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LITHUANIAN UNIVERSITY OF HEALTH SCIENCESMEDICAL ACADEMY

Dalia Latkauskienė

TREATMENT OF ANGLE CLASS IIMALOCCLUSION WITH THE CROWN

HERBST APPLIANCEDoctoral DissertationBiomedical Sciences,

Odontology (07B)

Kaunas, 2012

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The dissertation was prepared at the Department of Orthodontics ofLithuanian University of Health Sciences 2004–2012.

Scientific SupervisorProf. Dr. Antanas Šidlauskas (Lithuanian University of Health Sciences,

Medical Academy, Biomedical Sciences, Odontology – 07 B)

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LIETUVOS SVEIKATOS MOKSLŲ UNIVERSITETASMEDICINOS AKADEMIJA

Dalia Latkauskienė

ANTROS KLASĖS SĄKANDŽIOANOMALIJŲ GYDYMAS

VAINIKĖLIAIS TVIRTINAMUHERBSTO APARATU

Daktaro disertacijaBiomedicinos mokslai,

odontologija (07B)

Kaunas, 2012

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Disertacija rengta Lietuvos sveikatos mokslų universiteto Ortodontijosklinikoje 2004–2012 metais.

Mokslinis vadovasProf. dr. Antanas Šidlauskas (Lietuvos sveikatos mokslų universiteto

Medicinos akademija, biomedicinos mokslai, odontologija – 07B)

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CONTENTS

ABBREVIATIONS ....................................................................................... 7

INTRODUCTION ......................................................................................... 8

AIM OF THE STUDY................................................................................. 10

THE ORIGINALITY AND PRACTICAL USE OF THE STUDY ............ 11

1. LITERATURE REVIEW ........................................................................ 13

1.1.The origin of Class II ......................................................................... 131.2.Dentoskeletal characteristics of Class II malocclusions:differentiation between the subgroups ..................................................... 151.3. Conservative Class II treatment options ........................................... 171.4. Short historical background of the Herbst appliance ........................ 191.5. Treatment timing for the functional therapy ..................................... 191.6. The mechanism of skeletal Class II correction as a resultof Herbst therapy...................................................................................... 22

2. METHODOLOGY................................................................................... 28

2.1. Study subjects ................................................................................... 282.1.1. Inclusion criteria ........................................................................ 282.1.2. Diagnostic tools.......................................................................... 292.1.3. Unification of the patients.......................................................... 302.1.4. Evaluation of the skeletal maturity ............................................ 312.1.5. Protocol for cHerbst instalation and active treatment ................ 332.1.6 Follow-up period......................................................................... 382.1.7 Patient flow chart and final study group consolidation............... 44

2.2. Control group .................................................................................... 462.3. Cephalometric analysis ..................................................................... 472.4. Statistical analysis ............................................................................. 512.5. Method error ..................................................................................... 51

3.RESULTS ................................................................................................. 52

3.1. Class II correction mechanisms immediately after therapy andstability of results at one year follow up .................................................. 52

3.1.1. Skeletal changes ......................................................................... 523.1.2. Dental changes ........................................................................... 523.1.3 Class II correction combining dental and skeletal changes ........ 60

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3.2. Complications ...................................................................................623.3. Patients self-perception on treatment ................................................63

4. DISCUSSION ..........................................................................................65

4.1. Skeletal changes ................................................................................654.2. Dental changes ..................................................................................664.3. Complications ...................................................................................674.4. Success rate .......................................................................................684.5. Patient‘s attitude to treatment............................................................694.6 Treatment duration question ..............................................................704.7 Relapse and retention .........................................................................70

CONCLUSIONS..........................................................................................72

CLINICAL RECOMMENDATIONS .........................................................73

LIST OF PUBLICATIONS .........................................................................74

REFERENCES.............................................................................................74

SUPPLEMENTS..........................................................................................82

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ABBREVIATIONS

cHerbst – stainless steel crown HerbstCII:1 – Class II division 1CII:2 – Class II division 2BJFA – bite jumping functional devicesCVM – growth staging index according to cervical vertebraeRCT – randomized clinical trialCCT – controlled clinical trialICC – intraclass correlation coeficiant

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INTRODUCTION

Class II is one of the most common orthodontic malocclusions, it occursin about one third of the Lithuanian population [1] as well as in someEuropean countries [2] and the United States [3]. Functional jaw ortho-pedics is a specific type of treatment for Class II dentoskeletal disharmoniesassociated with mandibular retrusion. A wide range of fixed and removablefunctional appliances is available for correction of Class II skeletal andocclusal disharmonies, however their modes of action are diverse. Amongthe various types of orthopedic and functional devices, the Herbst appliancehas been proved to be effective for correcting Class II malocclusion [4-6].The Herbst device has become increasingly popular worldwide during thelast three decades mostly due to the compliance-free design of the applianceand clinical effectiveness.

Although the traditional banded Herbst has been shown to be clinicallyefficient [4-6] (Picture 1), it has several disadvantages, such as high break-age rate and frequent episodes of additional laboratory work during theactive treatment [7-8].

Picture 1. Banded Herbst

Therefore several modifications of the appliance were presented. In 1980Langford introduced the stainless steel crown Herbst (cHerbst) (Picture 2)[9].

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Picture 2. Crowned Herbst

In 1983 Howe and McNamara [10] described the current modification ofthe acrylic splint Herbst (Picture 3).

Picture 3. Acrylic Herbst

In 1984 Wieslander [11] presented the cast splint Herbst design (picture4) in combination with headgear.

Picture 4. Cast splint Herbst

In 1989 Valant and Sinclair [12] introduced the Herbst appliance with amandibular-acrylic splint and stainless steel crowns on maxillary firstmolars. Among those modifications the cHerbst appliance seemed to besimple to adjust and deliver to patients with reliable performance notinvolving extensive laboratory work.

Only a few studies on the effects of cHerbst are available in the literature[13-15]. Those studies on cHerbst reported the results after the fixedappliance therapy conducted immediately after the cHerbst, so the isolatedeffect of treatment with cHerbst device was not revealed [13,15]. Recentsystematic review by Barnett et al [14] stated that still there were notenough good quality studies to evaluate immediate changes after the bandedHerbst or cHerbst appliance were removed for growing individuals. No

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studies conducted on cHerbst reported the data on clinical success andcomplications of this appliance design.

AIM OF THE STUDY

The aim of this prospective study was to evaluate the mechanism ofClass II correction in the sample of growing Class II patients treated withthe cHerbst.

Tasks:1. To evaluate the cHerbst effect in growing patients (who

presented with stable Class I occlusion one year aftertreatment) immediately after treatment and at one year follow-up as the impact on the following dental and skeletalstructures:

a) maxilla;b) mandible;c) upper incisors;d) lower incisors;e) upper first molars;f) lower first molars.

2. To evaluate patients’ self-perception six months after treatment.

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THE ORIGINALITY AND PRACTICALUSE OF THE STUDY

This study is the first prospective clinical trial which evaluated Class IItreatment with the cHerbst as a single appliance with one-year post treat-ment follow up period. The cephalometric investigation of the study patientsevaluated unadulterated effects of the cHerbst treatment, because noadditional orthodontic appliances (including retainers) were used during thetreatment stage as well as during the 12 month follow-up period, so onlyisolated cHerbst appliance effect could be examined. Only a few studies onthe effect of cHerbst are available in the literature [13-15]. Those studies oncHerbst reported the results after the fixed appliance therapy conductedimmediately after the cHerbst, so the unadulterated cHerbst effect was notrevealed [13,15]. The systematic review by Barnett et al [14] stressed thatstudies published on cHerbst device reported only delayed treatment results.Recent systemized review by stated that still there had been not enoughinformation of good quality to evaluate immediate changes after the bandedHerbst or cHerbst appliance were removed for growing individuals.

To explain the mechanisms of Class II correction, the changes werecompared with maturity matched Class II controls from a historical samplepicked from University of Michigan and Denver growth studies. It would bedesirable to have an access to a control material of the same quality astreated material, but for ethical reasons it is no longer possible to performlongitudinal rentgenological registrations of untreated patients with post-normal occlusion. As well all the patients were treated in a private practise,they payed for their therapy and wanted to proceed with the effectivetreatment, so no delay could take place. Because of these two reasons ourclinical study was not a randomized clinical trial.

A considerable advantage of this prospective study is that the dropouts,complications, failure rates could be measured accurately. No other studyhad published failure rates of cHerbst before. As the result of the research,the orhodontists will receive a valuable message on the clinical aspects ofthe cHerbst and be able to inform the patients on the posible treatmentoutcomes as well as arrising complications.

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Another advantage of the research is that all the clinical part was mana-ged by the same investigator (D.L.) in the same private practice. Treatmentwas performed according to cHerbst protocol, being the same to all patientsstarting with the instalation of the appliance, activation and finishing withthe follow ups and evaluation of occlusion.

To control the bias of the study, two independent examiners were invitedto participate in the research: tracing of the cephalograms was accomplishedby the investigator Gundega Jakobsone in Riga Stradins University, Latviaand maturity according to the lateral cephalograms was assessed as well ascontrol group picked by another researcher Lorenzo Franchi in theUniversity of Florence, Italy. Investigators in Latvia and Italy were notaware of the treatment progress of the study patients.

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1. LITERATURE REVIEW

1.1. The origin of Class II

The relative influence of genetics and environmental factors in theaetiology of malocclusion has been a matter for discussion and controversyin the orthodontic literature. General conclusions are that, while phenotypeis inevitably the result of both genetic and environmental factors, there isirrefutable evidence for a significant genetic influence in many dental andocclusal variables. The influence of genetics however varies according tothe trait under consideration and in general remains poorly understood.Horowitz et al [16] studied fraternal and identical adult twin pairs usingonly linear cephalometric measurements, and he demonstrated highlysignificant hereditary variations in the anterior cranial base, mandibularbody length, lower face height, and total face height. Fernex et al [17] foundboys to show more similarities to their parents than girls. Facial skeletalstructures were more frequently transmitted from mothers to sons than frommothers to daughters. Female twins showed greater concordance in facialfeatures than male twins. While the profile outline coincided mostfrequently, this was not true of the cranial base and differences increasedwith age. Hunter et al. [18] found genetic correlation to be strongestbetween fathers and children, especially in mandibular dimensions (Picture1.1).

Picture 1.1. Mother and daughter with similar facial features

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Malocclusion may be defined as a significant deviation from what isdefined as normal or “ideal” occlusion [19]. Many components are involvedin normal occlusion. The most important are: 1) the size of the maxilla; 2)the size of the mandible, both ramus and body; 3) the factors whichdetermine the relationship between the two skeletal bases, such as cranialbase; 4) the arch form; 5) the size and morphology of the teeth; 6) thenumber of teeth present; and 7) soft tissue morphology and behaviour, lips,tongue, and peri-oral musculature. The term ‘ normal occlusion’ is arbitrary,but is generally accepted to be Class I molar relationship with good align-ment of all teeth and represents a situation that occurs in only 30–40 percent of the population [3].

The Class II malocclusion often reflects on the disharmony in the jawrelationship. In Caucasians it has been reported that increased overjet isbecause of a retrusive mandible only more often [3]. Since the mandible istoo far back or too small in most Class II patients, one sensible orthodontictreatment option in growing patients is to bring the mandible forward,aiming to enhance the growth of the condyle [6,20] and remodeling ofglenoid fossa [21,22]. The mandibular and facial growth pattern varieswithin the Class II patients from favorable vertical-forward condylar growthdirection and clockwise rotation of the mandible to unfavorable sagittalcondylar growth direction and counter clock-wise rotation of the mandibleas well as mandibular angle differences (Picture 1.2) [23].

Picture 1.2. Clockwise mandibular rotation with the short ramusof the mandible (left), counter-clockwise mandibular rotation

with the long ramus (right)

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The growth direction of the posterior cranial base varies and results in anopen or closed skull base angle. Subsequently, the glenoid fossa can be in amore posterior or anterior position which decides the position of the man-dible. Therefore, a retrusive mandible can be of normal size with its condylein a glenoid fossa, which is located posteriorly, or of a small size and/orabnormal shape with its condyle in a glenoid fossa which is located moreanteriorly. In conclusion, patients with severe overjet are not homogenous ineither overall facial or mandibular morphology or growth pattern. This willat least to some extent explain the often considerable individual variations inresponse to various orthodontic treatment mechanisms, such as bite jumpingtherapy using functional appliances.

1.2. Dentoskeletal characteristics of Class II malocclusions:differentiation between the subgroups

In dentofacial orthopedics a thorough knowledge of dentoskeletofacialmorphology and growth is essential for the diagnosis and treatmentplanning, as well as for the evaluation of the results. The cephalometriccharacteristics of Class II malocclusions have been analyzed in a number ofinvestigations [24-30]. The largest samples and the differentiation betweenthe subgroups: Class II division 1 (CII:1) (Picture 1.3) and Class II division2 (CII:2) (Picture 1.4) was performed by Pancherz et al [30].

Picture 1.3. Class II division 1 occlusion

Picture 1.4. Class II division 2 occlusion

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The differentiation of the subgroups is most important as CII:2 subjectsmay have a specific craniofacial morphology [31-33]. Pancherz et al [30]investigated two age groups of patients: 8–10 years (representing earlymixed dentition) and 11–13 years (representing late mixed dentition). Thepatients were devided into two subgroups: CII:1 and CII:2 and compared tothe “normal” population [34-35]. The authors reported that mandibularretrusion was a common characteristic for both subgroups as confirmed byother studies [26-29]. Due to normal growth and development [34-35] thefrequency of mandibular retrusion was expected to become lower with age.This was true for the CII:1 sample only. Deep bite and retroclination ofupper incisors could restrict the growth of the mandible in CII:2 subjects[30]. This assumption was confirmed by the observation that in these casesdentoalveolar development (Sella-Nasion-point B angle) in the mandiblewas restrained more than basal development (Sella-Nasion-point Pg angle)[30] (Picture 2.25).

This finding was supported by Arvystas MG observation [36]. Pancherzet al [30] also reported on the increase of low angle cases with age in bothsubgroups. Their data was in agreement with Bjork results on anteriormandibular growth rotation [37]. Another interesting finding by Pancherz etal [30] was that vast majority of cases (97-100%) in both subgroups hadshort lower facial heights. Similar results were reported on CII:1 [28,38] andCII:2 [32] samples by other researches. On the contrary, excessive verticaldevelopment of the lower face was found in the CII:1 samples studied byHunter et al [39] and McNamara et al [27]. The mandibular incisor incli-nation as reported by Pancherz et al [30] differed between the subgroups.The teeth were relatively more proclined in CII:1 subgroup and relativelymore retroclined in CII:2 subgroup. The same findings were detected bySolow [40] as the result of dentolaveolar compensation in response tomandibular retrusion (CII:1) and maxillary incisor retroclination (CII:2). Toconclude on dentofacial characteristics of Class II subgroups Pancherz et al[30] noted that no basic morphologic differences were detected that couldinfluence the principles of orthodontic treatment of CII:1and CII:2. In otherwords the same Class II correctors can be selected to treat both CII:1 andCII:2 malocclusions.

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1.3. Conservative Class II treatment options

Since the late 19th century many types of bite jumping functional devices(BJFA) have been advocated to treat Class II growing patients [41]. Thefundamental principle of all BJFA is to keep the mandible in protrusiveposition in an attempt to evoke condylar and then mandibular growth, whichin turn consolidates the repositioned mandible.

The classical functional appliances for Class II correction were loosefitting (e. g. Andresen type activator (Picture 1.5), Bionator (Picture 1.6)).

Picture 1.5. Andresen type activator

Picture 1.6. Bionator

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During the past 35 years, several authors suggested that functionalappliances should be attached to the dental arches with clasps (e. g. twinblock (Picture 1.7)) in order to improve the stability of the appliance and thecompliance of the patient.

Picture 1.7. Twin block

But the appliances still remained removable. The problem with theremovable BJFA is that appliances are bulky and difficult to function with.Nevertheless the patients are instructed to wear the removable BJFA for 9to14 hours per day in order to achieve desired Class II correction.Nowadays it is difficult to persuade the patients to wear appliances thatinterfere with the function and their daily life and duties [41]. The lack ofclinical success of functional appliances has in some circumstances beenattributed to lack of patient compliance in appliance wear [42]. Fixed BJFAmight be attached to the multibracket systems or function relying on directanchorage of upper and lower teeth with the help of bands or crowns. Avariety of BJFA is incorporated into modern orthodontics. For fixed BJFA,the fundamental design and biomechanics are well represented by Herbst(Pictures 1–4) appliance. The telescope mechanism of Herbst creates acontinuous mandibular protrusion. The Herbst appliance can be banded orsplinted (acrylic or casted) to the dental arch, so the patient cannot removethe appliance and BJFA works for 24 hours per day. Unlike removableBJFA which require prolonged treatment duration of approximately twoyears [41], the fixed BJFA impose a shorter treatment time of 6-12 monthsand are not dependant on patient’s compliance and cooperation [43].

Prospective investigations on removable BJFA (twin-block) reportedfollowing drop-out rates – 17% [44] and 50% [45].O‘Brien et al [42]reported that 12.9% of children had not completed the fixed BJFA Herbsttreatment and 33.6% had failed twin block therapy in the same study. Due to

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good patient compliance and clinical results the popularity of Herbst hasincreased so much during the past three decades that it is now the mostwidely used BJFA in the United States [46]. In conclusion to this section itcan be stated that fixed BJFA have certain qualities against the removableBJFA that are important in daily orthodontic practise. Herbst typeappliances do not interfere with function (patient can chew, speak, swallow,breathe normally with the device in situ), this way better patient compliancecould be achieved, besides fixed BJFA impose shorter treatment time thantheir removable counterparts.

1.4. Short historical background of the Herbst appliance

Emil Herbst introduced his device at the 5th International Dental Cong-ress in Berlin 1909. In 1934 Herbst presented 3 articles in ZahnarztlicheRundschau on his positive long term experiences with the appliance. EmilHerbst was criticized by his colleague Martin Schwarz about the treatmentmethod due to the possibility of the overload of the anchorage teeth withperiodontal damage as a consequence. After 1934 the Herbst appliance wasforgotten until it was rediscovered by Hans Pancherz in 1979 [47]. Possiblemodifications of the current Herbst appliance are presented in the intro-duction section.

1.5. Treatment timing for the functional therapy

The main objective of therapy with functional appliances such as cHerbstis to induce supplementary lengthening of the mandible by stimulatingincreased growth at the condylar cartilage. Additionally it is possible toimpact the growth of the other parts of the mandibular bone. The rate ofmandibular growth is not constant throughout the juvenile and adolescentperiods, with the existence of a pubertal peak in mandibular growthdescribed previously in classical cephalometric studies [23, 48, 49]. There isevidence which shows that the greatest effect of functional appliancesoccurs when the peak in mandibular growth is included in the treatmentperiod. Investigations of Petrovic et al [50, 51] revealed that the therapeuticeffectiveness of other Class II correctors – the Frankel appliance andBionator was most favourable when these appliances were used during theascending portion of the individual pubertal growth spurt. Hägg andPancherz [52] found that sagittal condylar growth in patients treated withthe Herbst appliance at the pubertal growth spurt was twice greater than thatobserved in patients treated 3 years before or 3 years after the peak. Baccetti

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et al [53] supported their data, concluding that the twin block therapy shouldbe performed during the growth peak or slightly after in order to get largerincrements in mandibular length and ramus height, more posterior condylargrowth, leading to enhanced mandibular lenghtening. On the contraryO‘Brian et al [42] reported that the growth increments were not greater inthe patient group treated during the growth spurt as compared to off-spurtgroup.

If we believe the theory that we can be more efficient „growing man-dibles“ during the growth spurt as suggested [50-53], we have to considerthe methodology on how to differentiate and determine the time point of thegrowth peek onset.

Different rates of mandibular growth at puberty, as well as the peak inmandibular growth velocity, can be detected on the basis of several methodsfor the assessment of skeletal maturity. These biological indicators includeincrease in body height [54], skeletal maturation of the hand and wrist [55],dental development and eruption [56,57], menarche, breast and voicechanges [58] and cervical vertebrae maturation [59,60]. With regard to thislast method, stages in the maturation of the cervical vertebrae showedsignificant correlations with pubertal changes in mandibular growth, asdemonstrated by O’Reilly and Yanniello [60]. The simplified version of thegrowth staging according to cervical vertebrae (CVM) was presented byBaccetti et al in 2005 [61]. In our study on the cHerbst therapy the stages ofcervical vertebrae maturation were used to match the treated group and theuntreated control group according to pretreatment and posttreatment skeletalmaturity. The ratings were performed by one of the inventors of CVMmethodology [61] – professor L.Franchi.

Another question is the clinical significance of the mandibular elongationas the result of Class II therapy in case we treat malocclusion in time(during the growth spurt). Most of the studies on Herbst appliance to provethe dentoskeletal impact of the device were presented by the same source [6,47, 52, 62-77], so to be objective on the final statements we have to refer tosystematic reviews and meta-analyses (to be discussed in the next section ofliterature review). Nevertheless, if the mandible really grows more as aresult of Herbst therapy, what happens when the treatment is over? Hansenet al [77] revealed that the growth period in which Herbst treatment hadbeen performed did not seem to have effect on the long term results.Interesting finding in their study was that after the 7 months of Herbst the-rapy the mandible had overgrown maxilla by an average 2.2 mm, after6.6 years after the treatment the overgrowth had been 2.1 mm and in thetotal observation period the figure was 4.3 mm. Recent study by Zhi-HaoYou et al [78] found no significant difference in mandibular growth between

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the Class II samples and the Bolton norms in their longitudinal study fromchildhood to early adulthood. Their results indicated that in the Class IIsubjects forward growth of the mandible was greater than that of the maxillaby 4.36mm on average. If we look at the forward maxillary-mandibulargrowth rates presented by authors [77, 78], these are very similar: 4.3mmagainst 4.6mm. This would suggest that the induced growth of the mandibleduring the Herbst therapy has vanished in long term and in the end ofgrowth process the projection of the lower jaw is more or less the same, nomatter, if the Class II patient was treated or not. Another interesting thoughtbrought by Hansen et al [77] was a claim that a stable occlusion after theHerbst or any other therapy could be of greater importance for the long termstability, than the post-treatment growth pattern or the growth period inwhich the patients were treated. That conclusion helped us whilst creatingtreatment protocol for our study. Hansen et al [77] conclusion was anedition to the earlier statement of Pancherz and Fackel [70] and brought upeven more discussion in Class II treatment topic. The Herbst appliance hadonly a temporary impact on the existing skeletofacial growth. After therapymaxillary and mandibular growth seemed to catch up with their earlierpatterns [70]. In spite of relapse to Class II occlusion due to recoveringgrowth changes, functional stability of occlusion remained due to tight ClassI contacts that obviously counteracted occlusal relapses[70]. After almost adecade Bremen and Pancherz published the paper on CII:1 treatmentefficiency [79]. Authors concluded that treatment of CII:1 was moreefficient in the permanent dentition than in the mixed dentition, in otherwords the interdigitation of occlusion in permanent dentition could improvethe stability comparing to interdigitation provided by the deciduous teeth.After several papers [70, 77, 79], H. Pancherz and his team presented thenew concept for conservative Class II treatment in adults [80]. In earlier[75] and later [81] papers Pancherz and his team claimed that Herbstappliance increased mandibular prognathism, additonally the skeletal andsoft tissue profile convexity had been reduced in all the adults treated withHerbst appliance. In his recommendations Pancherz concluded that growthadaptive therapy with the Herbst appliance was possible even after the ageof 20 and could thus replace surgery in milder skeletal Class II cases [80].

The conclusion to this section is that Herbst appliance as Class IIcorrector may be used for growth adaptation in children, adolesents,postadolescents, young adults and as a camouflage orthodontics in elderlyadults [80]. So the treatment onset time-span is much larger than suggestedfor the removable BJFA [41]. Induced growth of the mandible during theHerbst therapy disappears in long term, but the Class II remains correcteddue to stability of occlusion which counteracts the growth changes.

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1.6. The mechanism of skeletal Class II correctionas a result of Herbst therapy

The mechanism of Class II correction is still in dispute. Although all theBJFA strive to cure Class II, most dentoskeletal findings after the therapyare diverse and difficult to explain. As it was stressed before, most of thedata on Herbst comes from the same source and thus systematic reviewscould help us to find the answer to the question of the century: do we growthe mandible or not?

Chen et al [82] published systematic review on the efficacy of functionalappliances on mandibular growth and limited their search to randomizedclinical trials (RCTs). Chen et al [82] developed and implemented aMedline search strategy for the years 1966 to 1999. For the systematicreview, authors limited Medline search to studies performed on humans andwritten in English. The search was stratified for randomized control trialsand meta-analyses, which were viewed as providing the highest level ofevidence quality [82]. Reported results were inconclusive due to incon-sistencies in measuring treatment outcome variables, different treatment du-rations among studies. Besides treatment groups were compared with eitheruntreated controls or subjects undergoing other forms of treatment. Chen etal [82] noticed that in the last ten years, there had been an increasingnumber of studies of Class II treatment, though it was stressed that therewas still a need to conduct more randomized control trials to reduce themethodologic limitations. Authors concluded that once confounding variab-les such as discrepancies in age, treatment durations, lack of control-matc-hed groups, patient compliance, and patient accountability were minimized,one could identify which patients might or might not benefit from specifictreatment options. Although functional appliances could be used for otherpurposes, results suggested the need to reevaluate functional appliance usefor mandibular growth enhancement [82].

To broaden the scientific information on functional appliances and inorder to finalize the conclusions on BJFA, Cozza et al [4] suggested that therational systematic review should include not only RCTs, but alsolongitudinal prospective and retrospective controlled clinical trials (CCTs),because of the ethical problems and other substantial reasons for the paucityof RCTs in orthodontics. Cozza et al [4] review had a limited search strate-gy that focused only on mandibular growth changes. Authors searched formeta-analyses, RCTs, prospective and retrospective CCT’s published from1966 to 2005. Selected studies had to include growing patients, untreatedClass II control groups and mandible length had to be measured on lateralcephalogram using point condylion. Exclusion criteria were as follows: case

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reports, case series and descriptive studies, review articles, opinion articles,abstracts, laboratory studies, studies of adults, studies performed on magne-tic resonance imaging, measurements of total mandibular length using pointarticulare, treatment combined with extractions, treatment combined withfixed appliances, surgical treatments, success of therapy (at occlusal andskeletal levels) as criterion for case selection. To give the reader a quantita-tive appraisal of modifications in mandibular dimensions and sagittal posi-tion in Class II patients treated with functional appliances when comparedwith untreated Class II controls, the following data were evaluated for eachretrieved study: mandibular sagittal position (SNB), total mandibular length(co-gn or co-pg), mandibular ramus height (co-go), and mandibular bodylength (go-gn, go-me, or go-pg) (Table 2.3) [4]. Because most of the samp-les in the retrieved studies reported annualized mandibular changes (expres-sed as annualized mean differences between treated and untreated groups),annualization was applied to the data of the remaining samples (except forsamples with a treatment duration that was too short for annualization – lessthan 9 months). The actual amount of supplementary elongation in totalmandibular length after active treatment with the functional appliance wasalso analyzed. It is well known that different functional appliances requiredifferent treatment durations to reach the goal of Class II correction at theocclusal level [4]. Therefore, the review included an evaluation of both theeffectiveness and the efficiency of different types of functional appliances ininducing a supplementary elongation of the mandible with respect to cont-rols. Effectiveness could be defined as the ability of the appliance to inducea clinically significant supplementary elongation of the mandible withrespect to the controls at the end of the overall treatment period. Because ofthe average number of patients enrolled in the examined studies (ie, to thepower of the retrieved studies), clinical significance in mandibular dimen-sions was defined as at least a 2.0 mm difference between treated anduntreated groups [4]. Efficiency consists of an effective treatment in theshortest time. An appraisal of efficiency was performed by dividing thesupplementary elongation of the mandible during the overall treatmentperiod with the functional appliance by the number of months of activetreatment duration (coefficient of efficiency) [4].

Out of 22 articles (4 RCTs, 2 prospective CCTs, and 16 retrospectiveCCTs), fulfilling the inclusion criteria, four articles were on Herbst applian-ce effects on growing indiivduals [6, 83–85]. Three of these articles reportedtreatment effects with the acrylic splint Herbst appliance [83-85] and onewith the banded Herbst appliance (6). All 4 studies [6, 83-85] presentedsignificant favourable effects on mandibular growth. No articles on cHerbstthat could update the data of this systematic review were included. Authors

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concluded [4] that functional appliances produced a statistically significantannualized supplementary elongation in 23 of 33 samples for total mandibu-lar length, in 12 of 17 samples for mandibular ramus height, and in 8 of 23samples for mandibular body length, outcomes in terms of changes in man-dibular position in relation to the cranial base (SNB angle) were not clini-cally significant in any article. Authors noted [4] that the SNB angle was apoor indicator of the effectiveness of functional jaw orthopedics since inmost patients the initial correction of a Class II relationship involves not justposturing the mandible in a forward position: vertical opening of the bitetypically was involved, and a deep overbite was corrected, so a millimeterof increased lower anterior facial height camouflaged a millimeter ofincreased mandibular length, in that way the advancement of the chin pointat pogonion might not be evident if the vertical dimension is increased alongwith mandibular length [4].

The amount of supplementary growth of the mandible when comparedwith untreated Class II controls varied widely among the studies included inthe review [4]. Two-thirds of the samples in the 22 included studies reported aclinically significant supplementary elongation in total mandibular length (achanges greater than 2.0mm in the treated group compared with untreatedgroup), whereas some studies that were judged as medium-high quality by theauthors couldn’t confirm the significant mandibular changes [42, 86–88]. Itwas an interesting finding for Cozza et al [4] that none of the 4 RCTs reporteda clinically significant change in mandibular length induced by functionalappliances. To further explain this finding authors suggested to analyze theinfluence of treatment timing (skeletal maturity at the start of functionaltherapy) on treatment results [4] since it had previously been demonstratedthat the effectiveness of functional treatment of mandibular growthdeficiencies strongly depended on the biological responsiveness of thecondylar cartilage, which in turn depended on the growth rate of the mandible(expressed as prepeak, peak, and postpeak growth rates with regard to thepubertal growth spurt) [62, 63]. Only seven of the selected 22 studies in thereview reported information about their subjects’ skeletal maturity with abiological indicator (e. g., hand-wrist analysis, cervical vertebral maturationmethod), the amount of actual supplementary mandibular growth induced bytreatment (measured by co-gn or co-pg) was clinically significant (> 2.0 mm)in all the “peak” samples, meaning that patients were on a growth spurt,whereas none of the samples treated in the prepeak period had a clinicallysignificant amount of supplementary mandibular growth. Authors suggested[4] that the inclusion of the pubertal growth spurt in the treatment periodcould be regarded as a key factor in the attainment of clinically significantsupplementary mandibular growth with functional jaw orthopedics. Cozza et

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al [4] also concluded that the average coefficient of efficiency for functionaljaw orthopedics (average amount of actual supplementary elongation of themandible in treated subjects versus Class II controls after the overalltreatment period divided by the number of months of treatment in each study)was 0.16 mm per month. The Herbst appliance, as fixed BJFA had acoefficient of efficiency of 0.28 mm per month, the coefficient for theremovable BJFA such as following: Twin-block appliance was 0.23 mm permonth, the coefficient for the bionator (0.17 mm per month) was equal to theaverage coefficient, for the activator, it was slightly lower (0.12 mm permonth), the coefficient of efficiency for the Fränkel appliance, was the lowest(0.09 mm per month). Authors stressed the importance of the quality of thestudies [4]: in the quality analysis, six of the 22 studies were judged to be ofmedium/high quality. Four of these six articles were RCTs. The reason for amedium/high quality score instead of a high score was that these studies hadsome methodological limitations [4] such as no statistical analysis for themandibular skeletal changes or absence of blinding in measuring thecephalometric parameters. On the other hand, only two CCTs out of 22 werejudged to be of medium/high quality, whereas most CCTs were judged to beof medium quality [4]. The use of blinding in performing cephalometricanalysis of craniofacial skeletal changes was the main factor that accountedfor a higher score for these two CCTs. Only three of the 22 studies wereconsidered of low quality because they lacked both method error analysis andblinding in measurements [4]. Another problem whilst selecting the studiesfor the review was the lack of unification in measuring techniques [4]. Shen etal [89] stated that the parameters adopted to quantify the skeletal changeswere often created and determined by the individual researches and were notof consistence and compatibility between studies, so the problem of findingthe skeletal changes could be hidden in the cephalometric analysis used by theinvestigators. Besides mandibular length measurements in Cozza et al study[4] relied on point condylion (Table 2.3), which is known to be difficult todetermine cephalometrically [90, 91].

Another recent systematic review by Barnett et al [14] in 2008 had pur-pose to assess the scientific evidence on the efficiency of crown or bandedHerbst appliance in enhancing mandibular growth in growing Class IIindividuals. The main question of the review was: what maxillary and mandi-bular skeletal and relative dentoalveolar treatment effects were produced bycrown or banded Herbst compared to a Class II malocclusion nontreatedcontrol group considering growing individuals? Authors considered [14] thatthere was little doubt that measurable dental changes such as reduced overjetor molar correction occured in a favorable manner with the continuous use offunctional appliances, however, the degree of skeletal versus dentoalveolar

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change that underlied these treatment effects was still a source of debate. Asthe greatest controversy over the effectiveness of functional appliances assuggested by Barnett et al [14] was in part because of the method of analysisemployed by the published reviews. Authors stressed [14] that ideally, thetreatment effects of each appliance should had been examined individually,because each appliance had a theoretically different mechanism of action andapplication that would likely produce different movement based on therelative dental and skeletal changes. In other words the results of differentappliances could not be pooled together. However, most reviews had ana-lyzed several functional appliances simultaneously and had obscured the realeffects of each individual functional appliance by combining all the effects [4,82]. Another important issue considered by Barnett et al [14] that althoughboth removable and fixed functional appliances had been used for decades,with various forms coming in and out of popularity, removable appliancessuch as activators, bionators, and twin blocks had different time duration ofbeing worn by the patients whereas fixed functional appliances had theadvantage of not relying on patient compliance because they were fixed in themouth, thus always working, in that way fixed BJFA could not be comparedwith the removable BJFA and even worse if the results of both fixed andremovable appliances were pooled together to represent the skeletal effets.

Barnett et al [14] detected four reviews on Herbst appliance. Three ofthem analyzed exclusively Herbst effects [73, 92, 93] and one reportedHerbst effects individually while analyzing other functional appliances [4].Barnett et al [14] criticized the oldest review by Pancherz [73] for not beingsystemized and therefore influenced by bias. Flores-Mir et al [92] reviewconcentrated on soft tissue changes. A more recent review by Flores-Mir etal [93] analyzed the effects produced by the splint type Herbst, which haddifferent mode of action due to partially removable design and interocclusallayer of acrylic. The selection process by the year 2007 was also applied inthe next selection stage searching for full articles on Herbst appliance. Outof pontentially relevant 80 clinical trials identified by the database searchesBarnett et al [14] had found only 3 articles to fulfill the additional inclusioncriteria [6, 94, 95]. The additional criteria that minimized the number ofselected articles were: comparable Class II control group, randomized orconsecutively treated cases, measurements taken soon after appliance remo-val and no concurrent use of any orthodontic appliance during the evalua-tion period. Author pointed out that Pancherz H articles [6, 94] reported thesame group of subjects, but different measurements and the study by DeAlmeida et al [95] had a very young cohort, treated prior growth spurt. Eva-luating the skeletal effects reported in the selected studies, Barnett et al [14]concluded that minimal effects were demonstrated on the maxilla, as only

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two of the seven maxillary sagittal measured variables showed statisticallysignificant changes, whereas several significant (and nonsignificant) increa-ses were seen in mandibular length as compared to the untreated controls. Itappeared that the magnitude of the mandibular change lied in the 2 to 3 mmrange, depending on which measurement was considered, nevetheless, howmuch of this effect was an artifact of mandibular posturing had not beenevaluated. Authors suggested using open-mouth cephalograms to help in theidentification of condylion, the point on which relied most of the measu-rements. Barnett et al [14] stressed that the lack of a headgear effect on themaxilla was noteworthy. Considering dentoalveolar effects: maxillary inci-sors were retroclined, despite the fact that no appliances were used directlyon them in any of the studies included in this review, it was confirmed thatthose findings were similar to ones seen elsewhere with Herbst appliances[14]. There was no doubt for that statement, because the movement of theupper front teeth was influenced by the fact that all cases used in Barnett atal review were Class II division 1 and thus were already quite proclinedprior to treatment, which was not the case for all studies in the literature,whereas mandibular incisors showed a definite proclination, which was notsurprising given the force vectors involved with Herbst treatment.

Maxillary first molar position showed small but statistically significantamounts of intrusion, though authors questioned the clinical significance ofthis movement as well the upper first molar was also moved distally withinthe maxillary alveolus: this distal movement could account for the retrocli-nation of the maxillary central incisors via transeptal fibers [14]. Mandibularfirst molars showed an extrusive and anterior direction of movement thatcould be accounted for by the relative intrusion of the opposing maxillaryfirst molar, allowing for that small but significant amount of eruption [14].Barnett et al [14] stated that still there was not enough information of goodquality to evaluate immediate changes after the banded or crown Herbstappliance was removed for growing individuals. Because of the limitednumber of finally selected studies and the heterogenity of their metho-dology, authors did not attempt to do a meta-analysis with the data. Theyconcluded that there were mixed findings as to mandibular sagittal lengthand position, but also reported the proclination and anterior movement oflower incisors and improved first molar relationship, reduced ANB angleand increase in the mandibular plane angle, also no significant changes inthe maxillary base position were noted as an immediate result of Class IItreatment with the Herbst appliance. In order not to overlap with informa-tion, the literature review on dentoskeletal changes as the result of theHerbst therapy will be touched in the discussion section of our study as thecomparison with the data we have received.

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2. METHODOLOGY

2.1. Study subjects

Prospective study on cHerbst appliance started in 2006 and ended in2010. Study subjects were selected from the patients referred to KaunasOrtodontijos Centras clinic for orthodontic treatment. All the patients werediagnosed, consulted and treated by the same orthodontist (DaliaLatkauskienė) at the same orthodontic office. Subjects fulfilling below listedinclusion criteria were asked to participate in the study and were given thesubject consent forms in order to describe the purpose, procedures, benefits,risks, possible discomforts and precautions of the study and provide otherdetails that may be important for the patients, such as the possible sideeffects, withdrawals from the study and the use of personal data(supplement no1). In case the patient decided to be part of the study, he orshe was asked to sign a consent form (supplement no2). In case the patientwas a minor, the consent form was signed by the parents or caregivers. Bysigning the consent form, patients confirmed the voluntary participation inthe study and agreed to follow all the further instructions on treatment givenby the doctor (D.L). Patients also received additional information oncHerbst protocol prior to treatment (supplement no3), all the possiblequestions and comments were answered by the doctor (D.L.).

2.1.1. Inclusion criteriaTo be included in this prospective study patients had to present with: at least end-to-end Class II molar relationship bilaterally or more

severe; permanent dentition; no active hard tissue lesions; no previous orthodontic treatment or tooth extractions; no bone level problems detected in panoramic x-ray; no TMJ complaints; no tooth size, form and number anomalies; no facial development or mental syndroms (such as Down,

Treacher Collins, Crouzon, etc); no pregnancy.

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2.1.2. Diagnostic toolsInitial records were taken for each patient before the treatment onset: medical history (in order to find out about being pregnant, previous

orthodontic treatment, complaints on TMJ, development or mentalsyndroms- patients were asked during the consultation and theinformation was outlined into the patient‘s data card);

intraoral examination to detect the occlusion, teeth anatomy andhard tissue lesions (all patients were referred to their dentists for acheck-up prior to orthodontic treatment in order to solve lesions ofthe hard dental tissues);

dental casts as primary diagnostic source of teeth anatomy andocclusion;

panoramic x-ray in order to evaluate the bone level (bone level inpanoramic x-ray considered as normal if it starts from the enamel-cementum junction of tooth down to the apex, all along the dentalarches from second molar to second molar with no visible defectsas inspected by D.L.);

lateral cephalogram, it will be used to measure treatment resultsafter cHerbst therapy. Cephalograms were taken with the Frankfurthorizontal parallel to the floor with teeth in occlusion and lipsrelaxed. At least four cervical vertebrae had to be present in the x-ray in order to evaluate growth stage of the patient. Additonallateral cephalograms were performed immediately after cHerbsttreatment for all patients that finished therapy and at one-yearfollow–up time point in case the patient was included into the finalstudy group of stable Class I patients. All three lateral cephalo-grams were taken with the same equipment.

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2.1.3. Unification of the study patientsPrior to cHerbst all CII:2 patients received 022 slot MBT prescription

braces on the upper front eight teeth to convert the malocclusion into CII:1(Pictures 2.1, 2.2). Alignment started with 016 nickel titanium wire andprogressed up to 18 by 25 nickel titanium wire (Ormco, 1717 West CollinsAvenue, Orange, CA 92867). Braces either stayed for the whole activecHerbst treatment period or were removed after aligning- in that case aretainer was bonded on four upper front teeth. For CII:2 patients the firstdiagnostic lateral cephalogram was performed after the upper front teethwere aligned.

Picture 2.1. Class II:2 before alignment of the front teeth

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Picture 2.2. Class II:2 after alignment of the front teeth

2.1.4. Evaluation of the skeletal maturityIn order to control the bias of the study two more examiners were invited

to participate in the study, one of them - Professor Lorenzo Franchi(University of Florence, Italy), the inventor of the CVM index which wasused in this research [61]. Another examiner was invited to examine thelateral cephalograms of the selected patients. Both examiners were notinformed on the patient sample and treatment progress.Since one of the objectives in Class II treatment is to correct skeletalrelationships which happens best during the active growth [61], theestimation of skeletal maturity in examined individuals at the time oftreatment onset and discontinuation should be taken into account. Accordingto CVM maturity index [61] of pre-treatment (T1) and post-treatment (T2)lateral x-rays, patients were divided into two groups by investigator (L.F.) :Group 1 – growing patients who either started cHerbst treatment asprepubertal or pubertal (CS2 or CS3) and finished postpubertal (CS4 orCS5), patients who started postpubertal (CS4 or CS5) and finishedpostpubertal or adults (CS5 or CS6), Group 2 – patients who started andfinished Herbst treatment as adults (CS6). Illustrations to legends below(Pictures 2.3–2.5).

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Picture 2.3. Cervical stage 3 (CS3): two clinical examples- pubertal patients

Picture 2.4. Cervical stage 4 (CS4):two clinical examples- postpubertal patients

Picture 2.5. Cervical stage 6 (CS6):two clinical examples- adult patients

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2.1.5. Protocol for cHerbst instalation and active treatmentA standard bite jumper (cHerbst) (Ormco, 1717 West Collins Avenue,

Orange, CA 92867) was used as the only appliance for all patients. CHerbstwas delivered within one month of the patient‘s initial records and no otherappliances were used during the functional treatment phase. CHerbstappliance was produced and delivered in three visits: During the first visit separation of the lower first premolars was

performed (Picture 2.6).

Picture 2.6. Separation of lower first premolars

During the second visit in one week upper first molars wereseparated and lower first premolar crowns were fitted (Picture 2.7),alginate impression with the crowns in it was taken to the labo-ratory to produce welded lingual arch (Picture 2.8).

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Picture 2.7. Lower first premolar crowns fitted

Picture 2.8. Welded lingual arch

During the third visit in one week, the lingual arch with thepremolar crowns was cemented with Ketac-Cem glass-ionomercement (3M Espe Dental Products, St.Paul, MN 55144-1000),occlusal rests on lower first molars were secured with flowablecomposite (Picture 2.9), upper first molar crowns were fitted andfixed with the same glass-ionomer cement (Picture 2.10).

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Picture 2.9. Cemented lingual arch

Picture 2.10. Cemented upper first molar crowns

Appliance was activated edge-to-edge incisor relationship (Picture 2.11),function of lateral movements of the mandible checked (Picture 2.12) andactive treatment phase started (T1) No additional anchorage for the upperfirst molars was created.

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Picture 2.11. Appliance activation edge-to-edge, facial profileimmediate change after the instalation of the cHerbst

(appliance in situ on the lower photograph)

Picture 2.12. Lateral movements of the mandible

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Patients were seen once every four to six weeks to evaluate the appliancestatus and the need for activation. The activations were performed byplacing collars on pistons to make sure that the cusp of upper first premolarwas projecting in between the lower first and second premolars to helpnatural vertical occlusion settling process (Pictures 2.13, 2.14).

Picture 2.13. Activation to allow vertical settling of occlusion: vertical contacts immediately after cHerbst removal

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Picture 2.14. Stable occlusion 12 months after treatment

The appliance was removed after 12 months of active treatment (T2) andlateral cephalograms were taken on the same day.

2.1.6 Follow-up periodAfter cHerbst removal, no appliance to retain the occlusion was provided

and the patients were asked to come for a check-up visit after six months(T3).

At T3 natural settling of occlusion in Class I relationship was checkedand a treatment evaluation questionnaire was given to the patients (Picture2.15).

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Picture 2.15. Questionnaire to evaluate cHerbst treatment.

If occlusion was slipping back to Class II relationships at T3, the patientsreceived either an Andresen activator or started fixed appliance therapy(Pictures 2.16–2.19).

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Picture 2.16. Occlusion before treatment

Picture 2.17. Occlusion immediately after treatment

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Picture 2.18. Relapse to Class II malocclusion six months after treatment

Picture 2.19. Retention device provided for patients with unstable occlusion

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If occlusion was settling in Class I relationship, the patients were askedto come for the final checkup after six months (T4). If the occlusion at T4was stabilized in Class I relationship, final lateral cephalogram was perfor-med. In case of relapse at T4, the patients received an Andresen activator orstarted other treatment if agreed.

A patient with stable Class I occlusion one year after treatment withcHerbst is presented in Pictures 2.20–2.22.

Picture 2.20. Patient with stable occlusion one year after cHerbsttreatment: before treatment

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Picture 2.21. Patient with stable occlusion one year after cHerbsttreatment: immediately after cHerbst removal

Picture 2.22. Patient with stable occlusion one year after cHerbsttreatment: one year after cHerbst removal

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2.1.7. Patient flow chart and final study group consolidationThe flow chart of the patients throughout cHerbst treatment and obser-

vation periods is shown in Picture 2.23.

Picture 2.23. Flow chart of the treated patients

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Out of the 180 patients who started treatment five patients (2.8%) did notfinish the active phase: four patients due to numerous appliance breakageswhile one patient complained for increased episodes of migraine afterinsertion of the appliance. All 175 patients who finished the active phase oftreatment attained Class I occlusal relationship. During the six-monthsfollow-up period, 20 patients (11.4%) dropped from the study for severalreasons not associated with treatment while 56 patients (32%) started fixedappliance treatment due to esthetic reasons. At T3 (six months after the endof the active phase of treatment) a total of 99 patients received a check upvisit. During the 12-month follow-up period, 19 patients (19.2%) receivedan activator due to relapse, two patients (2%) were treated with fixedappliances due to esthetic reasons, and four patients (4%) did not show upfor the 12-month check up visit.

At T4 (12 months after the end of the active phase of treatment) a total of74 patients received a check up visit. Out of these 74 subjects, two patients(2.7%) received an activator due to relapse. Thus as a result of the cHerbstappliance used as a single appliance for a single phase therapy on a sampleof 175 patients, 72 patients (41.1%) achieved and maintained stable Class Irelationships at a one-year follow-up observation while 21 patients (12%)showed relapse. Other 58 patients (33.1%) passed to the second phase oftreatment with fixed appliances and in all cases a stable Class I relationshipwas achieved.

Seven of 72 stable patients refused to take the final cephalogram, thuslateral cephalograms of 65 patients with stable Class I occlusion wereavailable at the following observation periods: before treatment (T1), afteractive phase of treatment (T2) and at one year follow up (T4).

Consolidation of the final study group of growing subjects: forty patients(20 male, 20 female) with the mean age 13.6 ± 1.3 were judged as growingand included in the final study group, used to evaluate cHerbst effectsimmediately after treatment and at one year follow up. The patients startedtreatment either at puberty (CS3 n = 26) or at postpubertal stages (CS4 orCS5, n = 14) and they finished treatment either at a postpubertal stage (CS4or CS5 n = 26) or at the end of active growth (CS6 n = 14). Twenty fivepatients out of 65 were judged as adults at T1 and collected to a non-growing group of patients which was not analyzed cefalometrically in thecurrent study.

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2.2. Control group

It would be desirable to have an access to a control material of the samequality as final study group material, but for ethical reasons it is no longerpossible to perform longitudinal rentgenological registrations of untreatedpatients with post-normal occlusion. Besides as it is stressed in the literature[61], functional appliances work best during the pubertal growth spurt, itwould unethical to delay the treatment for the Class II patients in order touse them as controls. Examiner D.L. aimed to find the comparable controlgroup of Class II patients matched as to skeletal maturity to the treatedsample. Most of the European growth studies either present normative dataas Bhatia and Leighton sudy or the lateral cephalograms are perfomed intime points different from that in our study (such as growth studies inNorway and Poland). On the contrary, the Michigan Growth Study andDenver Growth Study are comprised of annual records and the subjects inthe study are primarily of Northern European ancestry. In the overallsample, there is a bias toward Class II malocclusion. There are 18 boys and30 girls with longitudinal records taken at the intervals of 12 monthsdeemed ideal as judged by the American Association of Orthodontists(www.aaoflegacycollection.org).As reported by professor James JA. McNamara, who is the curator of thedata, on the Michigan Growth study web page (www.aaoflegacycollection.org):based on the study two major atlases were published, in addition, there havebeen 66 papers published in refereed journals and well as eight other booksor chapters in books written by the curator and his colleagues that have useddata form the Michigan Growth Study, as well as Denver growth study thatwas copied and infiltrated into the Michigan Growth Study.Pofessor J. JA McNamara has kindly agreed and allowed examiner D.L. topick the controls from the Michigan Growth Study records.

The control group consisted of 18 subjects (11 males, 7 females) whowere selected from the longitudinal records of the University of MichiganElementary and Secondary School Growth Study and Denver GrowthStudy. The mean age of the control group was 13.9 ± 1.6 years. The controlgroup was matched to the treated group as to skeletal maturity at T1and T2observation periods by the independent examiner L.Franchi. Attempts toincrease the number of controls confronted the insufficient quality of lateralcephalograms at certain timepoints and limitations to select Cl-II patientswith three lateral cephalograms performed in exact 12 month intervals (thesame intervals as in our study).

There was no statistically significant difference in age between the groupsat any of the time points. Pretreatment characteristics and demographics of

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the treated and control groups are summarized in Tables 2.1and 2.2 (expla-nation of points outlined in Table 2.3). Treated subjects presented with moreproclined upper incisors as well as shorter midfacial length, significantdifference comparing to the control group.

Table 2.1. Demographics for the treated and untreated Class II Groups

Mean (SD)N Female Male

Age at T1, y Age at T2, y Age at T3, y

cHerbst group 40 20 20 13.6 (1.3) 14.8 (1.4) 15.9 (1.4)

Control group 18 7 11 13.9 (1.6) 14.7 (1.4) 15.7 (1.4)

Table 2.2. Pretreatment characteristics of the study subjects compared withmatched untreated Class II individuals. Mean values and standard devia-tions (SD) in parenthesis

Variable Study Group (n = 40) Control Group (n = 18) P value

Overjet (mm) 5.5 (2.2) 5.5 (2.4) 0.130

Overbite (mm) 5.6 (1.3) 4.5 (2.0) 0.758

SNA (degrees) 81.5 (2.9) 81.1 (3.8) 0.605

SNB (degrees) 76.7 (2.4) 76.6 (3.2) 0.910

SNpg (degrees) 78.1(2.6) 78.0 (3.3) 0.886

ANB (degrees) 4.8 (1.9) 4.5 (1.5) 0.449

co-A (mm) 86.6 (4.7) 83.6 (6.6) 0.045

co-gn (mm) 108.1 (5.4) 105.8 (7.3) 0.187

is to T-FMN (degrees) 111.5 (8.2) 104.4 (8.2) 0.003

ii to ml (degrees) 99.8 (7.0) 98.7 (7.6) 0.599

co-go-me (degrees) 121.5 (4.9) 119.8 (4.1) 0.178

2.3. Cephalometric analysis

Assistant professor Gundega Jakobsone (Riga Stradins University,Latvia) was invited as the second independent expert, not related totreatment process. G.Jakobsone hand traced the cephalograms perfomed atT1,T2,T3 on acetate paper. The tracings were digitized with Dentofacialplanner Plus software (Dentofacial Software, Toronto, Canada) on a compu-

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ter with a digitizing screen (Numonics Cooperation, Montgomeryville,USA). All cephalograms were matched according to enlargement.

A modified Pancherz cephalometric analysis was applied (Picture 2.24).Explanation of points used in cephalometric analysis outlined in Table 2.3.

Picture 2.24. A modified Pancherz cephalometric analysis

Table 2.3. Explanation of points used in cephalometric analysis

Abreviation ExplanationFMN Frontomaxillary nasal sutureT The most superior point of the anterior wall of sella turcica, at the junction

with tuberculum sellaeCo Condylion.The most superior midline point on the condyle of the mandible.Go Gonion. A point on the curvature of the angle of the mandible located by

bisecting the angle formed b ylines tangent to the posterior ramus and theinferior border of the mandible.

Pg Pogonion. The most anterior point of the chin.Me Menthon. The lowest point of the sympheseal shadow of the mandible seen

on a lateral cephalogram.Gn Gnathion. A point located by taking the midpont between pogonion and

menthon.S Sella. The geometric centre of the pituitary fossa.

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Table 2.3. Continued

Abreviation Explanation

N Nasion. The most anterior point of the frontonasal suture in the midsagittalplane.

A Subspinale. The most posterior midline point in he concavity between theans and the most inferior point on the alveolar bone overlying the maxillaryincisors.

B Supramentale. The most posterior midline point in the concavity of themandible between the most superior point on the alveolar bone overlyingthe mandibular incisors and pg.

Ans Anterior nasal spine. The anterior tip of the sharp bony process of themaxilla at the lower margin of the anterior nasal opening.

Pns Posterior nasal spine. The posterior spine of the palatal bone constitutingthe hard palate.

FMN and T point substitute nasion and sella of Pancherz analysis respec-tively. FMN and T point were earlier introduced by Franchi et al [96] as thereference points for studies of growing individuals.

Skeletal and dental changes were recorded using a grid system: the x axiswas drawn through T and FMN points while the y axis was constructedperpendicular to x axis through T-point.

Following landmarks were digitized and the changes were assesed in theconstructed grid system: condylion (co), gonion (go), A point, B point,pogonion (pg), menthon (me), gnathion (gn), upper first molar mesiobuccalcusp tip (ms), lower first molar mesiobuccal cusp tip (mi), upper incisor tip(is), lower incisor tip (ii).

Reference lines: T-FMN line, T-FMNp (T-FMN line perpendiculare), aline perpendicular to T-FMN through T point.

Measuring lines: maxillary plane (nl) a line connecting ans-pns points,mandibular line (ml) a line connecting go-me points.

Linear measurements: overjet (distance difference between is and iiprojected on T-FMN), overbite (distance difference between is and ii projec-ted on T-FMNp), mandibular length (co-gn), maxillary length (co-A), ramuslength (co-go), mandibular body length (go-me), condylion changes co ver(distance co to T-FMN), co hor (distance co-T-FMNp), maxillary basechanges A hor (distance A to T-FMNp), mandibular base changes B hor(distance B to T-FMNp) and pg hor (distance pg to T-FMNp) and me ver(me toT-FMN), upper first molar position ms hor (distance ms to T-FMNp),ms ver (distance ms to T-FMN), lower first molar position mi hor (mi to T-FMNp), mi ver (mi to T-FMN), upper incisor position is hor (is to T-

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FMNp), is ver (is to T-FMN), lower incisor position ii hor (ii to T-FMNp), iiver (ii to T-FMN).

Angular measurements: SNA, SNB, ANB, SNpg, co-go-me, is inclinationto T-FMN, ii to ml, ms axial line (mesiobuccal cusp to mesiobuccal root) toT-FMN inclination – ms to T-FMN line, nl to T-FMN, ml to T-FMN.

Measuring lines and angular measurements are outlined in Picture 2.25.

Picture 2.25. Measuring lines and angular measurements

Dental postition changes in sagittal direction were measured as follows: is hor=is/ T-FMNp minus Apoint/ T-FMNp: sagittal position of the

maxillary central incisor within the maxilla ii hor=ii/ T-FMNp minus pg/ T-FMNp: sagittal position of the

mandibular central incisor within the mandible ms hor=ms/ T-FMNp minus Apoint/ T-FMNp: sagittal position of

the maxillary permanent first molar within the maxilla mi hor=mi/ T-FMNp minus pg/ T-FMNp: sagittal position of the

mandibular first permanent molar within the mandible.

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2.4. Statistical analysis

Statistical analysis was performed with SPSS for Windows software(SPSS, Chicago, IL) at Riga Stradins university Department of Statistics.The data were tested for normality of distribution (Shapiro-Wilk test) andequality of variances (Levene’s test). Independent t-test was used to detectthe differences in the dentoskeletal characteristics between the treated andcontrol groups at start of treatment, as well as in the changes of themeasurements during the observation intervals (T1-T2, T2-T4 and T1-T4).The power of study was calculated considering the ANB angle as a sensitivevariable for the assessment of the orthopedic effects of Class II treatment.

In order to detect a clinically significant change of 2.0 degrees in theANB angle, with a SD for this angle of 1.3 degrees (as derived from aprevious study on the effects of the stainless steel crown Herbst) [15], adesired power of 0.80, and an alpha level of 0.05, the sample size should beof at least 8 subjects in each group when an independent sample t test isapplied (SigmaStat version 3.5, Systat Software, Point Richmond, Calif).

2.5. Method error

Twenty cephalograms selected randomly from the treated sample wereretraced and digitized by the same investigator (Gundega Jakobsone) on twoseparate occasions at least two weeks apart to calculate method error withDahlberg’s formula [97] and to assess the intraclass correlation coefficient(ICC). Method error for linear measurement ranged from 0.27 mm (lowerincisor to T – FMN line) to 0.72 mm (lower mandibular cusp to T - FMNline) and for angular measurements – 0.22 degrees for ANB angle to 1.19degrees for lower incisor inclination. ICC for linear measurements variedfrom 0.949 for overjet to 0.998 for B point to y – axis. For angularmeasurements it ranged from 0.962 (for maxillary plane to T – FMN line) to0.988 (for SNA and SNB angles).

52

3. RESULTS

3.1. Class II correction mechanisms immediately after therapyand stability of results at one year follow-up

Pretreatment characteristics of the groups are summarized in 2.2 table.No significant differences were found at T1 between the treated and controlsamples with the exception of midfacial length (co-A) and of the inclinationof the upper incisors to T-FMN (is to T-FMN) that were significantlygreater in the treatment group. There was no statistically significant diffe-rence in age between the groups at any of the time points. The dental andskeletal changes during the observation intervals are presented in Tables3.1–3.4.

3.1.1. Skeletal changesThe Herbst appliance had no effect on the sagittal position of the maxilla.

No significant change was found in the horizontal and vertical positions ofthe maxillary and mandibular landmarks with respect to the stablebasicranial reference system. During active treatment, total mandibularlength (co-gn) showed a statistically greater increase (1.3 mm; Table 3.2)with respect to the controls, an increase that was maintained in the posttreat-ment period (T1-T4 change, 1.5 mm), though not at a statistically significantlevel (Table 3.4). This change alteration in the amount of mandibulargrowth during active treatment was associated with a significantly greaterincrease in the SNB angle (0.7 degrees) and a significantly greater decreasein the ANB angle (-1.1 degrees) that remained stable in the follow up (T1-T4 change, 0.9 degrees and -0.6 degrees, respectively).

As for the skeletal vertical parameters, the palatal plane angle (nl to T-FMN) showed a significant clockwise rotation of 1.2 degrees in the treatedvs. the control group; this effect was maintained throughout the post-treatment period. No significant change was recorded in the inclination ofthe mandibular plane to FMN or in the co-go-me angle.

3.1.2. Dental changesThe treated group showed a significant reduction of overjet (-2.7 mm)

and correction of overbite (-2.3 mm) with respect to the controls. Althoughduring the posttreatment period a slight relapse was recorded for bothoverjet and overbite, statistically significant corrections were still presentwhen considering the T1-T4 period (-1.4 mm and -1.0 mm, respectively).

53

The upper first molars moved backward significantly by 2.7 mm andtipped distally significantly by 7.1 degrees as a result of treatment. Althougha significant portion of the tipping rebounded during the follow-up (2.7degrees), Class I relationship of the buccal segments was preserved and theupper molars remained significantly tipped back by 4.3 degrees in thetreated sample with respect to the controls. During treatment the upperincisors showed a significant uprighting (-2.6 degrees) that was maintainedwhen considering the T1-T4 follow up period (-2.3 degrees) but not tosignificant extent.

During active treatment in the treated sample the lower first molarsmoved forward significantly by 2.5 mm and extruded significantly by 1.0mm with respect to the controls. When considering the overall observationperiod the lower molars still showed a significant mesialization by 2.1 mmwhile the extrusion of the lower molars was not statistically significant. Thelower incisors proclined significantly by 5.4 degrees in the treated sample.During the T2-T4 period the lower incisors rebounded, however, whenconsidering the overall observation period the proclination of the lowerincisors was still significantly greater in the treated group with respect to thecontrols (2.8 degrees). Although the appliance exerted a significant verticalforce to the upper molars, no significant change in their vertical positionwas recorded. Vertical changes of the lower incisors in the study samplecould be attributed to proinclination. Comparison of the changes in thevariables during the observation periods T1-T2, T2-T4, T1-T4 between thesubjects treated with the crown Herbst appliance comparing and untreatedcontrols are shown in Table 3.1.

Table 3.1. Comparison of the changes in the variables during theobservation periods T1-T2, T2-T4, T1-T4 between the subjects treated withthe crown Herbst appliance comparing and untreated controls. Mean valuesand standard deviations (SD) in parenthesis

T1T2 T2T4 T1T4Variable

StudyGroup

ControlGroup

Pvalue

StudyGroup

ControlGroup

Pvalue

StudyGroup

ControlGroup

Pvalue

Skeletal changes

co hor -0.9(1.2)

-0.4 (1.3) 0.198 -0.6(1.1)

-0.5(1.2)

0.876 -1.5(1.5)

-1.0(1.5)

0.240

co ver 0.3(1.2)

0.9(1.3)

0.098 0.3(1.06)

0.0(1.3)

0.489 0.6(1.5)

0.9(1.7)

0.401

A hor 0.5(1.0)

0.9(1.2)

0.161 0.8(1.5)

0.3(1.8)

0.276 1.3(1.8)

1.3(2.0)

0.886

54

Table 3.1 Continued

T1T2 T2T4 T1T4Variable

StudyGroup

ControlGroup

Pvalue

StudyGroup

ControlGroup

Pvalue

StudyGroup

ControlGroup

Pvalue

Skeletal changes

B hor 1.7(1.9)

1.0(1.7)

0.185 0.7(1.8)

0.9(1.8)

0.752 2.4(2.6)

1.8(2.5)

0.467

pg hor 1.9(2.1)

1.4(2.1)

0.383 0.7(2.1)

1.0(2.1)

0.598 2.5(2.9)

2.4(3.1)

0.837

me ver 3.4(1.6)

2.6(2.7)

0.193 1.4(2.3)

1.2(1.0)

0.681 4.9(3.0)

3.8(3.4)

0.221

co-A 1.6(1.5)

1.3(1.8)

0.593 1.5(1.7)

1.0(1.3)

0.228 3.2(2.3)

2.3(2.1)

0.172

co-gn 4.0(1.8)

2.7(2.4)

0.026 1.8(2.2)

1.6(1.6)

0.737 5.8(2.9)

4.3(3.4)

0.082

co-go 2.7(3.7)

1.1(1.5)

0.071 1.6(2.7)

2.0(2.5)

0.556 4.4(3.8)

3.1(2.5)

0.214

go-me 1.4(3.1)

1.3 (2.7)

0.913 1.0(2.7)

0.8(2.0)

0.868 2.4 (3.4)

2.1(3.0)

0.752

SNA -0.3(0.9)

0.2(1.1)

0.142 0.4(1.0)

-0.3(1.0)

0.042 0.1(1.2)

-0.1(1.6)

0.549

SNB 0.8(1.0)

0.1(0.8)

0.014 0.3(0.9)

0.1(0.8)

0.504 1.1(1.1)

0.2(1.3)

0.014

SNpg 0.7(0.9)

0.3(0.6)

0.122 0.7(0.9)

0.1(0.9)

0.482 1.0(1.1)

0.4(1.3)

0.104

ANB -1.1(1.0)

0.0(0.7)

0.000 0.1(0.9)

-0.4(0.8)

0.118 -1.0(1.2)

-0.4(0.7)

0.035

nl toT-FMN

0.7(1.2)

-0.5(1.9)

0.005 0.0(1.0)

0.1(1.8)

0.880 0.7(1.1)

-0.4(1.8)

0.005

ml to T-FMN

0.3(1.9)

0.1(2.0)

0.684 -0.7(1.5)

-0.8(1.7)

0.740 -0.4(2.1)

-0.7(1.7)

0.488

co-go-me

0.6(2.8)

0.7 (1.7)

0.890 -0.5(1.9)

-0.6(1.6)

0.875 0.0(2.7)

0.1(2.5)

0.923

55

Table 3.1 Continued

T1T2 T2T4 T1T4Variable

StudyGroup

ControlGroup

Pvalue

StudyGroup

ControlGroup

Pvalue

StudyGroup

ControlGroup

Pvalue

Dental changes

Overjet -2.7(1.9)

0.0(0.8)

0.000 0.7(1.0)

-0.5 (1.2) 0.000 -2.0(1.6)

-0.6(1.6)

0.003

Overbite -2.7(1.3)

-0.4(0.7)

0.000 1.4(1.2)

0.0(0.7)

0.000 -1.4(1.0)

-0.4(1.0)

0.000

ms hor -1.6(1.6)

1.1(1.7)

0.000 2.1(2.5)

0.8(1.7)

0.055 0.6(2.7)

2.0(2.5)

0.065

ms ver 1. 4(1.2)

1.7(1.9)

0.501 1.5(1.6)

0.9(1.0)

0.077 3.0(1.9)

2.5(2.3)

0.332

Uppermolartipping

-5.7(4.5)

1.4(4.1)

0.000 4.4(4.5)

1.7(3.6)

0.028 -1.2(4.8)

3.1(5.1)

0.003

mi hor 3.6 (1.9)

1.1(1.7)

0.000 0.4(1.7)

0.9(1.6)

0.342 4.1(2.3)

2.0(2.4)

0.003

mi ver 2.6(1.3)

1.6(2.0)

0.031 0.8(1.8)

0.6(1.0)

0.774 3.6 (2.1)

2.3(2.3)

0.078

is hor 0.1(1.8)

1.0(1.3)

0.076 0.6(1.8)

0.2(1.6)

0.418 0.8(2.4)

1.2(2.1)

0.527

is ver 1.6(1.4)

1.1(1.6)

0.291 1.2(1.6)

0.5(1.0)

0.110 2. 8(1.9)

1.6(2.0)

0.041

ii hor 2.9(1.7)

1.0(1.6)

0.000 -0.1(1.5)

0.7(1.4)

0.075 2.8(2.1)

1.7(2.1)

0.058

ii ver 4.3(1.7)

1.5(2.0)

0.000 -0.2(1.9)

0.5(0.8)

0.192 4.2(2.1)

2.0(2.3)

0.001

Upperincisorinclination

-2.3(4.6)

0.3(2.1)

0.023 -0.6(3.3)

-1.0(2.6)

0.666 -2.9(4.9)

-0.6(2.9)

0.081

Lowerincisorinclination

4.6(4.1)

-0.8 (3.4)

0.000 -3.2(3.9)

-0.6(2.5)

0.013 1.4(4.6)

-1.4(4.0)

0.026

56

Descriptive statistics and statistical comparisons of the T1-T2, T2-T4,T1-T4 changes outlined in Tables 3.2–3.4.

Table 3.2. Descriptive statistics and statistical comparisons of the T1-T2changes

cHerbst Group Control GroupCephalometricmeasures Mean SD Mean SD

Netchange

P value

Skeletal measures

co hor (mm) -0.9 1.2 -0.4 1.3 -0.5 0.198

co ver (mm) 0.3 1.2 0.9 1.3 -0.6 0.098

A hor (mm) 0.5 1.0 0.9 1.2 -0.4 0.161

B hor (mm) 1.7 1.9 1.0 1.7 0.7 0.185

pg hor (mm) 1.9 2.1 1.4 2.1 0.5 0.383

me ver (mm) 3.4 1.6 2.6 2.7 0.8 0.193

co-A (mm) 1.6 1.5 1.3 1.8 0.3 0.593

co-gn (mm) 4.0 1.8 2.7 2.4 1.3 0.026

co-go (mm) 2.7 3.7 1.1 1.5 1.6 0.071

go-ge (mm) 1.4 3.1 1.3 2.7 0.1 0.913

SNA (°) -0.3 0.9 0.2 1.1 -0.5 0.142

SNB (°) 0.8 1.0 0.1 0.8 0.7 0.014

SNpg (°) 0.7 0.9 0.3 0.6 0.4 0.122

ANB (°) -1.1 1.0 0.0 0.7 -1.1 0.000

nl to T-FMN (°) 0.7 1.2 -0.5 1.9 1.2 0.005

ml to T-FMN (°) 0.3 1.9 0.1 2.0 0.2 0.684

co-go-me (°) 0.6 2.8 0.7 1.7 -0.1 0.890

Dental measures

Overjet (mm) -2.7 1.9 0.0 0.8 -2.7 0.000

Overbite (mm) -2.7 1.3 -0.4 0.7 -2.3 0.000

ms hor (mm) -1.6 1.6 1.1 1.7 -2.7 0.000

ms ver (mm) 1.4 1.2 1.7 1.9 -0.3 0.501

Upper molar tipping (°) -5.7 4.5 1.4 4.1 -7.1 0.000

mi hor (mm) 3.6 1.9 1.1 1.7 2.5 0.000

57

Table 3.2. Continued

cHerbst Group Control GroupCephalometricmeasures Mean SD Mean SD

Netchange

P value

Dental measures

mi ver (mm) 2.6 1.3 1.6 2.0 1.0 0.031

is hor (mm) 0.1 1.8 1.0 1.3 -0.9 0.076

is ver (mm) 1.6 1.4 1.1 1.6 0.5 0.291

ii hor (mm) 2.9 1.7 1.0 1.6 1.9 0.000

ii ver (mm) 4.3 1.7 1.5 2.0 2.8 0.000

Upper incisorinclination (°)

-2.3 4.6 0.3 2.1 -2.6 0.023

Lower incisorinclination (°)

4.6 4.1 -0.8 3.4 5.4 0.000

Table 3.3. Descriptive statistics and statistical comparisons of the T2-T4changes

cHerbst Group Control GroupCephalometricmeasures Mean SD Mean SD

Netchange

P value

Skeletal measures

co hor (mm) -0.6 1.1 -0.5 1.2 0.1 0.876

co ver (mm) 0.3 1.06 0.0 1.3 0.3 0.489

A hor (mm) 0.8 1.5 0.3 1.8 0.5 0.276

B hor (mm) 0.7 1.8 0.9 1.8 -0.2 0.752

pg hor (mm) 0.7 2.1 1.0 2.1 -0.3 0.598

me ver (mm) 1.4 2.3 1.2 1.0 0.2 0.681

co-A (mm) 1.5 1.7 1.0 1.3 0.5 0.228

co-gn (mm) 1.8 2.2 1.6 1.6 0.2 0.737

co-go (mm) 1.6 2.7 2.0 2.5 -0.4 0.556

go-me (mm) 1.0 2.7 0.8 2.0 0.2 0.868

SNA (°) 0.4 1.0 -0.3 1.0 0.7 0.042

SNB (°) 0.3 0.9 0.1 0.8 0.2 0.504

SNpg (°) 0.7 0.9 0.1 0.9 0.6 0.482

58

Table 3.3. Continued

cHerbst Group Control GroupCephalometricmeasures Mean SD Mean SD

Netchange

P value

Skeletal measures

ANB (°) 0.1 0.9 -0.4 0.8 0.5 0.118

nl to T-FMN (°) 0.0 1.0 0.1 1.8 -0.1 0.880

ml to T-FMN (°) -0.7 1.5 -0.8 1.7 0.1 0.740

co-go-me (°) -0.5 1.9 -0.6 1.6 0.1 0.875

Dental measures

Overjet (mm) 0.7 1.0 -0.5 1.2 1.2 0.000

Overbite (mm) 1.4 1.2 0.0 0.7 1.4 0.000

ms hor (mm) 2.1 2.5 0.8 1.7 1.3 0.055

ms ver (mm) 1.5 1.6 0.9 1.0 0.6 0.077

Upper molar tipping (°) 4.4 4.5 1.7 3.6 2,7 0.028

mi hor (mm) 0.4 1.7 0.9 1.6 -0.5 0.342

mi ver (mm) 0.8 1.8 0.6 1.0 0.2 0.774

is hor (mm) 0.6 1.8 0.2 1.6 0.4 0.418

is ver (mm) 1.2 1.6 0.5 1.0 0.7 0.110

ii hor (mm) -0.1 1.5 0.7 1.4 -0.8 0.075

ii ver (mm) -0.2 1.9 0.5 0.8 -0.7 0.192

Upper incisorinclination (°)

-0.6 3.3 -1.0 2.6 0.4 0.666

Lower incisorinclination (°)

-3.2 3.9 -0.6 2.5 2.6 0.013

59

Table 3.4. Descriptive statistics and statistical comparisons of the T1-T4changes

cHerbst Group Control GroupCephalometricmeasures Mean SD Mean SD

Netchange

P value

Skeletal measures

co hor (mm) -1.5 1.5 -1.0 1.5 -0.5 0.240

co ver (mm) 0.6 1.5 0.9 1.7 -0.3 0.401

A hor (mm) 1.3 1.8 1.3 2.0 0.0 0.886

B hor (mm) 2.4 2.6 1.8 2.5 0.6 0.467

pg hor (mm) 2.5 2.9 2.4 3.1 0.1 0.837

me ver (mm) 4.9 3.0 3.8 3.4 1.1 0.221

co-A (mm) 3.2 2.3 2.3 2.1 0.9 0.172

co-gn (mm) 5.8 2.9 4.3 3.4 1.5 0.082

co-go (mm) 4.4 3.8 3.1 2.5 1.3 0.214

go-me (mm) 2.4 3.4 2.1 3.0 0.3 0.752

SNA (°) 0.1 1.2 -0.1 1.6 0.2 0.549

SNB (°) 1.1 1.1 0.2 1.3 0.9 0.014

SNpg (°) 1.0 1.1 0.4 1.3 0.6 0.104

ANB (°) -1.0 1.2 -0.4 0.7 -0.6 0.035

nl to T-FMN (°) 0.7 1.1 -0.4 1.8 1.1 0.005

ml to T-FMN (°) -0.4 2.1 -0.7 1.7 0.3 0.488

co-go-me (°) 0.0 2.7 0.1 2.5 -0.1 0.923

Dental measures

Overjet (mm) -2.0 1.6 -0.6 1.6 -1.4 0.003

Overbite (mm) -1.4 1.0 -0.4 1.0 -1.0 0.000

ms hor (mm) 0.6 2.7 2.0 2.5 -1.4 0.065

ms ver (mm) 3.0 1.9 2.5 2.3 0.5 0.332

Upper molar tipping (°) -1.2 4.8 3.1 5.1 -4.3 0.003

mi hor (mm) 4.1 2.3 2.0 2.4 2.1 0.003

mi ver (mm) 3.6 2.1 2.3 2.3 1.3 0.078

is hor (mm) 0.8 2.4 1.2 2.1 -0.4 0.527

is ver (mm) 2. 8 1.9 1.6 2.0 1.2 0.041

60

Table 3.4. Continued

cHerbst Group Control GroupCephalometricmeasures Mean SD Mean SD

Netchange

P value

Dental measures

ii hor (mm) 2.8 2.1 1.7 2.1 1.1 0.058

ii ver (mm) 4.2 2.1 2.0 2.3 2.2 0.001

Upper incisorinclination (°)

-2.9 4.9 -0.6 2.9 -2.3 0.081

Lower incisorinclination (°)

1.4 4.6 -1.4 4.0 2.8 0.026

3.1.3 Class II correction combining dental and skeletal changesThe components of overjet and molar relationship correction during

treatment and post treatment changes are summarized in Pictures 3.1 and 3.2.

Dental and skeletal changes are presented in absolute values. Percentage are presentedin regard to their contribution to the correction of molar relationship.

Picture 3.1. Class II correction mechanism:molar correction

61

Dental and skeletal changes are presented in absolute values. Percentage are presentedin regard to their contribution to the correction of overjet.

Picture 3.2. Class II correction mechanism: overjet correction.

In the correction of molar relationship during treatment an importantparameter was distal movement of the upper molars, which almost comp-letely relapsed during the follow-up, thus at the end of the observationperiod the molar relationship was mainly corrected by forward movement ofthe mandible and of the lower molars.

The appliance produced an overjet reduction by equally changing thedental and skeletal parameters. During the follow-up period the changeswere mainly dental.

62

3.2. Complications

The complications during the active treatment phase for the patients whofinished cHerbst therapy were as follows: 19 patients (10.9%) came for anemergency visit due to unscrewing screws, 2 patients (1.1%) broke thelingual arch between premolars, 15 patients (8.6%) broke the occlusalpatients (1.7%) experienced loosening of the upper first molar crowns, 5patients (2.9%) bent the rods. Four patients experienced 2 complications, 1patient had 4 complications.

Picture 3.3. Broken occlusal rest

Picture 3.4. Broken molar attachment

63

3.3. Patients self-perception on treatment

Out of 99 patients who were given the questionnaires at T3, 87 responseswere obtained. A summary of the responses are given in Table 3.5. Theconclusions on appliance visibility were surprising: this cHerbst modifica-tion excludes additional anchorage on upper first premolars (bands) thatmight be visible during function or smiling, in that way patients couldcontrol visibility of the appliance depending on how much teeth they showwhile expressing emotions (Pictures 3.5, 3.6).

Table 3.5. Summary of the 87 responses to the questionnaire at T3

Esthetics Better72 (82.7%)

The same 15 (17.2%)

Worse 0

Function Better 45 (51.7%)

The same 42 (48.3%)

Worse0

Price Cheap12 (13.8%)

Reasonable 63 (72.4%)

Expensive 12 (13.8%)

Discomfort 2–3 days 25 (28.7%)

1 week 50 (57.5%)

Longer than 1 week 12(13.8%)

Appliancevisibility

At beginning48 (55.2%)

During the whole treatment17 (19.5%)

Not visible 22 (25.3%)

The sametreatment again

Yes 81 (93%)

No 6 (7%)

Medications Yes, 2-3 days 42 (48.3%)

Yes, first week 22 (25.3%)

No 23 (26.4%)

64

Picture 3.5. Forced smile with full appliance visibility

Picture 3.6. Reserved smile with limited appliance visibility

65

4. DISCUSSION

The aim of the study was to evaluate Cl-II correction mechanisms withthe cHerbst appliance by comparing the changes in the sucessfully treatedgroup of patients, who presented stable Class I occlusion one year aftertherapy, with the growth changes of untreated Class II individuals imme-diately after treatment and after one year follow up.

In the present study only the subjects with stable Class relationship 1year after the single active treatment phase with cHerbst were included inthe final study group. It also would have been of interest to analyze theunsuccessful cases, however from the subjects, who showed up for thefollow-up visits only eight growing patients experienced relapse and thenumber was too small to apply the statistical analysis. The study evaluatedunadulterated effects of the cHerbst appliance, because no additionalorthodontic appliances (including retainers) were used during treatmentstage as well as during the 12 month follow-up period.

A considerable advantage of the study was that treatment of theconsecutive subjects was conducted by a single operator according to a strictprotocol. The operator was not involved in the analysis of the data, thusreducing bias of the study. The study and control groups were matched bythe skeletal maturity at T1 and T2 by another independent examiner. Theuse of historical controls was due to the lack of ethical reasons to leaveClass II patients untreated at the developmental period (puberty) that isknown to represent the optimal time for orthopedic modifications [53,61].

4.1. Skeletal changes

The increase in mandibular length induced by cHerbst therapy was foundto be similar to that reported in some other studies [12, 13, 15]. During thefollow-up period, mandibular length increased the same amount in both thetreatment and the control groups. Thus at the end of one year observationperiod, the net increase of the mandible in the study group was 1.5 mmmore compared to the controls; however, this difference was not significantstatistically. This finding is consonant with the study by Pancherz andFackel [70] in which the band Herbst appliance was used as the onlyappliance. When comparing the skeletal and dentoalveolar changes 31months before and after treatment, they concluded that the Herbst appliancehad only a temporary impact on the existing craniofacial growth pattern.Nevertheless, the occlusal relationships were improved and the Class Irelationship was mantained 1 year after treatment.

66

In the majority of studies in which the first phase treatment with theHerbst appliance was followed by fixed appliances, a statistically significantnet increase in mandibular length at the end of treatment was recorded [15,83, 85, 99]. In most of those studies, an acrylic Herbst was used along withstepwise activation of the appliance [83, 85, 99]. The design and construc-tion of the acrylic Herbst could suggest better dentoalveolar anchorage aswell as the inhibition of vertical development because of the interocclusalcoverage of the splint. In a direct comparison of the acrylic splint andstainless steel crown Herbst appliance, however, the investigation of Burk-hardt and co-workers [13] indicated that the two appliance designs producedsimilar changes in horizontal and vertical skeletal position.

The moderate effect on mandibular length also can be explained at leastpartially by the difference in treatment strategies. Because previous studieson the factors influencing relapse after Herbst treatment [62, 65] emphasi-zed the importance of attaining a stable occlusion at the end of Herbstappliance therapy, the treatment objective of the present sample was toestablish Class I relationship during the active phase of treatment rather thanto “overtreat” the occlusion in to a “super Class I” relationship. At the startof treatment, the appliance was activated to an edge-to-edge relationship,and during treatment the buccal segments were controlled for settling, asmentioned earlier. As the lower incisors moved forward and the upperincisors retroclined, no further activation was possible in order to avoid thecreation of a negative overjet.

Several previous studies have suggested that the following treatmentstrategy should be employed to induce increase in condylar growth: (1)stepwise advancement, (2) a 6-month duration for each instance ofadvancement, and (3) initial advancement of at least 5 mm [100-102]. In thepresent sample, not all of these requirements could be realized due to thepredominant dentoalveolar effects of appliance. Although the cHerbstappliance had no significant effect in restraining sagittal growth of themaxilla, a significant restriction in vertical growth of the posterior maxillawas observed, an observation that also been reported in other studies of theHerbst appliance [6, 83-85].

4.2. Dental changes

Dentoalveolar changesSimilar to other studies [62, 103] significant dental relapse/rebound was

recorded during the follow-up period, even though a Class I relationshipwas maintained. Interestingly, in overjet correction skeletal changes contri-

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buted slightly more, while molar correction was achieved mainly by dentalmovements. Other studies have reported comparatively equal contributionof both components [6, 84, 85].

The Herbst appliance was shown to have a headgear effect, and the uppermolars were distalized and tipped backward significantly. This finding wasin agreement with other studies [6, 12, 83-85]. During the follow-up period,the upper molars tended to rebound to a more mesial position by 1.3 mm.However, a Class I relationship of the buccal segments was maintained. Asimilar observation was noted by Burkhardt et al [13], who explained thisphenomenon to be a result of a favorable growth pattern and dentoalveolarcompensation.

The appliance produced a moderate lingual tipping of the upper incisors,while the lower incisors were proclined significantly. Similar findings alsohave been demonstrated in some other samples [6, 83, 85]. Apparently suchfactors as the method of Herbst appliance anchorage in the mandible [104]or the amount of initial activation [62] does not affect the proclination of thelower incisors.

One year after treatment, the lower incisors rebounded by 2.6 degrees,resulting in overjet and overbite correction loss. Pancherz and Hansen [104]found that 80% of the lower incisors proclination recovered within 12months; however they noted that rebound of the incisors was not associatedwith significant crowding. An increase in overjet three years after success-fully treated Class II malocclusion also was reported for the twin blockappliance [105]. The appliance design facilitated forward movement of themolars within the mandible that was slightly greater than reported in othersamples [6, 84, 85]. Forward movement of the lower molars assisted inmolar relationship correction because the overall mandibular forward move-ment was slightly smaller than that reported in previous studies [6, 84, 85].

4.3. Complications

Patient’s cooperation is one of the most important factors influencing thechoice of orthodontic treatment. O’Brien et al [42] reported that the mainreason for the discontinuation of Herbst treatment was persistent debondingof the appliance, which was not found to be related to any operator orpatient factors. O’Brien et al [42] did not report on complications in detail,which would be interesting to know, because complications during cHerbsttreatment can be different. Some of these complications might be solved inthe dental chair during the same visit, while others need laboratoryassistance. Any laboratory work brings higher total cost of the treatment,

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extra visits and longer chair time. Sanden et al [7] reported that 67% pa-tients with the banded Herbst and 60% with the cast splint Herbst experien-ced complications. Although they reported that in the most of instancesloosening of the bands and splints occurred, complications involving highrepair costs such as breakages of bands (30%), splints (2%), and telescopes(6% in the banded Herbst and 4% in the cast splint Herbst), were seen lessfrequently [7].

Most of the complications experienced during our trial on cHerbst did notrequire additional laboratory expenses or expertise. Complications likebroken occlusal rests (8.6%) or unscrewed screws (10.9%) could be handledby local general dentists. However, the following other complicationsdemanded special skills of the operator and a visit of 20-30 minutes: bentrods (2.9%), broken upper first molars attachments (1.1%), loosening of theupper first molar crowns (1.7%). In two cases (1.1%) the lingual arch inbetween premolars broke, requiring laboratory assistance. We have noticedthat fixing cHerbst problems was not complicated, because the operator hada kit of spare parts of the appliance. When making the crown Herbstappliance, the major part of the appliance manufacturing was done by theclinician, leaving as only work for the technician the welding of the lingualarch.

Fracture of the occlusal rests was not judged as a complication if thelingual arch connecting the lower first premolars was still left in place. Ithas been reported that the efficiency of the mandibular anchorage using thebanded type of appliance was not dependent on the number of teethincorporated in the anchorage unit [66].

4.4. Success rate

Only five (2.8%) of the enrolled patients did not finish cHerbst treatmentin our study. Another prospective study on the Herbst appliance [42]reported a discontinuation rate of 12.9%. Prospective investigations on thetwin-block appliance showed even higher drop-out rates – 17% [14] and50% [15]. In the present study, Class I occlusion was obtained in 100% ofthe patients who finished functional treatment stage (T2). The highersuccess rate compared with that of the removable functional appliances[106, 107] could be attributed to the compliance-free design of the applian-ce. It should be noted, however, that in the studies on the activator treat-ment, unsuccessful cases were recorded also in the group of patients withgood compliance [106, 107]. In the current study we cannot presume whatamount of the patients who did not show up for the check up visits had

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developed relapse, but out of 99 patients who came for the check up 6months after the end of treatment, 19 patients (19.2%) had slipping backocclusion and they were assigned to retention with an activator. This is inagreement with Pancherz and Hansen [71] data on occlusal relapse as theauthors concluded that main relapse occurred within the first 6 months afterthe appliance had been removed. Although one year observation period wasrecommended to all patients, some of them urged to start fixed appliancetreatment immediately after cHerbst due to residual irregularities of thedental arches. When a removable functional appliance is used, an idealocclusion can be achieved only in 8 to 27% of the cases [107-109].

4.5. Patient‘s attitude to treatment

Another reason for the high discontinuation rate of the Herbst appliancein the study by O‘Brien et al [42] could be that treatment was provided at nocost to the child and parents. In our study all expenses of treatment werecovered by the patient’s family. If we consider the cost of the appliance, thecast cobalt-chromium design of the Herbst appliance would be as twicemore expensive as the cHerbst device because of the laboratory work. Afterdelivering cHerbst, both patient and parents were informed that several daysmight be needed to get used to the appliance and no hard food had to beconsumed for the whole treatment duration. The results of the questionnairerevealed that most of the patients got used to the appliance in less than oneweek.

Another issue that is very important for patient compliance is the estheticview of the Herbst appliance. The only part of the appliance that causedesthetic problems for the patients was the lower first premolar crowns. Theresults of the questionnaire revealed that visibility of the appliance disturbedmost of the patients only in the beginning of treatment, whereas one fifth ofthe patients were not satisfied with the esthetic view of the appliance for thewhole treatment period (Table 3.5).

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4.6. Treatment duration question

Unlike removable functional appliances, the fixed Class II correctors(e.g. Herbst appliance) impose shorter treatment time – 6-12 months toachieve Class I occlusion [43]. This brings considerable flexibility in theselection of treatment duration. There is still no agreement in the literatureon the exact duration of Herbst therapy. Pancherz [47] stated that the end oftreatment was defined by six months appliance wearing time and overcor-rected Class I occlusion. Valant et al [12] proposed ten months of treatment,while other authors [100,110] suggested twelwe months of Herbst therapy.

Although the use of Herbst appliance for Class II treatment has beeninvestigated by many authors, few clinical trials have evaluated anydifferent than edge-to-edge principles of appliance activation [100,110]. Noauthor has investigated the natural behavior of corrected occlusion afterremoval of appliance. We would suggest that Herbst appliance treatmentshould be discontinued when stable Class I occlusal contacts betweenopposing teeth are achieved. Treatment duration then would depend onClass II severity. The more severe the malocclusion, the longer it takes tocorrect it. As soon as no sagittal relapse occurs after appliance activation,stable vertical interocclusal contacts can develop due to vertical migrationof teeth not included in the anchorage system (pictures 2.11, 2.12).

4.7. Relapse and retention

According to Pancherz [65] , the main reasons of relapse after the Herbsttreatment are insufficient occlusal contacts and tongue thrust habits. Toachieve stable occlusion after the treatment, Pancherz and Ruf [76]suggested the use of Hawley retainers, functional appliances or multibracketsystem. Activator night-time retention is recommended to be performed forat least two years in adolescent patients and three to four years in post-adolescent and adult patients [76]. However, in another study Pancherz andHansen [71] found only a slight difference in the sagittal position of molarsbetween retention and non-retention cases and only in a short-term follow-up. The main disadvantage of the removable retainers is that cooperation isrequired and some patients might fail in that, so the whole idea of non-compliant Herbst therapy is affected. The solution might be to achieve astable occlusion during the Herbst treatment, so no removable device toconsolidate occlusion in Class I relationships is needed after applianceremoval.

In order to stabilize occlusion in the premolar segment, we activated theappliance so that the cusp of the upper premolar would fall into the inter-

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dental space of the lower first and second bicuspid building up a stabletriangle of contacts (Picture 2.12).

In order to increase occlusal contacts for these teeth, the clinician has twomore options: to grind the lower first premolar and upper first molar crowns,thus the layers of the metal and glass-ionomer cement are removed and theteeth can fit into occlusion better. Another option is to remove the occlusalrests on the lower first molars so that they could erupt. Contrarily to thecasted and acrylic splint, both banded and crown Herbst modifications allowvertical migration of the teeth, and, therefore, it can be assumed that theduration of the second phase of treatment would be shorter.

Out of 19 unstable patients six months after the end of treatment, 11 hadan end-to-end molar relationship prior to treatment. Cusp-to-cusp occlusalfunction might cause more attrition of the hard tooth structure than full cuspinterocclusal Class II relationship, thus insufficient interdigitation of theopposing teeth might be present at the end of cHerbst therapy. The solutionto this problem could be building up anatomy of the teeth that experiencedsevere attrition in order to increase interdigitation and create more stabilityfor achieved Class I relationship. Solow [40] stated that dentoalveolar adap-tive mechanism is a system that attempts to maintain relatively stable inte-rarch relationship under varying jaw relationships. In other words, theinterdigitation of occlusion plays important role in maintaining Class I den-tal relationship despite ongoing sagittal skeletal changes. Another possiblecause for relapse, lip-tongue dysfunction habit, was detected in four out of19 relapse patients in our study. The Andresen activator (night time useonly) has been found to be suitable device for these patients after Herbsttreatment as suggested by Pancherz [65]. The appliance holds the teeth inthe desired position and allows interocclusal adjustments.

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CONCLUSIONS

1. The occlusal correction of Class II growing patients who presentedstable Class I one year after cHerbst treatment was achieved primarydue to the dentoalveolar changes and only limited skeletal change:

a) the appliance had no effect on the sagittal position of themaxilla, but the maxillary plane rotated significantlyclockwise, and that was maintained throughout the observationperiod;

b) immediately after the cHerbst mandible was signifficantlylonger in the study group comparing to controls, whereas afterthe follow-up the difference was no longer significant;

c) cHerbst exerted significant effect on the upper incisorsimmediately after therapy, though no significant changes weredetected after the follow up, therefore the appliance could berecommended in dentolaveolar Class II cases, especially withthe upper arch crowding;

d) the lower incisors proclined significantly immediately aftertreatment and rebounded during the follow up, however at theend of the observation period proclination of the lower incisorswas still significant;

e) the upper first molars moved backward and tipped distallysignificantly as a result of treatment in growing sample. Theupper first molars remained significant tip back after follow-up;

f) the lower first molars moved forward significantly as a resultof therapy, the net change remaining significant after thefollow up.

2. The feedback on the cHerbst appliance therapy six months after thetreatment was mostly positive. Majority of the patients were satisfiedwith the esthetic effects and visibility of the appliance and got used tothe cHerbst in less than one week time, whereas only half of thequestionned patients admitted the improved chewing function due tocorrected Class II.

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CLINICAL RECOMMENDATIONS

Considering the movements of the teeth in the upper arch, cHerbst workssimilar to the headgear appliances with minimal effects on the upperincisors. Since the headgear is removable and extremely visible appliance, itis suggested that in cases with crowding in the upper front segment cHerbstcould substitute headgear appliances.

Due to distalisation of the upper first molars, as stressed in the resultssection, too much space is provided for the upper premolars, so these teethoften rotate and tip distally. In order to prevent rotations it is suggested tobond the braces not only on the front teeth in order to increase overjetbefore the onset of the functional phase of treatment, but also includepremolars.

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LIST OF PUBLICATIONS

1. Latkauskiene D, Jakobsone G, McNamara James A. A prospectivestudy on the clinical effectiveness of the stainless steel crown Herbstappliance. Progress in Orthod 2012;Vol 13, 2:100-108;

2. Latkauskienė D, Jakobsone G Immediate post-treatment crownedHerbst effects in growing patients. Baltic Dental and MaxillofacialJournal, 2012, Vol. 14, No. 3; 89-92.

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94. Pancherz H. Vertical dentofacial changes during Herbst appliancetreatment : a cephalometric investigation. Swed Dent J Supp 1982;15:189-96

95. de Almeida MR, Henriques JF, de Almeida RR, Weber U,McNamara JA Jr. Short-term treatment effects produced by theHerbst appliance in the mixed dentition. Angle Orthod 2005; 75:540-547

96. Franchi L, Baccetti T, McNamara JA. Treatment and posttreatmenteffects of acrylic splint Herbst appliance therapy. Am J OrthodDentofacial Orthop. 1999;115:429–438

97. Dahlberg G. Statistical methods for medical and biological students.New York: Interscience Publications 1940

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98. Siara-Olds NJ, Pangrazio-Kulbersh V, Berger J, Bayirli B. Long-term dentoskeletal changes with the Bionator, Herbst, Twin Blockand MARA functional appliances. Angle Orthod. 2010;80:18-29.

99. Baccetti T, Franchi L, Stahl F. Comparison of 2 comprehensiveClass II treatment protocols including the bonded Herbst andheadgear appliances: a double-blind study of consecutively treatedpatients at puberty. Am J Orthod Dentofacial Orthop. 2009;1135;698:e1-10.

100. Du X, Hagg U, Rabie AB. Effects of headgear Herbst and mandi-bular step-by-step advancement versus conventional Herbst applian-ce and maximum jumping of the mandible. Eur J Orthod. 2002;24:167-174.

101. Purkayastha SK, Rabie AB, Wong R. Treatment of skeletal class IImalocclusion in adults: stepwise vs single-step advancement with theHerbst appliance. World J Orthod. 2008;9:233-243.

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103. Lai M, McNamara JA Jr. An evaluation of two-phase treatment withthe Herbst appliance and preadjusted edgewise therapy. SeminOrthod.1998;4:46-58.

104. Pancherz H, Hansen K Mandibular anchorage in Herbst treatment.Eur J Orthod 1988;10:149-164

105. Mills CM, McCulloch KJ. Posttreatment changes after successfulcorrection of Class II malocclusions with the twin block appliance.Am J Orthod Dentofacial Orthop. 2000;118:24-33.

106. Tulloch JFC, Proffit WR, Phillips C. Influences on the outcome ofearly treatment for Class II malocclusion. Am J Orthod DentofacialOrthop 1997;111:533-542.

107. Casutt C, Pancherz H, Gawora M, Ruf S. Success rate and efficiencyof activator treatment. Eur J Orthod 2007;29:614-21.

108. Tulloch JFC, Proffit WR, Phillips C. Outcomes in a 2-phase clinicaltrial of early Class II treatment. Am J Orthod Dentofacial Orthop2004;125:657-67.

109. Bondevik O. How effective is the combined activator-headgeartreatment? Eur J Orthod 1991;13:482-5.

110. Hagg U, Du X, Rabie ABM. Initial and late treatment effects ofheadgear-Herbst appliance with mandibular step-by-step advance-ment. Am J Orthod Dentofacial Orthop 2002;122:477-85.

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SUPPLEMENTS

Supplement no1

SUBJECT INFORMATION SHEET No...

1. The purpose of this Subject Information Sheet is to inform you of theresearch study Herbst appliance effects on dental and skeletal struc-tures in growing patients conducted by orthodontist Dalia Latkaus-kienė and to invite you to take part in this study. This Subject Infor-mation Sheet describes the purpose, procedures, benefits, risks,possible discomforts and precautions of the study and provides otherdetails that may be important to you. If you decide to be part of thisstudy, you will be asked to sign a consent form. By signing thisdocument, you will confirm that you will follow all the instructionsgiven by your doctor. Please, take your time to carefully read thisdocument as it is very important that you understand the informationprovided herein. If you come across any unfamiliar words or have ahard time understanding any of the statements, you should ask yourdoctor. Before taking the decision, you may wish to discuss it withyour family member or friends. If a person to take part in the study isa minor, the consent form is to be signed by both the subject and thesubject's parent/caregiver.

2. The purpose of this research study is to assess the effects of the Herbstappliance on the patient’s jaws and teeth. The study will be conductedat the orthodontics clinic of Kauno ortodontijos centras, UAB inKaunas. For further information on the Herbst appliance and forvisuals illustrating clinical cases of the treatment, please refer to thewebsite of the said orthodontics clinic at www.ortodontijoscentras.lt.The study will involve 11–25 year-old patients who have been diagno-sed with malocclusion (faulty bite) and recommended the treatmentwith the Herbst appliance. The expected number of the subjects toenter the study is 180.

3. The primary goal of the study is to obtain new medical knowledge thatcould help improve the treatment of patients with the same biteproblems that you have. The Herbst appliance has been used inorthodontic treatment since 1980, and orthodontist Dalia Latkauskienėhas been using it in her clinical practice since 2004.

4. You are not eligible to take part in the study, if:

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a) you had previously received treatment with orthodontic applian-ces (e. g. you had been wearing a removable retainer);

b) you have been having a hard time properly taking care of yourteeth (the Herbst appliance makes it harder to take care of thehygiene of your teeth and mouth which may lead to dentalcaries);

c) you have been diagnosed by the orthodontist to have a disor-der/syndrome affecting the number, size and/or shape of yourteeth;

d) you have a painful temporomandibular (jaw) joint and/or itcracks/emits noises;

e) you are pregnant.5. You will receive your treatment with the Herbst appliance at the

orthodontics clinic of Kauno Ortodontijos Centras, UAB in Kaunas,following a standard protocol for the Herbst appliance (please find thedocument attached to this Subject Information Sheet). If you have anyfurther questions regarding the protocol, you may ask your doctor formore explanation; she will provide you with all the information thatyou need. It will take two years to complete this research study. If youparticipate in the study, you will have several x-rays performed (forthe purpose of assessing the effects of the Herbst appliance):a) Prior to the treatment: a panoramic X-ray to evaluate the condi-

tion of your teeth and a lateral cephalogram (X-ray image of thestructures of the head) to evaluate the position of your jaws andteeth. These X-rays are performed for all patients who come foran appointment at the orthodontics clinic of Kauno OrtodontijosCentras, UAB.

b) After completion of the treatment: a lateral cephalogram. The X-ray is performed for all patients who have completed thetreatment with any type of orthodontic appliance. It will be usedto evaluate the results of the treatment.

c) At one year after the treatment: a lateral cephalogram. It will beperformed only for patients taking part in the study. The X-raywill be used in evaluating further treatment results. The X-ray isfree of charge.

6. The treatment process and the follow-upa) For a year after the placement of the orthodontic appliance, the

patient will come to see the orthodontist every four to six weeks.The appliance will be adjusted at each visit to the orthodontist'soffice. Treatment with the Herbst appliance usually lasts for ayear.

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b) A follow-up is a part of the study following the treatmentperiod. During the follow-up, you will have to return to theclinic two times, i. e. once in six months. Patients who are nottaking part in the study have to come for such examinations, too.Your travel costs will not be reimbursed to you. At six monthsafter the removal of the appliance, you will receive aquestionnaire where you will have to evaluate the quality andother aspects of the treatment; filling out the questionnaire willbe mandatory. You will not have to provide any personal details.

7. The benefits of taking part in the study. During the study, you will notbe charged for your visits to the orthodontist's office. In case of abreakage, the appliance will be repaired at no cost. If your bitebecomes unstable during the follow-up period, the retainer will beprovided to you free of charge. The estimated financial benefits(according to the price list approved by Kaunas Ortodontijos Centras,UAB) may reach up to 400-1000 litas.

8. Injuries, discomforts and side effects. The patient may only suffer anyinjuries or side effects as a result of an X-ray (a lateral cephalogram)performed at the end of the follow-up period. The treatment requiredby the patient will depend on the type of malocclusion diagnosed, i.e.the bite problem identified. The standard treatment follows theprotocol of the orthodontics office. The patients taking part in thisstudy will have to come for appointments at the orthodontist’s officeas often as the non-participants treated with the Herbst appliance.Thus, participation in the study will not require any extra time.

9. Withdrawal from the study. Your participation in the study may bediscontinued if:a) you fail to keep your appointments. The patient will be charged

for the further treatment according to the price list approved byKauno Ortodontijos Centras, UAB;

b) you keep on deliberately breaking the orthodontic appliance anddo not follow the recommendations of the doctor. The patientwill be charged for the further treatment according to the pricelist approved by Kauno Ortodontijos Centras, UAB;

c) you fail to arrive on time for the interim visits scheduled duringthe follow-up period. In this case, the doctor does not bear anyresponsibility for the instability of treatment results;

d) you become pregnant during the study. The treatment is tocontinue at the expense of the patient according to the price listapproved by Kauno Ortodontijos Centras, UAB;

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e) you refuse to continue your participation in the study. Thetreatment is to continue at the expense of the patient accordingto the price list approved by Kauno Ortodontijos Centras, UAB.When withdrawing from the study, the subject may requirehis/her paper data record back and recover his/her X-rays.

10. For conducting this study, we will only need your date of birth, X-raysand paper data records of your visits. Your paper record will beidentified by a unique code number corresponding to your studyenrolment number. If you wish, you will not be required to provideyour name, surname, place of residence and other personal details. Forthe sake of your convenience and for the convenience of theinvestigator, we will need a telephone number which we could contactyou at if we need to reschedule your appointment. The codedinformation will only be available to the investigator and authoritieslegally authorised for this purpose (such as ethics committees,auditors, etc.).

11. Use of information collected during the study. The data from thereadings of the X-rays will be summarised. The study results will bepublished in the form of research articles in dentistry journals andother types of specialized publications on the topic.

Subject’s paper data record will be kept for five years from the end of thestudy. Your participation in this study is entirely voluntary, you willtherefore not receive any payments for your participation in the study.

If there is anything that is not clear to you or you have any concernsregarding the study, you may call at 8-3738-7560 (Orthodontics Clinic ofthe Lithuanian University of Health Sciences, Prof. A. Šidlauskas, ResearchSupervisor) or you may contact directly investigator Dalia Latkauskienė, at8-6157-1197.

Research supervisorProf. Antanas ŠidlauskasInvestigator/orthodontistDalia Latkauskienė

If you have any questions about your rights as a participant in a researchstudy, you may contact Kaunas Regional Biomedical Research EthicsCommittee, at (+370)37 32 62 43.

To be part of the study, please sign the consent form attached to thisdocument.

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Supplement no2

INFORMED SUBJECT CONSENT FORM

(If the subject is a minor, the consent form is to be filled out by thesubject and signed by both the subject and the subject’s parent/caregiver.The consent form is to be filled out on the behalf of the subject. If thesubject is an adult person, the form is to be filled out and signed by thesubject only.)

I have read and understand the information in this subject informationsheet and the protocol for the Herbst appliance. All of my questions havebeen answered to my satisfaction.

I, ………………………………………………………………………….,voluntarily agree to take part in the research study Herbst appliance effectson dental and skeletal structures in growing patients conducted by DaliaLatkauskienė.

.....................................................................…… ...............................Subject’s name, surname Signature

......................................................................…… ..............................Name, surname of the subject’s parent/caregiver Signature

Date..................................

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Supplement no 3

HERBST APPLIANCE PROTOCOL FOR THE PATIENT

Kauno ortodontijos centras

Protocol for the functional Herbst appliance installation and activetreatment.

The Herbst appliance is used in the treatment of Class II malocclusionwhich you have been diagnosed with at the visit to the orthodontist’s office.

The Herbst appliance has been used successfully since 2006. For moreinformation on the Herbst appliance, please refer to the website of theKauno Ortodontijos Centras at www.ortodontijoscentras.lt. The doctor willillustrate several clinical cases of the treatment with the Herbst appliance atyou request.

The Herbst appliance is installed in three steps, in the course of threevisits to the orthodontist’s:

At Visit 1: using rubber bands, separation of Tooth#34 and Tooth#44 isperformed;

At Visit 2 (1 week after Visit 1): Tooth#34 and Tooth#44 crowns arefitted and the alginate impression used for the manufacture of the lingualarch is taken;

At Visit 3 (1 week after Visit 2): the lingual arch is fixated with thecrowns, Tooth#16 and Tooth#26 crowns are fitted and fixated.

The duration of the Herbst treatment is 12 months. In the course of thetreatment, the appliance is activated as necessary. Repeated visits to theorthodontist’s office are scheduled every two months. After removing theappliance, the faulty bite pattern will be corrected, but the dental structureswill not be aligned, and the dental movement that occurs during the treat-ment can cause crowding of or gaps between your teeth. After completingthe Herbst treatment, the doctor will advise you on your further treatment,i.e. recommend a special functional appliance to be worn at night for 2 yearsafter the treatment is completed to preserve the results (this will require youto return to the orthodontist’s office every 3 months for a year’s time). Thisfunctional appliance will help keep the bite position stable but will not solvethe aesthetic issues, such the extra space between your teeth. The Herbsttreatment is usually followed by the treatment with a bracket system whichis used to resolve the anticipated aesthetic issues.

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I have read and understand the information in this protocol. I havereceived explicit and clear answers to all of my questions. I consent tocomply with the protocol.

......................................................................…… ..............................Signature of the patient or his/her parent/caregiver(if the patient is a minor)

Date..................................