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Research ArticleComparison of Activator-Headgear and Twin Block TreatmentApproaches in Class II Division 1 Malocclusion

Stjepan Spalj1 Kate Mroz Tranesen2 Kari Birkeland3 Visnja Katic1

Andrej Pavlic1 and Vaska Vandevska-Radunovic3

1Department of Orthodontics School of Medicine University of Rijeka Rijeka Croatia2Private Practice Tannregulering Kristiansand Kristiansand Norway3Department of Orthodontics Institute of Clinical Dentistry University of Oslo Oslo Norway

Correspondence should be addressed to Stjepan Spalj stjepanspaljmedriunirihr

Received 1 November 2016 Accepted 4 January 2017 Published 22 January 2017

Academic Editor Simona Tecco

Copyright copy 2017 Stjepan Spalj et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Thepurposewas to compare the treatment effects of functional appliances activator-headgear (AH) andTwinBlock (TB) on skeletaldental and soft-tissue structures in class II division 1 malocclusion with normal growth changes in untreated subjects The sampleincluded 50 subjects (56 females) aged 8ndash13 years with class II division 1 malocclusion treated with either AH (119899 = 25) or TB (119899 =25) appliances Pre- and posttreatment lateral cephalograms were evaluated and compared to 50 untreated class II division 1 casesmatched by age gender ANB angle and skeletal maturity A paired sample independent samples tests and discriminant analysiswere performed for intra- and intergroup analysis Treatment with both appliances resulted in significant reduction of skeletal andsoft-tissue facial convexity the overjet and the prominence of the upper lip in comparison to untreated individuals (119901 lt 0001)Retroclination of maxillary incisors and proclination of mandibular incisors were seen the latter being significantly more evidentin the TB group (119901 lt 005) Increase of effective mandibular length was more pronounced in the TB group In conclusion both AHand TB appliances contributed successfully to the correction of class II division 1 malocclusion when compared to the untreatedsubjects with predominantly dentoalveolar changes

1 Introduction

Early treatment of class II malocclusion aims to correct thesagittal relationship modify the pattern of facial growth andimprove both hard- and soft-tissue profile [1ndash4]Themajorityof the clinical studies recognize the useful effect of functionalappliances in sagittal correction of the malocclusion butagree that the treatment is mainly restricted to dentoalveolarchanges [5] Favorable skeletal changes which can modifythe growth pattern can also occur depending on individualgrowth potential [1 6]

A class II malocclusion may result from mandibulardeficiency maxillary excess or combination of both [7 8]Several varieties of functional appliances are currently in useaiming to correct the skeletal imbalances The combinationof an activator with headgear (AH) is used to provide greatercumulative skeletal changes than either appliance wouldprovide alone [9] They affect maxilla by decreasing forward

and downward growth of the maxillary complex whileallowing the forward growth of the mandible to continuethus influencing the profilemore favorably [9 10] TwinBlock(TB) appliance as well as most of other functional appliancesis designed to encourage adaptive skeletal growth by main-taining the mandible in a corrected forward position for asufficient period of time [1 4 11]

Many studies have investigated the effect of AH and TBappliance on the dental and skeletal variables However nostudies have provided a direct comparison of the treatmentchanges between them One study compared the effects ofboth appliances [3] but the evaluationwas limited to the soft-tissue profile changes

Therefore the aims of this study were to explore skeletaland dentoalveolar changes in class II division 1 patientstreatedwith TB andAHand to compare their treatment effectwith normal growth changes of untreated controls (CTRL)with the same malocclusion The hypotheses were as follows

HindawiBioMed Research InternationalVolume 2017 Article ID 4861924 9 pageshttpsdoiorg10115520174861924

2 BioMed Research International

Cm

PrnSBa

MP

NL

FA

FHNBa

NSL

NBNA

ANS

OrPt

CoPo

PNS

Go

Ba

S

S

E

Cm-Sn

Cm-Ls

A-Pg

Co-Gn

Co-A

N

PgGnMe

Li

Ls

Sn

In + 1

In minus 1

Ap minus 1

Ap + 1

Gl998400

Pg998400

Gl998400-Sn

Sn-Pg998400

Figure 1 Points and plains used in cephalometric analysis Gl1015840 (soft-tissue glabella) Prn (pronasale) Cm (columella) Sn (subnasale) Ls(labrale superius) Li (labrale inferius) Pg1015840 (soft-tissue pogonion) Pg (osseous pogonion) Gn (gnathion) Me (menton) Go (gonion) Ba(basion) Co (condylion) Po (porion) Pt (pterygoid point) S (sella) PNS (posterior nasal spine) ANS (anterior nasal spine) N (nasion) Or(orbitale) Ap + 1 (apicale superius) Ap minus 1 (apicale inferius) In + 1 (incisale superius) In minus 1 (incisale inferius) NSL (nasion-sella line) FA(facial axis) NL (nasal line) MP (mandibular plane) FH (Frankfort horizontal) E (Rickettsrsquo Esthetic line) and S (Steinerrsquos line)

(1) Both appliances havemore pronounceddentoalveolareffect in the treated groups than growth itself in theuntreated group

(2) TB stimulates more skeletal growth of mandible thanAH

(3) AH has better control of vertical dimension than TB

2 Materials and Methods

21 Study Population and Design The sample included 50subjects (56 females) aged 8ndash13 years (median 11) with classII division 1 malocclusion treated with either AH (119899 = 25)or TB (119899 = 25) appliances The data were collected retro-spectively among 151 subjects treated in the period of 2000ndash2015 at theDepartment of Orthodontics inOslo Norway andthe Department of Orthodontics in Rijeka Croatia Inclusioncriteria were distal molar occlusion overjet (OJ) gt5mm andhaving pre- and posttreatment lateral cephalograms Accord-ing to the cervical vertebral maturation method [12] theincluded subjects were in the prepeak stages (CS1ndashCS3)of skeletal maturation before treatment and CS3ndashCS5 aftertreatment

The AH appliance had all maxillary teeth covered withacrylic and included labial spring for the torque control ofthe incisors [13] High pull headgear was always used simul-taneously with the appliance TB appliance [14] with additionofmaxillary labial bow to aid the anterior retention andmakethemaxillary incisors retroclinedwas used in the other group

The expansion screw was incorporated in the maxillary plateand activated one quarter-turn each week for an averageperiod of six months Construction bite was the same in bothappliances with the anterior positioning ofmandible by 6mmand vertical opening by 4mm in the first molar area Thepatients were recommended to use the appliances for 12ndash14 hours per day Treatment was stopped when the patientsachieved molar class I occlusion or slight hypercorrection

Pretreatment (T1) andposttreatment (T2) lateral cephalo-grams were evaluated and compared to 50 untreated class IIdivision 1 cases matched by age gender ANB angle skeletalmaturation of cervical vertebrae and observation periodTheywere selected fromAmerican Association of Orthodon-tists Foundation Craniofacial Growth Legacy CollectionCephalometric analysis (Table 1 Figure 1) was performed oncalibrated pre- and posttreatment lateral cephalograms bytwo investigators (KMT and SS) using the cephalometricsoftware Facad (Ilexis AB Sweden) and AudaxCeph (AudaxSlovenia)

The study was in accordance with the Helsinki Decla-ration and the protocol was approved by the local ethicalcommittees in Norway (02-09-2010) and in Croatia (2170-24-01-15-2)

22 Statistical Analysis After inspection of histograms andquantile-quantile plots and testing the normality of the datawith the Shapiro-Wilk test a paired 119905-test was preformed toassess the statistical significance of changes occurring duringthe treatment with each appliance (intragroup analysis)

BioMed Research International 3

Table 1 Cephalometric variables used in the study

Number Variable Unit Description

1 NSBa ∘ Cranial base angle expression of the flexion of the cranial base(nasion-sella-basion)

2 SNA ∘ Angle of anterior part of cranial base (S-N) and point A (subspinale)on maxilla

3 SNB ∘ Angle of anterior part of cranial base (S-N) and point B(supramentale) on mandible

4 ANB ∘ Angle between point nasion and point on maxilla and mandible basalsagittal relation between the jaws

5 A-NPg mm The shortest distance from A point to the facial plane (N-Pg)expression of the skeletal convexity of the face

6 NLNSL ∘Angle between the nasal line (anterior to posterior nasal spine

ANS-PNS) and the nasion-sella line expression of the tilting of themaxilla relative to the anterior cranial base

7 MPNSL ∘ Angle of mandibular plane (Go-Me) relative to the anterior cranialbase

8 MPNL ∘ Angle of mandibular plane (Go-Me) and nasal line

9 FANBa ∘Lower angle between the facial axis (pterygoid point-gnathion) andthe nasion-basion line expression of the growth direction of the chin

and the relationship facial height and depth

10 UFH mmUpper facial height (middle third of the face) distance from nasionpoint to spina nasalis anterior measured perpendicular to Frankfort

horizontal (FH)

11 LFH mm Lower facial height (lower third of the face) distance from spinanasalis anterior to menton measured perpendicular to FH

12 UFHLFH Upper to lower facial height ratio

13 Co-A mm Distance from condylion to A point measurement of the effectivelength of midface

14 Co-Gn mm Distance from condylion to gnathion measurement of the effectivelength of mandible

15 Max Mand diff mm

Maxillomandibular differential length the difference between theeffective mandibular length (Co-Gn) and the effective midface length

(Co-A) gives an indication of the sagittal discrepancy betweenmaxilla and mandible

16 minus1MP ∘ Superoposterior angle of lower incisor long axis and mandibular plane17 +1NSL ∘ Inferoposterior angle of upper incisor long axis and a nasion-sella line18 minus1A-Pg angle ∘ Angle between the long axis of the lower incisor and A-Pg line19 +1A-Pg angle ∘ Angle between the long axis of the upper incisor and A-Pg line

20 minus1A-Pg distance mmDistance from the midpoint of the incisal edge of the most prominentmandibular incisor to A-Pg line expression of the protrusion of the

lower incisors

21 +1A-Pg distance mmDistance from the midpoint of the incisal edge of the most prominentmaxillary incisor to A-Pg line expression of the protrusion of the

upper incisors

22 Gl1015840-Sn-Pg1015840 ∘Lower angle formed by the line from glabella to subnasale and theline from soft tissue pogonion to subnasale expression of the

convexity of the soft tissue profile23 Cm-Sn-Ls ∘ Nasolabial angle expression of dentoalveolar protrusion

24 Li-E mm Distance from lower lip (labrale inferius) to Prn-Pg1015840 (RickettsrsquoEsthetic line)

25 Ls-E mm Distance from upper lip (labrale superius) to Prn-Pg1015840 (RickettsrsquoEsthetic line)

26 Li-S mm Distance from lower lip to Cm-Pg1015840 (Steinerrsquos line)27 Ls-S mm Distance from upper lip to Cm-Pg1015840 (Steinerrsquos line)

28 OJ mm Distance between the incisal edges of the most prominent maxillaryand mandibular incisors measured parallel to the occlusal line


Table 2 Gender age and treatment duration of the Twin Block(TB) Activator headgear (AH) and untreated control (CTRL)group

Treatment group119901

TB AH CTRLFemale gender (119873percentage)

15 (60) 13 (52) 28 (56) 0850lowast

Age before treatment(years)

Median (interquartilerange)

11 (10ndash12) 10 (9ndash11) 11 (10-11) 0336lowastlowast

Minndashmax 9ndash13 8ndash12 8ndash13Mean observation period(months)

Mean plusmn std deviation 142 plusmn 48 154 plusmn 55 149 plusmn 52 0745lowastlowastlowast

Minndashmax 8ndash24 12ndash24 10ndash24lowast1205942 test lowastlowastKruskal-Wallis test lowastlowastlowastANOVA

Independent samples test was used for intergroup analysis(between appliances groups) For the differences in agebetween groups the Kruskal-Wallis test was used and 1205942 fordifferences in gender Analysis of variance with the Student-Newman-Keuls post hoc test was used to test the amount ofchanges between treated groups and controls Effect size thatis the magnitude of the relationship was estimated by 119903 and1205782 Discriminant function analysis a multivariate techniquewas used to explore which changes in cephalometric parame-ters discriminate treatment groups and untreated subjects themost and how effective those parameters are in predictingtreatment group membership

Reliability that is consistency of measurements wasassessed on ten randomly selected cephalograms remeasuredwith a three-month interval Intraclass correlation coefficient(ICC) andDahlberg formulawere usedDahlberg formula formethod error is ME = sum11988922119899 where ldquo119889rdquo is the differencebetween two registrations and ldquo119899rdquo is the number of doubleregistrations [15] IBM SPSS 22 (IBM Corp Armonk USA)software was used for data analysis

3 Results

The reliability of measurements was good or excellent withICC ranging from 0660 for upper-to-lower facial height ratioto 0995 for inclination of mandibular plane relative to theanterior cranial base and ME from 03 for SNA to 66 fornasolabial angleThe error of themethodwas less than 10 ofthe biologic variation Power calculation of this study showedthe least detectable mean difference in diff ANB to be 11degree (80 test power with 95 significance level) Thepresent studywas not suitable for statistical analysis of genderdifferences in treatment effects due to small samples

At T1 the treatment groups had similar characteristics(Tables 2 and 3) and differences between genders in thosevariables were not significant Untreated subjects had lower

OJ at T1 (56 plusmn 21 119901 lt 0001) but higher OJ at T2 (59 plusmn 22119901 lt 0001) compared to the treated groups

Treatment with both appliances resulted in significantincrease of the SNB angle reduction of the ANB angle retru-sion and retroclination of the maxillary incisors protrusionand proclination of the mandibular incisors and reductionof the OJ (Table 3) Soft tissues demonstrated reduction ofconvexity and prominence of the upper lip and increasednasolabial angle

The untreated group manifested significant increase inthe SNB angle (119901 = 0005) upper and lower facial height(119901 le 0001) and increased maxillary and mandibular length(119901 lt 0001) with the mandible growing significantly morethan the maxilla (Table 4)

Treatment with the TB appliance resulted in increasedmandibular incisor proclination and protrusion compared tothe AH appliance (119901 lt 005 Table 5)

Treatment with both functional appliances resulted insignificant reduction of the ANB angle when compared tothe untreated population (119901 lt 0001 Table 5) It was mainlydue to the increase in the SNB angle and maxillomandibulardifferential length (difference between effective mandibularlength (Co-Gn) and the effective midface length (Co-A) 119901 lt0001) Both appliances significantly reduced the convexity ofthe hard and soft facial tissues in comparison to the untreatedpopulation (119901 lt 0001) Additionally retroclination of themaxillary incisors was noticed in both treatment groupsand was slightly but insignificantly more pronounced inthe AH group Proclination of the mandibular incisors wassignificantlymore pronounced in theTB group (119901 lt 005) Asa consequence OJ and the prominence of the upper lip weresignificantly reduced in comparison to the untreated subjects(119901 lt 0001)

In order to explore which variablesmostly distinguish thethree groups of subjects discriminant analysis was appliedChanges in cephalometric variables during treatment andobservation period were used as predictors Variables thatdemonstratedmost changes or differences were selected withspecial attention in obtaining the lowest possible correlationbetween predictors Two discriminant functions in this anal-ysis could be estimated both having significant discrimi-nating power Figure 2 demonstrates that functions clearlydiscriminate groups First discriminant function presentedin horizontal direction of Figure 2 distinguishes treated fromuntreated subjects Variables that comprise this first discrim-inant function are presented in Table 6 and their correlationswith the first discriminant function aremarked with asterisksin the first numeric column More effect size was seen in theposition of the incisors and soft tissues than in the skeletalchanges Changes in those features explained high proportionof variability of distinction between treated and untreatedsubjects (909 119901 lt 0001)

Second discriminant function presented in verticaldirection of Figure 2 and marked in the last column ofTable 6 mostly distinguishes the two treatment groups Moreeffect size was seen in inclination of incisors and mandibulargrowth than in the position of the lower lip Changes inthose features accounted for low variability of distinctionbetween treatment groups (91 119901 = 0041) Discriminant


Table 3 Pretreatment (T1) and posttreatment (T2) values of the investigated variables in the Twin Block (TB) and activator-headgear (AH)groups

TB119901lowast 119903lowastlowast

AH119901lowast 119903lowastlowastT1 T2 T1 T2

Mean plusmn SD Mean plusmn SD Mean plusmn SD Mean plusmn SDNSBa 1310 plusmn 45 1309 plusmn 46 0752 0065 1283 plusmn 51 1274 plusmn 50 0014 0476SNA 801 plusmn 32 798 plusmn 36 0118 0315 818 plusmn 28 817 plusmn 27 0432 0161SNB 742 plusmn 30 753 plusmn 33 lt0001 0751 762 plusmn 25 774 plusmn 25 lt0001 0835ANB 59 plusmn 16 44 plusmn 17 lt0001 0751 57 plusmn 17 42 plusmn 17 lt0001 0899A-NPg 49 plusmn 21 37 plusmn 23 lt0001 0661 42 plusmn 22 29 plusmn 24 lt0001 0831NLNSL 79 plusmn 29 76 plusmn 31 0359 0187 54 plusmn 25 52 plusmn 26 0420 0165MPNSL 352 plusmn 47 353 plusmn 52 0925 0019 333 plusmn 50 324 plusmn 47 0011 0488MPNL 273 plusmn 45 277 plusmn 48 0431 0162 279 plusmn 46 272 plusmn 46 0086 0343FANBa 861 plusmn 34 863 plusmn 37 0614 0104 875 plusmn 37 878 plusmn 40 0299 0212UFH 477 plusmn 30 493 plusmn 34 0001 0597 462 plusmn 48 467 plusmn 33 0534 0128LFH 568 plusmn 45 599 plusmn 47 lt0001 0784 573 plusmn 57 588 plusmn 44 0154 0288UFHLFH 844 plusmn 80 828 plusmn 72 0014 0474 807 plusmn 49 796 plusmn 53 0157 0286Co-A 810 plusmn 53 830 plusmn 43 0016 0467 830 plusmn 82 826 plusmn 42 0799 0053Co-Gn 999 plusmn 61 1050 plusmn 63 lt0001 0768 1026 plusmn 104 1051 plusmn 60 0162 0283Max Mand diff 189 plusmn 31 220 plusmn 43 lt0001 0743 196 plusmn 36 224 plusmn 35 lt0001 0784minus1MP 977 plusmn 74 1007 plusmn 74 0002 0572 955 plusmn 76 961 plusmn 64 0456 0153+1NSL 1076 plusmn 71 1005 plusmn 64 lt0001 0803 1101 plusmn 67 1027 plusmn 63 lt0001 0772minus1A-Pg angle 220 plusmn 58 275 plusmn 52 lt0001 0765 210 plusmn 73 237 plusmn 51 0002 0583+1A-Pg angle 385 plusmn 55 289 plusmn 47 lt0001 0893 379 plusmn 56 275 plusmn 52 lt0001 0867minus1A-Pg distance 03 plusmn 20 26 plusmn 17 lt0001 0875 00 plusmn 23 14 plusmn 20 lt0001 0775+1A-Pg distance 93 plusmn 19 64 plusmn 19 lt0001 0915 92 plusmn 20 56 plusmn 20 lt0001 0861Gl1015840-Sn-Pg1015840 203 plusmn 53 182 plusmn 56 0002 0583 185 plusmn 58 164 plusmn 52 0002 0586Cm-Sn-Ls 1169 plusmn 119 1181 plusmn 102 0589 0111 1077 plusmn 85 1138 plusmn 113 0005 0533Li-E 01 plusmn 25 minus05 plusmn 25 0120 0313 minus06 plusmn 35 minus15 plusmn 28 0020 0455Ls-E minus05 plusmn 20 minus22 plusmn 20 lt0001 0701 minus01 plusmn 22 minus19 plusmn 24 lt0001 0823Li-S 11 plusmn 24 07 plusmn 23 0327 0200 07 plusmn 33 minus01 plusmn 28 0050 0389Ls-S 13 plusmn 7 minus02 plusmn 16 lt0001 0661 20 plusmn 20 01 plusmn 22 lt0001 0861OJ 90 plusmn 25 38 plusmn 18 lt0001 0956 92 plusmn 23 43 plusmn 19 lt0001 0888lowastPaired samples 119905-testlowastlowastEffect size calculated by using the formula 119903 = radic1199052(1199052 + 119889119891) Cohen criteria for interpretation of effect size were used 119903 = 01ndash03 = small effect size 03ndash05 = medium and gt05 = large

analysis correctly classified 79of the subjects Correct groupmembership was retained in 96 untreated subjects 72 ofTB and 52 of AH group

4 Discussion

Both TB and AH functional appliances successfully reducedthe severity of class II malocclusion by a combination ofdental and skeletal changes Overjet SNB and ANB angleswere significantly improved in both groups All of thesechanges were significantly different from the changes in theuntreated control group suggesting positive treatment effectwith functional appliances The only variables that exhibitedsignificant differences between the two appliances after thetreatment were the proclination and the protrusion of themandibular incisors which were more pronounced in the TBgroup

The SNB angle significantly increased in both treatmentgroups which is in agreement with other studies [8 13 16]However these changes particularly in the TB group were

smaller than the previously reported and could be related tothe concomitant increase in the lower anterior facial heightlower incisor proclination and posterior displacement ofpoint B [14]

Great variability in increase in effective mandibularlength that is Co-Gn is demonstrated particularly in AHgroup The effective mandibular length increased mostly inthe TB group which is supported by numerous investigations[2 5 8] The amount of mean increase in mandibularlength in the AH group is similar to normal mandibulargrowth of untreated class II division 1 cases Supplementarymandibular length growth of 25mm in the TB subjects incomparison to untreated subjects in this study correspondswith the results reported in a recent meta-analysis [17] Oneof the several systematic reviews on the treatment effect ofremovable functional appliances reported that short-termevidence suggested mainly dentoalveolar rather than skeletaleffects however the skeletal changes were more pronouncedwith the TB appliance [5] The most recent meta-analysisrevealedmore supplementarymandibular growth in pubertal


Table 4 Mean values of the investigated variables in the untreatedcontrol group at the same pretreatment (T1) and posttreatment (T2)age as the treated groups

T1 T2119901lowast 119903lowastlowast

Mean plusmn SD Mean plusmn SDNSBa 1309 plusmn 42 1307 plusmn 47 0514 0093SNA 821 plusmn 24 824 plusmn 25 0174 0193SNB 758 plusmn 28 763 plusmn 26 0005 0384ANB 63 plusmn 20 60 plusmn 19 0204 0181A-NPg 52 plusmn 20 51 plusmn 21 0479 0101NLNSL 66 plusmn 33 67 plusmn 35 0772 0042MPNSL 350 plusmn 48 349 plusmn 50 0625 0070MPNL 284 plusmn 50 282 plusmn 53 0526 0091FANBa 879 plusmn 43 882 plusmn 42 0304 0147UFH 463 plusmn 31 476 plusmn 34 lt0001 0581LFH 565 plusmn 52 579 plusmn 60 0001 0463UFHLFH 823 plusmn 66 828 plusmn 73 0535 0089Co-A 813 plusmn 49 827 plusmn 53 lt0001 0512Co-Gn 998 plusmn 59 1024 plusmn 64 lt0001 0761Max Mand diff 185 plusmn 32 197 plusmn 40 0001 0461minus1MP 978 plusmn 55 969 plusmn 55 0105 0230+1NSL 1027 plusmn 72 1031 plusmn 72 0487 0100minus1A-Pg angle 227 plusmn 51 225 plusmn 52 0708 0054+1A-Pg angle 328 plusmn 67 324 plusmn 68 0345 0135minus1A-Pg distance 13 plusmn 23 12 plusmn 24 0749 0046+1A-Pg distance 69 plusmn 22 71 plusmn 27 0144 0207Gl1015840-Sn-Pg1015840 164 plusmn 44 168 plusmn 43 0258 0161Cm-Sn-Ls 1100 plusmn 139 1129 plusmn 96 0037 0293Li-E 14 plusmn 22 11 plusmn 23 0270 0157Ls-E 04 plusmn 22 minus01 plusmn 21 0017 0334Li-S 23 plusmn 22 22 plusmn 23 0783 0039Ls-S 21 plusmn 20 20 plusmn 22 0829 0031OJ 56 plusmn 21 59 plusmn 22 0068 0258lowastPaired samples 119905-testlowastlowastEffect size

than prepubertal class II malocclusion patients treated withfunctional appliances [18] Therefore treatment timing aswell as individual differences in treatment response may givea plausible explanation for the reported discrepancies

Both appliances in the current study had little insignifi-cant restraining effect on the maxilla Several investigationshave previously reported that forward growth of the maxillamay be inhibited during AH treatment [4 9 10 16] Otherscould not confirm this effect [13 19] Restricted forwardgrowth ofmaxilla in patients treated with TB is found inmostof the studies included in the systematic review by Ehsani etal [17] The labial bow used to increase retention and controlthe maxillary incisors in the TB appliance might have madethe maxillary incisors retroclined made the roots proclinedand affected the position of theApoint [11]Thus it is possiblethat the restraining effect on maxilla was more pronouncedbut was underestimated due to a forward movement of the ApointThe increased SNA angle in the control group is also insupport of this notion

Table 5 Comparison of the treatment changes (Δ) in theTwinBlock(TB) and activator-headgear (AH) group and untreated controls(CTRL)

ΔTB ΔAH ΔCTRL119901lowast 1205782lowastlowast

Mean plusmn SD Mean plusmn SD Mean plusmn SDNSBa minus01 plusmn 21 minus09 plusmn 16 minus02 plusmn 21 0313 0024SNA minus04 plusmn 12 minus02 plusmn 12 03 plusmn 15 0087 0049SNB 11 plusmn 10 12 plusmn 08 06 plusmn 13 0036 0066ANB minus15 plusmn 13a minus14 plusmn 07a minus03 plusmn 15b lt0001 0179A-NPg minus12 plusmn 13a minus13 plusmn 09a minus01 plusmn 14b lt0001 0161NLNSL minus04 plusmn 19 minus03 plusmn 16 01 plusmn 21 0588 0011MPNSL minus00 plusmn 17 minus09 plusmn 17 minus01 plusmn 21 0138 0040MPNL 04 plusmn 24 minus07 plusmn 19 minus02 plusmn 26 0283 0026FANBa 02 plusmn 20 03 plusmn 15 03 plusmn 20 0976 0001UFH 16 plusmn 22 05 plusmn 40 13 plusmn 19 0295 0025LFH 30 plusmn 24 15 plusmn 51 14 plusmn 26 0119 0043UFHLFH minus17 plusmn 32 minus11 plusmn 38 05 plusmn 58 0134 0041Co-A 20 plusmn 39 minus03 plusmn 67 14 plusmn 24 0114 0044Co-Gn 51 plusmn 44 25 plusmn 86 26 plusmn 22 0086 0049Max Manddiff 31 plusmn 29a 28 plusmn 23a 11 plusmn 22b 0001 0126

minus1MP 30 plusmn 44a 05 plusmn 36b minus09 plusmn 38b lt0001 0145+1NSL minus70 plusmn 53a minus73 plusmn 62a 04 plusmn 40b lt0001 0378minus1A-Pgangle 55 plusmn 48a 27 plusmn 38b minus02 plusmn 33c lt0001 0283

+1A-Pgangle minus96 plusmn 49a minus104 plusmn 61a minus05 plusmn 34b lt0001 0528

minus1A-Pgdistance 23 plusmn 13a 13 plusmn 11b minus01 plusmn 12c lt0001 0416

+1A-Pgdistance minus29 plusmn 13a minus36 plusmn 22a 02 plusmn 11b lt0001 0592

Gl1015840-Sn-Pg1015840 minus21 plusmn 30a minus20 plusmn 29a 04 plusmn 23b lt0001 0182Cm-Sn-Ls 12 plusmn 110 61 plusmn 100 29 plusmn 95 0207 0032Li-E minus06 plusmn 18 minus09 plusmn 19 minus03 plusmn 16 0290 0025Ls-E minus18 plusmn 18a minus18 plusmn 13a minus04 plusmn 12b lt0001 0205Li-S minus04 plusmn 18 minus08 plusmn 20 minus01 plusmn 16 0212 0032Ls-S minus15 plusmn 17a minus19 plusmn 11a minus00 plusmn 14b lt0001 0261OJ minus52 plusmn 16a minus49 plusmn 26a 03 plusmn 12b lt0001 0712lowastANOVA with Student-Newman-Keuls post hoc tests Groups in the samerow that share the same superscript letter do not differ significantlylowastlowastEffect size calculated according to formula 1205782 = between groups sumof squarestotal sum of squares Cohen criteria for interpretation of effectsize were used 1205782 = 002ndash013 = small effect size 013ndash026 = medium andgt026 = large

TheANB angle showed higher decrease in both treatmentgroups in comparison to the untreated controls The signifi-cant change in the TB groupwasmainly due to the significantskeletalmandibular effect concerning both angular and linearmeasurements In the AH group the nature of the ANBchanges is controversial and could be a combination ofdentoalveolar and skeletal changes in both jaws Some studiesindicate that reduction of the ANB angle is mainly due toa delayed forward growth of maxilla while some report


Table 6 Structural matrix of canonical discriminant functions

Function1 2

Δ+1A-Pg distance minus0699lowast minus0394Δminus1A-Pg distance 0476lowast minus0453Δ+1NSL minus0458lowast minus0108ΔLs-E minus0298lowast minus0076ΔGl1015840-Sn-Pog1015840 minus0277lowast minus0025ΔANB minus0275lowast minus0008ΔSNB 0153lowast 0112ΔSNA minus0131lowast 0087ΔUFHLFH minus0120lowast 0062Δminus1MP 0210 minus0387lowast

ΔCo-A minus0034 minus0383lowast

ΔMPNSL minus0045 minus0351lowast

ΔCo-Gn 0080 minus0340lowast

ΔLi-E minus0082 minus0150lowastlowastLargest absolute correlation between each variable and any discriminantfunction Variables ordered by absolute size of correlation within function

50

25

00

minus25

minus50

Func

tion2

minus50 minus25 00 25 50

Function 1

TB

TB

AH

AH

CTRL

CTRLGroup

Group centroid

Figure 2 Canonical discriminant functions graph

that reduced ANB angle is more dependent on increasedmandibular growth [16] Regardless of the treatment changesthat lead to reduction in the ANB angle the same effectcould not be demonstrated in the control groupThis findingfurther supports the fact that there is no self-correctionof class II malocclusion and that functional treatment isbeneficial for the patient

Several authors underline the importance of keepingcontrol of the vertical dimensions while correcting sagittaldiscrepancies [16 20] This is an imperative in patients with

a tendency for posterior rotation of the mandible Treatmentwith activator without a headgear showed effective condylargrowth and change in chin position however these changeswere not in the desired sagittal direction rather in thevertical one [21] In the present study the effects of thetwo appliances on vertical measurements are similar stillthe AH appliance seemed to have some tendency to controlthe vertical dimension by promoting anterior rotation ofthe mandible and this is a consistent finding [7 9 19 22]Posttreatment changes in mandibular plane inclination werenot observed in the TB groupThis is in accordancewithmoststudies however an increased mandibular plane inclinationhas also been reported [23 24] It should be emphasizedthat individual growth pattern varies and must be seen asan important factor contributing to the divergent treatmentresponse

Dentoalveolar changes played a dominant role in class IImalocclusion correction in both groups which is in agree-ment with other reports [11 13] Retroclination of maxillaryincisors is a consistent finding in many other TB [2 6 8] andAH studies [9 16 19] A more pronounced retrusion of theupper incisors was found in the AH group which may reflectthe additional headgear forces acting posteriorly on themaxillary apical base and alveolar structures Retroclinationand retrusion of prominent maxillary incisors may have apreventive effect since large overjet doubles the risk of dentaltrauma [25] The most prominent dentoalveolar effect in theTB group was proclination and protrusion of the mandibularincisors compared to the AH group Changes in the incli-nation of the lower incisors in functional appliances studiesare contradictory and probably not sufficiently controlled bytheir capping with acrylic [8 13 18 22]

At the end of the treatment both treatment groupsshowed similar reduction of the profile convexity and retru-sion of the upper lip These results are in agreement withprevious studies [9 16 24 26 27] However retrusion of thelip relative to the nose-chin linemay reflect growth of the nosebut also more forward chin position induced by functionaltreatment It should also be noted that there is a largevariation in treatment response for most of the soft-tissueparameters and sometimes themagnitude of the changesmaynot be perceived as clinically significant [28]

The discriminant analysis revealed that there was agreater difference between the control group and the twotreated groups than that between the TB and AH group Themajority of the changes could be attributed to treatment witheither of the two appliances but the treatment effect wasmoredentoalveolar than skeletal compared to the controls

5 Conclusions

Both AH and TB appliances contributed successfully to thecorrection of class II division 1 malocclusion when comparedto the untreated growing class II subjects producing pre-dominantly dentoalveolar effects TB appliance leads to morepronounced protrusion and proclination of the mandibularincisors than the AH group Treatment with TB results insome supplementary mandibular length growth while AHexerted some tendency to more control of the vertical


dimension of the lower anterior facial height Normal growthpattern in untreated class II subjects comprises forwardand downward growth displacement of the maxilla and themandible without major changes in basal sagittal relationbetween the jaws Clinical relevance of these findings is thatearly treatment may correct or at least ameliorate class IIdivision I malocclusion which is not self-corrective

Competing Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

This study is partially supported by University of Rijeka grant(13062153)

References

[1] J F Tulloch C Phillips and W R Proffit ldquoBenefit of earlyClass II treatment progress report of a two-phase randomizedclinical trialrdquoAmerican Journal of Orthodontics and DentofacialOrthopedics vol 113 no 1 pp 62ndash74 1998

[2] A K Jena R Duggal and H Parkash ldquoOrthopedic andorthodontic effects of twin-block appliancerdquo Journal of ClinicalPediatric Dentistry vol 29 no 3 pp 225ndash230 2005

[3] S K Varlik A Gultan and N Tumer ldquoComparison of theeffects of Twin Block and activator treatment on the soft tissueprofilerdquoEuropean Journal of Orthodontics vol 30 no 2 pp 128ndash134 2008

[4] K OrsquoBrien T Macfarlane J Wright et al ldquoEarly treatmentfor Class II malocclusion and perceived improvements infacial profilerdquoAmerican Journal of Orthodontics andDentofacialOrthopedics vol 135 no 5 pp 580ndash585 2009

[5] V Koretsi V F Zymperdikas S N Papageorgiou and MA Papadopoulos ldquoTreatment effects of removable functionalappliances in patients with Class II malocclusion a systematicreview and meta-analysisrdquo European Journal of Orthodonticsvol 37 no 4 pp 418ndash434 2015

[6] T Baccetti L Franchi L R Toth and J A McNamara JrldquoTreatment timing for Twin-block therapyrdquo American Journalof Orthodontics and Dentofacial Orthopedics vol 118 no 2 pp159ndash170 2000

[7] K OrsquoBrien J Wright F Conboy et al ldquoEffectiveness of earlyorthodontic treatment with the Twin-block appliance a multi-center randomized controlled trial Part 1 dental and skeletaleffectsrdquo American Journal of Orthodontics and DentofacialOrthopedics vol 124 no 3 pp 234ndash243 2003

[8] M J Trenouth ldquoProportional changes in cephalometric dis-tances during Twin Block appliance therapyrdquo European Journalof Orthodontics vol 24 no 5 pp 485ndash491 2002

[9] Y Ozturk and N Tankuter ldquoClass II a comparison of activa-tor and activator headgear combination appliancesrdquo EuropeanJournal of Orthodontics vol 16 no 2 pp 149ndash157 1994

[10] R Lehman A Romuli and V Bakker ldquoFive-year treatmentresults with a headgear-activator combinationrdquo European Jour-nal of Orthodontics vol 10 no 1 pp 309ndash318 1988

[11] A K Jena R Duggal and H Parkash ldquoSkeletal and den-toalveolar effects of Twin-block and bionator appliances inthe treatment of Class II malocclusion a comparative studyrdquo

American Journal of Orthodontics and Dentofacial Orthopedicsvol 130 no 5 pp 594ndash602 2006

[12] T Baccetti L Franchi and J A McNamara Jr ldquoThe CervicalVertebral Maturation (CVM) method for the assessment ofoptimal treatment timing in dentofacial orthopedicsrdquo Seminarsin Orthodontics vol 11 no 3 pp 119ndash129 2005

[13] M Lerstoslashl Oslash Torget and V Vandevska-Radunovic ldquoLong-term stability of dentoalveolar and skeletal changes afteractivator-headgear treatmentrdquo European Journal of Orthodon-tics vol 32 no 1 pp 28ndash35 2010

[14] D S Gill and R T Lee ldquoProspective clinical trial comparing theeffects of conventional Twin-block and mini-block appliancespart 1 Hard tissue changesrdquo American Journal of Orthodonticsand Dentofacial Orthopedics vol 127 no 4 pp 465ndash472 2005

[15] G Dahlberg Statistical Methods for Medical and BiologicalStudents Interscience Publications New York NY USA 1940

[16] G Marsan ldquoEffects of activator and high-pull headgear com-bination therapy skeletal dentoalveolar and soft tissue profilechangesrdquo European Journal of Orthodontics vol 29 no 2 pp140ndash148 2007

[17] S Ehsani B Nebbe D Normando M O Lagravere andC Flores-Mir ldquoShort-term treatment effects produced by theTwin-block appliance a systematic review and meta-analysisrdquoEuropean Journal of Orthodontics vol 37 no 2 pp 170ndash1762014

[18] G Perinetti J Primozic L Franchi and L Contardo ldquoTreat-ment effects of removable functional appliances in pre-pubertaland pubertal Class II patients a systematic review and meta-analysis of controlled studiesrdquo PLoS ONE vol 10 no 10 ArticleID e0141198 2015

[19] L R Dermaut F van den Eynde and G de Pauw ldquoSkeletal anddento-alveolar changes as a result of headgear activator therapyrelated to different vertical growth patternsrdquo European Journalof Orthodontics vol 14 no 2 pp 140ndash146 1992

[20] H Pancherz ldquoA cephalometric analysis of skeletal and dentalchanges contributing to Class II correction in activator treat-mentrdquo American Journal of Orthodontics vol 85 no 2 pp 125ndash134 1984

[21] S Ruf S Baltromejus and H Pancherz ldquoEffective condylargrowth and chin position changes in activator treatment acephalometric roentgenographic studyrdquo The Angle Orthodon-tist vol 71 no 1 pp 4ndash11 2001

[22] A Sidlauskas ldquoThe effects of the Twin-block appliance treat-ment on the skeletal and dentolaveolar changes in Class IIDivision 1 malocclusionrdquoMedicina (Kaunas) vol 41 no 5 pp392ndash400 2005

[23] L R Toth and J A McNamara Jr ldquoTreatment effects producedby the twin-block appliance and the FR-2 appliance of Frankelcompared with an untreated Class II samplerdquoAmerican Journalof Orthodontics and Dentofacial Orthopedics vol 116 no 6 pp597ndash609 1999

[24] N Tumer and A S Gultan ldquoComparison of the effects ofmonoblock and twin-block appliances on the skeletal anddentoalveolar structuresrdquoAmerican Journal of Orthodontics andDentofacial Orthopedics vol 116 no 4 pp 460ndash468 1999

[25] S Petti ldquoOver two hundred million injuries to anterior teethattributable to large overjet a meta-analysisrdquo Dental Trauma-tology vol 31 no 1 pp 1ndash8 2015

[26] A A Sharma and R T Lee ldquoProspective clinical trial com-paring the effects of conventional Twin-block and mini-blockappliances part 2 Soft tissue changesrdquo American Journal of


Orthodontics and Dentofacial Orthopedics vol 127 no 4 pp473ndash482 2005

[27] S McDonagh J P Moss P Goodwin and R T Lee ldquoA prospec-tive optical surface scanning and cephalometric assessment ofthe effect of functional appliances on the soft tissuesrdquo EuropeanJournal of Orthodontics vol 23 no 2 pp 115ndash126 2001

[28] C Flores-Mir and P W Major ldquoCephalometric facial softtissue changes with the twin block appliance in class II divi-sion 1 malocclusion patients A systematic reviewrdquo The AngleOrthodontist vol 76 no 5 pp 876ndash881 2006

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anatomy Research International

PeptidesInternational Journal of


Hindawi Publishing Corporation httpwwwhindawicom

International Journal of

Volume 2014

Zoology


Molecular Biology International

GenomicsInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


BioinformaticsAdvances in

Marine BiologyJournal of



Signal TransductionJournal of


BioMed Research International

Evolutionary BiologyInternational Journal of



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ArchaeaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Genetics Research International


Advances in

Virolog y

Hindawi Publishing Corporationhttpwwwhindawicom

Nucleic AcidsJournal of

Volume 2014

Stem CellsInternational



Enzyme Research



Microbiology


Cm

PrnSBa

MP

NL

FA

FHNBa

NSL

NBNA

ANS

OrPt

CoPo

PNS

Go

Ba

S

S

E

Cm-Sn

Cm-Ls

A-Pg

Co-Gn

Co-A

N

PgGnMe

Li

Ls

Sn

In + 1

In minus 1

Ap minus 1

Ap + 1

Gl998400

Pg998400

Gl998400-Sn

Sn-Pg998400

Figure 1 Points and plains used in cephalometric analysis Gl1015840 (soft-tissue glabella) Prn (pronasale) Cm (columella) Sn (subnasale) Ls(labrale superius) Li (labrale inferius) Pg1015840 (soft-tissue pogonion) Pg (osseous pogonion) Gn (gnathion) Me (menton) Go (gonion) Ba(basion) Co (condylion) Po (porion) Pt (pterygoid point) S (sella) PNS (posterior nasal spine) ANS (anterior nasal spine) N (nasion) Or(orbitale) Ap + 1 (apicale superius) Ap minus 1 (apicale inferius) In + 1 (incisale superius) In minus 1 (incisale inferius) NSL (nasion-sella line) FA(facial axis) NL (nasal line) MP (mandibular plane) FH (Frankfort horizontal) E (Rickettsrsquo Esthetic line) and S (Steinerrsquos line)

(1) Both appliances havemore pronounceddentoalveolareffect in the treated groups than growth itself in theuntreated group

(2) TB stimulates more skeletal growth of mandible thanAH

(3) AH has better control of vertical dimension than TB

2 Materials and Methods

21 Study Population and Design The sample included 50subjects (56 females) aged 8ndash13 years (median 11) with classII division 1 malocclusion treated with either AH (119899 = 25)or TB (119899 = 25) appliances The data were collected retro-spectively among 151 subjects treated in the period of 2000ndash2015 at theDepartment of Orthodontics inOslo Norway andthe Department of Orthodontics in Rijeka Croatia Inclusioncriteria were distal molar occlusion overjet (OJ) gt5mm andhaving pre- and posttreatment lateral cephalograms Accord-ing to the cervical vertebral maturation method [12] theincluded subjects were in the prepeak stages (CS1ndashCS3)of skeletal maturation before treatment and CS3ndashCS5 aftertreatment

The AH appliance had all maxillary teeth covered withacrylic and included labial spring for the torque control ofthe incisors [13] High pull headgear was always used simul-taneously with the appliance TB appliance [14] with additionofmaxillary labial bow to aid the anterior retention andmakethemaxillary incisors retroclinedwas used in the other group

The expansion screw was incorporated in the maxillary plateand activated one quarter-turn each week for an averageperiod of six months Construction bite was the same in bothappliances with the anterior positioning ofmandible by 6mmand vertical opening by 4mm in the first molar area Thepatients were recommended to use the appliances for 12ndash14 hours per day Treatment was stopped when the patientsachieved molar class I occlusion or slight hypercorrection

Pretreatment (T1) andposttreatment (T2) lateral cephalo-grams were evaluated and compared to 50 untreated class IIdivision 1 cases matched by age gender ANB angle skeletalmaturation of cervical vertebrae and observation periodTheywere selected fromAmerican Association of Orthodon-tists Foundation Craniofacial Growth Legacy CollectionCephalometric analysis (Table 1 Figure 1) was performed oncalibrated pre- and posttreatment lateral cephalograms bytwo investigators (KMT and SS) using the cephalometricsoftware Facad (Ilexis AB Sweden) and AudaxCeph (AudaxSlovenia)

The study was in accordance with the Helsinki Decla-ration and the protocol was approved by the local ethicalcommittees in Norway (02-09-2010) and in Croatia (2170-24-01-15-2)

22 Statistical Analysis After inspection of histograms andquantile-quantile plots and testing the normality of the datawith the Shapiro-Wilk test a paired 119905-test was preformed toassess the statistical significance of changes occurring duringthe treatment with each appliance (intragroup analysis)
















horizontal (FH)





15 Max Mand diff mm





lower incisors


upper incisors











15 (60) 13 (52) 28 (56) 0850lowast









3 Results
















4 Discussion






















Function1 2






50

25

00

minus25

minus50

Func

tion2


Function 1

TB

TB

AH

AH

CTRL

CTRLGroup

Group centroid








5 Conclusions




Competing Interests


Acknowledgments


References







































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology
















horizontal (FH)





15 Max Mand diff mm





lower incisors


upper incisors











15 (60) 13 (52) 28 (56) 0850lowast









3 Results
















4 Discussion






















Function1 2






50

25

00

minus25

minus50

Func

tion2


Function 1

TB

TB

AH

AH

CTRL

CTRLGroup

Group centroid








5 Conclusions




Competing Interests


Acknowledgments


References







































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology





15 (60) 13 (52) 28 (56) 0850lowast









3 Results
















4 Discussion






















Function1 2






50

25

00

minus25

minus50

Func

tion2


Function 1

TB

TB

AH

AH

CTRL

CTRLGroup

Group centroid








5 Conclusions




Competing Interests


Acknowledgments


References







































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology







4 Discussion






















Function1 2






50

25

00

minus25

minus50

Func

tion2


Function 1

TB

TB

AH

AH

CTRL

CTRLGroup

Group centroid








5 Conclusions




Competing Interests


Acknowledgments


References







































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


















Function1 2






50

25

00

minus25

minus50

Func

tion2


Function 1

TB

TB

AH

AH

CTRL

CTRLGroup

Group centroid








5 Conclusions




Competing Interests


Acknowledgments


References







































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology



Function1 2






50

25

00

minus25

minus50

Func

tion2


Function 1

TB

TB

AH

AH

CTRL

CTRLGroup

Group centroid








5 Conclusions




Competing Interests


Acknowledgments


References







































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology



Competing Interests


Acknowledgments


References







































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology












Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology








Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

Documents

Comparison of Activator-Headgear and Twin Block Treatment ...downloads.hindawi.com/journals/bmri/2017/4861924.pdf · Comparison of Activator-Headgear and Twin Block Treatment Approaches