontic treatment. For example, palatal mini-screws have been used to facilitate distal movement ofthe anterior teeth in lingual treatment, and have beenused with a modified pendulum appliance to distalisethe upper teeth.21,22 The Graz implant-supportedpendulum appliance uses miniscrews and a titaniumminiplate to distalise the upper molars.23

The bone in the anterior region of the midline of thepalate is considered an ideal site for insertion of aminiscrew, but there is a lack of detail about thethickness of palatal cortical bone antero-posteriorlyand medio-laterally, particularly in adults.11,24 In thepresent study we aim to use cone beam technology todetermine the thickness of the palatal bone at fourlevels posterior to the incisive foramen. At each level


Assessment of palatal bone thickness in adultswith cone beam computerised tomography

Antonio Gracco, Lombardo Luca, Mauro Cozzani and Giuseppe SicilianiDepartment of Orthodontics, University of Ferrara, Ferrara, Italy

Aims: To determine the most suitable region of the palate for the insertion of miniscrews.Methods: The subjects were 72 adult patients between 20 and 44 years of age. The thickness of the bony palate was determined with digital volumetric tomography. Bone thickness was measured 4, 8, 16 and 24 mm posterior to the incisiveforamen and 0, 3, and 6 mm lateral to the midline of the palate.Results: The thickest bone was found 4 mm behind and 6 mm lateral to the incisive foramen. The bone thinned progressivelyfrom anterior to posterior and from medial to lateral. A median ridge of bone was present in the 8, 16 and 24 mm sections. In these sections the thickest bone was close to the suture.Conclusion: The hard palate offers several suitable sites for the insertion of miniscrews for orthodontic purposes. The areasbehind the incisive foramen and to one side of the median palatal suture have adequate bone for miniscrews.(Aust Orthod J 2007: 23; 109–113)

Received for publication: August 2007Accepted: September 2007

GRACCO ET AL


bone thickness will be measured at the suture 3 and 6mm on both sides of and at right angles to the medianpalatal suture.

Material and methods

The digital volumetric tomograms of 72 healthyadults (34 males, 38 females), between 20 and 44 years of age, were randomly selected from the files held in the Postgraduate School of Ortho-dontics of the University of Ferrara. We excluded subjects with craniofacial malformations and/or syndromes, individuals with a history of facial traumaand those who had undergone surgery to the facialstructures.

Data were obtained using the Newtom 3G VolumeScanner QRsr1 Verona, a cone beam X-ray machine.Images obtained from this scanner have the advan-tages of sufficient detail and a lesser radiation dosage

when compared with a conventional CT.25–26 Thesettings used were: 12 inch field of view, 110 kVp(AP-LL), 2.00 mA (AP) e 1.00 mA(LL), exposuretime 5.4 s, slice thickness 0.50 mm.

Using the NNT Newtom 3G software, we identifiedthe incisive foramen on the axial section of the upperjaw for each subject. Paracoronal views of the palatalregion were reconstructed at 4, 8, 16 and 24 mm pos-terior to the incisive foramen. Measurements of thebone height were then made at the median palatalsuture, and 3 mm and 6 mm on both sides of and atright angles to the suture (Figures 1 and 2). Twentymeasurements for each patient were made on thecomputer display monitor with the Newtom 3Gmeasurement software. The measurements of palatalheight in 27 patients were carried out by two different investigators.

The method error was determined with Dahlberg’sformula and the systematic error with the Student’s t-test, where p < 0.05 was considered significant. On average, the method errors of the measurementsat the suture were 0.54 (p = 0.062), 3 mm on rightand left sides of the suture it was 0.55 mm (p = 0.478)and 0.43 mm (p = 0.654) respectively, and 6 mm onthe right and left sides of the suture it was 0.57 mm(p = 0.116) and 0.54 mm (p = 0.152) respectively. Nostatistically significant difference was found in any ofthese cases.

Figure 1. Paracoronal sections 4, 8, 16 and 24 mm posterior to the incisive foramen.

Figure 2. Rendering of a 16 mm paracoronal view.

Taking into account that the distribution of the sample was not normal or symmetrical, the Kruskal-Wallis test was used to highlight any differences with-in the sample in relation to side (right/left), distancefrom the midline (3 mm/6 mm), or linked to the dif-ferent sections/levels (4, 8, 16 and 24 mm from theincisive foramen).

Results

The means and the standard deviations of palatalbone thickness in the sample are reported in Table Iand Figure 3. Considerable variation in bone thick-ness was found at all sites. There were no statisticallysignificant differences in the thickness of palatal bonein the male and female patients.

Bone thickness – antero-posteriorlyThe bone in the midline of the palate was, on average, 8 mm thick 4 mm behind the incisive fora-men. The midline bone thickness fell, on average, to 6–7 mm 8 mm behind the foramen and to 5–6mm 16 and 24 mm behind the foramen. The thick-ness of the bone 6 mm and 3 mm on the left and

right sides of the suture also thinned as the sectionsmoved from anterior to posterior. Considerable vari-ation in bone thickness was found in all sections. For example, in one subject there was 6 mm of bone (6 mm to the left) in the 24 mm section and atthe same site in another subject the bone was only 1 mm thick.

At the suture, no significant differences in mean bonethickness were found between the 4 mm and the 8mm paracoronal sections or between the 16 and 24mm paracoronal sections. Bone in the former twosections was, on average, thicker than the bone in thelatter two sections.

Bone thickness – medio-laterallyThe mean palatal bone thicknesses calculated for eachsection (4, 8, 16 and 24 mm from the incisive fora-men) at 3 and 6 mm to the right and left of the suturewere compared using the Kruskal-Wallis test. No sig-nificant differences were found between the left andthe right sides of the palate.

We compared bone thickness at the suture and 3 mmand 6 mm to the right and left of the suture in eachpatient and in each paracoronal section of the palateusing the Kruskal-Wallis test. In the sample we foundthat the bone at the suture in the 24 mm section wassignificantly thicker than that found at 6 mm on theright and left sides of the suture. In all other cases thebone at the suture was not significantly thicker thanthe bone 3 mm and 6 mm on the right and left sidesof the suture.

We also compared the thickness bone 3 mm to theleft of the suture with that found at 6 mm to the leftof the suture in each section (4, 8, 16 and 24 mm) ineach patient, and then repeated the comparisons forthe right side of the palate. No statistically significantdifferences were found.

Discussion

To understand how the morphology of the palatechanges antero-posteriorly and medio-laterally wemeasured the thickness of the cortical bone in fourparacoronal sections (4, 8, 16, and 24 mm from theincisive foramen) taken with a cone beam X-raymachine. The thickest bone (approximately 1 cm) wasfound in the most anterior and lateral sites, that is 4mm behind the incisive foramen and 6 mm lateral tomedian palatal suture. Although the bone thinned

ASSESSMENT OF PALATAL BONE THICKNESS WITH CBCT


Figure 3. The mean palatal bone thicknesses at different distances from theincisive foramen (4, 8, 16 and 24 mm) and 0, 3 and 6 mm on both sidesof the suture. The vertical bars denote 0.95 confidence intervals.

GRACCO ET AL


progressively from anterior to posterior and frommedial to lateral, a marked ridge of bone was left inthe vicinity of the suture. This median ridge of bonewas 6–7 mm thick 8 mm behind the foramen, butonly 4 mm thick in the 16 and 24 mm sections. Thebone in the most lateral sites (i.e. 6 mm lateral to themedian palatal suture) also thinned progressivelyfrom anterior to posterior and from medial to lateral.Bone thickness fell from approximately 1 cm in the 4mm paracoronal section, to 5–6 mm in the 8 mmsection, to 2–3 mm in the 16 and 24 mm sections.

Our findings agree with and extend the work reported by previous studies of palatal bone thicknessin children and adolescents.2,27–29 In our previousstudy, we measured the thickness of the palatal bonein paracoronal sections in patients between 10

and 15 years of age.28 In agreement with our presentfindings we found that the thickest bone in childrenand adolescents was in the most anterior part of the palate 6 mm to the right and left of the medianpalatal suture. While the bone in the posterior regionof the palate was markedly thinner it is in the form oftwo plates of bone. The overlying mucosa in this areais also thinner. Because of these factors this area cansupport an appropriately sized miniscrew.

The length of a miniscrew is thought to be an impor-tant factor in screw stability. In the anterior region ofthe palate, miniscrews with a functional (threaded)part of approximately 10 mm can be used, althoughwe found in some individuals the bone in this areawas very thin. Eight millimetres behind the incisiveforamen, the functional part can, on average, be atleast 8 mm in length, while in the posterior part ofthe palate (16–24 mm from the incisive foramen)4–5 mm miniscrews can be used in some individuals.The length of a miniscrew should also take intoaccount the thickness of the palatal mucosa, which isthickest in the mid-palatal suture area 4 mm behindthe incisive papilla. Moving posterior from the papilla the mucosa is consistently 1 mm thick, whichis a favourable thickness for a miniscrew.27

This study highlights the importance of selecting thecorrect length of miniscrew so that both corticalplates are engaged by the screw and the nasal cavity isnot penetrated. To ensure that screws do not loosen ithas been suggested that the diameter of a palatalscrew should be no less than 2 mm.20 Miniscrewswith smaller diameters (1.2–1.3 mm) may be justifiedif they are to be placed in inter-radicular alveolarbone where there is a risk of damage to the roots ofthe teeth. However, in the midpalate there are noblood vessels, nerves and other structures likely tointerfere with insertion or cause complications whenlarge diameter miniscrews are used.

There is a general consensus that the suture, despitebeing one of thickest sites in the palate, is not suitablefor insertion of miniscrews due to incomplete calcifi-cation. Even in adult subjects the possibility existsthat connective tissue in the suture might becomeinterposed between a screw and the surrounding boneand cause the screw to loosen.4–8 The sites adjacent tothe suture offer better sites for placement of mini-screws. The greater density and resistance of the boneadjacent to the suture compensates for the thinnerbone found posteriorly and laterally.

Table I. Palatal bone thickness.

Distance Distancefrom frommedian incisive Mean SD Min Maxsuture foramen

(mm)

6 mm R 4 10.4 3.24 3.8 18.98 5.6 2.38 1.7 11.3

16 2.8 1.01 1.3 5.924 2.4 0.87 0.8 5.0

3 mm R 4 8.3 3.04 2.9 16.48 5.1 1.89 1.7 10.2

16 2.9 0.85 1.7 6.724 2.9 1.27 1.3 6.9

Suture 4 8.7 3.16 2.9 17.28 6.6 2.03 2.5 10.9

16 4.0 1.36 1.7 8.024 3.9 1.66 1.3 8.5

3 mm L 4 8.3 2.88 2.8 16.48 5.2 2.05 1.7 10.4

16 2.9 1.26 0.8 6.724 2.8 1.19 1.3 5.9

6 mm L 4 10.0 3.16 3.4 19.38 5.8 2.13 1.7 11.0

16 2.7 1.23 1.2 7.624 2.3 0.91 1.0 6.3

ASSESSMENT OF PALATAL BONE THICKNESS WITH CBCT


Conclusions

Although the bone forming the palate thins progres-sively from anterior to posterior and from medial tolateral, the bone in the posterior part of the palate issuitable for the insertion of screws of appropriatediameter and length. The bone in the latter site is laiddown in the form of two plates.


Dr Antonio GraccoVia E. Scrovegni 235100 PadovaItalyTel: +39 0532 202 528Fax: +39 0532 202 528Email: [email protected]

References1. Poggio PM, Incorvati C, Velo S, Carano A. ‘Safe Zones’: A

guide for miniscrew positioning in the maxillary andmandibular arch. Angle Orthod 2006;76:191–7.

2. Costa A, Pasta G, Bergamaschi G. Intraoral hard and softtissue depths for temporary anchorage devices. SeminOrthod 2005;11:10–15.

3. Deguchi T, Nasu M, Marakami K, Yabuuchi T, Kamioka H,Takano-Yamamoto T. Quantitative evaluation of corticalbone thickness with computed tomographic scanning fororthodontic implants. Am J Orthod Dentofacial Orthop2006;129:721.e7–12.

4. Wehrbein H, Glatzmaier J, Mundwiller U. Diedrich P. TheOrthosystem: a new implant system for orthodontic anchor-age in the palate. J Orofac Orthop 1996;57:142–53.

5. Wehrbein H, Merz BR, Hämmerle CH, Lang NP. Bone-to-implant contact of orthodontic implants in humans sub-jected to horizontal loading. Clin Oral Implants Res 1998;9:348–53.

6. Wehrbein H, Feifel H, Diedrich P. Palatal implant anchor-age reinforcement of posterior teeth: a prospective study.Am J Orthod Dentofacial Orthop 1999;116:678–86.

7. Wehrbein H, Merz BR, Diedrich P, Glatzmaier J. The use ofpalatal implants for orthodontic anchorage. Design andclinical application of the Orthosystem. Clin Oral ImplantsRes 1996;7:410–6.

8. Wehrbein H, Merz BR, Diedrich P. Palatal bone support fororthodontic implant anchorage – a clinical and radiologicalstudy. Eur J Orthod 1999;21:65–70.

9. Misch CE. Contemporary implant dentistry, 2nd ed.,Mosby, St. Louis, 1999, p. 113.

10. Kyung SH, Hong SG, Park YC. Distalization of maxillarymolars with a midpalatal miniscrew. J Clin Orthod 2003;37:22–6.

11. Bernhart T, Vollgruber A, Gahleitner A, Dörtbudak O, HaasR. Alternative to the median region of the palate for place-ment of an orthodontic implant. Clin Oral Implants Res2000;11:595–601.

12. Schlegel KA, Kinner F, Schlegel KD. The anatomic basis forpalatal implants in orthodontics. Int J Adult OrthodOrthognath Surg 2002;17:133–9.

13. Martin W, Heffernan M, Ruskin J. Template fabrication fora midpalatal orthodontic implant: technical note. Int J OralMaxillofac Implants 2002;17:720–2.

14. Tosun T, Keles A, Erverdi N. Method for the placement ofpalatal implants. Int J Oral Maxillofac Implants 2002;17:95–100.

15. Bantleon H, Bernhart T, Crismani AG, Zachrisson BU.Stable orthodontic anchorage with palatal osseointegratedimplants. World J Orthod 2002;3:109–16.

16. Cousley R. Critical aspects in the use of orthodontic palatalimplants. Am J Orthod Dentofacial Orthop 2005;127:723–9.

17. Gedrange T, Bourauel C, Kobel C, Harzer W. Three-dimen-sional analysis of endosseous palatal implants and bonesafter vertical, horizontal, and diagonal force application. EurJ Orthod 2003;25:109–15.

18. Lee J-S, Kim DH, Park Y-C, Kyung S-H, Kim T-K. The effi-cient use of midpalatal miniscrew implants. Angle Orthod2004;74: 711–14.

19. Melsen B. Mini-implants: Where are we? J Clin Orthod2005;39:539–47.

20. Carano A, Velo S, Leone P, Siciliani G. Clinical implicationof the miniscrew anchorage system. J Clin Orthod 2005;39:9–24.

21. Park H-S. A miniscrew-assisted transpalatal arch for use inlingual orthodontics. J Clin Orthod 2006;40:12–16.

22. Kircelli B H, Pektas Z, Kircelli C. Maxillary molar distaliza-tion with a bone-anchored pendulum appliance. AngleOrthod 2006;76:650–9.

23. Kinzinger G, Wehrbein H, Byloff F K, Yildizhan F, DiedrichP. Innovative anchorage alternatives for molar distalization –an overview. J Orofac Orthop 2005;66:397–413.

24. Yildizhan F. Strukturparameter des medianen gaumens undorthodontische verankerungsimplantate. Eine radiologische,histologische und histomorphometrische Studie. Med DissAachen 2004.

25. Mozzo P, Procacci C, Tacconi A, Martini PT, Andreis IA. Anew volumetric CT machine for dental imaging based on thecone beam technique: preliminary results. Eur Radiol 1998;8:1558–64.

26. Hatcher DC, Aboudara CL. Diagnosis goes digital. Am JOrthod Dentofacial Orthop 2004;125:512–5.

27. Kim HJ, Yun HS, Park HD, Kim DH, Park YC. Soft-tissueand cortical-bone thickness at orthodontic implant sites. AmJ Dentofacial Orthop 2006;130:177–82.

28. Gracco A, Lombardo L, Cozzani M, Siciliani G. Quanti-tative evaluation with CBCT of palatal bone thickness ingrowing patients. Prog Orthod 2006; 7:164–74.

29. King K. Paramedian palate morphology in the adolescent: acone beam computer tomography study. Am J OrthodDentofacial Orthop 2005;128:262.

Introduction

Almost 70 years ago Brodie, Downs, Goldstein andMyer1 published the first cephalometric appraisal ofpatients treated with the edgewise appliance. In 12patients with Class II division 1 malocclusions theynoted that in every case the anterior end of theocclusal plane tipped downwards during treatment,opening the angle between the Bolton and occlusalplanes. They reported also that following treatmentthe angulations of the teeth and occlusal plane tended to recover. They found Class II elastics openedthe angle between the Bolton and occlusal planes and Class III elastics closed it, and a downward and

backward rotation of the mandible occurred in anumber of cases.

Other studies have confirmed that elevation of themolars during orthodontic treatment is accompaniedby an increase the height of the face, a downward andbackward rotation of the mandible and downwardtipping of the anterior end of the occlusal plane, par-ticularly if Class II elastics are used.2–9 On one handit has been argued that the increase in face height maybe permanent and on the other hand that it isreversible.8,10,11 The evidence is, however, incon-clusive because only a few studies have used Class IIdivision 1 malocclusion controls, the few prospective


Vertical changes in treated and untreated Class IIdivision 1 malocclusions

Craig Sharp,* Michael Harkness† and Peter Herbison‡

Specialist practice, Auckland,* Oral Health, Canterbury District Health Board, Christchurch† and Department of Preventive and SocialMedicine, University of Otago, Dunedin,‡ New Zealand

Background: Treatment-induced increases in the height of the face may be permanent.Aims: To determine if appliance-induced increases in the heights of the upper and lower molars in girls with Class II division 1malocclusion, and the consequential increase in the height of the face are maintained.Methods: Ten angles and 10 distances were measured on lateral cephalometric radiographs of 11 year-old girls (Range:8.5–14.8 years) with treated (N = 9) and untreated (N = 8) Class II division 1 malocclusions. The intervals between the initialand recall records were, on average, 12 years (Range: 7.6–15.7 years) for the girls in the treatment group, and 8 years(Range: 4–13 years) for the girls in the untreated/control group. In the treatment group eight girls were treated with the Beggappliance and Class II elastics.Results: Upper and lower molar dentoalveolar heights in both groups increased significantly between the initial and recall visits.There were no significant differences between the molar heights in the groups at the start or at recall. Anterior face height (AFH)also increased significantly in both groups between the initial and recall visits. At recall, AFH in the treatment group was significantly greater than AFH in the control group. This finding is attributed to a similar-sized difference between the groups atthe start, to the longer period between the initial and recall records in the treatment group and to lesser variation in both groupsat recall. In both groups, posterior face height increased significantly between the initial and recall stages. At the conclusion ofthe study there were no statistically significant differences between the treated and control groups in either overjet or the inclination of the upper incisors. Relapse of the upper incisors in the treatment group and retroclination of the upper incisors inthe control group reduced the initial differences between the groups. These changes are attributed to altered lip posture andincreased lip pressures in adolescence. At recall, angles SNA and SNB were significantly smaller in the treatment group.Conclusion: The heights of the upper and lower molars and the face increased in both groups. Orthodontic treatment may haveno lasting effects on either the height of the face or the heights of the molars in girls with Class II division 1 malocclusion.(Aust Orthod J 2007; 23: 114–120)

Received for publication: September 2007Accepted: October 2007

VERTICAL CHANGES IN CLASS II DIVISION 1 MALOCCLUSIONS


studies of Class II division 1 treatment have eithernot reported vertical changes and/or the subjects havenot been followed long-term.

The aim of this retrospective study is to determine ifappliance-induced increases in the heights of themolars and the consequential increase in the height ofthe face are maintained.

Subjects and methods

The subjects were girls with Class II division 1 mal-occlusions referred to the Department of Ortho-dontics, University of Otago between 1970 and1981.12 The following inclusion criteria were used:

1. Class II division 1 malocclusion12 with an incisoroverjet > 5 mm at the initial consultation. Overjetwas measured on study casts taken at the initial consultation.

2. Lateral cephalometric radiographs taken at thestart and end of treatment, and at least five years fromthe end of treatment (if no retention was used) or fiveyears from the cessation of all retention.

3. Lateral cephalometric radiographs taken at the initial consultation for the girls who did not havetreatment, and at least 3.5 years after the initial consultation.

4. All radiographs were taken with the teeth in theintercuspal position.

Of the 41 girls who met these criteria 30 had beentreated and 11 had not been treated. After ethicalapproval had been obtained attempts were made totrace the girls through School of Dentistry records,past telephone directories, family members and theNew Zealand electoral roll. Eventually, nine girls whohad been treated (Treatment group) and eight girls

who had not been treated (Control group) weretraced, and agreed to return for the recall records. Inthe treatment group five girls were treated with theBegg appliance and four first premolar extractions;one girl with four first premolar extractions, the Beggappliance and headgear; one girl was treated non-extraction with headgear and the Begg appliance; onegirl with four first premolar extractions and remov-able appliances; and one girl with two upper first premolar extractions, the Begg appliance and head-gear. At the initial consultation the mean ages of thegirls were: Treatment group 11.7 years (SD: 1.74) andthe Control group 11.9 years (SD: 2.20). The ages ateach stage and the intervals between the various stagesare given in Table I.

MethodsThe radiographs were taken with either a Margoliscephalostat with a Meyer anode-generator (up to1978) or a Wehmer cephalostat with an Amrad-Craig1 anode-generator (from late 1978). Because thecephalostats had different tube-subject and subject-film distances, the enlargements of both machineswere calculated from radiographs of the same wiremesh positioned midway between the ear posts.Image magnification in the Margolis cephalostat was1.1287 and in the Wehmer cephalostat it was 1.0866.As the majority of the radiographs were taken withthe Margolis equipment all linear measurements onradiographs taken with the Wehmer cephalostat wereconverted to the same magnification as those takenwith the Margolis cephalostat. Angular dimensionswere not affected by the different magnifications ofthe two cephalostats. No difficulty was experiencedidentifying which cephalostat had been used becausethe film sizes and images of the ear posts were different.

Table I. Ages of the control and treatment groups.

Control Treatment

Mean (SD) Range Mean (SD) Range(years) Min Max (years) Min Max

Age – initial records 11.9 (2.20) 8.5 14.8 11.7 (1.74) 9.1 14.5Age – end of treatment 14.7 (1.59) 12.9 17.0Retention period 1.9 (0.70) 1.0 3.1Age – recall records 20.2 (4.02) 14.4 27.4 23.8 (2.74) 20.7 28.6End – recall 7.2 (1.81) 5.3 10.6Initial – recall 8.3 (2.84) 4.0 13.1 12.1 (2.66) 7.6 15.7

SHARP ET AL


The coordinates of the reference points shown inFigure 1 were digitised directly three times with areflex metrograph. The cursor was moved several centimetres away from each point between digitis-ations. The means of the three digitisations were usedto calculate the measurements described in the legendto Figure 1.

To estimate the errors in the method of measurement,10 radiographs were randomly selected from theControl and Treatment groups and digitised using themethods described above. The same radiographs wereredigitised eight days later. The combined errors inidentification of the reference points and digitisation

were calculated with Dahlberg’s formula, and differ-ences between the two sets of measurements with thepaired t-test.13 Significant differences at the 5 per centlevel of significance were found for the variables:OL/MxL, OL/MnL, and the perpendicular distancefrom the incisal edge of the upper incisor to the max-illary plane (UIperp/MxL). The mean difference forOL/MxL was 0.81 degree (SEM difference: 0.17degree), for OL/MnL it was –0.65 degree (SEM dif-ference: 0.24 degree) and for UIperp/MxL it was 0.20mm (SEM difference: 0.11 mm). In agreement withBaumrind and Frantz,14 we consider that large dentalrestorations affected our ability to locate the referencepoints for the occlusal plane consistently. The signifi-cant finding for the upper incisor dentoalveolarheight (UIperp/MxL) may be due to a slight shift inlocation of the reference points for this dimension. Inspite of these differences we consider that the methodof measurement met the requirements of the study.Poor definition on the films taken with the olderMargolis equipment did not allow us to use stableanatomical structures.

Comparisons between the Initial, End and Recallmeasurements in the Treatment sample were carriedout in two steps: an analysis of variance was used todetermine if any statistically significant differences (p < 0.05) occurred between the same measurementsat the three stages. Duncan’s new multiple range testswere then carried out to determine whether the sig-nificant differences occurred between the Initial –End, End – Recall and/or Initial – Recall stages.Comparisons within the Control group were carriedout with paired t-tests, and between the Control andTreatment groups with t-tests for unpaired data. The0.05 level of probability was used in all tests.

Results

The means and standard deviations of the variablestogether with the comparisons within and betweenthe groups are given in Table II. The groups signifi-cantly different with Duncan’s multiple range test areindicated by letters.

Control groupInitial – Recall

No statistically significant differences were foundbetween the angular measurements at the initial andrecall stages. There were, however, statistically signifi-cant increases in upper molar dentoalveolar height

Figure 1. Reference points and measurements.SNA: sella-nasion-A point (1-2-4)SNB: sella-nasion-B point (1-2-9)ANB: A point-nasion-B point (4-2-9)MxL/MnL: ANS-PNS/Me-Go (3-13/10-11) FH/MxL: Or-Po/ANS-PNS (18-19/10-11)FH/MnL: Or-Po/Me-GO (18-19/10-11)OL/MxL: ANS-PNS/U6DCT-PMCT (14-16/3-13)OL/MnL: U6DCT-PMCT/Me-GO (14-16/10-11)UI/MxL: UIA-UIE/ANS-PNS (5-6/3-13)LI/MnL: LIE-LIA/Me-Go (7-8/10-11)Overjet: UIE-LL (6-20)Overbite: LIE-LL (7-20)UIperp/MxL: UIE perp/ANS-PNS (6/3-13)U6perp/MxL: U6MCT perp/ANS-PNS (15/3-13)LIperp/MnL: LIE perp/Me-Go (7/10-11)L6perp/MnL: LIE perp/ANS-PNS (17/10-11)AFH: N-Me (2-10)PFH: S-Go (1-11)UIperp/OL: UIE perp/U6DCT-PMCT (6/14-16)LIperp/OL: LIE perp/U6DCT-PMCT (7/14-16)



(U6perp/MxL), the lower molar dentoalveolar height(L6perp/MnL), anterior face height (AFH) and posterior face height (PFH). AFH and PFH increasedby 9.3 mm and 7.7 mm respectively (Table II).

Treatment group Initial – End of treatment

During treatment the upper incisors were tippedpalatally (UI/MxL), and the occlusal plane – maxil-lary plane angle (OL/MxL) increased significantlyfrom 15.4 degrees to 20.5 degrees. There were fivestatistically significant differences between the linearmeasurements at the Initial and End stages (Table II).During treatment the overjet and overbite werereduced 7.9 mm and 2.6 mm respectively, and theperpendicular heights of the upper (U6perp/MxL)and lower (L6perp/MnL) molars increased 2.2 mm

and 2.9 mm respectively. The AFH increased 7.9 mmduring treatment.

End of treatment – Recall

There were three significant differences between theend of treatment and recall stages: the Frankfort –mandibular planes angle (FH/MnL) decreased 4.9degrees; the occlusal plane – maxillary plane angle(OL/MxL) decreased 6.2 degrees; overbite increased2.1 mm.

Initial – Recall

The inclination of the upper incisors to the maxillaryplane (UI/MxL) remained significantly less at therecall stage in spite of a 7 degree relapse after treat-ment. By contrast, there were six significant lineardifferences. The mean overjet difference between the

Table II. Comparison of the cephalometric variables in the control and treatment groups.

Variables Control (N=8) Treatment (N=9) Control vs Treatment

Initial Recall Initial End Recall Initial RecallAngles Mean (SD) Mean (SD) p* Mean (SD) Mean (SD) Mean (SD) p† p†

SNA 82.3 (4.08) 81.8 (2.01) > 0.05 80.6 (3.74) 79.4 (4.47) 78.9 (2.94) > 0.05 < 0.05SNB 77.3 (3.02) 77.0 (1.26) > 0.05 75.3 (3.53) 73.9 (4.00) 74.2 (2.53) > 0.05 < 0.05ANB 5.0 (1.46) 4.8 (1.78) > 0.05 5.3 (2.48) 5.4 (3.05) 4.8 (3.02) > 0.05 > 0.05MxL/MnL 27.1 (3.69) 25.8 (3.70) > 0.05 28.9 (4.42) 29.4 (4.65) 26.2 (6.57) > 0.05 > 0.05FH/MxL 2.5 (2.25) 3.3 (1.96) > 0.05 1.8 (1.68) 1.6 (1.03) 2.4 (1.25) > 0.05 > 0.05FH/MnL 26.5 (4.09) 23.9 (4.48) > 0.05 27.2 (4.17) 29.9 (3.36) b 24.9 (6.36) b > 0.05 > 0.05OL/MxL 13.0 (3.69) 10.9 (2.83) > 0.05 15.4 (3.09) a 20.5 (4.62) a,b 14.3 (4.88) b > 0.05 > 0.05OL/MnL 14.1 (5.24) 14.8 (3.81) > 0.05 13.4 (3.13) 9.2 (5.48) 11.9 (6.35) > 0.05 > 0.05UI/MxL 114.1 (4.88) 110.6 (4.48) > 0.05 119.7 (4.87) a,c 100.4 (8.30) a 107.8 (9.60) c < 0.05 > 0.05LI/MnL 98.5 (6.48) 101.9 (4.45) > 0.05 97.5 (9.11) 97.8 (6.43) 97.2 (8.00) > 0.05DistancesOverjet 8.6 (2.60) 6.9 (2.99) > 0.05 11.4 (2.68) a.c 3.5 (1.60) a 5.8 (2.58) c < 0.05 > 0.05Overbite 4.2 (2.11) 3.3 (2.06) > 0.05 5.2 (1.89) a 2.6 (1.38) a,b 4.8 (1.75) b > 0.05 > 0.05U1perp/MxL 27.8 (2.75) 30.3 (2.20) > 0.05 28.7 (2.45) c 30.6 (2.39) 31.8 (2.11) c > 0.05 > 0.05U6perp/MxL 20.6 (2.83) 24.2 (1.72) < 0.05 22.0 (2.47) a,c 24.2 (2.15) a 26.0 (2.02) c > 0.05 > 0.05LIperp/MnL 39.2 (3.19) 41.8 (3.25) > 0.05 42.0 (3.50) 41.2 (3.08) 43.6 (3.51) > 0.05 > 0.05L6perp/MnL 28.9 (1.75) 32.5 (1.00) < 0.05 30.1 (2.59) a,c 33.0 (2.20) a 34.0 (2.80) c > 0.05 > 0.05N-Me 113.8 (4.28) 123.1 (2.77) < 0.05 117.4 (8.07) a.c 125.2 (4.48) a 127.7 (5.48) c > 0.05 < 0.05S-Go 72.0 (6.09) 79.7 (3.80) < 0.05 74.2 (4.03) 78.7 (3.04) 83.8 (9.04) c > 0.05 > 0.05UIperp/OL 0.9 (2.90) 0.7 (2.30) > 0.05 3.7 (1.83) 3.8 (2.25) 1.5 (2.71) < 0.05 > 0.05LIperp/OL 2.9 (1.64) 2.1 (2.02) > 0.05 5.3 (1.13) 4.6 (2.24) 4.5 (2.24) < 0.05 < 0.05

* Paired t - test† Unpaired t - testThe letters indicate groups significantly different at p < 0.05 with Duncan’s multiple range test

SHARP ET AL


initial and recall stages was 5.6 mm. The upper incisor dentoalveolar height (UIperp/MxL) increased3.1 mm, and the upper (U6perp/MxL) and lowermolar (L6perp/MnL) dentoalveolar heights increased4.0 mm and 3.9 mm respectively. The AFH increased10.3 mm and the posterior face height (PFH)increased 9.6 mm.

Control vs TreatmentInitial stage

The upper incisors in the treatment group were significantly more proclined, the overjet was signifi-cantly larger, the upper incisors (UIperp/OL) weresignificantly below the occlusal plane and the lowerincisors (LIperp/OL) were significantly above theocclusal plane compared with the control group.

Recall stage

There were only two significant angular differencesbetween the groups at this stage. Angles SNA andSNB were significantly smaller in the treatmentgroup compared with the control group (Table II).The standard deviations in both angles at recall wereless than those found initially. There were also twosignificant linear differences between the two groups:AFH was significantly greater in the treatment group,and the lower incisors were above the occlusal plane(LIperp/OL) to a greater extent than in the controlgroup.

Discussion

We set out to determine if the increase in the heightof the face that invariably occurs when the molars areextruded during orthodontic treatment, was per-manent, or whether it was ‘reversible’.10 That is to say,the upper and lower molars and the mandible end upin the positions they would have occupied, had treat-ment not been carried out. We followed a group of 11year-old girls with untreated Class II division 1 mal-occlusions for 8 years, and a similar-aged group ofgirls with treated Class II division 1 malocclusions for12 years. After taking into account several differencesat the outset, the age difference at the conclusion ofthe study (the treatment group were three years olderthan the control group) and the lesser amounts ofvariation at the conclusion of the study, it appearsthat the upper and lower molars and mandible endedup in the positions they would have occupied hadtreatment not been carried out. The ages of the girls

at the start were similar. It would appear that orthodontic treatment may have no lasting effects oneither the vertical height of the face or the verticalheights of the molars in girls with Class II division 1malocclusion.

This study was very small because of the difficultieswe had finding patients that met the inclusion criteria, who could be located many years after theirinitial consultation and then persuaded to return forrecords. Because it was a small study it did not havemuch power to detect differences between the groups.The small numbers made it impossible for us toadjust for obvious differences, such as the length offollow-up. But in spite of the size of the study we didfind some statistically significant differences at recall, which we will discuss below. The subjects were not randomly allocated to the groups at the out-set so the possibility of some selection bias cannot beruled out.

In longitudinal cephalometric investigations it isessential to keep errors to a minimum so that they donot overwhelm the changes being measured. Themain errors can arise from repositioning an individ-ual in the cephalostat on different occasions, fromcombined errors of identification of the referencepoints and from the measurements made. Difficultiesin identifying the landmarks are considered thesource of greatest errors in cephalometric investiga-tions. It was not possible to check the repositioningerrors because the lateral cephalometric radiographshad been taken over a 12 year period by different people using two cephalostats. However, positioningerrors are generally small in relation to the variationfound between different individuals and the variationwhen the same individual is followed longitudinally.

We investigated the errors in identification and meas-urement by remeasuring 10 randomly selected radio-graphs. We attributed two of the three significant differences to the difficulty we had in locating the ref-erence points for the occlusal plane because the teethconcerned had large restorations.14 The third findingwe attributed to a slight shift when constructing theplanes to measure the height of the incisal edge of theupper incisor from the occlusal plane. All measure-ments were taken directly off the films without anintervening tracing. Where a reference point proveddifficult to locate we used other radiographs belong-ing to the subject to aid identification of the point inquestion. This procedure probably reduced the error

variance within individuals, and as it was not used forall reference points systematic errors will be negligible.

Elevation of the upper and lower molars during treat-ment was accompanied by a significant increase inanterior face height. Anterior face height was also significantly greater in the treatment group, as compared with the control group, at recall. Somemight argue that this difference was evidence of anappliance-induced permanent increase in face height,but there were some notable differences between thegroups at recall. Firstly, anterior face height was 3.5mm longer (but not significantly so) in the treatmentgroup at the start, secondly the treatment group was,on average, 3.5 years older than the control group atrecall, and thirdly there was less variation within thegroups at recall which would increase the probabilityof finding a significant difference between the twogroups.

In agreement with other studies the overbite wasreduced during treatment, but relapsed after treat-ment.5,7,15–17 Bearing in mind that anatomically stable landmarks could not be used, the increase inoverbite appears to be due to continued verticaldevelopment of the upper and lower incisors relativeto the occlusal and maxillary planes. The overbitereduced slightly, but not significantly so, in the con-trol group. There was no significant difference inoverbite between the two samples at recall.

During treatment the upper incisors were retroclined19 degrees and the overjet reduced 8 mm. Followingtreatment, however, the upper incisors proclined 7 degrees and the overjet increased 2.2 mm. Similarchanges during and following treatment have beenreported by others.1,6,15,16,18–20 At the start of thestudy, both the overjet and the inclinations of theupper incisors to the maxillary plane were signifi-cantly larger in the treatment group than in the control group. Therefore, the absence of any statistic-ally significant differences in either overjet or theinclination of the upper incisors at recall was un-expected, particularly as the upper incisors wereretracted during treatment. A number of smallchanges in the angulations of both upper and lowerincisors appear to have combined to produce thesefindings. Changes in the inclinations of both upperand lower incisors in the control group reduced theoverjet approximately 2 mm, whereas the upper incisors relapsed 2.2 mm in the treatment group: inonly one subject was the overjet less at recall than at

the end of treatment and in eight girls it relapsed. Inview of these changes it is not surprising that therewas no significant difference in overjet at the recallstage. In the control group the upper incisors retro-clined 3.5 mm between initial and recall, and thelower incisors proclined about 3.5 mm. It has beenreported that the upper incisors retroclined and thelower incisors proclined naturally in children withuntreated Class II division 1 malocclusions.21,22

Several investigators have observed that in many adolescents lip posture changes from ‘lips apart’ to‘lips together’.23,24 It is postulated that as a lip sealdeveloped labial to the upper incisors they would beretroclined by pressure from the lower lip, and thelower incisors would be free to procline because theywould no longer be subjected to pressure from thelower lip.

Although there was no significant difference betweenthe SNA angles in the treatment and control groupsat the start of the study, this angle was significantlysmaller in the treatment group at recall. Palatal move-ment of point A, and slightly lesser variation in bothgroups at recall would account for this finding. PointA would be expected to move palatally in the six subjects who had their upper incisors torqued palatally.6,25 There was a small, but statistically sig-nificant difference in angle SNB at recall. This find-ing is less easily explained as the lower incisors werenot torqued lingually in the treatment group, but thelesser variation in both groups at recall may accountfor this finding.

During treatment, the lower molars were extrudedslightly more than the upper molars (2.9 mm and 2.2mm respectively) and the anterior end of the occlusalplane was tipped downwards 5 degrees. Followingtreatment however, the upper molars erupted morethan the lower molars, 1.8 mm and 1.0 mm respec-tively. The vertical ‘recovery’ of the molars after treat-ment lends support to the notion that each molar hasa separate potential for vertical development/eruption.26,27 Continued vertical development of theteeth and the alveolar process throughout life pro-vides a mechanism for adjustment of molar heightsafter treatment.27,28

Conclusions

1. Orthodontic treatment may have no lasting effects onthe vertical heights of the molars, incisors and faces of11 year-old girls with Class II division 1 malocclusion.



SHARP ET AL


2. The increase in overbite post-treatment appearedto be due to continued vertical development of theupper incisors relative to the maxillary and occlusalplanes and relapse of the lower incisors.

3. Altered lip posture in adolescence and altered softtissue pressures on the teeth may be responsible forretroclination of the upper incisors in the untreatedindividuals, with a consequential reduction in theoverjet.


Dr Craig SharpPrivate Bag MBE N330AucklandNew ZealandTel: 00 64 9 524 9231 Fax: 00 64 9 520 0950Email: [email protected]

References1. Brodie AG, Downs WB, Goldstein A, Myer E.

Cephalometric appraisal of orthodontic results. AngleOrthod 1938;8:261–351.

2. Tovstein BC. Behaviour of the occlusal plane and relatedstructures in the treatment of Class II malocclusions. AngleOrthod 1955;25:189–98.

3. Hanes RA. Bony profile changes resulting from cervical traction compared with those resulting from intermaxillaryelastics. Am J Orthod 1959;45:353–64.

4. Ricketts RM. The influence of orthodontics on facial growthand development. Angle Orthod 1960;30:103–33.

5. Bijlstra RJ. Vertical changes during Begg treatment. TransEurop Orthod Soc 1969, p 385–95.

6. Crytzer MR. Tooth movement with the Begg technique.Begg J Orthod Theory Treat 1969;5:81–96.

7. Herzberg R. A cephalometric study of Class II relapse. AngleOrthod 1973;43:112–8.

8. Menezes DM. Changes in tooth position and vertical dimen-sion during Begg treatment. Brit J Orthod 1974;2:85–91.

9. Reddy P, Kharbanda OP, Duggal R, Parkash H. Skeletal anddental changes with nonextraction Begg mechanotherapy inpatients with Class II Division 1 malocclusion. Am J OrthodDentofacial Orthop 2000;118:641–8.

10. Melsen B. Effects of cervical anchorage during and aftertreatment: An implant study. Am J Orthod 1978;73:526–40.

11. Fidler BC, Artun J, Joondeph DR, Little RM. Long-termstability of Class II, Division 1 malocclusions with sucessfulocclusal results at end of active treatment. Am J OrthodDentofacial Orthop 1995;107:276–85.

12. British Standards Institution 1983 BS4492, British StandardGlossary of Terms relating to Dentistry. London: BritishStandards Institution, 1983.

13. Dahlberg G. Statistical methods for medical and biologicalstudents. New York; Interscience: 1940:90–5.

14. Baumrind S, Frantz RC. The reliability of headfilm meas-urements. I. Landmark identification. Am J Orthod 1971;60:111–27.

15. Bennett TG, Tulloch JFC, Vig KWL, Webb WG. Overjetstability after treatment of Class II division 1 malocclusions.Brit J Orthod 1974;2:239–46.

16. Bresonis WL, Grewe JM. Treatment and post-treatmentchanges in orthodontic cases: overbite and overjet. AngleOrthod 1974;44:295–9.

17. Wood CM. The effect of retention on the relapse of Class IIDivision 1 cases. Brit J Orthod 1983;10:198–202.

18. Huggins DG, Birch RH. A cephalometric investigation ofupper incisors following their retraction. Am J Orthod1964;50:852–6.

19. Banks PA. An analysis of complete and incomplete overbitein Class II division 1 malocclusions (an analysis of overbiteincompleteness). Brit J Orthod 1986;13:23–31.

20. Looi LK, Mills JRE. The effect of two contrasting forms oforthodontic treatment on the facial profile. Am J Orthod1986;89:507–17.

21. Schaeffer A. Behaviour of the axis of human incisor teethduring growth. Angle Orthod 1949;19:254–75.

22. Bjork A. Variability and age changes in overjet and overbite.Am J Orthod 1953;39:779–800.

23. Ballard CF. Conclusions resumees actualles de l’auteur rela-tives au comportement musculaire. CR Soc Francd’Orthopedie 1960;31:513–24.

24. Walther DP. Some causes and effects of malocclusion. DentPractit 1960;10:139–54.

25. Holdaway RA. Changes in the relationship of points A andB during orthodontic treatment. Am J orthod 1956;42:176–93.

26. Murphy T. Compensatory mechanisms in facial heightadjustment to functional tooth attrition. Aust Dent J 1959;4:312–23.

27. Ainamo J, Talari A. Eruptive movement of the teeth inhuman adults. In: The eruption and occlusion of teeth. Eds.Poole DFG, Stack MV. Colston papers No. 27.Butterworths, London. 1976, 97–107.

28. Behrents RG. Growth in the aging craniofacial skeleton.Monograph 17, Craniofacial Growth Series, Center forHuman Growth and Development, The University ofMichigan. Ann Arbor: Michigan, 1985;99–128.

Introduction

The number of patients undergoing orthodontictreatment with fixed appliances has increased steadilyin recent decades.1 The majority of patients have beentreated to improve their dentofacial aesthetics, andonly a minority have required treatment for medicalor dental reasons. Several indices, such as the Index ofOrthodontic Treatment Need, have been developedto objectively score orthodontic treatment need, but no malocclusion index has a periodontal com-ponent.2 While crowded teeth are unsightly and frequently used to justify orthodontic treatment, they are also difficult to clean and might act as sitesfor the accumulation of dental plaque.

The aetiology and pathogenesis of periodontal diseases are known to be multifactorial, but dentalplaque, not malocclusion, is the essential precursor.3,4

It could be argued that as orthodontic appliances,particularly the brackets and bands, promote theaccumulation of plaque and make tooth cleaning

more difficult, they increase the risk of developinglocalised periodontal disease.

The aims of this paper are to review the published literature on the periodontal consequences of malo-cclusion and those parts of fixed orthodontic appli-ances (brackets and bands) that retain dental plaquein proximity to the periodontal tissues. A descriptionof the impact of orthodontic treatment on the perio-dontium, both short- and long-term, is included.

Material and methods

The PubMed database was searched for original arti-cles on: ‘orthodontics and gingivitis/periodontology/plaque/microbiology/histology’, ‘bracket and gingi-vitis/periodontology/plaque/microbiology/histology’,‘crowding/spacing/overbite/overjet/open bite/cross-bite/traumatic occlusion and gingivitis/periodontol-ogy/plaque/microbiology/histology’. Only articlespublished between 1970 and 30 April 2007 wereused.


The relationships between malocclusion, fixedorthodontic appliances and periodontal disease. A review of the literature

Jan van Gastel,* Marc Quirynen,† Wim Teughels,† Carine Carels*

Department of Orthodontics* and Department of Periodontology,† Catholic University Leuven, Belgium

Aims: To review the literature on the periodontal implications of malocclusion and fixed orthodontic appliances.Methods: The PubMed database was searched for original articles on ‘orthodontics and gingivitis/periodontology/plaque/microbiology/histology’, ‘bracket and gingivitis/periodontology/plaque/microbiology/histology’, ‘crowding/spacing/over-bite/overjet/open bite/crossbite traumatic occlusion and gingivitis/periodontology/plaque/microbiology/histology’. Only articles published between 1970 and 30 April 2007 were used. The search was augmented by screening the references citedin each paper for additional articles that might have been missed by the electronic search.Results/Conclusions: Dental plaque is the primary cause of gingival inflammation and periodontitis. Conditions that encouragethe growth and retention of dental plaque result in a localised gingivitis, which rarely progresses to periodontal disease. Only afew studies report attachment loss during orthodontic treatment. The contradictory findings on the impact of malocclusion andorthodontic appliances on periodontal health may be partly due to the selection of materials and differences in the researchmethods employed.(Aust Orthod J 2007; 23: 121–129)

Received for publication: September 2007Accepted: November 2007

VAN GASTEL ET AL


The titles and abstracts of all potentially relevant arti-cles were first reviewed. The full text versions of allrelevant articles, articles with ambiguous titles andabstracts were then purchased and reviewed. Thesearch was augmented by screening the referencescited in each paper for additional articles that mighthave been missed by the electronic search.

ResultsPathogenesisDental plaque

Dental plaque is a complex biofilm that providesnutrients and protection for periodontopathic bac-teria.5 It is the primary cause of gingival inflamma-tion and periodontitis.6 The Gram-positive andmostly aerobic micro-organisms that initially coloniseintra-oral hard surfaces are replaced by predominantlyGram-negative and anaerobic micro-organisms.7,8

T. forsythia, P. gingivalis, A. Actinomycetemcomitansand P. intermedia are found more frequently inpatients with gingivitis and periodontitis than inhealthy subjects.

The quantity and the quality of dental plaque areimportant factors in the onset of periodontitis. Manyfactors, such as the characteristics of intra-oral hardsurfaces (surface roughness, surface free energy),9–11

have been found to be positively correlated with therate of growth of dental plaque.12 The presence ofgingival inflammation will also promote the growthof plaque.13,14

Host reaction

In 1976 Loesche15 postulated his ‘specific plaquehypothesis’ and stated that certain micro-organismsin the dental plaque were pathogenic, and that over-growth of these species would result in increased gingival inflammation due to the host’s immuneresponse.

The transition from a reversible gingivitis to an irre-versible periodontitis is probably regulated by thebacteria-host reaction. Fransson et al.16,17 examinedthe host reaction to dental plaque in gingival speci-mens taken from young and old individuals, andreported that in the older subjects inflammation wasmore marked and there was a higher density of B-cells. They postulated that these differences weredue to the different experiences of the young and oldto microbial challenges.16,17

Family studies suggest that environmental factors(e.g. oral hygiene and smoking) are major determi-nants of variance in adult periodontitis.18 Data fromtwin studies indicate that about half the populationvariance in periodontitis can be attributed to geneticfactors.19–25 Moreover, there is mounting evidencethat genetic variations in or near the cytokine genes may influence the inflammatory response inindividuals with periodontitis.26–28

Intra-arch orthodontic anomaliesArch-length discrepancies

Despite the fact that relationships between archlength discrepancies and periodontal health havebeen studied frequently, there is little evidence thatmalocclusion and/or irregularity of the teeth affectgingival health. While it seems logical that removal ofdental plaque is more difficult in crowded dentitionsand that this might impact on periodontal health,modern concepts of periodontal health now empha-sise the significance of the biologic, systemic and pro-inflammatory mediators in the development ofperiodontitis.29

In teenagers a low, but statistically significant, corre-lation was found between tooth irregularity (tilting,rotation, displacement, crowding) and the plaque andgingival inflammation scores.30 Tooth irregularity wasless important than the extent of the plaque and cal-culus deposits.30 Ashley et al.31 also provided somesupport for the concept of an association betweenincisor irregularity and gingivitis. They reported astronger association occurred when a labio-linguallydisplaced incisor was overlapped by an adjacent tooththan when it was not overlapped by an adjacenttooth. In spite of this finding the level of oral hygieneseemed to be the most important factor.31

It would appear that irregular teeth are more difficultto clean and, therefore, more likely to develop gingi-vitis. In his study of army recruits Ainamo32 reportedthat periodontal disease was more marked adjacent tomalaligned maxillary anterior teeth and less markedin the premolar areas. He concluded that there wereno associations between malaligned teeth and perio-dontal disease at extremes of oral hygiene.32 ButIngervall,33 who conducted a study of dental studentswith perfect oral hygiene who had refrained frominterdental cleaning for 40 days, reported there wasan equal increase in gingivitis in both the crowded

and non-crowded dentitions. He disagreed withAinamo’s conclusion that in individuals with aver-age oral hygiene (brushing three times a day and nointerdental cleaning) a crowded dentition did notenhance the accumulation of dental plaque and thedevelopment of gingivitis.

Ngom et al.34 recently reported varying degrees ofcorrelation between intra-arch relationships and periodontal health. The plaque and gingivitis indiceswere significantly correlated with crowding and dis-placed lower anterior teeth. Crowding in the lowerdental arch was the only parameter that was signifi-cantly correlated with the severity of periodontal disease. A trend towards more favourable periodontalconditions in young subjects with a spaced denti-tion31,34–36 has also been reported, but the findingswere not statistically significant. Other researchershave reported significant associations between thenumber of open contacts and gingival health in children.31,36 It is interesting to note that there wasno evidence of a similar relationship in adults.37,38

Alhaija and Al-Wahadni39 recently investigated associations between mild crowding and periodontaldisease in individuals with good oral hygiene. Theaverage number of sites with labio-lingually displacedteeth overlapped or not overlapped by adjacent teethwas 1.81 + 1.30 and 1.39 + 1.10 respectively. Theyfound no significant associations between crowdingand periodontal disease in subjects with good oralhygiene. Their findings in subjects with good oralhygiene were supported by Ashley et al.31 However,Ashley et al. found significant associations betweenirregularity and gingivitis in subjects with moderateand poor oral hygiene,31 which disagrees withAinamo’s32 suggestion that when the oral hygiene was poor or non-existent, an association betweencrowding and gingivitis is less likely to be found.

Staufer and Landmesser40 investigated the risk ofindividuals with different types of anterior crowdingdeveloping periodontal disease, and whether the riskwas associated with the severity of crowding. Theyreported there was a greater risk of chronic gingivalinflammation in the anterior region in older individ-uals when the crowding exceeded the threshold valueof 3 mm.

Mouth-breathing can also be a cofactor in the devel-opment of gingivitis in crowded dentitions. Jacobsonand Linder-Aronson41 reported that mouth breathers

with crowding were more likely to develop gingivitisthan nose breathers with crowded dentitions.

Inter-arch orthodontic anomaliesOpen bite

Open bites and incompetent lips may lead to thedevelopment of a localised gingival recession aroundthe upper incisors. In their study of 101 subjects whohad not received orthodontic treatment Ngom et al.34

reported that open bites were significantly, and positively, correlated with the plaque and gingivitisscores, the gingival bleeding index, loss of clinicalattachment and pocket depth.34 Machtei et al.42 com-pared the lengths of the clinical crowns, the amountof gingival recession, oral habits and the periodontalindices in children with untreated anterior open biteswith a matched control group. Although the plaqueindices in the two groups were similar the open-bitegroup had significantly longer clinical crowns andmore gingival inflammation. This may be due to thegreater virulence of dehydrated plaque. It has beensuggested that a localised gingival recession maydevelop around the upper incisors in young childrenwith an open bite and incompetent lips.41,42

Crossbite

Excessive forces are exerted in centric relation andmaximal occlusion on teeth in crossbite, especiallywhen a ‘forced bite’ is present. Ngom et al.34 reporteda significant correlation between a crossbite and gingival recession,34 which may be due to primaryocclusal trauma. In centric relation and at the end ofthe closing phase during mastication, a tooth in cross-bite may contact an opposing tooth prematurely. Whenthis occurs the occlusal loads on the tooth in crossbiteare unfavourable and may lead to gingival recession.While some researchers have reported higher perio-dontal scores in cases with crossbites, otherresearchers did not find any significant associationsbetween crossbites and periodontal parameters.44

Occlusal trauma

Although the influence of occlusal interferences onthe health of the periodontium has been studiedextensively, the evidence that occlusal interfer-ences either initiate periodontal break-down or con-tribute to the progression of periodontal disease isinconclusive.45–47 Some researchers consider that

MALOCCLUSION, FIXED ORTHODONTIC APPLIANCES AND PERIODONTAL DISEASE


VAN GASTEL ET AL


occlusal interferences/trauma are not a cause of perio-dontal disease,48 but they may contribute to the pro-gression of the disease.47 Using evidence from an animal study Lindhe and Ericsson48 argued thatocclusal trauma played a role in the progression ofperiodontal disease. Indirect evidence from a ran-domised clinical trial of patients with periodontitisalso suggested that occlusal trauma may contribute tothe break-down of the periodontal tissues.49 Bugett et al. reported a significant gain in attachment inpatients with periodontitis who received conven-tional periodontal therapy and occlusal adjustmentcompared with those who received conventional therapy but no occlusal adjustment.49

These findings do not justify prophylactic adjustmentof the occlusion with orthodontic treatment to pre-vent periodontal disease. However, occlusal interfer-ences may be a significant risk factor in the progres-sion of existing periodontal disease, and removal ofocclusal interferences/trauma may significantlyimprove the outcome achieved with periodontaltreatment.49 In healthy mouths occlusal trauma doesnot result in periodontal breakdown.

Overjet

Higher plaque scores and less alveolar bone have beenfound in individuals with an increased overjet. In astudy of 19 year-old male military recruits Brojnaas etal.50 compared recruits with overjets >8 mm withrecruits with ‘nearly ideal’ occlusions. They reportedthat the alveolar bone height was 1 mm less in theupper incisor region and 0.4 mm less in the lowerincisor region in the overjet group compared with thecontrol group.50 In a large, longitudinal study of 12year-old Welsh children Davies et al.51 reported a sig-nificant association between the mean plaque score,bleeding on probing and anterior overjet.51 Theyreported that plaque accumulation and gingivitisoccurred at the extremes of overjet, both positive andnegative. Other researchers have reported similarresults; significantly higher plaque scores were foundin subjects with increased overjets.34 Buckley’s30 fail-ure to find a significant correlation between overjetand the plaque and gingival indices would appear tocontradict these findings. However, Buckley’s study isnot directly comparable to the studies reported byBrojnaas and Davies:30,50,51 Buckley used threegroups and his large overjet group had individualswith overjets only >3 mm.

Overbite

Increased overbite can result in the lower incisorsimpinging on the palatal mucosa or upper incisorsimpinging on the lower labial mucosa. Both con-ditions can result in recession and when this occursorthodontic treatment is indicated.52 In less severecases with no soft tissue damage, treatment may notbe required. Bjornaas et al.50 demonstrated a signifi-cant reduction in alveolar bone heights in the upper(0.7 mm) and lower (0.5 mm) incisor regions in armyrecruits with overbites >5 mm compared with age-peers with an ‘nearly ideal’ occlusions.50 Ngom etal.34 also reported significant positive correlationsbetween increased overbite and attachment loss andpocket depth, but found no significant correlationsbetween overbite and oral hygiene parameters. Onthe other hand, Buckley30 did not find any relation-ship between overbite and periodontal health.

Orthodontic treatment

The amount of dental plaque increases when ortho-dontic brackets, bands and fixed appliances areplaced.53–58 Most patients, even those with good oralhygiene, develop a generalised gingivitis followingappliance placement, but usually there is no loss ofattachment. Some studies have, however, reportedloss of attachment during orthodontic treatment withfixed appliances.59–61

Reliable indicators of early inflammation are thecrevicular fluid flow (µl/min) and the composition ofcytokines in this fluid.62 Several techniques for thecollection of crevicular fluid have been described.62

Cytokines, which mediate the host immunologicalresponse to exogenous antigens, are also produced byconnective tissue cells such as fibroblasts andosteoblasts and are involved in normal physiologicalturnover and bone remodelling. Cytokines are lowmolecular weight proteins (< 25 kDa) produced bycells that regulate or modify the action of other cellsin an autocrine (acting on the cell of origin) orparacrine (acting on adjacent cells) manner. The definition includes the interleukins (ILs), tumournecrosis factors (TNFs), interferons, growth factors,and colony stimulating factors. A major difficulty inunderstanding cytokine biology is the sheer num-ber and complexity of these factors. Another problem is that several factors such as IL-1 and TNF exhibit overlapping biological activities (redun-dancy) and many have multiple biological effects



pleiotropy). In clinical studies it may be difficult todistinguish between cytokine responses to inflamma-tion and tooth movement during orthodontic treatment.

A clinical manifestation of the inflammatory reactionis the increase in pocket depth caused by gingivalhypertrophy (pseudo-pocket formation). Variousexplanations for this reaction in orthodontic patientswith fixed appliances have been suggested in the literature: allergic reactions, mechanical irritation,cytotoxic effects of the band/bracket or bondingmaterial and changes in (subgingival) microbiology.

Comparisons of orthodontically treated and untreat-ed groups have revealed some interesting findings. Ina longitudinal study Sadowsky et al.63 compared sub-jects who had received orthodontic treatment duringadolescence with a matched group of subjects withmalocclusions that had not been treated. The groupswere matched for race, sex, age, socio-economic status, oral hygiene and dental awareness. Althoughthe general prevalence of periodontal disease in thegroups was similar, a detailed analysis of the groupsdisclosed that the orthodontically treated group hadmild to moderate periodontal disease in the upperposterior and lower anterior regions. While ortho-dontic treatment in adolescence is not an importantdeterminant of periodontal health in the long-term, some unfavourable periodontal changes may be found in orthodontic patients in adulthood.Further research is needed to elucidate whether thesechanges are due the type or duration of the ortho-dontic treatment. Conversely, lack of orthodontictreatment in adolescence does not appear to influencethe development of periodontal disease in adultlife.63,64

A significant improvement in oral hygiene may fol-low orthodontic treatment. Davies et al.65 recordedplaque indices, bleeding indices, and the degree ofdental irregularity of the anterior teeth in ortho-dontically treated and untreated children. The chil-dren were re-examined three years after the baselineexamination. They reported significant reductions inthe plaque and gingivitis scores on all tooth surfacesin both groups at the 3-year examinations. The children who had received orthodontic treatment had greater reductions, but these appeared to be dueto behavioural factors rather than to improved toothalignment.

Microbiology

Orthodontic appliances create a favourable environ-ment for the accumulation of microbiota and foodresidues, which may cause caries or periodontal dis-ease. Naranjo et al.58 observed a change in the micro-organisms populating the subgingival dental plaqueafter the placement of brackets. The plaque gingivitisscores increased significantly. Levels of P. gingivalis, P.intermedia/P. nigrescens, T. forsythia, and Fusobacter-ium species were significantly elevated after bracketplacement as compared with the untreated controlgroup. Super-infecting micro-organisms such as E.cloacae, K. oxytoca, K. pneumoniae, and S. marcescenswere also found in the treatment group.58 Lee et al.66

succeeded in detecting significant differences in thesubgingival dental plaque retrieved from areas of gin-givitis in patients with and without fixed appliances:T. forsythia, T. denticola, and P. nigrescens were morecommon in the orthodontic patients than in the con-trol patients.66 These results indicate that followingplacement of fixed appliances, the pathogenic micro-organisms in the dental plaque increased with a con-sequential increase in gingivitis. No differences inperiodontal pocket depth were found. Changes in thetypes of micro-organisms were restricted to the dentalplaque on the teeth supporting the orthodontic appliance.58,66

Local changes occur in the microbiota and periodon-tal tissues following placement of an orthodonticappliance. Huser et al.67 carried out clinical and bac-teriological examinations at the beginning of ortho-dontic treatment and up to 90 days after placementof banded orthodontic appliances. They reportedincreased plaque and bleeding scores on the bandedteeth as compared with the control sites. The probingdepth, however, remained within normal values inthe test and control groups. They also examined thecomposition of the dental plaque with dark-fieldmicroscopy, and found increased percentages ofspirochetes, motile rods, filaments, and fusiforms atthe test sites after banding. Over the 90 days therewere no significant changes in the distributions ofmicro-organisms in the control group.67 In two smallgroups of banded and control patients Diamanti-Kipioti et al.68 observed an increase in black pig-mented bacteria without an increase in the gingivaland plaque indices. The mean pocket depthsincreased significantly from baseline levels in theexperimental group, but not the control group.68 In a

similar study Petti et al.69 compared the influence offixed and removable orthodontic appliances on thesupra- and subgingival microflora. Their data indicatethat while gingivitis and periodontitis did not occurin patients with good oral hygiene during the first sixmonths of treatment, changes in the oral microbiotaover time suggest that patients with fixed appliancesrisk developing gingivitis and periodontitis.69 Theabovementioned studies show that changes in themicrobial environment after the placement of fixedorthodontic appliances are accompanied by increasedgingivitis.

The effects of the different materials used in modernorthodontics on the mictobiota and periodontalhealth have not been studied thoroughly. Türkkakra-man et al.70 investigated the influence of differentmethods of archwire ligation (steel ligatures versuselastomeric rings) on the intra-oral microbial floraand periodontal health. Although teeth ligated withelastomeric rings exhibited slightly higher numbers ofmicro-organisms than the teeth ligated with steel ligature wires, the differences were not statistic-ally significant. There were no differences in the gingival index, plaque index or pocket depths of the bonded teeth. However, the gingivae around theteeth ligated with elastomeric rings were prone tobleeding.70 Van Gastel et al.,53 in a randomised clin-ical trial with split-mouth design, compared thegrowth of plaque, clinical periodontal parameters andthe crevicular fluid flow on teeth bonded with twodifferent bracket types with non-bonded controlteeth. They showed a significantly higher number ofaerobes as well as anaerobe colony forming units(CFU) on the bonded teeth compared to the non-bonded controls. There were also significant differ-ences between the teeth bonded with the differentbrackets. Most important of all was the significantdifference in the ratio CFU aerobe/CFU anaerobebecause this indicates the pathogenicity of the dentalplaque layer. They concluded that the design of anorthodontic bracket system can make the oral environment less favourable for the development of plaque.

Histology

In a longitudinal study of gingival biopsies from thebuccal sites opposite molars Zachrisson demonstratedthat, shortly after the insertion of bands, the gingivalconnective tissue was infiltrated by inflammatory

cells.55 The dominant cell type in the first month waslymphocytes, but subsequently plasma cells domin-ated. The topography of the leukocytic infiltrate alsodiffered: plasma cells were located more centrally inthe connective tissue, while lymphocytes and PMNswere located more superficially, close to the epi-thelium. After band removal the inflamed gingivallesions gradually recovered, but acanthosis of the sulcular epithelium persisted in some areas.

Diedrich et al.71 also described the histopathologicalpicture of an established gingival lesion. It consistedof a detached and severely damaged epithelial attach-ment, subgingival plaque, massive leukocyte infiltra-tion (mainly lymphocytes, PMNs and plasma cells)and loss of collagen fibres, resulting in destruction ofthe intra-papillary fibre apparatus. The transseptalfibres, the final protective barrier opposing microbialinfiltration of the alveolar bone, were infiltrated tovarying degrees by cells. The cellular infiltration wasparticularly marked interdentally because of the sub-gingival position of the band margins. At one of thesesites the connective tissue attachment was severelydamaged, resulting in apical migration of the pocketepithelium, leading to a transition from chronic gin-givitis to an initial irreversible periodontal lesion.71

The cement gaps of the orthodontic bands wereanalysed and were widest at the cervical margins(average gaps of 0.28 mm). In 85 per cent of the bandmargins defects in the cement margins were colonisedwith loosely dispersed dental plaque.71

Conclusions/clinical implications

1. Dental plaque is the primary cause of gingivalinflammation and periodontitis. Transition from areversible gingivitis to an irreversible periodontitis isregulated by the bacteria-host reaction, which may bestudied by analysis of the crevicular fluid. Conditionsthat encourage the growth and retention of dentalplaque increase the risk of developing localised periodontal disease. The gingivitis that develops during orthodontic treatment,57,58,65,67,81 is not likely to develop into a periodontitis. Only a fewstudies report attachment loss during orthodontictreatment.59–61

2. Crowding has no adverse effects on periodontalhealth in cases with excellent oral hygiene, but incases with average oral hygiene,31–33 crowding pro-motes the accumulation of dental plaque, which may

VAN GASTEL ET AL


impact detrimentally on the health of the perio-dontium.31–33,40,43 In the majority of cases with poororal hygiene crowding has no effect on periodontalhealth.31–33 It is difficult to determine when gingi-vitis due to crowding will progress to adult periodontis.

3. Orthodontic closure and restorative closure of adiastema are contraindicated because both can have negative effects on periodontal health, especiallyin adults in their third and fourth decades oflife.31,34–36,72

4. A localised gingival recession may develop aroundthe upper incisors in children with an anterior openbite and incompetent lips, possibly because lipincompetence leads to dehydration of the plaque.41,42

A positive association has been found between anopen bite, the plaque score and periodontalhealth.34,42

5. Crossbites have no detrimental impact on plaquescores and periodontal health.34,44

6. Occlusal trauma does not initiate periodontalbreakdown, but it may play a role in the progressionof periodontal disease.45,46,73 Removal of occlusaltrauma may result in a significant gain in attachmentin patients with periodontitis.

7. Orthodontic treatment of severe overjets (>7 mm)and overbites (>5 mm) may be justified from a perio-dontal point of view.34,50,51 Long-term studies arerequired to clarify the periodontal implications of anincreased overjet and overbite.

8. Periodontal screening should be an essential part ofthe orthodontic diagnosis.74 Before any orthodontictreatment is started patients should have excellentoral hygiene and the periodontium should be healthy.Loss of attachment before orthodontic treatment isnot a contraindication for orthodontic treatment in ahealthy mouth.75–80

9. The contradictory findings on the impact of mal-occlusion and orthodontic appliances on periodontalhealth may be due to the selection of material and todifferences in the research methods employed.


Dr J.L. van GastelFaculty of MedicineSchool of Dentistry, Oral Pathology and Maxillo-Facial Surgery

Department of OrthodonticsU.Z. St. RafaelKapucijnenvoer 33B-3000 LeuvenBelgiumTel: +32 16 33 24 49Fax: +32 16 33 24 13Email: [email protected] [email protected]

References1. Shaw WC, Richmond S, O’Brien KD, Brook P, Stephens

CD. Quality control in orthodontics: indices of treatmentneed and treatment standards. Br Dent J 1991;170:107–12.

2. Brook PH, Shaw WC. The development of an index oforthodontic treatment priority. Eur J Orthod 1989;11:309–20.

3. Socransky SS. Relationship of bacteria to the etiology ofperiodontal disease. J Dent Res 1970;49:203–22.

4. Socransky SS. Microbiology of periodontal disease – presentstatus and future considerations. J Periodontol 1977;48:497–504.

5. Marsh PD. Dental plaque: biological significance of abiofilm and community life-style. J Clin Periodontol 2005;32 Suppl 6:7–15.

6. Loe H. Physiology of the gingival pocket. Acad Rev CalifAcad Periodontol 1965;13:6–14.

7. Socransky SS, Haffajee AD, Cugini MA, Smith C, Kent RLJr. Microbial complexes in subgingival plaque. J ClinPeriodontol 1998;25:134–44.

8. Socransky SS, Haffajee AD. Periodontal microbial ecology.Periodontol 2000 2005;38:135–87.

9. Quirynen M, Marechal M, Busscher H, el-Abiad M, ArendsJ, van Steenberghe D. The influence of surface character-istics on the early bacterial colonization of intra-oral hardsurfaces. J Clin Dent 1988;1 Suppl A:A14–19.

10. Quirynen M, Marechal M, Busscher HJ, Weerkamp AH,Arends J, Darius PL et al. The influence of surface free-ener-gy on planimetric plaque growth in man. J Dent Res1989;68:796–9.

11. Quirynen M, Marechal M, Busscher HJ, Weerkamp AH,Darius PL et al. The influence of surface free energy and sur-face roughness on early plaque formation. An in vivo studyin man. J Clin Periodontol 1990;17:138–44.

12. Quirynen M, Bollen CM. The influence of surface rough-ness and surface-free energy on supra- and subgingivalplaque formation in man. A review of the literature. J ClinPeriodontol 1995;22:1–14.

13. Quirynen M, Dekeyser C, van Steenberghe D. The influenceof gingival inflammation, tooth type, and timing on the rateof plaque formation. J Periodontol 1991;62:219–22.

14. Ramberg P, Axelsson P, Lindhe J. Plaque formation athealthy and inflamed gingival sites in young individuals. JClin Periodontol 1995;22:85–8.

15. Loesche WJ. Chemotherapy of dental plaque infections.Oral Sci Rev 1976;9:65–107.

16. Fransson C, Berglundh T, Lindhe J. The effect of age on thedevelopment of gingivitis. Clinical, microbiological and histological findings. J Clin Periodontol 1996;23:379–85.

17. Fransson C, Mooney J, Kinane DF, Berglundh T. Differencesin the inflammatory response in young and old human



subjects during the course of experimental gingivitis. J ClinPeriodontol 1999;26:453–60.

18. Haffajee AD, Socransky SS, Lindhe J, Kent RL, OkamotoH, Yoneyama T. Clinical risk indicators for periodontalattachment loss. J Clin Periodontol 1991;18:117–25.

19. Corey LA, Nance WE, Hofstede P, Schenkein HA. Self-reported periodontal disease in a Virginia twin population. JPeriodontol 1993;64:1205–8.

20. Michalowicz BS, Aeppli D, Virag JG, Klump DG, HinrichsJE, Segal NL et al. Periodontal findings in adult twins. JPeriodontol 1991;62:293–9.

21. Michalowicz BS. Genetic and inheritance considerations inperiodontal disease. Curr Opin Periodontol 1993;11–17.

22. Michalowicz BS. Genetic and heritable risk factors in perio-dontal disease. J Periodontol 1994;65:(Suppl:)479–88.

23. Michalowicz BS. Genetic risk factors for the periodontal diseases. Compendium 1994;15:1036, 1038, 1040 passim

24. Michalowicz BS, Wolff LF, Klump D, Hinrichs JE, AeppliDM, Bouchard TJ et al. Periodontal bacteria in adult twins.J Periodontol 1999;70:263–73.

25. Michalowicz BS, Diehl SR, Gunsolley JC, Sparks BS, BrooksCN, Koertge TE et al. Evidence of a substantial genetic basisfor risk of adult periodontitis. J Periodontol 2000;71:1699–707.

26. Cullinan MP, Westerman B, Hamlet SM, Palmer JE, FaddyMJ, Lang NP et al. A longitudinal study of interleukin-1gene polymorphisms and periodontal disease in a generaladult population. J Clin Periodontol 2001;28:1137–44.

27. Lopez NJ, Jara L, Valenzuela CY. Association of interleukin-1 polymorphisms with periodontal disease. J Periodontol2005;76:234–43.

28. Taylor JJ, Preshaw PM, Donaldson PT. Cytokine gene poly-morphism and immunoregulation in periodontal disease.Periodontol 2000 2004;35:158–82.

29. Socransky SS, Haffajee AD. The bacterial etiology ofdestructive periodontal disease: current concepts. JPeriodontol 1992;63:322–31.

30. Buckley LA. The relationships between malocclusion, gingi-val inflammation, plaque and calculus. J Periodontol 1981;52:35–40.

31. Ashley FP, Usiskin LA, Wilson RF, Wagaiyu E. The relation-ship between irregularity of the incisor teeth, plaque, andgingivitis: a study in a group of schoolchildren aged 11–14years. Eur J Orthod 1998;20:65–72.

32. Ainamo J. Relationship between malalignment of the teethand periodontal disease. Scand J Dent Res 1972;80:104–10.

33. Ingervall B, Jacobsson U, Nyman S. A clinical study of therelationship between crowding of teeth, plaque and gingivalcondition. J Clin Periodontol 1977;4:214–22.

34. Ngom PI, Diagne F, Benoist HM, Thiam F. Intra-arch andinterarch relationships of the anterior teeth and periodontalconditions. Angle Orthod 2006;76:236–42.

35. Silness J, Roynstrand T. Effects on dental health of spacingof teeth in anterior segments. J Clin Periodontol 1984;11:387–98.

36. Feldens EG, Kramer PF, Feldens CA, Ferreira SH.Distribution of plaque and gingivitis and associated factorsin 3- to 5-year-old Brazilian children. J Dent Child 2006;73:4–10.

37. Artun J, Osterberg SK. Periodontal status of teeth facingextraction sites long-term after orthodontic treatment. JPeriodontol 1987;58:24–29.

38. Jernberg GR, Bakdash MB, Keenan KM. Relationshipbetween proximal tooth open contacts and periodontal disease. J Periodontol 1983;54:529–33.

39. Abu Alhaija ES, Al-Wahadni AM. Relationship betweentooth irregularity and periodontal disease in children withregular dental visits. J Clin Pediatr Dent 2006;30:296–8.

40. Staufer K, Landmesser H. Effects of crowding in the loweranterior segment – a risk evaluation depending upon thedegree of crowding. J Orofac Orthop 2004;65:13–25.

41. Jacobson L, Linder-Aronson S. Crowding and gingivitis: acomparison between mouthbreathers and nosebreathers.Scand J Dent Res 1972;80:500–4.

42. Machtei EE, Zubery Y, Bimstein E, Becker A. Anterior openbite and gingival recession in children and adolescents. IntDent J 1990;40:369–73.

43. Silness J, Roynstrand T. Relationship between alignmentconditions of teeth in anterior segments and dental health. JClin Periodontol 1985;12:312–20.

44. Geiger AM, Wasserman BH. Relationship of occlusion andperiodontal disease. Part X. Relation of cross-bite to perio-dontal status. J Periodontol 1977;48:785–9.

45. Shefter GJ, McFall WT, Jr. Occlusal relations and periodon-tal status in human adults. J Periodontol 1984;55:368–74.

46. Pihlstrom BL, Anderson KA, Aeppli D, Schaffer EM.Association between signs of trauma from occlusion andperiodontitis. J Periodontol 1986;57:1–6.

47. Waerhaug J. The infrabony pocket and its relationship totrauma from occlusion and subgingival plaque. JPeriodontol 1979;50:355–65.

48. Lindhe J, Ericsson I. The influence of trauma from occlu-sion on reduced but healthy periodontal tissues in dogs. JClin Periodontol 1976;3:110–22.

49. Burgett FG, Ramfjord SP, Nissle RR, Morrison EC,Charbeneau TD, Caffese RG et al. A randomized trial ofocclusal adjustment in the treatment of periodontitispatients. J Clin Periodontol 1992;19:381–7.

50. Bjornaas T, Rygh P, Boe OE. Severe overjet and overbitereduced alveolar bone height in 19-year-old men. Am JOrthod Dentofacial Orthop 1994;106:139–45.

51. Davies TM, Shaw WC, Addy M, Dummer PM. The relationship of anterior overjet to plaque and gingivitis inchildren. Am J Orthod Dentofacial Orthop 1988;93:303–9.

52. Zimmer B, Seifi-Shirvandeh N. Changes in gingival reces-sion related to orthodontic treatment of traumatic deepbites in adults. J Orofac Orthop 2007;68:232–44.

53. van Gastel JL, Quirynen M, Teughels W, Coucke W, CarelsC. Influence of bracket design on microbial and periodontalparameters in vivo. J Clin Periodontol 2007;34:423–31.

54. Kloehn JS, Pfeifer JS. The effect of orthodontic treatmenton the periodontium. Angle Orthod 1974;44:127–34.

55. Zachrisson S, Zachrisson BU. Gingival condition associatedwith orthodontic treatment. Angle Orthod 1972;42:26–34.

56. Alexander SA. Effects of orthodontic attachments on thegingival health of permanent second molars. Am J OrthodDentofacial Orthop 1991;100:337–40.

57. Sallum EJ, Nouer DF, Klein MI, Gonçalves RB, Machion L,Wilson Sallum A et. al. Clinical and microbiologic changesafter removal of orthodontic appliances. Am J OrthodDentofacial Orthop 2004;126:363–6.

58. Naranjo AA, Triviño ML, Jaramillo A, Betancourth M,Botero JE. Changes in the subgingival microbiota and peri-odontal parameters before and 3 months after bracket place-ment. Am J Orthod Dentofacial Orthop 2006;130:275.e17–22.

59. Zachrisson BU, Alnaes L. Periodontal condition in ortho-dontically treated and untreated individuals. I. Loss ofattachment, gingival pocket depth and clinical crownheight. Angle Orthod 1973;43:402–11.

VAN GASTEL ET AL


60. Zachrisson BU, Alnaes L. Periodontal condition in ortho-dontically treated and untreated individuals. II. Alveolarbone loss: radiographic findings. Angle Orthod 1974;44:48–55.

61. Zachrisson BU. Cause and prevention of injuries to teethand supporting structures during orthodontic treatment.Am J Orthod 1976;69:285–300.

62. Griffiths GS. Formation, collection and significance of gin-gival crevice fluid. Periodontol 2000 2003;31:32–42.

63. Sadowsky C, BeGole EA. Long-term effects of orthodontictreatment on periodontal health. Am J Orthod 1981;80:156–72.

64. Polson AM, Subtelny JD, Meitner SW, Polson AP, SommersEW, Iker HP et al. Long-term periodontal status after ortho-dontic treatment. Am J Orthod Dentofacial Orthop1988;93:51–8.

65. Davies TM, Shaw WC, Worthington HV, Addy M, DummerP, Kingdon A. The effect of orthodontic treatment on plaqueand gingivitis. Am J Orthod Dentofacial Orthop 1991;99:155–61.

66. Lee SM, Yoo SY, Kim HS, Kim KW, Yoon YJ, Lim SH et al.Prevalence of putative periodontopathogens in subgingivaldental plaques from gingivitis lesions in Korean orthodonticpatients. J Microbiol 2005;43:260–5.

67. Huser MC, Baehni PC, Lang R. Effects of orthodonticbands on microbiologic and clinical parameters. Am JOrthod Dentofacial Orthop 1990;97:213–18.

68. Diamanti-Kipioti A, Gusberti FA, Lang NP. Clinical andmicrobiological effects of fixed orthodontic appliances. JClin Periodontol 1987;14:326–33.

69. Petti S, Barbato E, Simonetti D’Arca A. Effect of ortho-dontic therapy with fixed and removable appliances on oralmicrobiota: a six-month longitudinal study. New Microbiol1997;20:55–62.

70. Türkkahraman H, Sayin MO, Bozkurt FY, Yetkin Z, Kaya S,Onal S. Archwire ligation techniques, microbial coloniz-ation, and periodontal status in orthodontically treatedpatients. Angle Orthod 2005;75:231–6.

71. Diedrich P, Rudzki-Janson I, Wehrbein H, Fritz U. Effectsof orthodontic bands on marginal periodontal tissues. A his-tologic study on two human specimens. J Orofac Orthop2001;62:146–56.

72. Broadbent JM, Williams KB, Thomson WM, Williams SM.Dental restorations: a risk factor for periodontal attachmentloss? J Clin Periodontol 2006;33:803–10.

73. Lindhe J, Ericsson I. The influence of trauma from occlu-sion on reduced but healthy periodontal tissues in dogs. JClin Periodontol 1976;3:110–22.

74. Turpin DL. Periodontal screening: a basic part of the ortho-dontic examination. Angle Orthod 1994;64:163–4.

75. Kokich VG. Adult orthodontics in the 21st century: guide-lines for achieving successful results. World J Orthod 2005;6Suppl:14–23.

76. Mathews DP, Kokich VG. Managing treatment for theorthodontic patient with periodontal problems. SeminOrthod 1997;3:21–38.

77. Melsen B. Orthodontic treatment of patients with perio-dontal lesions. J Parodontol 1987;6:285–96.

78. Melsen B, Agerbaek N, Eriksen J, Terp S. New attachmentthrough periodontal treatment and orthodontic intrusion.Am J Orthod Dentofacial Orthop 1988;94:104–16.

79. Melsen B, Agerbaek N, Markenstam G. Intrusion of incisorsin adult patients with marginal bone loss. Am J OrthodDentofacial Orthop 1989;96:232–41.

80. Williams S, Melsen B, Agerbaek N, Asboe V. The ortho-dontic treatment of malocclusion in patients with previousperiodontal disease. Br J Orthod 1982;9:178–84.

81. Alstad S, Zachrisson BU. Longitudinal study of periodontalcondition associated with orthodontic treatment in adoles-cents. Am J Orthod 1979;76:277–86.



Introduction

Many adult patients will agree to orthodontic treat-ment when the benefits, such as improved facial aesthetics and the preservation of periodontally com-promised teeth, are explained to them.1,2 Patientswith active periodontal disease threatening thelongevity of their dentitions are often unaware of thisfact, despite the appearance of spaces between teeththat were previously in contact and/or previouslywell-aligned incisors that have become flared and protrusive.2 The first step in the management of these complex clinical problems is to ensure that thepatient understands the importance of the proceduresprior to orthodontic treatment. These generallyinvolve improved oral hygiene, better diet and exten-sive periodontal treatment, often involving flap surgery. Because treatment for these cases has certainrisks and limitations, such as loss of teeth and incom-plete treatment, patients should give their informedconsent before any orthodontic treatment is under-taken. For his part the orthodontist should use lightforces, and a force system capable of completing the

desired treatment with the minimal damage to analready compromised periodontal attachment.3,4

In this report we describe a case with vertical and hori-zontal bony defects in both arches. A successful out-come for this patient depended on the establishmentof a comprehensive treatment plan, and extensiveperiodontal treatment before orthodontic treatmentto retract procumbent incisors could be undertaken.5

Case report

A 47 year-old male Caucasian asked for an orthodon-tic evaluation. He had noticed that his previouslywell-aligned maxillary incisors had become spacedand protrusive. Apart from this observation he wasunaware of the health of his teeth and their support-ing tissues. He was mesofacial and had a symmetricalface with a mildly convex profile (Figure 1). The max-illary incisors and lower lips were protrusive.

Dental analysisThe patient had a bilateral Class I molar relationship,with flared and procumbent maxillary incisors, an


Treatment of a Class I deep bite malocclusion in aperiodontally compromised adult

Marcelo do Amaral Ferreira and Rogério do Amaral FerreiraPrivate practice, Curitiba, Paraná, Brazil

Background: Light forces and an appropriate force system should be used to treat adult patients with periodontal disease.Aims: To describe the orthodontic treatment of an adult patient with a Class I deep bite malocclusion, horizontal and verticalbone loss and root resorption.Methods: After periodontal surgery and initial alignment of the maxillary incisors with a fixed orthodontic appliance the maxillary incisors were splinted together as a single unit. A double palatal arch and sectional buccal archwires were used foranchorage. The palatal arch and splint were joined by a NiTi coil spring (100 g). The incisor segment was then intruded andretracted with a force acting just below the centre of resistance of the splinted incisor teeth. The force system avoided extrudingthe maxillary molars. The maxillary teeth were then rebonded to close the spaces between maxillary lateral incisors andcanines. A Hawley appliance was used for retention. Treatment was completed in 22 months. Conclusions: Surgical treatment and intrusion with light forces encouraged the development of periodontal attachment to theteeth affected by severe horizontal and vertical bone loss. Retraction of the proclined incisors improved the facial aesthetics.(Aust Orthod J 2007; 23: 130–136)

Received for publication: May 2006Accepted: August 2007

TREATMENT OF A DEEP BITE MALOCCLUSION IN A PERIODONTALLY COMPROMISED ADULT


overjet of 8 mm and an overbite of 5 mm. Themandibular incisors impinged on the palatal mucosa.Although the maxillary dental midline was coincidentwith the facial midline, the mandibular midline was2 mm to the right side of the maxillary midline(Figure 2). The lower arch was constricted with theright second premolar inclined lingually. The curve of Spee was increased, and there was 3 mm of crowd-ing in the mandibular arch. The Bolton analysis suggested a slight tooth size discrepancy in themandibular anterior region. The patient had no temporomandibular symptoms and there were noclinical signs of temporomandibular joint dys-function. There was no history of bruxing or para-functional activity.

Radiographic evaluation

The pretreatment panoramic film confirmed that allpermanent teeth, except the third molars, were present. It also confirmed that the maxillary right lat-eral and central incisors, the maxillary right secondpremolar and mandibular right lateral incisor wereroot filled (Figure 3). There were vertical and hori-zontal bony defects in both arches, particularlyinvolving the maxillary right lateral and central incisors. Bone had been lost along more than half themesial and distal root surfaces of these teeth. Therewas also evidence of external root resorption involv-ing the maxillary central and lateral incisors. Themandibular condyles appeared to be asymmetrical.

Figure 1. Pretreatment profile and frontal photographs.

Figure 2. Pretreatment intra-oral photographs.

FERREIRA AND FERREIRA


Periapical views confirmed the extensive bone lossand external resorption.

The lateral cephalogram confirmed that the patienthad a skeletal 1 relationship, protruding maxillaryincisors and proclined lower central incisors (Table I,Figure 4).

Problem listThe principal problems were: generalised severechronic periodontitis with horizontal and verticalbone loss, particularly on the maxillary incisors;external root resorption involving the maxillary right incisors; proclined maxillary incisors with an 8mm overjet and severe lip strain on closure; themandibular incisors impinged on the palatal mucosa.

The first objective was to improve the patient’s perio-dontal health by improving his oral hygiene, by deepscaling and root planing, and periodontal surgery ofthe teeth with deep pockets. When this objective hadbeen met the intention was to align the teeth in botharches, to reduce the overbite and overjet by intrud-ing and retracting the maxillary anterior teeth with aforce acting just below the combined centre of resist-ance of the incisors; to obtain facial balance with thelips in contact when at rest; to provide a stable andfunctional occlusion.

TreatmentRoot scaling, planing and modified Widman flap sur-gery were used to correct the bony defects and remove

Figure 3. Pretreatment panoramic radiograph.

Figure 4. Pretreatment cephalometric radiograph. Figure 5. Estimated centre of resistance for lateraland central incisors. The open circle indicates theestimated centre of resistance for maxillary lateraland central incisors.



debris and granulation tissue from the teeth withpockets. Ten days later the periodontal status wasconsidered to be healthy and under control.3 Afterthe treatment plan and risks had been explained tothe patient, it was decided to band and bond botharches with a 0.022 x 0.028 inch preadjusted brackets and use 0.0175 inch multistrand archwiresto align the teeth. The initial archwires were replaced

one month later with 0.014 inch stainless steel arch-wires and then, at monthly intervals, 0.016 inchstainless steel and 0.016 x 0.016 inch NiTi archwires.When final alignment had been obtained, the incisorbrackets were removed and impressions were takenfor a modified splint plate to intrude and retract themaxillary incisors as a single unit, with the retractionforce passing slightly below their combined centre ofresistance (Figure 5).6 The objectives were to retractthe upper incisors with minimal extrusion, and withlittle/no molar extrusion. The splint plate wouldensure that the incisors acted as a single unit duringretraction. A closed 100 g NiTi coil spring (GACInternational, Japan) was stretched between a hookset into the acrylic splint section of the appliance anda hook on the palatal arch soldered to the upper firstmolar bands (Figure 6). Two sectional 0.016 x 0.022inch stainless steel wires were placed buccally in themaxillary arch. A 0.017 x 0.025 inch stainless steelarchwire was placed in the lower arch. After intrusionand retraction of the maxillary incisors, the incisorbrackets were rebonded and a continuous 0.017 x0.025 inch TMA archwire placed. Approximately,one month later this was followed by a 0.019 x 0.025inch TMA wire. A hybrid archwire (0.019 x 0.025inch TMA wire in the incisor segment and sectional

Figure 6. Upper appliance. Double palatal arch, NiTi closed coil frompalatal arch to splint, sectional buccal archwires.

Table I. Summary of cephalometric findings.

Area Measurement Standard Pretreatment Post- Differencetreatment

Maxilla to cranial base SNA (°) 82 ± 4 80 79 1Mandible to cranial base SNB (°) 76 ± 3 77 76 1

SN-Go-Gn (°) 32 34 35 1FMA (°) 22 ± 3 26 27 1

Maxillo-mandibular ANB (°) 5 ± 2 3 3 0Maxillary dentition 1 to NA (mm) 4 12 7 5

1 to SN (°) 103 120 100 201 to NA (°) 22 40 21 191/FPI (°)Ballard 107 132 113 19

Mandibular dentition 1 to NB (mm) 4 6 8 21 to NB (°) 25 25 26 1

IMPA (°) 95 ± 6 92 95 3Interincisal relationship 1/1 (°) 127 ± 10 111 129 18Occlusal plane Occ. Pl (°) 14 12 16 4Soft tissue Z angle (°) 78 ± 5 76 77 1Facial height index13 PFH (mm) 30 to 60 (41) 54 54 0

AFH (mm) 39 to 80 (60) 71 74 3FHI 0.70 0.76 0.72 0.04



0.019 x 0.025 inch stainless steel wires in the buccalsegments joined with 0.017 x 0.025 inch NiTi T-loops) was used to close the spaces between themaxillary lateral incisors and canines. No elastics wereworn during treatment. The finishing archwires were0.019 x 0.025 inch stainless steel.

The appliance was removed and Hawley retainersplaced in both arches. The maxillary Hawley appli-ance had canine hooks for light anterior elastics. Thepatient was referred to his dentist to determine ifthere was any need for occlusal adjustment after 22months of active treatment. No occlusal adjustmentwas necessary.

Post-treatment the right side molars were in an end-to-end relationship and the canines in Class II relationship, which may have been avoided if the

right second premolar had been extracted. Thisoption was rejected because it considered space closure could result in the incisor extrusion and pro-longed treatment. The left side molars and caninesmaintained a Class I relationship, and the midlinesand bone levels improved significantly (Figures 7 to9). The maxillary incisors were monitored with radio-graphs and no increase in root resorption wasobserved post-treatment. Root resorption in ortho-dontic patients has been associated with a number ofsystemic conditions, but in patients with chronicperiodontal conditions it may occur in the absence ofan orthodontic force.7,8

The post-treatment cephalometric tracing showsgood control of the vertical occlusal plane (Table I,Figures 10 and 11). The skeletal relationship (angle

Figure 7. Post-treatment profile and frontal photographs.

Figure 8. Post-treatment intra-oral photographs.



ANB) was maintained, and the maxillary incisorswere retroclined and extruded slightly. The man-dibular incisors were proclined slightly and themandibular molars distalised and slightly extruded.The maxillary molars were protracted bodily.

Discussion

The external root resorption, severe bone loss andprocumbent incisors limited the treatment approach,which was chosen to minimise the risk of furtherattachment loss and root resorption. Due to the factthat there had been significant bone loss around the

maxillary incisors pretreatment and periodontal surgery had been carried out, loss of the interdentalpapillae was expected. As a result, dark spaces were present between the anterior teeth at the end oftreatment.

One of the aims of the appliance used was to apply a light and predictable force (about 25 g to each incisor) from a 100 g NiTi coil spring stretchedbetween the splint and palatal sections of the appli-ance. A second aim was to arrange the force vectorslightly below the combined centre of resistance ofthe incisors so that the incisors would be tipped

Figure 9. Post-treatment panoramic radiograph.

Figure 10. Post-treatment cephalometric radiograph.

Figure 11. Pre- and post-treatment cephalometric superimpositions. Superimposition on S-N plane at sella (left), and area superimpositions on ANS-PNS at ANS andmandibular plane at menton (right).

palatally. In the present case true palatal translation ofthe maxillary incisors may have reduced the over-jet, but it would not have reduced the marked incisorproclination associated with the periodontal condition.

A combined orthodontic-periodontal approach isessential for the successful management of adults witha malocclusion and severe horizontal and verticalbone loss.3 The first steps are to stabilise the patient’speriodontal condition with good home care and periodontal treatment. It is also necessary to obtaingood compliance from the patient. Providing there isno further periodontal disease a new attachment maybe formed after orthodontic intrusion. There is alsosome evidence that periodontal surgery produces apositive stimulus for new bone formation.3,9–11

The small decrease in the facial height index (from 76degrees to 72 degrees) occurred because the verticaldimension increased slightly.12,13 We attribute thischange to the small amount of mandibular molarextrusion as there was a corresponding increase in theocclusal plane to Frankfort plane angle. There wereno adverse effects on the vertical positions of the maxillary incisors.

After orthodontic treatment there were still signifi-cant bony defects and gingival margin discrepancies, especially in the maxillary anterior and posteriorregions. The periodontal tissues appeared healthy,there was minimal apical root resorption and theroots of the teeth were in good positions. Favourablefacial aesthetics were also achieved. Interdigitation ofthe teeth on the right side could have been better hadthe second premolars been extracted but, as we havementioned above, this option was rejected to avoidprolonged treatment, possible loss of teeth and extru-sion. However, a good functional result was obtainedwith group function in lateral excursions and anter-ior guidance with posterior disocclusion. The midlinedeviation was also corrected.

Summary

Pretreatment periodontal surgery and intrusion withlight forces encouraged the development of a perio-dontal attachment to the teeth affected by severe horizontal and vertical bone loss. Following ortho-dontic alignment the maxillary incisors were splintedtogether and retracted with a force acting just belowthe combined centre of resistance of the maxillaryincisors. Anchorage was provided by a palatal archand sectional buccal archwires and retraction by a

closed coil spring. Retraction of the proclined incisorsimproved the facial aesthetics.


Dr Marcelo do Amaral Ferreira1183, Pref. Omar Sabbag AvenueJd. Botanico Zip Code 80.210.000Curitiba, ParanáBrazilTel: +41 3262 2672Email: [email protected]

References1. Busson E. Contribution des Techniques Pluridisciplinaires a

l´Esthétique. Orthod Fr 1991;62:191–249.2. Melsen B. Management of severely compromised orthodon-

tic patients. In: Nanda R, ed. Biomechanics in clinicalorthodontics. Philadelphia: WB Saunders, 1997: 294–319.

3. Cardaropoli D, Re S, Corrente G, Abundo R. Intrusion ofmigrated incisors with infrabony defects in adult periodon-tal patients. Am J Orthod Dentofacial Orthop 2001;120:671–5.

4. Burstone CJ. Deep overbite correction by intrusion. Am JOrthod 1977;72:1–22.

5. Turley P. An American Board of Orthodontics case report:the surgical-orthodontic management of a Class I malo-cclusion with excessive overbite and periodontal bone loss.Am J Orthod Dentofacial Orthop 1993;104:402–10.

6. Vanden Bulcke MM, Burstone CJ, Sachdeva RCL, DermautLR. Location of centers of resistance for anterior teeth dur-ing retraction using the laser reflection centers technique.Am J Orthod Dentofacial Orthop 1987;91:375–84.

7. Davidovitch Z, Godwin S, Young-Guk P, Taverne AAR,Dobeck JM, DeSanctis GT. The etiology of root resorption.In: McNamara JA, Trotman CA, eds. Orthodontic treat-ment: Management of unfavorable sequelae. Ann Arbor:Center of human growth and development, University ofMichigan 1996:93–117.

8. Owman-Moll P, Kurol J. Root resorption after orthodontictreatment in high- and low-risk patients: analysis of allergyas a possible predisposing factor. Eur J Orthod 2000;22:657–63.

9. Roberts WE, Chase DC. Kinetics of cell proliferation andmigration associated with orthodontically induced osteogen-esis. J Dent Res 1981;60:174–81.

10. Nemcovsky CE, Beny L, Shanberger S, Feldman-Herman S,Vardimon A. Bone apposition in surgical bony defects fol-lowing orthodontic movement: a comparative histomorpho-metric study between root and periodontal ligament-dam-aged and periodontally intact rat molars. J Periodontol2004;75:1013–19.

11. Corrente G, Abundo R, Re S, Cardaropoli D, CardaropoliG. Orthodontic movement into infrabony defects inpatients with advanced periodontal disease: a clinical andradiological study. J Periodontol 2003;74:1104–9.

12. Vaden JL, Harris EF, Behrents RG. Adult versus adolescentClass II correction: a comparison. Am J Orthod DentofacialOrthop 1995;107:651–61.

13. Horn AJ. Facial height index. Am J Orthod DentofacialOrthop1992; 102:180–6.



Introduction

Miniscrews, or temporary anchorage devices (TAD),have become increasingly popular because of theirability to provide stable anchorage and facilitate toothmovement, often in directions not possible with con-ventional methods. In a previous paper miniscrewswere introduced and the direct and indirect appli-cation of forces from these devices described.1 Thesites for miniscrews and some of their limitationswere discussed. Although many cases require simul-taneous tooth movement in several directions the following cases have been selected to illustrate the useof direct and indirect forces from miniscrews.

Case reportsCase 1. Extraction treatment – use ofdirect forceA 35 year-old woman presented with the chief com-plaint of an unsightly upper left canine that hademerged high in the labial sulcus. She felt the promi-nence of the canine gave her an unattractive smile andhad affected her self-esteem. The overjet and overbitewere within normal limits and both upper and lowermidlines had shifted to the left side. The secondbicuspids and molars were restored. In the lower archthe bicuspids and left lateral incisor were crowdedand a small, peg-shaped supernumerary tooth wasimpacted between the left canine and second bicus-pid (Figures 1 and 2, Table I). The objectives were toreduce the prominence of tooth 23 and relieve thecrowding in both jaws without a detrimental changein her profile, to correct the midlines and close anyresidual extraction spaces.

The treatment preference was to extract teeth 15, 25,45 and the supernumerary tooth to provide space tocorrect the crowding in both arches. The wider firstbicuspids would provide a better occlusion with theopposing teeth and offer more occlusal guidance thanthe smaller second bicuspids. Furthermore, shouldthe extraction spaces open post-treatment they wouldbe less visible and easier to close.

Buccal miniscrews were placed in the mandiblebetween the left second bicuspid and canine and theright first and second molars (Figure 3a). Buccal andpalatal miniscrews were placed in the maxilla betweenthe right and left first and second molars (Figures 3band 3c). The sites for the miniscrews were determinedby the location of the crowding and the midline dis-crepancies. As there were adequate spaces between theroots of the teeth the devices were inserted at thebeginning of the treatment. However, in many casesminiscrews are placed after the teeth have been aligned.

Composite onlays were added to the occlusal surfacesof the upper molars to prevent interference from thecusps of the bicuspids during retraction (Figure 3b).2Lingual buttons were bonded to the palatal surfacesof the upper canines and first bicuspids and the teethretracted with short lengths of elastomeric chain tothe palatal miniscrews (Figures 3b and 3c). This is anexample of a direct force.1 As treatment progressedthe composite molar onlays were removed and com-posite pads bonded to the palatal surfaces of theupper central incisors (Figure 3c). The extractionspaces closed within 10 months and the midlineswere corrected over the ensuing months. There wereno detrimental changes in her profile (Figure 1).


Use of miniscrews as temporary anchorage devicesin orthodontic practice. II - Case reports

George AnkaSpecialist practice, Tama-shi, Tokyo, Japan

Aim: To illustrate the use of miniscrews to facilitate tooth movement mesially, distally and vertically.Method: Three cases are presented showing the use of miniscrews and direct and indirect forces.(Aust Orthod J 2007; 23: 137–146)

Received for publication: March 2006Accepted: September 2007

ANKA


Table I. Cephalometric findings.

Case 1 Case 2 Case 3

35 y 6 m 37 y 9 m 15 y 4 m 17 y 2 m 16 y 0 m 18 y 4 m

Facial angle 82.2 86.5 82.1 85.7 85.6 86.0Convexity 6.3 7.4 3.6 3.4 -5.0 -4.3A-B plane -3.2 -4.8 -0.7 -1.8 4.8 4.8Y-axis 66.3 62.4 67.7 64.6 65.1 64.9FH to SN 7.8 11.0 9.0 13.4 7.4 6.4

77.4 79.1 75.0 74.1 75.6 77.575.0 75.8 73.9 72.5 79.0 80.12.4 3.3 1.1 1.6 -3.4 -2.6

N-Pog to SN 74.4 75.6 73.1 72.3 78.2 79.6Nasal floor to SN 15.3 15.4 9.6 7.6 10.3 7.5Nasal floor to FH 7.4 4.4 0.6 -5.8 2.9 1.1Mandibular plane to SN 40.5 39.2 49.1 49.9 39.7 38.5Mandibular plane to FH 32.6 28.2 40.1 36.5 32.4 32.1Ramus plane to SN 98.9 100.0 95.8 91.1 103.7 93.4Ramus plane to FH 91.0 89.0 86.9 77.7 96.3 87.0Gonial angle 121.6 119.2 133.2 138.8 116.1 125.1U1 to SN 93.6 97.1 110.9 101.0 106.8 110.4U1 to FH 101.5 108.0 119.9 114.5 114.1 116.8L1 to mandibular plane 88.4 96.9 78.4 85.7 90.0 77.6Interincisal angle 137.5 126.8 121.6 123.4 122.6 133.6Occlusal plane to SN 24.9 21.9 22.7 24.9 20.9 16.9Occlusal plane to FH 17.1 10.9 13.7 11.5 13.5 10.5

Figure 1. Pre- and post-treatment profile views of Case 1.

SNASNBANB

USE OF MINISCREWS – CASE REPORTS


Figure 2. Pretreatment intra-oral photographs of Case 1.

Figure 3. (a) Buccal miniscrews between teeth 26, 27 and 33, 35 (reflected image).(b) Palatal miniscrews between teeth 16, 17 and 26, 27, elastomericchains to lingual buttons and composite additions to the occlusal surfaces ofthe molars. Only the left buccal miniscrew is visible.(c) A later stage in treatment: palatal and buccal miniscrews and anteriorbiteplanes on teeth 11, 21.

(a)

(c)

(b)

ANKA


Treatment was completed in 21 months, which in ourexperience is a slightly shorter period than conven-tional treatment would have taken (Figure 4). How-ever, the miniscrews gave us greater freedom in thechoice of the extraction sites, provided ample anchor-age to complete the treatment and avoided use of anyextra-oral device. Therefore, the success of treatmentwas not threatened by a failure to wear an extra-oralappliance.3,4 Although the miniscrews were removed atthe time of debonding they may be left in place untilthe clinician is confident that relapse is unlikely.

Case 2. Nonextraction treatment – use ofindirect forceA 15 year-old girl presented with a forward tongueposture and tongue thrust during swallowing, shorttongue frenulum and bimaxillary protrusion. She was concerned about the positions of the upper anterior teeth and her gummy smile (Figure 5). Theanterior teeth in both jaws were crowded, the overbitereduced and the overjet increased (Figure 6). She had

an acceptable profile (Table I). The main objectiveswere to improve the positions of the upper anteriorteeth, particularly tooth 11, and reduce the gummysmile.

Extraction of bicuspids was considered and wouldhave been the treatment choice prior to the intro-duction of miniscrews.5–7 In this case we decided notto extract bicuspids, but to distalise the teeth with theaid of miniscrews. All third molars were present. Afterconsultation with the patient and her parents, thelower third molars were extracted and the remaininglower molars uprighted. A tongue frenectomy wasalso carried out, followed by myofunctional therapy.The patient and her parents would not agree to havethe upper third molars extracted, which limited dis-talisation of the upper molars. In cases such as thisretention of the upper third molars may be associatedwith relapse of the upper molars.

After the extraction of the lower third molars, fixedappliances were placed to align and level the teeth inboth jaws. Four months after bonding the appliances,

Figure 4. Post-treatment intra-oral photographs of Case 1.



palatal miniscrews and an upper palatal arch bar wereused to intrude the upper molars and increase theoverbite (Figure 7). When the overjet and overbitewere corrected we turned our attention to the gummysmile, and after consulting the patient we placed twofurther miniscrews between the upper central and lateral incisors (Figure 7b).

Short Class III intra-oral elastics were used to improvethe interdigitation and upright the lower incisors. Tocorrect the upper midline the anterior section of thepalatal arch was removed and the horizontal sections(extended arms) and elastomeric chain used to dis-talise the molar on one side without affecting theteeth on contralateral side (Figure 7c). Distalisationusing an extended arm should be done carefully as themolar to which the arm is attached may rotate. When

the upper molars are displaced relative to each otheran extended arm(s) should be used from the begin-ning of treatment. We have found that if the molarson one side have to be moved more than 2–3 mm,bilateral chain from buccal and palatal miniscrewswill prevent the molar from rotating and ensure thatit moves distally without binding.

In the present case the appliance was removed after17 months of treatment (Figure 8). The protrusiveupper teeth and gummy smile were corrected and thetendency to an open bite reduced: the latter proved tobe the most difficult part of the correction (Figures 5and 8). During treatment the mandible rotated clock-wise, in spite the small amount of molar intrusionevident on the cephalometric tracings (Figure 9, Table I). After treatment the patient was pleased

Figure 5. Full face photographs of Case 2 at the start of treatment and post-treatment. Patient smiling.


ANKA


(c)

Figure 7. (a) Palatal arch with short chains to miniscrews. (b) Labial miniscrews covered with wax between teeth 11, 12 and 21, 22. (c) Extended palatal armsmade from horizontal sections of the palatal arch, elastics not shown.


(a) (b)

with her profile and ability to eat foods that she hadpreviously found difficult to incise.

Case 3. Nonextraction, skeletal 3 open bitecorrection – indirect forceA mild skeletal jaw discrepancy may be camouflagedby repositioning the teeth so that a favourable result,both functionally and aesthetically, is obtained. Asthe skeletal discrepancy worsens orthodontic treat-ment alone cannot meet these objectives and orthog-

nathic surgery is the preferred choice of treatment.Skeletal malocclusions with a vertical component,such as an anterior open bite, are especially difficultto treat with conventional orthodontic methods.8.9

The following case demonstrates the value of mini-screws for treatment of a skeletal 3 open bite mal-occlusion after earlier orthodontic treatment hadfailed. Class II open bite malocclusions can also betreated successfully with the aid of miniscrews andextraction of bicuspids.10



Figure 9. Cephalometric tracings of Case 2.

Figure 10. Pre- and post-treatment profile views of Case 3.

(a) (b)

This 16 year-old boy presented with a skeletal 3 mal-occlusion with an anterior open bite. His chief com-plaint was of an anterior crossbite. He had hadorthodontic treatment before, but the appliance hadbeen removed because of poor hygiene and lack ofcooperation. The patient had passed the peak adoles-cent growth spurt in height. He had a Class III profile and a protrusive lower lip (Figure 10a). Healso had an anterior open bite and the upper centralincisors and left lateral incisor were in crossbite(Figure 11). The patient’s chin and the lower midlinewere displaced to his left side. The latter was 3 mm tohis left side (Figure 11b). The mandible was not dis-placed on closure into the intercuspal position. Thecephalometric findings indicated that he had a mod-erate skeletal 3 malocclusion (Table I).

The primary objectives were to correct the anterioropen bite and anterior crossbite. The treatment

options discussed with the patient and his parentswere orthodontic treatment and orthognathic sur-gery. The latter was considered should further facialgrowth worsen either the open bite or anterior cross-bite.9 The treatment preference was for nonextractionorthodontic treatment with miniscrews to retract thelower molars as much as possible, particularly themolars on the right side, so that the lateral skeletaldiscrepancy could be camouflaged.

Following levelling and alignment of the teeth inboth arches with fixed appliances, buccal miniscrewswere placed between the lower first and secondmolars and buccal extended arms added to the firstmolar bands (Figure 12a). The molars were moveddistally with elastomeric chain between the mini-screws and arms, and coil springs between the molars.After the anterior crossbite had been corrected apalatal arch with hooks was added to the upper first

ANKA


(a) (b)

Figure 12. Side and palatal views of the appliances. The posterior maxillary teeth have been intruded and distalised slightly.

(a) (b) (c)


molar bands and the upper arch retracted and intrud-ed using the palatal miniscrews (Figure 12b). Thecase responded well to the treatment and themandibular lateral skeletal discrepancy was less con-spicuous (Figures 11 to 14). The treatment time was2 years and 2 months. Throughout treatment thepatient had myofunctional therapy, which may assistwith retention.

Miniscrews, as temporary anchorage devices, offernew possibilities in orthodontic treatment. Thechoice of teeth to be extracted does not depend onthe anchorage value, teeth can be moved in directionswhich are often not possible with conventional fixedmethods, and compliance is usually assured. Directforces from a miniscrew to a tooth are a simple andeffective means of moving teeth. Indirect forces,

which offer a wider range of manoeuvres than simpledirect forces, usually require a palatal arch andextended arms soldered to either the upper or thelower molar bands.

Summary

Miniscrews, in combination with palatal arches withhooks and extended arms from the first molars, canbe used to correct malocclusions in non-compliantpatients and malocclusions that are difficult to treatusing traditional methods.

Acknowledgments

To the dedicated scientists and clinicians responsiblefor developing temporary anchorage devices.




Figure 14. Pre- and post-treatment cephalometric tracings of Case 3.


Dr George AnkaKeio Seiseki Sakura Gaoka A Bldg. 2FSekido 1-11-1Tama-shiTokyoJapanTel: 00 81 42 337 2525Fax: 00 81 42 339 0918Email: [email protected]

References1. Anka G. Use of miniscrews as temporary anchorage devices.

I – Introduction. Aust Orthod J 2006;22:131–9.2. Anka G. Management of non-compliant Class II Div 1

extraction cases with jumping appliance Forsus DPR – asuggestion of the use of Gurin lock and anterior fixed biteplate. Ortodontia 2004;9:122–33.

3. Cole WA. Accuracy of patient reporting as an indicator ofheadgear compliance. Am J Orthod Dentofacial Orthop2002;121:419–23.

4. Agar U, Doruk C, Bicakci AA, Bukusoglu N. The role ofpsycho-social factors in headgear compliance. Eur J Orthod2005;27:263–7.

5. Tong H, Chen D, Xu L, Lui P. The effect of premolar extrac-tions on tooth size discrepancies. Angle Orthod 2004;74:508–11.

6. Boley JC, Mark JA, Sachdeva RC, Buschang PH. Long-termstability of Class I premolar extraction treatment. Am JOrthod Dentofacial Orthop 2003;124:277–87.

7. Janson G, Brambilla AC, Henriques JF, de Freitas MR,Neves LS. Class II treatment success rate in 2- and 4-pre-molar extraction protocols. Am J Orthod DentofacialOrthop 2004;125:472–9.

8. Beckmann SH, Segner D. Changes in alveolar morphologyduring open bite treatment and prediction of treatmentresult. Eur J Orthod 2002;24:391–406.

9. Proffit WR, Bailey L’T, Phillips C, Turvey TA. Long-termstability of surgical open-bite correction by Le Fort Iosteotomy. Angle Orthod 2000; 70:112–7.

10. Xun C, Zeng X, Wang X. Microscrew anchorage in skeletalanterior open-bite treatment. Angle Orthod 2007;77:47–56.

ANKA


Introduction

Class II malocclusions occur in a significant numberof orthodontic patients. Distalisation of the uppermolars, aimed at increasing the lengths of posteriorbuccal segments, is a frequently used method of treat-ment for this condition.1 This type of therapy is indicated in patients with a normal or hypodivergentface, a deep bite with or without a flat facial profile,missing upper third molars, and when patientsand/or their guardians refuse extraction treatmentand the orthodontist deems nonextraction treatmentappropriate ethically. It is contraindicated in patientswith increased facial divergence or a skeletal open biteas distalisation may result in extrusion of the uppermolars, and an increase in the vertical skeletal dimen-sion and backward and downward movement of themandible.

Typically, the upper molars are moved distally beforethe premolars and anterior teeth are retracted.Distalisation is more effective if it is carried out beforethe premolars have emerged and prior to emergenceof the upper second molars as it allows the leewayspace to be exploited.2,3 Distalisation at this time

significantly shortens the treatment time and lessensthe need for extractions.4

The popularity of distalisation has led to the evol-ution of a large number of intra-oral and extra-oralappliances for this purpose. Extra-oral appliances,such as headgear, rely on a system of anchorage located external to the oral cavity to discharge theunwanted reaction forces. Intra-oral devices, on the other hand, may be subdivided into single archand intermaxillary or two arch appliances. The former are usually used in the upper jaw and mayinclude: NiTi springs and wires, magnets, Jones jig,pendulum and the distal jet appliances.5–10 Two archappliances, which exploit the mandibular arch foranchorage, include devices such as: the Herbst appliance, Jasper jumper, cantilever bite jumper,mandibular anterior and repositioning appliance(MARA) and eureka spring appliance.11,12

Of the devices available for distalisation, we prefer touse a modification of Carano’s distal jet appliancebecause it achieves about the same amount of distal-isation in the same time frame as other distalisingappliances. The distal jet appliance also leads to less


Molar distalisation with skeletal anchorage

Antonio Gracco, Lombardo Luca and Giuseppe SicilianiDepartment of Orthodontics, University of Ferrara, Ferrara, Italy

Background: Distalisation of the upper molars can be used to treat a dental Class II deep bite malocclusion with a flat facialprofile. It is a useful procedure when extraction treatment has been refused and providing distalisation is an appropriate solutionto the patient’s problem. Aims: To describe distalisation of the upper buccal segments using a modified distal jet appliance and miniscrew. Methods: Two case reports are presented. The first case was treated with a distal screw appliance: a modified distal jet appliance with a palatal miniscrew and without the premolar arms. The Nance button was anchored to the palatal bone by aminiscrew inserted through a posterior locating plate. Locating holes in the plate ensured that the miniscrew was inserted into a site with optimal bone in the posterior part of the palate. The second case was treated with a similar distal screw appliance,but in this case the locating plate was embedded in the acrylic button. The miniscrew was inserted through a prepared hole inthe button and plate. The locating hole(s) ensured that a screw could be inserted into an optimal site to one side of the medianpalatal suture.Conclusions: The distal screw appliance can be used to distalise upper teeth with minimal or no anchorage loss. (Aust Orthod J 2007; 23: 147–152)

Received for publication: August 2007Accepted: September 2007

GRACCO ET AL


tipping during distalisation, it does not produceunwanted vertical changes, it does not rely on patientcompliance and, finally, after the active distalisationphase the Nance button can be used for anchoragecontrol.10,13

Distal screw appliance

Use of the distal jet appliance, as with all intra-oraldistalising appliances, involves a certain amount ofanchorage loss, which consists of an unwelcomemesial movement of the premolars and an increase inoverjet.1 Indeed, Nishii et al.,14 who used a distal jetappliance, found that the second premolars moved0.6 mm mesially for each millimetre of molar distal-isation. Furthermore, they observed that the maxil-lary incisors also moved labially (approximately 2.4mm of labial movement per millimetre of distal-isation) and proclined approximately 4.5 degrees.Ngantung et al.15 observed that greater mesial tipping(approximately 12.2 degrees) occurred if the upperarch was banded at the time distalisation was under-taken.

Anchorage stability is often an essential factor for thesuccessful treatment of Class II malocclusions, andunstable anchorage can lead to unfavourable occlusalrelationships and complicate subsequent treatmentprocedures. Many implant systems have beenemployed in attempts to ensure stable skeletalanchorage during molar distalisation such as: the

Graz implant-supported pendulum, the bioresorb-able implant anchor for orthodontics system, theStraumann orthosystem, the Frialit-2 implant system,the Oric implant system, the onplant system and,more recently, non-osseointegrated or partiallyosseointegrated orthodontic miniscrews.16

In order to achieve distalisation of the upper molarswithout anchorage loss, Carano combined the distaljet appliance with miniscrews.17 He placed the mini-screws palatally in the interradicular spaces eitherbetween the premolars or between the molars andpremolars. He chose these sites based on work carriedout by Poggio,18 who indicated that the optimal sitesfor implants in the maxilla were the interradicularspaces between the first molar and second premolar,the first and second molars and the first and secondpremolars. However, these sites are not without com-plications. Insertion of miniscrews between the molarand premolar roots requires a surgical protocol, doesnot allow good oral hygiene and, most importantly,impedes distal movement of the premolars. For thesereasons we modified the original distal jet applianceto exploit skeletal anchorage in the palate. We alsosimplified the device and placement of the mini-screws and reduced the bulk of the appliance.

In order to discover the ideal sites for miniscrews inthe palate, we measured the thickness of the palatalbone at four sites on both sides of the median palatalsuture in children and adolescents between 10 and 15

Figure 1. Initial version of the distal screw appliance (left) and latest version (right). Note the absence of stabilising arms, the positions of the locating plates and thelocating holes for the miniscrews.

years of age.19 We found that the palatal bonethinned progressively from anterior to posterior andfrom medial to lateral. Our data supports Carano and co-workers,13 that the anterior paramedianregions of the palate are the sites of choice for mini-screws. In children and adolescents the thickest bonewas found 4–8 mm behind and 6 mm lateral to theincisive foramen. Posterior sites are suitable forimplants, despite the fact there is less bone, because inthis area there are double cortical plates covered withthin mucosa.19

Based on these data we modified the original distal jetappliance by removing the arms for premolar anchor-age and adding a stainless steel locating plate to theNance button. We have called this appliance the dis-tal screw appliance. Initially, we tried adding a shapedstainless steel plate to the posterior periphery of theNance button. The plate had holes for miniscrews atappropriate distances on both sides of the medianpalatal suture. In our latest version we have incorpor-ated the locating stainless steel plate into the resin andpierced both resin and plate with six holes, 3 mm and6 mm on both sides of the median palatal suture(Figure 1). The holes in this latest modification takeadvantage of the thicker bone anteriorly and, as a result,the appliance is more secure than our first design.

The distal screw appliance has some additionaladvantages over the conventional distal jet appliance.By removing the premolar stabilising arms the

appliance is less bulky and spontaneous distalisationof the premolars can occur in the early stages of treat-ment. Furthermore, the combination of the Nancebutton and a palatal miniscrew provides maximumanchorage upon completion of distalisation. Unlikeother intra-oral distalising appliances, which requirethe upper molars to be distalised before the premolarsand anterior teeth can be retracted, the distal screwappliance allows the premolars to move spontaneous-ly or to be moved distally. Once a Class I molar rela-tionship has been achieved any residual spaces in theupper arch can be closed. In our experience this appliance results in shorter treatment and chair timesand requires less patient compliance than otherdesigns.

Case 1

A 12 year-old girl with a Class II malocclusion presented in our clinic and we decided to treat theproblem by distalising the upper molars (Figure 2).We used a distal screw appliance with a pierced locat-ing plate extending posteriorly from the Nance button and a 9 mm miniscrew. The appliance wasactivated monthly and the upper molars were dis-talised without loss of anterior anchorage in 4 months(Figures 3 and 4). During treatment the premolarsspontaneously moved distally (Figure 4).

We found that the upper first molars were moved dis-tally 3.88 mm and tipped distally 3.08 degrees with

MOLAR DISTALISATION WITH SKELETAL ANCHORAGE


Figure 2. Case 1. Pretreatment intra-oral views of the mild Class II malocclusion in a 12 year-old girl.

GRACCO ET AL


respect to the base of the cranium.20 There was noappreciable change in the position of the upper incisors. The premolars spontaneously moved 1.68mm distally and tipped 3.74 degrees distally. Ourdata agrees with the data published by Carano, whoreported a mean molar distalisation of 3.2 mm anddistal tipping of 3.1 degrees in 20 patients treatedwith the distal jet appliance.1 However, Carano’sappliance resulted in the upper premolars movingmesially 1.3 mm and tipping 2.8 degrees mesially.1

Case 2

This 15 year-old male adolescent presented at ourclinic with a Class II malocclusion, a hypodivergentprofile and slight anterior crowding. To obtain a Class

I dental relationship we decided to distalise the uppermolars with a distal screw appliance. We removed thepremolar arms and embedded a stainless steel locatingplate in the Nance button. The plate and acrylic hadholes for miniscrews, 3 mm and 6 mm on both sidesof the median sagittal plane. In this case a single 1.5mm diameter, 9 mm miniscrew was used. After 9months treatment a Class I molar relationship wasachieved. (Figures 5 and 6).

The upper occlusal photographs show how theabsence of the stabilising arms on the premolars permitted spontaneous distal migration of the anteri-or teeth and partial resolution of the crowding. Ontracings of the patient’s pre- and post-treatmentcephalometric radiographs the upper molars were dis-talised 3.88 mm and tipped distally 3.08 degrees. Thepremolar crowns also moved 1.68 mm distally andtipped 3.74 degrees distally while the incisorsremained more or less stable. (Figure 7).

Conclusions

The distal screw appliance is a modified distal jetappliance without the premolar arms and with alocating plate embedded in the Nance button. Thelocating plate allows a miniscrew to be placed in thethick palatal bone to one side of the median palatalsuture. The absence of the premolar arms permits thepremolars to spontaneously move distally. It can beused to distalise the teeth in the upper arch with

Figure 3. Case 1. Molar distalisation with the initial design and spontaneous distal movement of the uppersecond premolars.

Figure 4. Case 1. Pre- and post-distalisation tracings superimposed on maxilla.

MOLAR DISTALISATION WITH SKELETAL ANCHORAGE


Figure 5. Case 2. Pretreatment intra-oral views of the mild Class II malocclusion in the 15 year-old malepatient.

Figure 6. Case 2. Molar distalisation with the latest design of the distal screw appliance and spontaneousdistal movement of the second premolars.

Figure 7. Case 2. Pre- and post-distalisation tracings superimposed on maxilla. Note there was minimal change in the upper incisors.

minimal or no anchorage loss and in a relatively shorttreatment time. The appliance does not rely onpatient compliance.


Antonio GraccoVia E. Scrovegni 235100 PadovaItalyTel: +39 (0532) 202 528Fax: +39 (0532) 202 528Email: [email protected]

References1. Bolla E, Muratore F, Carano A, Bowman J. Evaluation of

maxillary molar distalization with the distal jet: a compar-ison with other contemporary methods. Angle Orthod 2002;72:481–94.

2. Gianelly AA. A strategy for nonextraction Class II treat-ment. Semin Orthod 1998;4:26–32.

3. Gianelly AA. Leeway space and the resolution of crowdingin the mixed dentition. Semin Orthod 1995;1:188–94.

4. Gianelly AA. Crowding: timing of treatment. Angle Orthod1994;64:415–18.

5. Gianelly AA. Distal movement of the maxillary molars. AmJ Orthod Dentofacial Orthop 1998;114:66–72.

6. Kalra V. The K-Loop molar distalizing appliance. J ClinOrthod 1995;29:298–301.

7. Blechman AM. Steger ER. A possible mechanism of actionof repelling, molar distalizing magnets. Part I. Am J OrthodDentofacial Orthop 1995;108:428–31.

8. Jones RD, White JM. Rapid class II molar correction withan open-coil jig. J Clin Orthod 1992;26:661–4.

9. Hilgers JJ. The pendulum appliance for Class-II noncom-pliance therapy. J Clin Orthod 1992;26:706–14.

10. Carano A, Testa M. The distal jet for upper molar distaliz-ation. J Clin Orthod 1996;30:374–80.

11. Beccari S, Sfondrini G, Gandini P. The Herbst and JasperJumper method in the orthodontic fixed appliance.Ortognatodonzia Italiana 1992;4:525–40.

12. Blackwood HO. Clinical management of the Jasper Jumper.J Clin Orthod 1991;25:755–60.

13. Carano A, Testa A, Bowan J. The distal jet simplified andupdated. J Clin Orthod 2002;36:586–90.

14. Nishii Y, Katada H, Yamaguchi H. Three-dimensional eval-uation of the distal jet appliance. World J Orthod 2002;3:321–7.

15. Ngantung V, Nanda RS, Bowman SJ. Postreatment evalua-tion of the distal jet appliance. Am J Orthod DentofacialOrthop 2001;120:178–85.

16. Papadopoulos M. Orthodontic treatment of the class II non-compliant patient. Mosby, Elsevier, 2006:15–54.

17. Carano A, Velo S, Leone P, Siciliani G. Clinical implicationsof the miniscrew anchorage system. J Clin Orthod 2005;39:9–24.

18. Poggio PM, Incorvati C, Velo S, Carano A. ‘Safe Zones’: aguide for miniscrew positioning in the maxillary andmandibular arch. Angle Orthod 2006;76:191–7.

19. Gracco A, Lombardo L, Cozzani M, Siciliani G.Quantitative evaluation with CBCT of palatal bone thick-ness in growing patients. Prog Orthod 2006;7:164–74.

20. Ghosh J, Nanda RS. Evaluation of an intraoral maxillarymolar distalization technique. Am J Orthod DentofacialOrthop 1996;110:639–46.

GRACCO ET AL



Editorial

In his Comment Professor Herbison mentions‘MCID’ or minimal clinically important difference,which has been defined as, ‘the smallest difference inscore in the domain of interest which patients perceiveas beneficial and which would mandate, in theabsence of troublesome side effects and excessive cost,a change in the patient’s management’.1 Other morestraight-forward definitions are, ‘the smallest differ-ence in a score that is considered to be worthwhile orimportant’,2 ‘the minimum absolute risk reduction forwhich patients would take a treatment given theirunderstanding of the risk without that treatment’3 or,an interesting variation, the mean score for an optimalresult minus the mean score for a group with a sub-optimal result.4 Quite simply it is the smallest difference patients (and clinicians) would care about.

When we get around to using them in orthodonticsMCIDs will first, and foremost, tell us what is clinic-ally important and what isn’t. As Professor Herbisonmentioned, a MCID is often larger than a statisticallysignificant difference, which in the absence of a clinic-ally significant difference might be of little practicalimportance. They will help us judge the benefits whencomparing two methods of treatment (e.g. functionalsand headgear or early and late treatment); they willhelp researchers who are planning studies to calculatethe sizes of their samples and, therefore, will give usinformation on the usefulness of their data; they willenable us to make inferences about the percentage ofpatients improved by a method of treatment; and theywill allow us to make cost-effectiveness comparisons.5With MCIDs we will have a much better idea whatare appropriate and effective methods of treatment.

A MCID is more likely to be ‘context-specific’ (i.e. theconditions present when something like a 5 mmreduction in overjet occurs) than a fixed number suchas a 5 mm reduction in overjet with no conditions.6Finding out what is clinically important might startwith a discussion with colleagues and patients and endup gathering both subjective and objective infor-mation. The input from patients could be in the form

of a quality of life questionnaire, and from the clinic-ians a measurement of, say, overjet, crowding or use of a rating scale. As you can imagine there will be disagreements as to what constitutes a MCID becausethere will be different opinions of what is clinicallyimportant. But according to some authors there aresolutions to virtually all the scientific hurdles.7,8

Of the nine methods used in medicine to measure aMCID the method that attracted me was the one thatdoes not rely on memory and does not require longi-tudinal follow-up.9 Instruments that rely on memoryare fallible and may provide misleading evaluations ofwhat patients actually experienced.5,10,11 Part of theproblem comes when they are asked to remember thefrequency of events over a fixed period of time (e.g. ‘Inthe last three months how often have you had sores inthe mouth?’ Can you remember?). Problems can alsooccur when patients are lost from the study, if they can’t be bothered answering the same question-naire time and time again or if the quality of theirresponses diminishes over time.

The innovative approach used by Redelmeier etal.10,11 gets around the problem of relying on patients’memories by pairing patients with the same conditionand asking them to compare themselves with theirpairs rather than relying on their memories of the pastcondition. Clinician administered surveys or measurescan be used as well. Although the method has somedisadvantages, such as the difficulty of assembling arepresentative group of patients for a sufficient periodof time, its advantages may more than compensate forits disadvantages.5,11 But devising a MCID may bejust the start of the story: it has been suggested that aMCID (or for that matter one of the indices we use)for improvement may not be the same as one for dete-rioration: this should be followed-up.6 Measurementerrors, MCIDs and quality of life instruments havenot received the attention they deserve from the pro-fession. Some of the innovative approaches used inmedicine may be of value to us.

Michael Harkness

What is a minimal clinically important difference?

EDITORIAL

Australian Orthodontic Journal Volume 23 No. 2 November2007154

References1. Jaeschke R, Singer J, Guyatt GH. Measurement of health status:

ascertaining the minimal clinically important difference.Control Clin Trials 1989;10:407–15.

2. Hays RD, Woolley JM. The concept of clinically meaningfuldifference in health-related quality of life research.PharmacoEconomics 2000;18:419–23.

3. Man-Son-Hing M, Laupacis A, O’Connor A et al. Warfarinfor atrial fibrillation; the patient’s perspective. Arch InternMed 1996;156:1841–8.

4. Quinn JV, Wells GA. An assessment of clinical wound evaluation scales. Acad Emerg med 1998;5:583–6.

5. Wright JG. The minimal important difference: Who’s to saywhat is important? J Clin Epidemiol 1996;49:1221–2.

6. Beaton DE, Boers M, Wells GA. Many faces of the minimalclinically important difference (MCID): a literature reviewand directions for future research. Curr Opin Rheumatol2002;14:109–14.

7. Sloan JA. Assessing the minimally clinically significant dif-ference: scientific considerations, challenges and solutions.COPD 2005;2:57–62.

8. Kirwan J. Minimal clinically important difference: the crockof gold at the end of the rainbow? J Rheumatol 2001;28:439–44.

9. Wells G, Beaton D, Shea B et al. Minimal clinically impor-tant differences: Review of methods. J Rheumatol 2001;28:406–12.

10. Redelmeier DA, Guyatt GH, Goldstein RS. Assessing theminimally important difference in symptoms: A comparisonof two techniques. J Clin Epidemiol 1996;49:1215–19.

11. Redelmeier DA, Guyatt GH, Goldstein RS. On the debateover methods for estimating the clinically important differ-ence. J Clin Epidemiol 1996;49:1223–4.


Letter

Force and tooth movement

Sir,

I am writing in response to the article in the last issueof the Journal by Drs Hong, Woods and Stella on thetopic of 3D-CT radiographic scanners.1 The authorsmention a number of ways the data collected by thesescanners can be applied in dentistry. With specific reference to their uses in orthodontics, the authorsrefer to recent work measuring the cross-sectional area and volume of muscles. The maximum cross-sectional or projected area of the tooth roots can alsobe obtained and is the dimension which, knowing thevalue of the force applied, provides us with the averagepressure exerted on the tissues surrounding a toothduring orthodontic tooth movement. This writer2 andRen, Maltha and Kuijpers-Jagtman3 conducted experiments relating force and tooth movement.When the forces to obtain optimal rates of toothmovement were converted to pressures by dividing theforce values by the average value of the projected rootarea of the distal surface of upper cuspid (0.97cm2),the average optimum pressure for this writer’s experi-ment was 203 cN cm-2. In Ren’s experiment the forcelevel at which the highest rates of tooth movementoccurred was, in most subjects, 200 cN giving an average optimum pressure of 206 cN cm-2, bothexperiments confirming the estimates of Jarabak andFizzell,4 based on Smith and Storey’s results.5,6 Theseare average values. Individual values may vary according to bone density. This information is alsoobtainable from the scanners.

Other dimensions obtainable are total root volumeand the volume of the root enclosed in bone. Thesetogether with projected area, could enhance the accuracy of the determination of the appropriate force to apply, whether for anchorage or for tooth

movement – another field of research – to lead on

from Dr Chris Miles’ study of the root volume of thepermanent dentition.7

It is clear that these scanners will provide us withmuch more information, enabling us to prescribeforces, which will deliver optimal rates of movementand treat our patients as individuals, rather than treat-ing them with one ‘dosage’ of force delivered by theone type of appliance.

Brian Lee3 Lynden RoadBonnet HillTasmania 7053AustraliaEmail: [email protected]

References1. Hong JC, Woods M, Stella D. Three-dimensional com-

puted craniofacial tomography (3D-CT): potential uses andlimitations. Aust Orthod J 2007;23:55–64.

2. Lee BW. The force requirements for tooth movement, PartIII: the pressure hypothesis tested. Aust Orthod J 1996;14:93–7.

3. Ren Y, Maltha JC, Van’t Hof MA, Kuijpers-Jagtman AM.Optimal force magnitude for orthodontic tooth movement: amathematical model. Am J Orthod Dentofacial Orthop2004;125;71–7.

4. Jarabak JR, Fizzell JA. Technique and treatment with thelightwire appliances: light differential forces in clinicalorthodontics. St. Louis: Mosby, 1963. 353–79.

5. Storey E, Smith R. Force in orthodontics and its relation totooth movement. Aust J Dent 1952;56:11–18.

6. Storey E, Smith R. The importance of force in orthodontics.Aust J Dent 1952; 56:291–304.

7. Miles C. An analysis of tooth root volume. Masters thesis1986, University of Melbourne.

155

Letters and brief communications are welcomed and need not concern what has been published in the Australian Orthodontic Journal. We will printexperimental, clinical and philosophical observations, reports of work in progress, educational notes and travel reports relevant to orthodontics. Wereserve the right to edit all Letters to meet our requirements of space and format. All financial interests relevant to the content of a Letter must be disclosed.The views expressed in Letters represent the personal opinions of individual writers and not those of the Australian Society of Orthodontists Inc., the Editor,or BPA Print Group Pty Ltd.


Comment

Why would anyone be interested in measurementerror?

Many papers in orthodontics start the results sectionwith an assessment of measurement error. For some orall measurements a proportion is measured again,Dahlberg’s formula is applied and the results pre-sented.1 It is almost a rite of passage for a paper, but it is not always appropriate and often it is an unneces-sary complication for the paper and does not aid interpretation.

When talking about the results for groups of peoplethen the measurement error is almost irrelevant in theabsence of bias. An unbiased measurement is made up of two parts, the true measurement and themeasurement error:

Recorded measurement = true measurement+ measurement error

The measurement error has special properties, it willbe centred around zero, as there is no reason to suspecta bias. Results close to zero will be more common thanthose far from zero, and negative results would be justas common as positive results. This distribution ofresults is called the normal distribution of errors, usually just the normal distribution. One consequence

of this is that if you repeatedly measure the samedimension the sum of the errors will approach zero asthe positive and negative values cancel each other out.It follows that for a reasonable number of measure-ments the sum, and therefore the mean of the recorded measurements, is the same as the sum or themean of the true measurements.

Thus, when using the mean of a number of measure-ments of the same dimension the measurement errordoes not affect the mean, and also it will not affect thedifference between two means. What the measure-ment error does affect is the standard deviation, and as a consequence the standard error of the mean islarger the larger the measurement error. Thus, withincreasing measurement error, the difference betweenthe means of two groups has to increase before it is statistically significant.

When using a measurement there are two propertiesto keep in mind: reproducibility and validity. Thereproducibility has to do with measurement error: it iswhether you get the same result if you repeat the samemeasurement. The validity is to do with bias, whetherthe measurement is a good estimate of the true value.The relationship between these is shown in the figure.

The illustration clearly shows that for the interpre-tation of measurements, validity is much more

Reproducible

Yes No

xxxxxxxxx x x x xxx xx xxYes

Valid True value True value

xxxxxxxxxx x x x xxx xxxxNo

True value True value

Figure. Reproducibility and validity.


COMMENT

157

important than reproducibility. If the measure is validthen you still get an approximation to the trueanswer, even though a lack a reproducibility makesthis less precise. Validity is often not an issue inorthodontics as lengths and angles are the usual typeof measurements, and there is no obvious reason whythese may not be valid with good technique and iflandmarks are identified consistently.

Where reproducibility may be an issue is when youare trying to apply results to individuals. The numbergiven by Dahlberg’s formula1 is the amount that maybe due to measurement error. So to be sure that themeasurement has changed in an individual it shouldbe larger than this value. This should not be confusedwith the minimally clinically important difference(MCID),2–4 which is the difference that needs to happen before the patient thinks that it is worth-while. The MCID contains both objective and subjective information. It would almost certainly be larger than the number given by Dahlberg’s formula.

Of course all efforts should be taken to prevent bias(which is a systematic lack of validity) from affectingmeasurements. For example, landmarks should beconsistently identified, different magnificationsshould be allowed for and skulls, or heads, should beconsistently orientated before taking radiographs orphotographs. Other commentators on errors haveconcentrated on reducing bias,5 but bias and repro-ducibility are independent – it is possible to have biasin a highly reproducible measurement or no bias inan unreproducible measurement.

So in conclusion, if the paper is presenting the resultsfor groups, or for differences between groups, it ishard to see how measurement error is useful in theinterpretation of the results. It is only if the results areto applied to individuals that it becomes useful, butin that case a MCID, which is more difficult to determine, is even more useful.

Peter HerbisonDepartment of Preventive and Social MedicineDunedin School of MedicinePO Box 913Dunedin 9054New ZealandTel: 00 64 3 479 7217Fax: 00 64 3 479 7298Email: [email protected]

References1. Dahlberg G. Statistical methods for medical and biological

students. New York: Interscience,1940:90–5.2. Neely JG, Karni RJ, Engel SH, Fraley PL, Nussenbaum B,

Paniello RC. Practical guides to understanding sample sizeand minimal clinically important difference (MCID).Otolaryngology – Head & Neck Surgery 2007;136:14–18.

3. Barrett B, Brown D, Mundt M, Brown R. Sufficientlyimportant difference: expanding the framework of clinicalsignificance. Med Decis Making 2005;25:250–61.

4. Wells G, Beaton D, Shea B, Boers M, Simon L, Strand V etal. Minimal clinically important differences: review of methods. J Rheumatol 2001;28:406–12.

5. Houston WJB. The analysis of errors in orthodontic measure-ments. Am J Orthod 1983;83:382–90.

When should we finish with aClass I molar relationship?

‘The best evidence can inform, but can neverreplace, individual clinical expertise because it is thisexpertise which decides whether the evidence appliesto the individual patient and, if so, how it should beintegrated into a clinical decision.’1

Like many professions we should review the conceptswe use daily in our practices. In this technological agewe have the ability to access and appraise informationthat may be important to our specialty and, if neces-sary, change our working hypotheses.1 I have beenstruck by the confusion that can arise in the minds ofour students and non-orthodontists with one of ourmost fundamental concepts: the Class I molar occlu-sion. When should we consider alternatives to a ClassI molar occlusion?

With the popularity of nonextraction treatment and the availability of preformed archwires and othermatériel required to treat malocclusion, it isinevitable that an increasing number of non-special-ists will take up orthodontic treatment. What theprofession must remember is that these people lackthe knowledge and experience of the specialist andgenerally accept concepts that we may question ormay have even discarded. Since Angle2 described normal occlusion and attributed the greatest impor-tance to the first permanent molars, we have used theClass I occlusion of the first molars as the ideal occlusion.3 Obviously, there are circumstances whenalternatives to a Class I occlusion should be con-sidered, but what are they? I attempted to find an

answer to this question by systematically searchingthe electronic database for the best available evidence.I also hand-searched six well-known orthodonticjournals: the American Journal of Orthodontics andDentofacial Orthopedics, the Angle Orthodontist, theEuropean Journal of Orthodontics, the World Journal of Orthodontics, the Journal of Orthodontics and the Journal of Clinical Orthodontics. I looked for rele-vant clinical papers and case reports, which mightprovide me with the evidence needed to answer myquestion.

In view of the lack of articles in the literature, I hadto fall back on the case report sections published inthe above mentioned orthodontic journals. The fol-lowing is a brief illustration of some of the publishedcase reports to highlight the problem:

The British Journal of Orthodontics, Case Report Section:

1. Hickman4 published two cases that had been sub-mitted for the William Houston Gold Medal in1997. In his first case report, Hickman stated thatone of the aims of treatment was to, ‘Produce a goodbuccal segment cusp fossae relationship and func-tional occlusion’. In the treatment plan he mentionedthat, ‘The molar relationship was to be a full unitClass II between the upper first molars and the lowersecond molars, and the upper first premolars were tomimic the maxillary canines’. But in his second casereport the aim of his treatment was to, ‘. . . produceClass I mutually protected functional occlusion, camouflaging the mild Class II skeletal discrepancywith . . .’

2. Foong5 also published two cases and he had moreor less the same treatment plan which was directed to,‘Achievement of good occlusal interdigitation forimproved stability of treatment and function’. Hementioned in the post-treatment assessment that, ‘. . . the incisors and canines showed a good Class Irelationship’ and continued, ‘The molar relationshipswere in full Class II because of upper second pre-molar extractions.’ In his second case he mentionedthat, ‘Good occlusal interdigitation and arch align-ment were obtained at the end of treatment’. Thepost-treatment intra-oral photographs of this caseshowed that incisors, canines and first molars were ingood Class I relationships.

3. Mullane6 published two cases and stated in theaims of treatment that he intended, ‘To establish aClass I buccal segment relationship bilaterally’.

In the World Journal of Orthodontics:

1. Costa Pinho et al.7 described camouflage treat-ment of a case with a skeletal Class III malocclusion.They stated in the treatment plan that, ‘An overjetand overbite correction was then attempted, byobtaining a Class I canine relationship, and therefore,a functional occlusion . . .’. In their conclusion theystated that, ‘The proposed treatment objectives wereachieved. These objectives were to obtain a stabledental articulation, good esthetics, and functionalresults in spite of the skeletal disharmony and dentalClass III malocclusion’.

The American Journal of Orthodontics and DentofacialOrthopedics:

1. Bilodeau,8 in an American Board of Orthodonticscase report, pointed that his first objective was to,‘Correct the Class II dental relationship’.

2. Popp et al.9 in their case report, ‘Nonsurgical treat-ment for a Class III dental relationship: A casereport’; stated in their treatment objectives; ‘2. Toestablish Class I canine relationship.’ and ‘6. To estab-lish a functional occlusion.’ However, in the treat-ment plan their second point was to, ‘Establish ClassIII molar and Class I canine relationship.’

Confused? From these case reports published in threeof our most prestigious journals one could concludethat a Class I molar relationship at the end of treat-ment is a matter of debate. It appears to me that wehave at least two schools of thought. The first schoolbelongs to the group that believes a Class I molar rela-tionship is the main objective of orthodontic treat-ment. Interestingly, Popp et al.9 acknowledged theexistence of an alternative form when they concludedthat, ‘Although some may not consider this an idealocclusion, balanced tooth contact can be obtained ina Class III relationship.’ The second school holds theview that Class II or III molar relationship is accept-able providing that there is a balanced functionalocclusion and Class I canine relationship. In thisregard occlusal equilibration after treatment could beconsidered as an essential part of an orthodontictreatment protocol.

I would be interested to know when a Class I molarrelationship should be a treatment objective andwhen it need/should not be an objective?

Hussam M. Abdel-KaderOrthodontic DepartmentFaculty of Dental Medicine

COMMENT


Al-Azhar UniversityCairoEgyptTel: +202-3305-0468, +202-3749-0983Email: [email protected] site: http://www.geocities.com/hussamkader

References1. Harrison EJ. Current products and practice; Evidence-based

orthodontics: where do I find evidence? J Orthod 2000;27:71–8.

2. Angle FH. Classification of malocclusion. Dental Cosmos1899;41:248–64.

3. Andrews L. The six keys to normal occlusion. Am J OrthodDentofacial Orthop 1972;6:296–309.

4. Hickman J. The William Houston Gold Medal 1997.Clinical Section, Br J Orthod 1999;26:81–8.

5. Foong KW. The Gold Medal Prize in the Conjoint M. Orth.Exam of the Royal College of Surgeons of Edinburgh Heldin Hong Kong, 1996. Clinical Section, J Orthod 2000;27:1–10.

6. Mullane C. The William Houston Gold Medal 1998.Clinical Section, BJ Orthod 2000;27:119–25.

7. Costa Pinho TM, Ustrell Torrent JM, Correia Pinto JGR.Orthodontic camouflage in the case of a skeletal Class IIImalocclusion. World J Orthod 2004:5:213–23.

8. Bilodeau JE. American Board of Orthodontics Case Report.Am J Orthod Dentofacial Orthop 1997:111:487–91.

9. Popp TW, Gooris CGM, Schur JA. Nonsurgical treatmentfor a Class III dental relationship: A case report. Am JOrthod Dentofacial Orthop 1993:103:203–11.


COMMENT

159


Tom Graber’s achievements and involvement in dentistry have been adequately dealt with in otherpublications1 and supplementary literature and do notrequire repetition here. I have therefore confined thisobituary to my personal associations with him bothhere and at conferences overseas.

Tom visited Australia more than once and at his firstvisit lectured to State Branches of the Australian Society of Orthodontists. He opened his lecture to theVictorian Branch showing his first slide, which was aphotograph of the mushroom cloud of an atomicexplosion, with the words, ‘This picture represents theeffect that the Begg Technique is having on ortho-dontics in the United States’. At a time when orthodontic teaching was largely empirical and thepredominant technique used in Melbourne was thataccording to Strang’s text book, this came as rather ashock to his audience.

He focused the attention of Australian orthodontistson the work of Dr Begg but ironically lived longenough to see the technique wane as an entity but survive in the adoption by other techniques of the useof lighter forces exerted over a long range of action.

His nature has been variously described as generous,humane, compassionate, vibrant, interesting and exu-berant. As well, I found him to be loving of his craftand dedicated to his profession.

Brian W. Lee

1. Am J Orthod Dentofacial Orthop 2007;132:272–3.

I have known Tom Graber for many years. My husband Milton first met Tom when we were in theUnited States, 1960-63. Thanks to Tom we had anumber of introductions to orthodontists in Europe.We travelled through Europe for several months onour way home to Australia in 1963. Milton kept up aconstant correspondence with Tom, and I finally methim at an orthodontic meeting in Chicago in 1977.He gave me the impression of being such a vibrant,interesting and friendly person. We had travelled toChicago with our youngest son Michael, who wasthen 12. Tom and his gracious wife Doris took us totheir holiday home by a beautiful lake for several days.We did have such a happy and relaxing time, althoughTom was always on the go. Michael turned 13 whilethere and Tom took us and several others to a BunnyClub on his birthday. A birthday he has never forgot-ten! Since then I have met Tom at orthodontic meet-ings in many places. He and Doris have travelled tomany exotic places, and he kept himself remarkablyfit. He was a wonderful host and enjoyed good food,wine and company. We also had the privilege of visit-ing him and Doris in their home in Chicago. The lasttime I saw Tom was at the orthodontic meeting in SanFrancisco in 2005. Although in his eighties, he wasstill full of vitality and passionate about orthodontics.

He wrote me such a lovely letter when Milton passedway suddenly last year. He started with ‘Sad, Sad,Sad’. Tom, I feel the same about you.

Helen Sims

Obituary

Thomas Graber

1917 – 2007


Skeletal Anchorage with Microimplants

A. Korrodi RittoPublisher: Facies(www.ritto-appliance.com)Price: Euro125ISBN: 978 972 99576 3 5

The expressed aim of the Portuguese author of thisslim English language book (76 pages of text with 5pages of references and 283 separate images) is to pro-vide ‘a practical manual and convenient referencework, particularly for those who intend to take theirfirst steps in this area’. The identity of the target read-ership is open to question, for it may be misconstruedas providing sufficient guidance for general dentistswho wish to overcome their existing deficiencies inmanaging orthodontic anchorage.

This publication provides basic descriptions, practicaltips, and cautions in use of various types of micro-implants, TADs, or whatever one wishes to call thesescrew devices. However, it assumes that the reader hasadequate knowledge of the mechanical principles tobe employed, such as identifying ‘centres of resist-ance’, and direction and amount of force applied forvarious orthodontic movements that are illustrated.This assumption is exemplified by the absence of anydetail in the text and in most of the captions accom-panying the illustrations (some even lacking adequatevisualisation of auxiliaries used) to explain how theforce devices were applied for tooth- or arch-segmentmovements. Also, some diagrams, particularly thoserelating to the use of palatal screw anchorage, ignorepredictably adverse effects of various tooth-movingmechanisms that are illustrated.

The book has numerous illustrated examples wherethe use of microimplant anchorage is highly questionable because of low anchorage requirements.

In addition, arguments of low invasiveness and lowcosts that are put forward, imply universal applicationbut neglect emphasising that the essential startingpoint is adequate orthodontic diagnosis to determinewhether or not such anchorage is needed. Thus, inex-perienced clinicians ‘taking their first steps’ with theaid of this text are being misdirected to unnecessaryuse of these screws, while also being encouraged toembark on correction of complex malocclusions forwhich they may not be adequately equipped to ‘keepout of trouble’.

Perhaps this text would be of some use in a special learning situation that links applications of theprinciples of orthodontic diagnosis and mechanicswith the use of microimplant anchorage, also provid-ing opportunity for ‘hands-on’, guided, experience.

Keith Godfrey

Oral Cavity Reconstruction

Edited by Terry A. Day andDouglas A. Girod Publisher: Taylor and Francis Group LLC Price: A$300.00 ISBN 10: 1-57444-892-7 ISBN: 978-1-57444-892-4

Orthodontists and orthodontic trainees occasionallyhave to deal with patients who have undergone sur-gical treatment for oral cavity tumours. This textbook,which is written in the United States, with contribu-tions by Australian surgeons, provides an excellentoverview to the care of patients who present with oraltumours, particularly the reconstructive aspects. Thereare excellent introductory chapters on the principles oforal cavity reconstruction, oral anatomy, function andphysiology. There is a good overview of the varioustumours that may affect the oral cavity, as well as somebenign conditions, including osteoradionecrosis. The

Book reviews

chapters on planning, diagnostic evaluation and sur-gical approaches to the oral cavity complement theintroductory section.

The anatomical challenges in reconstruction are tack-led, including the lips, the buccal mucosa, the tongueand floor of mouth, the hard and soft palates, and themandible. Each anatomical region has excellent dia-grams and clinical photographs to assist the reader inunderstanding the complex issues of reconstruction.For completeness there is an excellent chapter pre-senting an overview of cleft lip and palate reconstruc-tion in the infant. Prosthodontic issues are brieflydealt with, including the use of osseointegratedimplants to support prostheses. The concludingchapters on the rehabilitation of speech and swallow-ing, functional assessment tools, quality of life andnew horizons for the future cap off this excellent text-book. The quality of life issues may be of specialinterest to orthodontists who manage patients under-going surgical orthognathic procedures.

This book is recommended as background readingfor orthodontists and orthodontic trainees who mayhave an interest in surgical oral cavity reconstruction.It is ideally suited to oral and maxillofacial, otolo-laryngology head and neck, and reconstructive plasticsurgical trainees at the beginning of their training, toacquaint them with the range and spread of issuesand options available in oral cavity reconstruction.

David Wiesenfeld

Radiographic Cephalometry: From Basics to3-D Imaging. Second edition

Alexander Jacobson andRichard L. JacobsonPublisher: Quintessence PublishingCompany, Inc.Price: US$110.00ISBN: 0-86715-461-0

Radiographic Cephalometry: From Basics to 3-DImaging is an updated American book, which is pub-lished worldwide. This textbook sets the standard forapplication of cephalometrics in orthodontics. The

book is divided into chapters that first describe therole of cephalometrics, the history and techniques ofcephalometrics followed by the more frequentlyutilised cephalometric analyses applied to contem-porary orthodontic diagnosis. The latter chaptersintroduce the use of digital imaging and three-dimensional cephalometry.

The contributors include many eminent orthodonticand radiographic imaging experts, includingCoenraad Moorrees, Richard Weems, Page Caufield,Scott McClure, André Ferreira, James Vaden, HerbKlontz, Lionel Sadowsky, Joseph Ghafari, LysleJohnston, Shane Langley, Christos Viachos, DavidSarver, Mark Johnston, William Harrell, DavidHatcher and James Mah. This impressive list of con-tributors supports the excellence of the knowledgebase compiled for the second edition of the textbook.Even with the numerous contributors to the textbookthe authors have maintained a similar format andlevel of complexity within each area under discussion.

The early chapters focus on the basic principles ofutilisation of cephalometrics in diagnosis and treat-ment planning, and a brief history of the backgroundleading up to, and the foundations of, the use ofcephalometrics in orthodontics. The technical aspectsand general principles of the cephalometer andobtaining an accurate radiograph are outlined. Thebasics of tracing techniques and landmark identifica-tion are clearly and concisely summarised. Each con-temporary cephalometric analysis is summed up witha detailed description and good illustrations, alongwith applications of the analysis. Keeping pace withadvances in 3-D cephalometric imaging the textbookillustrates the advantages and applications of the newtechnology to contemporary orthodontics. The finalchapter is a critical discussion of the reliability ofcephalometrics. The reality of the limitations ofcephalometrics is discussed.

The textbook is co-authored by Alex and RichardJacobson, and as in their previous textbooks the illus-trations are clear and easily interpreted. The authorsand the publisher have arrived at a balance of colourand contrast that allows excellent representation ofimages. Where necessary, contrasting colours areutilised to clearly outline a diagram or make a point.The computer images are presented with outstandingclarity and definition. The sharpness of the images iscarried over into the digital imaging and 3-D imagingchapters of the textbook.

BOOK REVIEWS


The textbook includes an extremely useful CD-ROM. Manual and digital tracing templates are avail-able on the CD-ROM. These templates are valuabletraining tools and provide practical interpretation ofcephalometric analysis. Also on the CD-ROM arevideo clips that illustrate the unique capabilities andfunctions of 3-D imaging. The video clips demon-strate 3-D imaging technology that would otherwisebe difficult, if not impossible, to display within thepages of a textbook.

Radiographic Cephalometry: From Basics to 3-DImaging is a highly recommended and useful resourcetextbook for all medical and dental libraries, dentaland postgraduate students and orthodontists and oraland maxillofacial surgeons.

Mike Razza

Tip-Edge Plus Guide. 6th Edition

Peter KeslingPublisher: TP Orthodontics, Inc(www.tportho.com)Price: US$109.15

The Tip-Edge Plus Guide and The DifferentialStraight-Arch Technique (Sixth Edition) by PeterKesling continues in hard cover form what essen-tially started out as a technique manual for the newlydeveloped Tip-Edge appliance in the 1980s.

The manual has evolved through its six editions andmany revisions, but retains a core base of funda-mental information which is unchanged. The bookretains the look and feel of a specific technique/appliance oriented manual. As such it is a valuablereference for protagonists of light-wire treatment andespecially Tip-Edge operators. New students of Tip-Edge will find it particularly instructive when startingout and it is best combined with ‘a well organisedcourse given by qualified instructors who have yearsof experience and can demonstrate excellent results’(Tip-Edge Plus Guide).

The Sixth Edition contains comprehensive guidanceon the use of the newest evolution of the appliance,the Plus bracket, which utilises a flexible auxiliaryround wire through deep tunnels in each bracket toachieve final root positioning (including torque, inconjunction with full size rectangular wires in thebracket slot).

The opening pages of ‘The Guide’ outline the evol-ution of the Tip-Edge and Tip-Edge Plus appliance.Mention is made of the philosophy behind the differ-ential straight-arch technique with specific referenceto the individual components of the technique andso-called differential mechanics. This outline is alsosupported at the end of the text by a précis of the concept of attritional occlusion, cited as central to thephilosophy of the technique. Contemporary studentsof orthodontics may take exception to the applicationof the concept in a modern context, but as is often thecase, offhand dismissal would leave a void in theirknowledge and understanding. This is particularly soas much of current orthodontics embraces, knowinglyand unknowingly, tenets of light-wire treatment.

The section on diagnosis and treatment planningmay be seen by some as simplistic and lacking sophis-tication. However the information put forward inthis part is still useful and applicable in many situations and, it must be remembered, is not the primary focus of ‘The Guide’ which is the appliance and technique. The appliance in question and itsapplication in standard and common treatment situations are well-detailed in the body of the text.

The latter part of ‘The Guide’ sets out in succinctform the records of 28 cases treated with Tip-EdgePlus, followed by 16 pages of a question and answerseries taken from the Tip-Edge Today newsletters.Following on are several selected articles from thesenewsletters. While such an archive can never ‘cover allbases’ an examination of this part is almost sure toreveal to, or remind the reader of, some useful tips orgems of information.

‘The Guide’ is completed by a good glossary andindex. The overall text is supported by an extensivebibliography which may be seen nevertheless as notbroad or comprehensive.

The Tip Edge Plus Guide (Sixth Edition) would be auseful addition to any orthodontic library, bearing inmind its genesis and understandable bias.

Stephen Langford


BOOK REVIEWS

163

Clinical Problem Solving in Orthodontics andPaediatric Dentistry

Declan Millett and Richard WelburyPublisher: Elsevier(www.elsevier.com.au)Price: A$98.00ISBN: 0443072655

As outlined by the authors in the preface, this bookhas been written for dental students and dentists intheir early years of practice. There are 37 chapterscovering topics such as ‘absent upper lateral incisors’,‘anterior open bite’, ‘mottled teeth’, ‘oral ulceration’and ‘palatal canines’.

The format of the book is based upon a series of clin-ical scenarios representative of a range of problemsencountered in paediatric dentistry and orthodontics.The scenarios are used as a basis for discussing theaetiology, diagnosis and treatment of the variousproblems which are addressed.

The authors have set out each chapter in a verymethodical fashion. The patient history is outlined,followed by the examination process which involvesthe various diagnostic tests and investigations neededto establish a problem list. Clinical photographs, radiographs, diagrams and tables are used effectivelythroughout the text.

At the end of each chapter, a highlighted ‘key point’is noted. These key points create a very good overviewof the subject and are designed to trigger informationrecall.

When more than one treatment option is appropri-ate, these have been outlined with pros and cons ofeach option. For example, in chapter 6, the topic is‘infra-occluded primary molars’. In the scenariogiven, both mandibular deciduous second molars areankylosed. Treatment options are presented when themandibular second premolars are present and whenthey are missing. Options of extracting the ankyloseddeciduous molars and closing the space ortho-dondically are given as well as holding on to the

retained deciduous molars and eventually replacingthem with a prosthesis. The merits and consequencesof each option are discussed.

Some of the treatment approaches reflect the authors’preferences and other alternatives are not alwaysgiven. For example, in chapter 7, twin block therapyis described as ‘a means of growth modification witha functional appliance’. Other types of functionalappliance therapy are not mentioned. Removableappliance treatment is also used in many cases wherefixed orthodontic mechanics would be more efficient.This either reflects the authors preferences inmechanotherapy or removable appliance treatment isdeemed more appropriate for dental students andgeneral practitioners for whom the book is written.

In summarising a particular topic the authors use atype of flow chart called ‘Mind maps’. Like the ‘Keypoint’ concept, these would be useful for studentsduring the revision process.

I would recommend this text to dental students, general practitioners and dental educators wishing todemonstrate the concept of developing a logicalapproach to problem solving.

Chris Theodosi

Pocket Atlas of Dental Radiology

Friedrich A. Pasler and HeikoVisserPublisher: ThiemePrice: US$44.95ISBN:9781588903358/9783131398017

This pocket book is an English translation of a 2003German text which was designed to assist under-graduate and postgraduate students, and practicingclinicians with aspects of dental radiology. The title ofthe book undersells its scope, since half of the text isdevoted to radiographic pathology and half to radi-ographic technique, radiographic anatomy and imageprocessing.

BOOK REVIEWS


The book follows an unusual format which is relatively information dense, with the left page containing text and the right page containing illus-trations and images, with some 798 radiographsincluded. The tab is also colour-coded to allow readyreference to the various chapters. This somewhatunusual format proves very effective in being able tofind information rapidly.

The first half of the book begins with panoramic radi-ography and then moves on to intra-oral radiographsand then to skull films. Some coverage is provided ofcomputed tomography and magnetic resonanceimaging, although these sections of the book couldcertainly benefit from being expanded, given theincreasing use of computed tomography in variousaspects of contemporary dental practice.

A specific section is devoted to determining the location of malpositioned teeth and this would be ofconsiderable interest and relevance to practitionerswith a strong orthodontic component in their prac-tice. There is a short, but very up-to-date, discussionof radiographic film and conventional film processingand a good coverage of processing and film position-ing errors. The text has a good coverage of digital systems and includes up-to-date information of bothphosphor-plate and sensor systems with a useful discussion of both CMOS and CCD digital sensors.This section is followed by a short, but useful, dis-cussion of radiation exposures with some useful reference tables.

The remaining half of the book is devoted to diagnostic radiology, ranging from dental caries, periodontal and endodontic pathology, through tolesions of the jaws, maxillary sinsuses and temporo-mandibular joints. The useful section is included,devoted specifically to traumatology and an excellentsection is included on the identification of foreignbodies. The quality of the images provided is routinely very high and the line illustrations are particularly well drawn. Numerous photographs ofradiographic technique are included, which are up-to-date and which address issues such as infectioncontrol. Numerous radiographs have detailed codesto identify particular aspects of radiographic anatomyand users at all levels of experience will find these particular useful.

Overall, I found this a very well put together book,which has not suffered in any way from the process oftranslation. It is information dense, but in a way

which is useful, providing within a small number ofpages, an intense coverage of a particular topic.Unlike a number of radiographic texts which are usedin dentistry at the moment, the technical coverage ofaspects of digital imaging is of very high quality andis remarkably up-to-date. The illustrations and diagrams are a particular strength of the book andclearly much effort has been expended to make theseboth very simple and also very realistic. This bookwill be of value to clinicians at all levels of experienceand, while not designed to be an oral pathology text,provide a very useful coverage of all common and lesscommon lesions that are likely to be encountered. Ican see it getting intensive use by undergraduates andpostgraduates, as well as being a ready reference tohave on the shelf in clinical practice.

Laurence Walsh

Applications of Orthodontic Mini-Implants

Jong-Suk Lee, Jung Kook Kim,Young-Choi Park and RobertL. Vanarsdall Publisher: Quintessence Publishing 2007Price: US$168.00ISBN: 978-0-86715-465-8

This book is mandatory reading for all periodontists,surgeons and orthodontists who use or want to usethe new technology called orthodontic miniscrewimplants, also known as temporary anchorage devicesor TADs. This technology is full of promise, but hasoften delivered disappointment. Many remedies aregiven in this book, which contains a complete knowl-edgebase up to 2007 on orthodontic mini-implants.It is a knowledgebase that began about seven yearsago. Many of the studies cited are still pending pub-lication in mainstream journals. Consequently, thisbook contains much new research and knowledge inthe field of mini-implants.

Its Korean authors are all orthodontic university pro-fessors, and are the scientists behind many of thestudies cited. Their studies have refined the designtheory and the protocols for use of TADs. The devices


BOOK REVIEWS

165

are very specialised and differ from implants designedfor dental prosthetics. The initial chapters impart acomplete education in the complex concepts involvedin mini-implants, including, the principles of metalengineering, the histological and biological responsesto the devices and protocols for the use of mini-implants. Previously unpublished anatomical consid-erations are illustrated using cadaver and 3D dentalCT imaging research. Serious consideration of forcevector relationships is fundamental to success whenplanning orthodontic mini-implants, and this topic isextremely well-covered. After reading only a fewpages, I realised the folly of using any implants beforefully digesting the whole text, and then I realised thatthese devices have many more applications than I pre-viously thought. The book is very instructive inmechanotherapy generally.

Many problems in clinical orthodontics are nowproblems ‘we used to have’ because mini-implantshave relegated them to the past. The paradigm shiftis huge! Chapter 1 covers the evolution of non-integrating mini-implants for temporary anchorage.This concept is totally different from the osseointe-grated implants used for tooth prosthetics. There are67 references at the end of this chapter. Chapter 2deals with the biological principles, including: heal-ing at the implant-tissue interface, differences in bonetrauma and healing with pre-drilled and self-drillingimplants and factors lessening survival of healthy tissue at the implant interface (127 references).Chapter 3 covers the mechanical design and operatorhandling of a mini-implant from its tip to its top, andhow these factors bear on the success or failure of amini-implant. For instance, why is there a differencein success between the right and left sides? This chap-ter has 63 references. Chapter 4 covers treatmentplanning, and is illustrated with cadaver cross-sections. There are many, clear illustrations showingin great detail: suitable and unsuitable bones formini-implants, the extent of the attached and freemucosa influencing the choice of site, the thickness ofthe mucosa and the many other hazards. We are ledto conclusions about the proper choice of implantlength, thickness, taper, transmucosal height andangulation. All possible sites of placement are verythoroughly discussed (32 references).

Chapter 5 on 'Surgical procedures' explains the keysto obtaining a stable implant: implant handling,importance of proper hand tools, direct and indirect

approaches, covered placement, length, diameter,angle, vibration, speed, cooling and loading. Also dis-cussed are: pre-operative planning, appointmentscheduling, grip of tools, posture, marking, pre-drilling, direct and indirect approaches, guiding,forces used, post-operative care and patient instruction,removal, loosening, fracture, periodontal injury, damageto teeth and soft tissues, pain, covering over, infectionand choice of an inappropriate site (19 references).

Chapter 6 on 'Mechanics' covers: the three-dimensional movement of the dentition, how toavoid what used to be unwanted extrusive effects inconventional mechanics, how to effect what was pre-viously difficult intrusion, effecting extrusion,implant positioning for proper force vectors, indirectuse of anchors, force thresholds, possible orthopaediceffects, the advantage of using ‘force-driven’ mechan-ics over ‘shape-driven’ mechanics, how TADs extendGraber’s classical envelopes of tooth movement, non-surgical correction of vertical excess, whole arch dis-talisation to avoid extractions for moderate crowdingand en masse arch movement to correct dental mid-line discrepancies. There are many case illustrationsin this chapter (28 references).

Chapter 7 reveals a novel paradigm that totallychanges some orthodontic concepts. In 1900, Angle’sparadigm was of a static occlusion; in the 1980s and1990s Proffit’s was of a soft and hard tissue environ-ment limited by ‘envelopes’ of tooth movement. NowTADs stretch all limits of previous envelopes of treat-ment. ‘Loss of anchorage’ is no longer a limit; it doesnot exist. Molar intrusion by braces is easy, so thatnon-surgical treatment of severe open bite andgummy smiles is routine. Tooth displays (within thelip lines) can now be elevated or depressed, pro-tracted, canted or retracted, and moved transverselyor unilaterally without surgery. Our guides are nowaesthetic, face-driven treatment goals in non-growingpatients, and are no longer bound by the limitationsthat existed prior to skeletal anchorage. Occlusalplanes can be tipped according to the aesthetic goalsof treatment. Levelling can be planned for occlusion,A-P and transverse occlusal plane, for gingival mar-gins and for healthy alveolar bone heights. Our VTOis now a much more detailed calculation, since wehave better control of more variables. The chaptercontains an excellent review of these principles and ofsmile aesthetics with many case illustrations (60 references).

BOOK REVIEWS


Chapter 8 details the new mechanical concepts needed for orthodontic appliances working in ournew A-P anchorage paradigm. These include how tocontrol tooth tip, torque, archform distortion andbowing, control of arch level and arch canting, bodily and en masse retraction and protraction ofteeth, control of transverse and vertical bowingeffects, midline deviations, molar distalisations andperiodontal bunching problems. There is a detaileddiscussion of the force vectors needed for tooth movement. These vectors dictate the proper position-ing of the mini-screws and lever arms. Inexperiencedclinicians need to be cautious because with secure anchorage (compared with old paradigmmechanics) the wanted and unwanted tooth move-ments will be larger than without a mini-screw TAD.Typical issues include over retraction and over intrusion (implants are apical to the occlusal plane),plane canting, root resorption and pushing teeth outof the alveolar trough and out of attached mucosa (24references).

Chapter 9, 'Vertical control', demands a very detailedappreciation of the force vectors acting on teeth axesin all in three dimensions, as well as in the incisal A-P positions and occlusal planes. Archwiresdesigned for tooth intrusion will normally extrudeadjacent teeth (because much less force is needed forthis), unless a mini-implant anchor is added to thesystem. The position of a TAD will influence the out-come. The efficiency of the mechanics varies with dis-tance from a TAD to the target teeth. ‘Force-driven’mechanics work more efficiently than ‘shape-driven’mechanics, but the side-effects need to be controlled.Monitoring of the periodontium, root resorption,torque, tip, arch symmetry and facial change areimportant. Incisor extrusion without increasing thefacial vertical dimension (formerly a difficultmanoeuver) can now be achieved when implants bolster the anchor teeth. Control of incisor tipping(that accompanies intrusion - extrusion) must beplanned into the mechanics. Molar intrusion is athree-dimensional exercise needing mindful controlof the tilt of the occlusal plane, molar vertical posi-tion, molar tip and torque, molar axis, centre of rotation of the segment being intruded and the rootareas of the teeth to be moved. All these things will bechanged by intrusive forces from implants, so controlneeds to be planned. Single force intrusive vectors canbe joined with continuous arch mechanics to help

cancel side-effects from each force system. Cross-archsplinting will control movement of the upper molarroots, but it reduces efficiency. Cross-arch splintingrequires palatal and buccal implants and for both firstand second molars to be splinted, but it prevents uni-lateral intrusion which needs its own type of specialplanning. Positioning an implant and force system asfar posteriorly as possible is a key to successful controlof the second molar palatal cusp and intrusion. Lowermolar intrusion is especially difficult due to densebone and limited sites for implants. Second molarsneed greater intrusion, but the bone in the area isoften inadequate or inaccessible. Therefore, to con-trol the second molars, indirect anchorage must beused with torque from the buccal. For controlling A-P tipping of an occlusal plane, two implants setapart are needed. Lingual mandibular implants arepossible, but very difficult. Molar extrusion requirespush mechanics off the implants. If used unilater-ally this can correct occlusal plane canting (32 references).

Chapter 10 discusses transverse control. Asym-metrical maxillary crossbite and scissor-bite are situ-ations where mini-implants can assist by bolsteringanchorage on the side needing expansion or con-traction. Single force mechanics to individual orsmall groups of teeth that need uprighting are veryeffective (22 references). Chapter 11 covers pre-prosthetic orthodontic preparation. Mini-implantsprovide anchorage regardless of the condition of thedentition. This final chapter illustrates the usefulnessof creating space for prostheses, for periodontalimprovement and for alveolar bone augmentationthrough tooth movement. Miniscrew implants areespecially useful for the precise control required ofanchor teeth (12 references).

This book is an exquisitely designed and illustratedassistant to the use of the new orthodontic mini-implant technology. It is a timely arrival because thetechnology is new and poorly understood by many inthe profession. The technology promises good things,but unfortunately it has instead delivered much frus-tration to its users. Thankfully, remedies to many ofthe problems are given in this book. The book hastwo basic themes. The first is the biological, mechan-ical theory and material design concepts, which arebased on considerable scientific and engineeringknowledge. The second theme is the practical andclinical application of this knowledge. There are


BOOK REVIEWS

167

many high quality, detailed and annotated sketchesand clinical photographs. It is also the best book onmechanotherapy I have read.

The book illustrates the design concepts embodied inthe 'Orlus' implant system exclusively, in which someof the authors may have a financial interest. This factdoes not detract in the slightest from the value con-tained in the book. Although very high failure rates

are frequently reported, the authors claim very lowfailure rates when observing their principles and useof materials. It is a very significant contribution to thefield of mini-implants.

Geoff Wexler

BOOK REVIEWS



When was your first trip to Japan?

My first trip to Japan was in 1969 en route to Europe.I stayed for a couple of days and gave my first lectureon the Begg technique at the Nippon (Japan) DentalCollege in Tokyo, when Kei Enoki was the Head andKosuke Motohashi was the second-in-command.

Was this the first time that the Japanese hadbeen introduced to the Begg technique?

No, it wasn’t the first time the Japanese had encoun-tered the Begg technique. I don’t recall now, how ithappened. I suppose it was probably after Dr Begg’spublications in the American Journal of Orthodontics.The Japanese were very technology conscious andwere heavily influenced by the Americans after WWII. Japan also had a long association with Germanybecause they saw the Germans as being very proficientmechanically and technically, as well as in chemistry.The Japanese would always seek the latest informationand technology.

Did the Japanese see Australia at the cuttingedge and want the latest informationregarding the Begg technique?

Exactly. Enoki was keen to find out more and came toAustralia, but I have forgotten the date of his first trip.I think it was after I went to Japan for the first time asI remember, I lectured and had lunch with him. It wasrather funny. I was taken out, after I had been lectur-ing in the morning, to a meal of raw fish which I hadnever eaten before. After lunch I think I must haveturned a very green colour and felt horribly ill. I wasawfully embarrassed because I had to lie down for anhour and just couldn’t move. However, the lectureshad to go on and with thoughts of Australian pride Ipersevered, but it was a terrible experience.

I was not certain how I would be received during thatfirst visit to Japan. The Japanese were a passive audi-ence and Enoki was very nice. He had a strong west-ern background and was the head of the department.He obtained his dental degree in America before WWI and had an interesting history because he was nearlyinterned during WW II. The Japanese authoritiesthought he was too pro-western as he could speakEnglish very well and had many connections.

Whenever I went back to Japan there was always a special dinner, often in conjunction with the BeggSociety. Enoki always attended and I remember himtelling me at one stage about the decision to lure meto Japan to teach. Enoki said that the Japanese hadheard of me and had read Raleigh Williams’ publi-cations. It was decided to ask me come to Japanbecause I worked with Dr Begg and, therefore, couldexplain the technique and its latest concepts. TheJapanese were hungry for information and they wouldask questions related to lectures and to previouscourses and visits. When you gave lectures they wouldphotograph all of your slides and tape record yourtalk. After the courses small study groups formedwhich re-examined everything that was said andeverything that was shown. They were disciplined andthey worked very hard.

Were the presentations in Japan aimed atorthodontic postgraduate students or fororthodontists?

For everyone! I think that the first course had about80 participants. The course went for a week, and itwas difficult lecturing to a Japanese group and soEnoki acted as an interpreter. At the end, he and Iwere physically and mentally exhausted because thecourse started at 8.00 am and finished at 6.00 pm. It

Interview

An interview with Milton Sims – Part 2Simon Freezer, Craig Dreyer and Wayne Sampson

The following is the continuation of an interview conducted with Milton Sims during 2000.

Simon Freezer is in private practice in Adelaide and is a senior clinical tutor in orthodontics at the University of Adelaide, Craig Dreyer is senior lecturer inorthodontics at the University of Adelaide and Wayne Sampson holds the P.R. Begg Chair in Orthodontics at the University of Adelaide. Part I was published in the November 2006 issue of the Australian Orthodontic Journal.

INTERVIEW


was non-stop. We were required the entire time forteaching typodont work, lecturing, making and look-ing at archwires, reviewing mechanics, answeringquestions, giving seminars and drawing diagrams onthe blackboard: the days invariably finished late.

I would be taken back to the hotel and asked to beready in 15 minutes to go out for dinner. It was prettyhard as all you wanted to do was to rest and get undera hot shower. Often the evening dinner did not finishuntil 1.00 am and you would go back to the hotel tounload all of the slides from the previous lectures andprepare for the next day. Because of the languageproblem, the presentations had to be visually intenseand so there were a lot of slides to take away. Sometimes, you wouldn’t get to bed until 2.00 am or3.00 am.

However, at the end of every course there was a finaldinner. On these occasions, as at other large politicalmeetings or formal receptions, a gold screen was usually erected. The gold screen in Japan means thatit is an important and formal occasion. The formalcourse dinner would always be held at a top classhotel; in places like the Imperial Hotel or othersnearby. The comfort of these hotels made up for the pain and stress of preparation. A good hotel was needed because it provided the facilities to get yourself going.

Getting back to the gold screen, there was always oneerected at the final dinners. At these dinners someonewould sing, someone would write a poem or tell afunny story and then others were requested to go outto the front and perform. This is the Japanesekaraoke. I can’t remember if we ever had a pianothere, but they used to do all sorts of things. I havelost track of the times that I had to sing ‘Sakura’. Thisis a traditional Japanese cherry blossom song and Iwould sing it after a couple of sake, which is a deadlydrink. The traditional Japanese restaurants are prettyexpensive particularly when geishas serve you. Thesegirls were beautifully dressed and I remember oncehaving so much sake that I thought that I wouldnever be able to stand. It was terrible. You sit on the floor on a cushion for three hours like a yogaexponent without having any practice.

Enoki told me that warriors did this when theyreturned from battle. The survivors would have a traditional dinner with the Daimyo (he was theprince or the leader) in his castle and be served bygeishas. Of course the warriors would drink sake until

they passed out. Anyway, the geisha serving me at thefinal dinner was very nice and continued to pour memore sake. I told her that I should not have any more otherwise I could pose some social difficulties. Shelooked at me with understanding and, with a smile,told me not to worry. So for the rest of the eveningwe were on very good terms.

Did you do all of the presentations by yourself, or was there someone else fromAdelaide to help?

In all of my visits to Japan I was the only presenter,but I travelled with my wife. I had to do it all becausethere were few others available at that time. It tookmonths to prepare for the courses, and it would takeages to settle after arriving back home because therewas a backlog of work to manage. The trips wereorganised by Enoki who arranged the fare and accom-modation, which was a 5-star hotel. Helen and I weremet at the airport by a chauffeur-driven limousinewhich drove us around and showed us the sights. We

Figure 1. Helen and Milton Sims on the day of Milton’s investiture as anOfficer of the Order of Australia.


INTERVIEW

171

were shown a great deal of Japan, but more par-ticularly sights that westerners often didn’t see, all due to the kindness of Enoki. We were taken to his-torical temples, we saw museums, art galleries, placeswhere jewellery was made and even saw a Japanesewedding by chance. Enoki was with us on all but oneof those trips, and they were really nice when youreflect on them.

Was this the time when you became interested in Japanese art?

I had no prior knowledge about Japanese art, but myinterest started on my first visit. I asked one ofEnoki’s staff from the college to take me back to agallery (it was the one time Enoki wasn’t with me). Itwas a very wet day and it was decided to go to anearby print shop instead. I had not seen an extensiverange of Japanese images before and I liked what Isaw. The proprietor was eager for a sale and said thatall of the artists were good. When I asked the price ofthe piece that I really liked, I was told A$500. I onlyhad A$550 to get me to Europe and home again andso I decided to be discretionary. If I had bought thatpicture it would now be worth $100,000 and, in fact,you probably would not even get it for that price.That is how much Japanese art has appreciated in 30years. That was my artistic chance, one of my artisticchances that I missed.

On another occasion, we were taken to an inn nearKyoto. It was the most expensive inn in Japan wherethe royal family regularly visited. It was traditionallyJapanese and it was my first experience of sleeping ona futon on the floor.

In the corner of the room there was, what looked like,a wine barrel made of Japanese cedar with a lid. It wasfull of hot water and that was your bath. I put my handin it several times and the water was almost boiling. Idon’t know how anyone could get in it. But, the foodand the attention at the inn were all out of this world!

I gather that the visits to Japan were part oftrips to Europe to give orthodontic lectures.How often did you travel overseas to providecourses, and what changes did you encounter?

There are benefits in going away and giving a course.I enjoyed travelling and presenting and did it becauseI represented my country and also to help build cred-ibility for the program in the university. People haveoften asked me about the number of papers that Ihave published. It is forgotten that dentistry is a clin-

ical field, so clinicians find it difficult to competewith full-time researchers. I admit that I became a little tired of being asked this question and repliedthat publications have absolutely nothing to do withprofessional standing, which dumbfounded my aca-demic colleagues. I believe that there is only onemeasure of professional standing and that is the number of times you have been asked to travel over-seas and address a meeting and/or give a course. Thatis the only criterion. Some recognition would begained from writing papers, but in a clinical subject(unless you were asked overseas) a university schoolhad little standing.

If you consider the number of times that I went over-seas and also appreciate the time in preparing for eachtrip, it would take many nights and weekends athome getting ready. A huge amount of materialneeded to be organised and I would take away 1500slides at times, not just of theory, but records oftreated cases. This resulted in a request to the uni-versity to provide me with a clinical camera. The university was not interested and declined and so Ihad to buy my own in order to obtain records todemonstrate patient treatment, otherwise you couldn’t lecture. People had to be shown what youactually did.

During your visits to Japan, did you noticeinnovation or their own modifications to theBegg technique?

Well, many things that they tried had already beentried. The Fujita mushroom technique came out ofBegg as an incidental. The Japanese were innovativeand they tried different things, but I think that themajor influence would have been Fujita because hetook the Begg technique and applied it to the lingual.

When did he do that as I believe that multiple lingual orthodontic appliances werepatented in Japan in 1976?

I became aware in about 1975 that Fujita had startedto experiment with lingual Begg and was trying todevelop something quite different. Dr Begg expectedme to rigidly adhere to the technique, because itbecame confusing for people if you talked about vari-ations and improvisations without first having anunderstanding of the basics. A classic example of howthis could happen was when I was asked to speak atthe London congress in 1973. There was a group oftranslators converting my talk into Japanese. I said in

my lecture that I thought it was wrong to tip the teethback so far in the second stage of treatment and follow this with strong torquing auxiliaries. The teethwere tipped back and then tipped forward again andI felt that this was wrong and unnecessary.

Two weeks after that congress I returned to Australiavia Moscow and Tokyo. I spent about four days inMoscow and I arrived back in Adelaide whereuponDr Begg was on the phone. Someone had sent him anairmail letter and he was ropable. He said that I wasgoing against his teaching and he knew what was right. I do not think that he ever forgave me fordeviating from his principles and offering my opinion.

Dr Begg had his finger on the pulse and was alwaystrying to oversee the development of the technique.People would write to him and suggest changes tomechanics because they had heard a lecture reportingbeneficial effects. The Japanese were inclined toaccept the technique and perfect it and I think thatthey realised that I was trying to give them the rightinformation.

On one particular course in Japan a curious andunfortunate thing happened. I was in the middle of awire bending session on a Monday morning and thewhole group was standing around me. A gentlemanwalked up and tapped me on the shoulder, excusedhimself and said that my house had burnt down. Ijust looked at him, said ‘Thank you’, and kept work-ing. I thought that this was silly. He came and tappedme again and repeated the news that my house hadburnt down. I asked him how he knew and he saidthat a message had been received from my wife’s brotherwho tried to contact me in Tokyo. I was a bit shaken,but I continued working for about 15 minutes tryingto focus on what I was doing. I finally rang my motherand she said that she saw it on TV. By that time, thenews had spread and after a few days, all of the peoplein Adelaide had recognised the property and had beento see it. I had to arrange for a guard to be put on thehouse, to safeguard the little that remained.

When was this?

This was in 1973.

INTERVIEW


Figure 2. Milton Sims with participants at the first Begg technique course in 1969.

How did your wife take the news?

I decided not to tell Helen so that she continued toenjoy the trip. The course organisers were going to take us to Kyoto to sightsee and so I thought that I would keep quiet. I told her what had happened to the house when flying home from Japan. I remembered that particular year for manyreasons.

After the 1973 course, the Japanese started comingdown to Adelaide in force and after the first year,Enoki brought a fabulous interpreter. In fact, thisinterpreter attended courses both in Australia andJapan until the last course I gave in Tokyo during the1980s. I remember during a course one afternoon inTokyo I told the interpreter that she might as wellgive the talks for the next hour because I was going tohave a cup of tea. Her interpretive skills were so goodthat she almost knew what I was going to say next.She had heard me many times in Japan and againwhen they brought her down to Adelaide for updatecourses. She was expected to be the travel agent,mother confessor and do all of the organising aboveand beyond the call of an interpreter.

You used to have a little Polaroid camera formaking slides. Is this what you used to prepare your lectures?

In 1976, I purchased my first computer in Londonand a program for making slides. Prior to that I usedto use cut-outs and photograph them. In America, weused to buy plaster letters with pins in them. Youcould get these in photographic shops and they wereused for making movie titles. The letters were pushedinto a pin board and then I would photograph themon Kodak film. Slides were made of paper cut-outs ofteeth and I think that I still have a few of the cut-outsthat I made in America. In the early days, magnetswere put on them to show how teeth could move.This gained popularity and all presenters starteddoing it to show tooth movement. Gradually, thequality of slides kept improving and you always hadto make them better to keep up with the trend. It wasalways a lot of work. The next trend was to tie slidestogether and photograph them and also to put acolour film over a black and white photograph. Wegraduated to use Letraset and photographed the slidetext in black and white, which looked better thanphotography of typewritten letters. Eventually, slidescould be made electronically and in colour with a

Polaroid lens and even with three-dimensional effects.Multicoloured slides could be made with nice titlesand added graphs. Processes improved and becamemore sophisticated. Additional images could bescanned and coloured with a palette to make a multi-pictorial slide. Slides became more than just titles.Today, we have PowerPoint and the ability to makethree-dimensional movies. Technology has broughtus a long way.

When was the Begg heyday in Japan?

The heyday for Begg would have been in the 1970s.Begg was practised everywhere and we could neveraccommodate all the people who wanted to attendcourses. There were always too many.

It was curious because in those days, by governmentrule and regulation, there were no specialties in den-tistry per se, as a Japanese dentist was expected to doeverything. The people who came to the courses werenot specialists, but were general practitioners whohad a special interest in orthodontics.

Enoki appreciated that the Begg technique was idealfor treating the typical Japanese malocclusion becauseit was protrusive with significant crowding. Therewere no anchorage problems that were often experi-enced with other techniques, and there were few biteopening issues. Extraction spaces could be easilyclosed and often you didn’t need much torquebecause the teeth were so protrusive at the start.Enoki also mentioned that, even to this day, theJapanese do not like to undergo orthognathic surgery.There are a couple of clinicians, but one in particular,Dr Etsu Kondo who practises in Tokyo, is extraordin-arily proficient in treating difficult skeletal Class IIImalocclusions with Begg. In fact, Kondo spoke at theASO congress in Melbourne in 1996, but becausethere was a concurrent program she had competitionin another hall. She showed some marvellous casesthat many missed.

The Begg technique is still being used in Japan andEurope, although its heyday has passed.

How have things changed in Japan?

Things have changed in the same way that they havechanged in America. When I first went to Americathey didn’t know much about me, but because I wastalking about the Begg technique, four or five hundred attended my lectures. I lectured about


INTERVIEW

173

anchorage control and the treatment of extractioncases. The Begg technique turned America upsidedown and the same thing happened in Japan. TheAmericans and Japanese found that unless they wereproficient orthodontists there were problems in fin-ishing. Kesling developed the positioner because of the finishing problems. The positioner becamepopular and a similar thing is happening now withthe new invisible orthodontics; it’s really a modernKesling positioner.

Do you have any thoughts on the evolutionof orthodontic appliances?

The world really does go around in orthodontics. It’sgone back to Angle’s time and I don’t believe that anyorthodontist with any serious experience can argueagainst that claim. The bracket fundamentally is notany different from most straight-wire systems. Themetal band has gone and the slot has been angulated.Dr Begg said that Angle had tried brackets withangled slots, but felt they were impractical. The worldsince Angle’s time has seen the bonding of attach-ments which have angulated bases or the angle of theslot on the face changed. It is still fundamentally anangled bracket with the same problems previouslyexperienced by Angle. I think Tip-Edge based on theSved bracket was a very smart move. The Svedbracket is like two ‘V’s’ and in fact I met Sved once inNew York. He showed me some of his non-extraction

cases 30 years out of treatment and they were quiteincredible. I think that Peter Kesling’s adaptation of astraight-wire bracket, the cutting-off of opposite slotcorners offered great potential for the edgewise people and I think for the Begg people too. It was agreat step forward. At the time, the Begg techniquewas being isolated by practitioners who saw edgewiseas a way to make life easier. That’s how it was marketed.

When I went to private practice, I started to use Tip-Edge exclusively because it was hard to obtain at theDental School. The brackets were more expensivethan edgewise brackets, but I found that they workedwell. A few Americans indicated that they used Tip-Edge brackets on canines because anchorage was notlost. They used the traditional edgewise conceptsexcept on the canines. Dr Begg always said that wasone of the major problem areas with extraction cases,as anchorage was lost in trying to get the caninesback. The Keslings said that their greatest sales wereto the edgewise practitioners who bought the Tip-Edge canine bracket. I found that if I didn’t bracketand band my bicuspids until the last stage of treat-ment I could, with the Tip-Edge appliance, get thebite open and not lose anchorage. In fact, I think thatI probably used the lightest torque possible on anter-ior teeth. I was using a 0.020 inch base arch (origin-ally I used 0.022 inch wire but then I cut it back to0.020 inch) and on that 0.020 inch I wound a

INTERVIEW


Figure 3. Participants at the 1977 course on the Begg technique in Japan.

torquing arch that was usually 0.009 inch. Once I put that arch on, I did not have to remove it. It used to take me a while to prepare it and never alongside the patient. There was a simple reason forthat. If you made one and you were almost throughfinishing it (remember 0.009 inch wire is not thateasy to handle) and it broke, your appointmentperiod for the session will be absolutely ruined. Ialways made the archwires and auxiliaries at home. I measured the distances between the canines and theincisors and, when the patients attended, I could simply attach the arches and dismiss them. I usedvery light Class II elastics, changed no more thanonce every five days. I closed extraction spaces withelastic chain and applied it stretched one link frommolar to canine.

So that’s four teeth that you stretched intothree links?

No, it would vary a little depending on where thehooks were placed on the lingual of the molar and abonded button on the canine. The distance on aclosed piece of chain may have been six links fromhook to hook and that was stretched to five links.

So this is on the lingual?

Yes, on the lingual so it couldn’t be seen. I wouldmeasure how much chain I would need and stretch itone link and put it on. If space opened, torque wastoo strong. I used to show this overseas and it wasmisunderstood. In fact, I had one of my cases trans-fer to Canada. I set the patient up and made the referral, but the patient came back 12 months laterand I had more work to do because a torquing auxiliary was placed that was far too strong. It was so strong that half of the extraction space had opened up. That excessive amount of torque wasbeing taught in the States. I treated the mother of this patient at the dental school almost 30 years earlier. She had early Begg therapy and she still has agreat dentition.

Was part of the problem the pre-formedauxiliaries that were being made?

I think that is what happened. Raleigh Williams wasa great operator in both edgewise and Begg. I thinkhe was still working with edgewise concepts in theback of his mind. His torquing archwires had a verystrong action.

Where was he from initially?

I think that Raleigh was from Chicago and was, infact, one of the tutors at the Tweed course. He andKesling were both tutors. To be a tutor there you hadto have the seal of approval from Charlie Tweed. Doyou know that Tweed was like Begg? Tweed presentedthe same attitude and approach to treatment via a dif-ferent mechanism, but he was after the same result asBegg.

I am guessing here but you have to try and lookbehind the scenes. The first thing you need to realiseis that Bob Ricketts was trained by Brodie at Chicago.Brodie, for the whole of his practising life was anAngle disciple, therefore, a nonextraction adherent.After Brodie retired from Illinois, Frans van der Linden asked him over to Nijmegen where he taughtstudents nonextraction mechanics. When I was on atrip to Holland I remember being asked out to dinner and speaking to one of the van der Linden’sstudents. We had a very interesting conversation. Iasked how his cases were going and he said that someof the nonextraction cases will hold up and some ofthem won’t. Brodie was always nonextraction in hisschool, but Ricketts was not totally nonextraction.Ricketts wasn’t going to copy Begg, but was going totry and get around the extraction dilemma. He wassmart enough to realise that edgewise mechanics inthose days couldn’t effectively open the bite. This waswhy segmented arches and intrusion arches becamepopular with those who wanted to have the best ofboth worlds.

In Japan, the tendency was to follow what was hap-pening in America and their American connectionswere very strong. I think that there are some very toprate orthodontists in Japan. One thing I haven’t toldyou is that there were two Begg groups in Japan.There was the Enoki group in Tokyo and the Kamedagroup in the Nigata branch of Nippon Dental Uni-versity. The Begg Society was formed by Enoki andmy last visit in 1997-1998 was the farewell meetingof the Tokyo Begg Society. It was fortunate because Inearly didn’t go.

The Tokyo Begg Society arranged this final trip andindicated that two business class tickets would be pro-vided for Helen and me. I thanked them and agreedto go, but a little later the deal was renegotiated. Alesser amount was offered which wasn’t going to buyme a single economy fare and pay for accommo-dation and so I declined. The Society renegotiated for


INTERVIEW

175

business class fares and three days’ accommodation towhich I agreed and went up there and spoke. At thattime Enoki was very sick and they asked me if a videocould be made to send to him.

However, I am still in contact with Kameda andreceive his journal of publications which show excel-lent treatments. He is now leading the Begg move-ment in Japan, although some have moved away fromthe technique. I have a feeling that you have to havesomeone leading the charge like TP rely on RichardParkhouse. Richard is marvellous, but it is pretty hardto be a one-man band. Perhaps you can imagine theoverseas travel and the efforts to keep courses going.Leading the Begg charge in the early days was a prettybig thing and it was hard on my family. Few peopleappreciated the time and commitment involved.

I think if we are going to ever get the answer to yourquestion about what is happening in Japan, we willhave to go back to Kameda. My guess is the Beggtechnique will last as long as Kameda, as long as he isat his University. He was young when he started, buthe must be getting towards the end of his term. He would be nearly 65 years of age and, usually,retirement age is 65.

In Japan, the universities are highly competitive andEnoki, when I went over there for the first time, waspresident of the Japanese Orthodontic Society. Hewas of some importance. Before he died, he was madean honorary life member of the International Associ-ation for Dental Research in Japan and was a personof high esteem. He ran the big dental complex at

Nippon Dental University in Tokyo, which was oneof the major schools in the country. The other onewas Tokyo Medical and Dental School and Fujimoribecame its Head. Tokyo had a medical attachmentand now there is the first department and the seconddepartment of Oral Biology and, therefore, the firstand second departments of orthodontics. It is so largeand the government provides finance. The schoolsasked me up there at minimal cost because the gov-ernment provided tax relief for courses. It is a bit likeEurope. It is said that Europeans pay more tax thanAustralians. This is probably true, but how do youthink that the Europeans buy their boats to have onthe canals in Sweden, Holland and Denmark?Because these are allowable tax deductions! It wouldbe good if the mortgage on your house was taxdeductible as it is in Holland. That is why they do sowell.

I went to the University of Utrecht when it was amagnificent new school in 1980. I have not seen any-thing to rival it in Australia. The facilities and theteaching laboratories were superb. The beautiful clinics for teaching were highly sophisticated, fundedand coordinated. In the entrance hall there was amuseum of dental items going back to the 14th and15th century. In an open foyer as you entered therewere restored old dental clinics. Things have certainlychanged.

The authors are indebted to Helen Sims for her helpful advice and clarification of places and names.

INTERVIEW



Management of tooth resorption

G.S. Heithersay

Root resorption has been a concern to orthodontistsfor over a hundred years. This timely article reviewsthe diagnosis and management of root resorption and offers an alternative classification. The well-used classification provided by Andreasen in 1970 inwhich resorption is divided into external and internaltypes is limited in its application, and does not coverthe range of possible aetiologies. The article’s sug-gested alternative classification of resorption com-prises three categories, namely a) trauma-induced, b)infection-induced and c) hyperplastic resorption andprovides a more comprehensive classification based onaetiology.The sections on infection-induced and hyper-plastic root resorption are excellent reviews of the cur-rent status of endodontic management of these conditions. Although written for the general dentalpractitioner, the information is essential for the specialist who encounters resorptive pathology in the orthodontic assessment and management ofpatients.Tooth resorption related to orthodontic treatmentfalls into the category of trauma-induced resorptionwhich is subdivided into a) surface, b) transient apicalinternal, c) pressure, d) orthodontic and e) replace-ment resorption. The placement of an orthodonticforce on a tooth has the potential to cause toothresorption, but pressure from other external agents(e.g. a developing tooth) also provides the possibilityof root damage. The author explains that the removalof the pressure usually controls the situation. Theproblem of replacement resorption holds particularconcern for the orthodontist who then has to clinic-ally deal with the problem of ensuing permanenttooth ankylosis. A range of options is provideddepending on the speed of the replacement and thecircumstances of the affected tooth.This article neatly summarises the current under-standing and management of root resorption

and is mandatory reading for those who practice dentistry.

Australian Dental Journal Supplement 2007; 52: S105–21

Frictional properties of aesthetic brackets

C.A. Reicheneder, U. Baumert, T. Gedrange, P. Proff, A. Faltermeier and D. Muessig

Previous studies on the frictional resistance of aesthetic(ceramic) brackets have invariably found a higher levelof resistance with most archwires tested. However,does this apply to self-ligating aesthetic brackets? Theauthors set out to test the frictional properties of twopopular self-ligating aesthetic brackets against fourconventionally ligated aesthetic brackets. Because ofthe need for sliding mechanics, an upper premolarbracket with a 0.022 inch channel, according to theRoth prescription, was selected from several manu-facturers and a number of rectangular archwires of differing dimensions and materials were examined.Frictional values were recorded using a Zwick testingmachine in which each bracket/archwire combinationwas tested 10 times with new brackets each time. Inaddition, one manufacturer’s brackets were aged priorto frictional testing by placement in a chewing simulator, which replicated masticatory cycles andtemperature changes occurring in the oral cavity.Appropriate statistical analysis was applied. Theresults indicated that one manufacturer’s brackets weresignificantly superior to all others. The particularbrackets required the lowest frictional forces in all wiredimensions and qualities. The ‘aged’ brackets pos-sessed higher resistance values compared with newbrackets indicating that bracket ‘wear and tear’increased resistance to sliding.The article was an endorsement of aesthetic self-ligating brackets, but comparisons with stainless steelbrackets would have completed the investigation. Inaddition, confusion still exists between friction andbinding as friction is used to encompass both terms.

European Journal of Orthodontics2007; 29: 359–65

Recentpublications

Abstracts of recently published papers reviewed by the Assistant Editor, Craig Dreyer

RECENT PUBLICATIONS


Cost-effectiveness and patient satisfaction:Hawley and vacuum-formed retainers

L. Hichens, H. Rowland, A. Williams, S. Hollinghurst, P. Ewings, S. Clark, A. Ireland and J. Sandy

Over the past 10 years there has been a significantincrease in the use of vacuum-formed retainers ratherthan the more conventional acrylic and wire varieties.Is this change more cost-effective for an orthodonticpractice? The authors examined this question bycomparing National Health Service and orthodonticpractices in regional England and patient satisfactionwith the various appliances. This was achieved via asatisfaction questionnaire completed while thepatients were waiting for their retainer check 3 and 6months into retention. Clinical effectiveness of the appliances was judged bya change in maxillary and mandibular incisor align-ment over the six-month retention period, while acost analysis was based on influencing factors such as:initial cost of the retainers, clinical time, laboratorycosts, replacement retainers plus data related to eachpatient’s time and travel. Results indicated thatpatients preferred the vacuum-formed retainersbecause of better aesthetics and speech, in addition tofewer breakages. There was no difference in the levelof discomfort. Vacuum-formed retainers stabilisedthe teeth better than acrylic and wire retainers, andwere more cost-effective from the practice and thepatients’ perspectives. The study concluded thatpatients and clinicians preferred vacuum-formedretainers because of their cheapness, compatibilityand effectiveness.

European Journal of Orthodontics2007; 34: 113–27

Decontamination of orthodontic bands following size determination and cleaning

P.E. Benson and C.W.I. Douglas

Orthodontic molar bands are expensive and are re-used after unsuccessful trial fitting during a patientbanding. Wrong-sized bands are cleaned and ster-ilised for reuse, but how effective is the decontami-nation process? This was the question that theauthors attempted to assess. Thirty-two patients hada band trial-fitted to each first permanent molar,which provided a sample of 128. Bands were ran-domly assigned to decontamination or no decontam-ination groups with additional unused/unfittedbands tested to determine baseline contamination.

Bands for decontamination were placed in an ultra-sonic cleaning bath for 15 minutes. Subsequently, allbands were placed in phosphate-buffered saline andassayed by enzyme-linked immunosorbent assay(ELISA) for albumin, and also to detect the presenceof blood and salivary amylase. Although there was areduction in the amounts of amylase, 50 per cent ofthe decontaminated bands showed detectableamounts of protein, but the quantity of albumin wasnot statistically significant. After decontamination,bands would have been placed in an autoclave tocomplete the cleaning/sterilising cycle, but theauthors question the effectiveness of the sterilisationgiven the unclean nature of many of the bands. Theauthors concluded that ultrasonic cleaning of trial-fitted molar bands was not completely effective orefficient, and other means of cleaning organic material from appliances should be investigated.

Journal of Orthodontics2007; 34: 18–24

Elective orthognathic treatment decisionmaking: a survey of patient reasons andexperiences

J. Stirling, G. Latchford, D.O. Morris, J. Kindelan, R.J.Spencer and H.L. Bekker

Why do patients embark on an orthognathic surgicaltreatment plan? After all, orthognathic procedures areelective and should not be entered into without care-ful consideration. The malocclusions that this type ofsurgery manages are seldom life threatening, yetpatients risk complications and morbidity by under-taking these procedures. The question was asked bythe authors who answered it by conducting a cross-sectional survey of patients who were making, or hadmade, a surgical treatment decision in an 18–42month period prior to the study in 2003. Question-naires assessed patient demographics, dental historyand psychopathology, and follow-up interviewsexplored patients’ reasons for, and experiences of,orthognathic treatment. Of the 138 patientsapproached, only 61 participated, whose mean agewas 25 and, of whom, two-thirds were female. Whilepsychopathology scores were within normal range,the interview analysis indicated that patients enteredorthognathic surgery to improve their ‘bite’ as well asto regain a more normal facial appearance. Patientsreported that they were provided with enough serviceinformation, but the risks and benefits of the surgerywere poorly explained. The survey revealed that


RECENT PUBLICATIONS

179

patients possessed strong emotions regarding theirfacial appearance and the surgery that they received,but current practice did not satisfy their psychologi-cal needs and, in some instances, made them feelworse and undervalued. Furthermore, orthognathicpatients did not appear to be making informed deci-sions regarding their surgical treatment. Cliniciansneeded to be aware of the psychology of their patientsas many had unmet needs in relation to their decisionmaking, and the emotional effects relating to treat-ment. The study concluded that, in addition tofocussing on the psychopathology of patients, meas-ures should be considered for the improvement in thepatients’ emotional, social and functional well-being.

Journal of Orthodontics2007; 34: 113–27

Oral health benefits of orthodontic treatment

D.J. Burden

What are the benefits of orthodontic treatment? Ithas been considered that orthodontic treatment hasprovided oral health-related benefits apart from thecosmetic and psychosocial improvements thatpatients seek. In order to answer the question theauthor conducted a review of the literature to findevidence of oral health benefits. The results of the literature search indicated that claims of reduced susceptibility to dental caries, periodontal disease,temporomandibular disorder and traumatic dentalinjury could not be supported. The author contendsthat the oral health benefits of orthodontic treatmentare limited.

Seminars in Orthodontics1007; 13: 76–80


In appreciationReviewers for the Australian Orthodontic Journal

George Anka, Tokyo, JapanDavid Armstrong, Sydney, NSWTheo Baisi, Sydney, NSWSaeed Banabilh, Kelantan, MalaysiaMatthew Barker, Wellington, New ZealandAndrew Barry, Wollongong, NSWPeter Barwick, Auckland, New ZealandDerek Barwood, Auckland, New ZealandJoseph Bleakley, Biggera Waters, QJames Bokas, Burwood, VicKaren Brook, Auckland, New ZealandDarryle Bowden, Cape Schanck, VicJay Bowman, Michigan, USA Peter Brockhurst, Mt Beauty, VicBarbara Carach, Ringwood, VicIsmail Ceylan, Ataturk, TurkeyMujalin Chawengchetta, Khon Kaen, ThailandJonathan Chi, Castle Hill, NSWPeter Cistulli, Sydney, NSWAnthony Collett, Ferntree Gully, VicJohn Coolican, Chatswood, NSWRhonda Coyne, Cairns, QEdward Crawford, Melbourne, VicMarguerite Crooks, Christchurch, New ZealandAli M. Darendeliler, Sydney, NSWSaxton Dearing, Napier, New ZealandCraig Dreyer, Adelaide, SABernadette Drummond, Dunedin, New ZealandStephen Duncan, Sydney, NSWPeter Dysart, Dunedin, New ZealandTheodore Eliades, Nea Ionia, GreeceRay Enlow, Dunedin, New ZealandMark Ewing, Hamilton, New ZealandCarlos Flores-Mir, Alberta, CanadaKelvin Foong, SingaporePeter Fowler, Christchurch, New ZealandElissa Freer, Brisbane, QTerry Freer, Brisbane, QJohn Fricker, Manuka, ACTDavid Fuller, Brighton, VicJoseph Geenty, Fairy Meadow, NSWKeith Godfrey, Sutherland, NSWMithran Goonewardene, Perth, WAUrban Hagg, Hong Kong, P.R. ChinaRoger Hall, Toorak, VicPatrick Hannan, Warana, QWinifred Harding, Dunedin, New ZealandJames Hartsfield, Indianapolis, USA

Michael Hase, Melbourne, VicJames Hawkins, Sydney, NSWDavid Healey, Dunedin, New ZealandAndrew Heggie, Melbourne, VicPeter Herbison, Dunedin, New ZealandChristopher Ho, Brisbane, QKip Homewood, Berwick, VicDouglas Holborow, Dunedin, New ZealandJan Huggare, Huddinge, SwedenNigel Hunt, London, United KingdomChung-Ju Hwang, Seoul, KoreaMichael Hyde, Canberra, ACTHideki Ioi, Fukuoka, JapanJohn Jenner, Adelaide, SALysle Johnston, Michigan, USA Malcolm Jones, Cardiff, WalesAndrew Kalafatas, Booragoon, WASanjivan Kandasamy, Midland, WAChia-Tze Kao, Taichung, Taiwan, Republic of ChinaByron Kardachi, Adelaide SAThomas Kardos, Dunedin, New ZealandPetrina Kat, Campbelltown, SAHeather Keall, Auckland, New ZealandMartin Kean, Geraldine, New ZealandPeter Keay, Sunnybank, QOm Kharbanda, Mumbai, IndiaJules Kieser, Dunedin, New ZealandRussell Kift, Maitland, NSWVincent Kokich, Tacoma, USAAnne Marie Kuijper-Jagtman, Nijmegen, The NetherlandsMark Kum, Christchurch, New ZealandRobert Kusy, Chapel Hill, NC, USAStephen Langford, Adelaide, SABrian Lee, Hobart, TasGavin Lenz, Brisbane, QKerry Lester, Sydney, NSWPeter Lewis, Gordon, NSWRussell Lovatt, Christchurch, New ZealandAndrew Lush, Nelson, New ZealandRandal McAlister, Auckland, New ZealandFraser McDonald, London, United KingdomPatricia Medland, Benowa, QWilliam Medland, Benowa, QMurray Meikle, SingaporeChristopher Miles, Clifton Hill, VicPeter Miles, Caloundra, QSteven Moate, Forestville, NSWKylie Moseling, Burwood, Vic

180

Over the past five years the following individuals have generously contributed their time, knowledge and expertise reviewing articles for the Journal. Wesincerely thank them and acknowledge their considerable contributions which have improved the quality of the Journal.


IN APPRECIATION

181

John Muir, Auckland, New ZealandColin Nelson, Chermside, QRichard Olive, Brisbane, QRichard Oliver, Cardiff, WalesJohn Owen, Midland, WAHyo-Sang Park, Deagu, KoreaSheldon Peck, Boston, USAEdward Peel, Sydney, NSWNeil Pender, Liverpool, United KingdomAndrew Pepicelli, Murrumbeena, VicAngela Pierce, Adelaide, SANeil Pinto, Wagga Wagga, NSWDavid Plunkett, Chester, UKShari Prove, Redcliffe, QAndrew Quick, Dunedin, New ZealandMichael Razza, Perth, WAMarie Reichstein, Adelaide, SASheena Reilly, Melbourne, VicLindsay Richards, Adelaide, SAStephen Richmond, Cardiff, UKChristopher Robertson, Dunedin, New ZealandDavid Rogers, Perth, WAIsao Saito, Nigata, JapanRichard Salmon, Adelaide, SAWayne Sampson, Adelaide, SAJonathan Sandy, Bristol, UKMark Savage, Wanganui, New ZealandAndrew Savundra, Willerton, WAPaul Schneider, Melbourne, VicMichael Schulze, Auckland, New ZealandPeter Scott, Melbourne, VicSteven Scott, The Gap, QWilliam Shaw, Manchester, United Kingdom

Tracey Shell, Moonee Ponds, VicMilton Sims, Adelaide, SAShanti Sivaneswaran, Westmead, NSWKirsty Skidmore, Bristol, United KingdomLesley Snape, Christchurch, New ZealandSteve Soukoulis, Adelaide SAJane Spark, Sydney, NSWRobert Stallworthy, Wellington, New ZealandAntony Stankevicius, Launceston, TasPamela Stevenson, Cardiff, WalesAnthony Sutton, Mackay, QMichael Swain, Dunedin, New ZealandKazuto Terada, Niigata, JapanGuilherme Thiesen, Florianópolis, SC, BrazilMurray Thomson, Dunedin, New ZealandAndrew Toms, Adelaide, SAGrant Townsend, Adelaide, SAColin Twelftree, Adelaide, SAVicki Vlaskalic, San Francisco, CA, USAHilton Wasilewsky, Woollahra, NSWWilliam Weekes, Gosford, NSWAnthony Weir, Corinda, QGeoffrey Wexler, Toorak, VicGregory White, Hawthorn, VicSamuel Whittle, Canberra, ACTPeter Wilkinson, Broadbeach Waters, QMatthew Williams, Wellington, New ZealandMichael Woods, Melbourne, VicPamela Wong, Alexandra Hills, QMasaru Yamaguchi, Chiba, JapanDaxter Yeo, Aspley, QBjorn Zachrisson, Oslo, Norway


Dentyl 2-phase formula mouthwashDentyl pH mouthwash is nowavailable in Australia. This 2-phase oil-water mouthwashcontaining cetylpyridinium chloride helps fight bacteria,bad breath and plaque,according to the manufac-turers. Available in SmoothMint and Refreshing Clove, itis alcohol-free to reduce stinging and burning.

To receive a free sample call Key Pharmaceuticals on1800 653 373For further information contact Symbion DentalTel: 1800 888 262Website: www.dentylph.com.au

Anterior Contraster setAccording to Ortho Organizers,the Anterior Contraster set assistsin presentation of quality slidesand prints. They are made ofanodised aluminium and can beautoclaved. The handles areconveniently shaped so thatpatients can hold them in place.Autoclavable only (no cold sterilization). Adult and child sizesare included in the set.For further information contact Ortho OrganizersTel: 1800 645 813 NZ 0800 440 883Website: www.orthoorganziers.com.au

Occlusal ContrastersThe Ortho Organizers’ OcclusalContraster is designed to simplifyocclusal mirror views, and preventlips, nostrils and moustaches fromappearing in the photograph, accord-ing to the manufacturers. The otherend can be used to ‘black-out’ thebackground in lateral photos.

Autoclavable only (no cold sterilisation). Available in adultand child sizes. Sold individually or in a set.For further information contact Ortho OrganizersTel: 1800 645 813 NZ 0800 440 883Website: www.orthoorganziers.com.au

VectorTASOrmco’s new VectorTAS tempor-ary anchorage system is a co-ordinated system of miniscrews,attachments and instrumentsdesigned specifically for ortho-dontics. VectorTAS providesTAD-specific auxiliary attach-ments and protocols to simplifytreatment mechanics and to facilitate placement and utilisationof temporary anchorage, according to the manufacturers. For further information contact Ormco Pty LimitedTel: 1800 023 603 NZ 0800 446 140

Bendistal pliersBendistal pliers from OrthoOrganizers are specificallydesigned to bend nickel titan-ium archwires. A simple intra-oral adjustment using the V-Bend technique cinches thewires without annealing ortwisting. The pliers can be usedto place permanent bends in lig-ated archwires, according tothe manufacturers.

For further information contact Ortho OrganizersTel: 1800 645 813 NZ 0800 440 883Website: www.orthoorganziers.com.au

New products

New products are presented as a service to our readers, and in no way imply endorsement by theAustralian Orthodontic Journal.

Australian Orthodontic Journal Volume 23 No.2 November 2007 183

2008February 12–15Federation of Orthodontic Associations of Central America andPanamanian Orthodontic Society XCI Congress, Sheraton Hotel,Panama City, Republic of Panama.

March 1–521st Australian Society of Orthodontists’ Congress, Gold CoastConvention and Exhibition Centre, Gold Coast, Queensland,Australia. Theme: State of the art – state of the science.Email: [email protected]: www.aso08.com.au

March 5–8Asociación Mexicana de Ortodoncia 41st Annual Session, HotelCamino Real, Tijuana, Mexico.Website: www.tijuana2008.com

March 28–306th Asian Pacific Orthodontic Congress of the Asian-PacificOrthodontic Society, Shangri-la Hotel, Bangkok, Thailand.Email: [email protected]: www.apoc2008.com

April 12–1310th International Symposium of the Greek Orthodontic Society,Titania Hotel, Athens, Greece.Email: [email protected]: www.grortho.gr

May 7Australian Society of Orthodontists’ Victorian Branch Half DayMeeting. Part I: Infection control in the orthodontic setting. Part II:Medical emergencies and CPR.Email: [email protected]

May 9–11British Orthodontic Society Spring Meeting, Celtic Manor, NrNewport, S Wales.Website: www.bos.org.uk

May 9–11Società Italiana di Ortodonzia & Société Français de OrthopèdieDentofaciale Mediterranean Orthodontic Integration Project.Theme: Efficiency, timing and the future in Orthodontics. Palazzodel Casino, Venice-Lido, Italy.Website: www.venice-sido-sfodf-moip.com

May 16–20American Association of Orthodontists’ Convention and 108thAAO Annual Session, Colorado Convention Center, Denver,Colorado, USA.Website: www.aaomembers.org/mtgs/annual/2008

June 10–1484th Congress of the European Orthodontic Society, Lisbon,Portugal.Website: www.eos2008.com

June 23–25Thai Association of Orthodontists’ Scientific Meeting. Theme:Interdisciplinary treatment. Bangkok, Thailand.Website: www.thaiortho.org

August 27–30XII Congreso Internacional de Ortodoncia of the ChileanOrthodontic Society, Casa Piedra Convention Center, Santiago,Chile.Website: www.sociedadortodonciachile.org

September 11–1360th Annual Scientific Meeting of the Canadian Association ofOrthodontists, Delta Winnipeg Hotel, Winnipeg, Manitoba,Canada.Website: www.cao-aco.org

September 14–17British Orthodontic Society Conference, Brighton, UnitedKingdom.Website: www.bos.org.uk

September 24–27FDI Annual World Dental Congress, Stockholm, Sweden.Website: www.fdiworldental.org

September 27–291st World Implant Orthodontic Conference and 7th Asian ImplantOrthodontic Conference, Seoul, Korea.Website: www.wioc2008.com

October 16–18XII International Symposium on dentofacial development and func-tion of the Egyptian Orthodontic Society, Cairo, Egypt.Website: www.dfdfcairo.com

December 13–14Taiwan Association of Orthodontists’ 21st Annual Conference,Taipei, Taiwan.Website: www.ao.org.tw

December 19–21 43rd Indian Orthodontic Conference, Mumbai, India.Website: www.434rdioc.org

Orthodontic calendar

CALENDAR

Australian Orthodontic Journal Volume 23 No.2 November 2007184

2009

May 1–5American Association of Orthodontists’ Convention, BostonConvention Center, Boston, Massachusetts, USA.

June 9–14European Orthodontic Society Congress, Finlandia Hall,Helsinki, Finland.Website: www.eos2009.fi

September 2–5FDI Annual World Dental Congress, SingaporeWebsite: www.fdiworldental.org

September 10–12Canadian Association of Orthodontists’ 61st Annual ScientificMeeting, Grand Okanagan Lakefront Resort and ConferenceCentre, Kelowna, British Columbia, Canada.Website: www.cao-aco.org

2010

February 6–97th International Orthodontic Congress and 4th Meeting of theWorld Federation of Orthodontists, Sydney, Australia.Website: www.wfosydney.com

Please direct all meeting queries for inclusion in the calendar to Dr Tony Collett Tel: (+61 3) 9756 0519Email: [email protected]


Author indexAbdel-Kader H, 30, 157

Amoah G, 36

Anka G, 137

Armstrong D, 96

Balalaie A, 46

Banabilh S, 89

Bernabé E, 50,

Borges-Yáñez, 50

Carels C, 121

Cerny R, 24

Chan HJ, 55

Closs L, 41

Cozzani M, 109

Darendeliler M Ali, 96

Dinsuhaimi S, 89

Ferreira M, 130

Ferreira R, 130

Flores-Mir C, 50

Godfrey K, 65

Goonewardene M, 16

Gracco A, 109, 147

Harkness M, 76, 114, 153

Heravi F, 104

Herbison P, 114, 156

Ho CT, 1, 8, 79

Jones SP, 36

Kachiwala VA, 72

Kajan ZD, 46

Kalha A, 72

Kandasamy S, 16

Kraikosol K, 65

Kravchuk O, 1, 8

Lee B, 155

Ling K-K, 1, 8

Luca L, 109, 147

Moazzami SM, 104

Nasab NK, 46

Olive R, 1, 8

Petocz P, 96

Quirynen M, 121

Rattanayatikul C, 65

Raveli D, 41

Rösing C, 41

Sharp C, 114

Shen G, 96

Siciliani G, 109, 147

Singh GD, 89

Squeff K, 41

Stella D, 55

Suzina AH, 89

Synnott P, 78

Tahmasbi S, 104

Tennant M, 16

Teughels W, 121

van Gastel J, 121

Vattraphudej T, 65

Vigneshwaran J, 72

Woods M, 55

Subject index

Adult treatment

Treatment of a Class I deep bite mal-occlusion in a periodontally compro-mised adult, 130

Airway

Cranial base and airway morphology inadult Malays with obstructive sleepapnoea, 89

Aesthetic

Comparison of surgical and non-surgicalmethods of treating palatally impactedcanines. II – Aesthetic outcomes, 8

Book reviews

Risk Management in Orthodontics:Experts’ Guide to Malpractice, 78

Colour Atlas of Dental Hygiene –Periodontology, 79

Skeletal Anchorage with Microimplants,161

Oral Cavity Reconstruction, 161

Radiographic Cephalometry: FromBasics to 3-D Imaging. Second Edition,162

Tip-Edge Plus guide. 6th Edition, 163

Clinical Problem Solving in Ortho-dontics and Paediatric Dentistry, 164

Pocket Atlas of Dental Radiology, 164

Application of Orthodontic Mini-Implants, 165

Bone-plate screw

Treatment of skeletal 2 malocclusionusing bone-plate anchorage. A casereport, 65

Brackets

Accuracy of bracket placement by orthodontists and inexperienced dentalstudents, 96

Static frictional resistances of poly-crystalline ceramic brackets with con-ventional slots, glazed slots and metalslot inserts, 36

Camouflage treatment


Case reports


Space closure using the Hycon device. A case report, 72


Use of miniscrews as temporary anchor-age devices in orthodontic practice. II –Case reports, 137

Molar distalisation with skeletal anchor-age, 147

Index to Volume 23The Australian Orthodontic Journal

Casein phosphopeptides

Effect of Topacal C-5 on enamel adja-cent to orthodontic brackets. An in vitrostudy, 46

Ceramic brackets


Class II division 1 malocclusions


Vertical changes in treated and untreatedClass II division 1 malocclusions, 114

Comment

Why would anyone be interested inmeasurement error? 156

When should we finish with a Class Imolar relationship? 157

Cone beam computerisedtomography (CBCT)

Assessment of palatal bone thickness inadults with cone beam computerisedtomography, 109

Contact relationships

Changes in interdental papillae heightsfollowing alignment of anterior teeth, 16

Cranial base


Crossbite

The relationship between malocclusion,fixed orthodontic appliances and perio-dontal disease. A review of the literature,121

Crowding


Deep bite malocclusion


Dental caries


Dental changes


Dental plaque


Distal screw appliance


Distalistion


Editorial

Forty years of publication, 76

What is a minimal clinically importantdifference? 153

Enamel caries


Face height


Fibre reinforced composites

Fracture characteristics of fibre rein-forced composite bars used to pro-vide rigid orthodontic dental segments,104

Finite element morphometry(FEM)


Fixed lingual retention

The reliability of bonded lingual retainers, 24

Fracture load

Fracture characteristics of fibre rein-forced composite bars used to providerigid orthodontic dental segments, 104

Gingival recession

Lower intercanine width and gingivalmargin changes. A retrospective study,41

Hycon device


Impact

The impact of orthodontic treatment onnormative need. A case-control study inPeru, 50

Intercanine width

Lower intercanine width and gingivalmargin changes. A retrospective study, 41

Interdental papilla


Interview

An interview with Milton Sims, Part 2,169

Lateral cephalometric

Sella turcica bridges in orthodontic andorthognathic surgery patients. A retro-spective cephalometric study, 30

Letter

Force and tooth movement, 155

Long term outcomes

Comparison of surgical and non-surgicalmethods of treating palatally impactedcanines. I – Periodontal and pulpal out-comes, 1

Lower retainers


Miniscrew




Morphometrics


INDEX


Obituary

Thomas Graber, 160

Occlusion


Open gingival embrasures


Orthodontic brackets


Orthodontic treatment


Lower intercanine width and gingivalmargin changes. A retrospective study,41




Orthodontic treatment need


Orthognathic surgery


Open bite


Orthodontics

Fracture characteristics of fibre rein-forced composite bars used to providerigid orthodontic dental segments, 104


Outcomes


Overbite


Overjet



Palatally impacted canines


Palatal bone thickness


Periodontal disease


Periodontal health


Periodontal responses


Periodontal treatment


Pocket depth


Pulpal responses


Reliability of retainers


Satisfaction


Sella turcica bridge


Sliding mechanics


Space closure


Spacing


Static friction


Surgical exposure


Temporary anchorage device



INDEX

187187

INDEX


3D-CT

Three-dimensional computer cranio-facial tomography (3D-CT): potentialuses and limitations, 55

Three-dimensional computedtomography

Three-dimensional computer cranio-facial tomography (3D-CT): potentialuses and limitations, 55

Topacal C-5


Typodont study

Accuracy of bracket placement by ortho-dontists and inexperienced dental students, 96

Upper retainers


Young adults


Subscriptions

Please arrange my subscription commencing with the next issue; or with Volume No

Amount A$

Payment details

q cheque or bank draft (in Australian dollars), payable to the Australian Orthodontic Journal, or

qMaster card

q VISA card

Card No. / / / Expiry date /

Name Signature

Street address

State/Province Zip/Postal code Country

Return to: The Subscriptions Manager Administration:Australian Orthodontic Journal Tel: (+61 2) 9431 8666 PO Box 576 Fax: (+61 2) 9431 8677Crows Nest NSW 1585, Email: [email protected] Website: www.aso.org.au/aoj

Subscription Order Form

$

The annual subscription rate of the Australian Orthodontic Journal for non-member individual and institutional

subscribers is A$200.00 (A$100.00 per issue), including postage and handling. GST is applicable for Australian

subscribers. Postage is by airmail. Payment should be made in Australian dollars, by cheque or Australian bank

draft, payable to the administration office: The Australian Orthodontic Journal, PO Box 576, Crows Nest, NSW

1585, Australia, or by credit card.

Documents

class II (comments).pdf