Tratamento da maloclusão Classe II esquelética com Herbst em adultos: avanço em

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Tratamento da maloclusão Classe II esquelética com Herbst em adultos: avanço em uma etapa X avanço em mais de uma etapa

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shimanto k purkayastha bds morth morthrcsed mracds orth1 a bakr m rabie phd msc cert ortho2 ricky wong bds morth phd morthrcs3 treatment of skeletal class ii malocclusion in adults stepwise vs single-step advancement with the herbst appliance aim to compare 2 groups of mature patients treated with the herbst appliance and present a new protocol based on tissue responses to enhance skeletal response methods lateral cephalograms taken before and after treatment for 2 groups of patients the first treated with the herbst appliance with maximum jumping and the second with the herbst appliance with stepwise advancement were examined with conventional cephalometric analysis and the sagittalocclusal analysis of pancherz to assess the dental skeletal and soft tissue changes results the mode of correction of the class ii malocclusion was through skeletal and dental changes however in the stepwise sample the amount of correction due to skeletal changes was higher in both groups the soft tissue profile convexity was reduced significantly conclusion herbst appliance therapy can be considered a modality for the correction of skeletal class ii malocclusions in mature patients and should be added to orthodontia s armamentarium world j orthod 2008;9:233­243 1specialist orthodontist in private practice canberra city australian capital territory australia 2professor of orthodontics faculty of dentistry prince philip dental hospital university of hong kong hong kong 3assistant professor of orthodontics faculty of dentistry prince philip dental hospital university of hong kong hong kong correspondence professor a bakr m rabie prince philip dental hospital university of hong kong 34 hospital road hong kong fax 852 2559 3803 e-mail rabie@hkusua.hku.hk reatment options for the nongrowing skeletal class ii mandibular retrognathic patient were traditionally twofold the first was orthodontic camouflage treatment which is by definition a compromise the soft tissue convexity that presents with mandibular retrusion is not addressed rather the esthetics are worsened as the upper lip becomes flatter and the nose more prominent the second option is orthognathic surgery whilst this directly addresses the skeletal structures at fault and reduces facial convexity it involves the risk of surgery under general anesthesia more recently pancherz et al reported a third alternative which is the reactivation of condylar adaptive growth in young adults.1­6 t recent discoveries in basic sciences have led to the realization that condylar growth can be reactivated in mature individuals animal and genetic studies 7­28 have proven the ability of an appliance that applies tensile strain to the condyle to stimulate growth and remodel the glenoid fossa thus indicating that patients previously considered too old could be treated with a functional appliance the clinical significance pertains to the patient who presents with borderline skeletal class ii malocclusion and does not place too much emphasis on the facial profile the severity may not warrant surgical intervention but the detrimental esthetics of camouflage therapy can be avoided with orthopedics funda233 copyright © 2007 by quintessence publishing co inc printing of this document is restricted to personal use only no part of this article may be reproduced or transmitted in any form without written permission from the publisher

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purkayastha et al world journal of orthodontics fig 1 19-year-old female originally treated with headgear and extraction of first premolars the herbst appliance phase was 12 months left pretreatment right posttreatment the profile convexity reduction excluding the nose was 4 degrees mental to improving the face of a class ii patient is reducing the facial profile convexity which can be achieved via adult orthopedics this study aimed to compare a group of adult skeletal class ii patients to a similar previously studied group.1 methods and materials all patients received herbst appliance therapy followed by multibracket appliance treatment fifteen chinese patients 11 females and 4 males were treated in the orthodontic department of the university of hong kong and compared to 23 caucasian patients 19 females and 4 males treated in the orthodontic department of the university of giessen in germany the sample data for the latter sample was previously published.1 at 234 the end of treatment all patients had an ideal class i occlusion with normal overjet and overbite the mean pretreatment age of the german sample was 21.9 years 15.7 to 44.4 years that of the hong kong patients was 22.0 years 16.6 to 39.3 years the mean pretreatment overjet was 7.14 mm standard deviation 2.0 mm and 8.9 mm sd 2.7 mm for the hong kong and german samples respectively figs 1 to 3 both samples were treated with a casted splint herbst appliance.29,30 the hong kong sample was treated with a stepwise advancement at the time the herbst is fitted the mandible is advanced 4 mm subsequent advancements eliminate any remaining overjet in the german sample the mandible was advanced to an incisal edge-to-edge position copyright © 2007 by quintessence publishing co inc printing of this document is restricted to personal use only no part of this article may be reproduced or transmitted in any form without written permission from the publisher

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volume 9 number 3 2008 purkayastha et al fig 2 21-year-old female the herbst appliance phase was 12 months left pretreatment right posttreatment soft tissue profile convexity reduction excluding the nose was 3 degrees the functional phase in the german sample was 7 to 9 months while the hong kong sample was treated with a functional appliance for 12 months maturity was determined by handwrist radiographs individuals were considered mature if hand-wrist radiograph stage r-ij or r-j had been reached the presence of r-ij indicates that the postpubertal period has begun.31 the material comprised lateral cephalograms obtained before and after herbst and multibracket treatment the lateral head films were taken in centric occlusion to minimize method error the 2 cephalometric tracings for each subject were conducted in the same session the 2 cephalograms for each patient were then traced with an interval of at least 2 weeks and mean values of the registrations were calculated all linear and angular measurements were rounded to the nearest 0.5 mm and 0.5 degrees respectively no correction was made for linear magnification approximately 6 to 8 for all samples sagittal-occlusal analysis of pancherz 32 fig 4 and cephalometric analysis fig 5 were conducted as described by ruf and pancherz.1 means and standard deviations were calculated for all linear and cephalometric variables method error was calculated using dahlberg s formula 33 me d 2 /2n method error did not exceed 0.7 mm for linear variables 1.0 degree for angular measurements and 1.2 for index variables unpaired t tests were undertaken to assess differences between the hong kong and german samples and the magnitude of change between the 2 groups paired t tests were conducted to assess treatment changes within each sample 235 copyright © 2007 by quintessence publishing co inc printing of this document is restricted to personal use only no part of this article may be reproduced or transmitted in any form without written permission from the publisher

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purkayastha et al world journal of orthodontics fig 3 18-year-old female the herbst appliance phase was 12 months left pretreatment right posttreatment soft tissue profile convexity reduction excluding the nose was 3 degrees fig 4 left points used in the sagittalocclusal analysis of pancherz fig 5 right points used in the cephalometric analysis 236 copyright © 2007 by quintessence publishing co inc printing of this document is restricted to personal use only no part of this article may be reproduced or transmitted in any form without written permission from the publisher

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volume 9 number 3 2008 purkayastha et al table 1 cephalometric values of hong kong and german samples german pretreatment posttreatment mean sd mean sd hong kong pretreatment posttreatment mean sd mean sd 80.1 75.2 76.3 4.8 3.8 2.6 36.7 10.9 25.7 4.7 53.4 48.6 170.8 161.2 136.0 1.8 2.6 2.7 3.2 4.0 1.5 2.5 2.5 7.0 3.9 4.3 0.6 2.0 3.9 6.4 7.1 7.0 2.8 3.8 79.9 76.3 77.1 3.5 2.8 ­1.0 36.7 11.3 25.4 2.0 53.7 48.9 174.1 164.1 137.4 ­0.3 3.3 2.7 3.3 4.1 1.4 2.5 2.4 8.0 4.1 5.4 0.0 2.1 5.1 6.9 7.2 6.6 3.4 3.3 sna deg snb deg snpg deg anb deg anpg deg wits mm ml/nsl deg nl/nsl deg ml/nl deg overbite mm spa-gn index mm spp-go index mm napg deg ns/sn/pgs deg ns/no/pgs deg ul-e mm ll-e mm 80.5 75.2 76.8 5.2 3.6 2.5 34.1 7.3 26.8 4.4 54.6 41.4 172.1 159.7 126.3 ­3.1 ­1.6 3.2 4.1 4.3 1.7 2.3 2.1 8.6 3.2 7.9 1.8 1.8 5.3 5.2 6.3 3.9 2.3 3.3 80.6 76.1 77.5 4.5 3.0 1.5 33.4 6.8 26.7 2.0 55.0 42.4 173.2 162.8 127.3 ­4.4 ­1.9 3.3 4.4 4.6 1.8 2.5 2.0 9.0 3.6 7.7 0.7 1.7 5.2 5.4 6.8 4.3 2.5 3.0 table 2 pretreatment cephalometric value differences of hong kong and german samples mean sna deg snb deg snpg deg anb deg anpg deg wits mm ml/nsl deg nl/nsl deg ml/nl deg overbite mm spa-gn index mm spp-go index mm napg deg ns/sn/pgs deg ns/no/pgs deg ul-e mm ll-e mm 0.4 0.0 0.6 0.4 ­0.2 ­0.1 ­2.5 ­3.7 1.1 ­0.2 1.1 ­7.2 1.3 ­1.5 ­9.7 ­4.9 ­4.2 t 0.4 0.0 0.4 0.7 0.2 0.1 0.1 3.2 0.5 0.5 1.8 4.5 0.7 0.7 5.5 5.9 3.6 p .05 p .01 p .001 p .0001 results significant differences were found for several pretreatment cephalometric variables the hong kong sample had an increased maxillary plane angle relative to the cranial base by 3.7 degrees and a greater posterior facial height index by 7.2 mm soft tissue convexity including the nose was 9.7 degrees less in the hong kong sample as well as a greater protrusion of the upper and lower lip of 4.9 mm and 4.2 mm respectively these are consistent with the expected variations for the 2 ethnic groups34 tables 1 and 2 237 copyright © 2007 by quintessence publishing co inc printing of this document is restricted to personal use only no part of this article may be reproduced or transmitted in any form without written permission from the publisher

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purkayastha et al world journal of orthodontics table 3 cephalometric values comparison of treatment changes of hong kong and german samples mean german sd 0.6 0.8 0.9 0.8 0.9 1.3 1.3 1.5 1.6 2.0 0.7 1.5 1.6 1.8 2.0 1.1 1.1 t 0.8 5.0 4.0 ­4.3 ­3.3 ­4.1 ­2.6 ­1.7 ­0.3 ­6.1 2.8 3.4 3.3 8.4 2.5 ­5.6 ­1.1 mean ­0.2 1.1 0.8 ­1.3 ­1.1 ­3.6 0.1 0.4 ­0.3 ­2.7 0.3 0.3 3.3 2.9 1.4 ­2.1 0.7 hong kong sd 0.8 0.5 0.4 0.8 0.7 1.8 1.8 1.8 2.4 0.6 1.0 3.2 2.2 1.1 0.8 1.7 2.4 t ­1.0 9.5 7.6 ­6.3 ­6.1 ­7.7 0.1 0.7 ­0.5 ­16.7 0.1 0.4 5.7 10.6 7.2 ­4.7 1.2 mean 0.3 ­0.3 ­0.1 0.6 0.5 2.6 ­0.7 ­0.9 0.2 0.2 0.2 0.7 ­2.2 0.2 ­0.4 0.8 ­1.0 difference sd 1.6 2.4 1.3 2.9 2.6 5.4 1.6 1.8 0.3 1.2 0.7 0.9 3.8 0.9 2.0 2.0 1.6 t 1.4 1.3 0.6 2.3 1.7 5.1 1.5 1.6 0.3 0.4 0.6 0.9 3.5 0.5 0.7 1.9 1.8 sna deg snb deg snpg deg anb deg anpg deg wits mm ml/nsl deg nl/nsl deg ml/nl deg overbite mm spa-gn index mm spp-go index mm napg deg ns/sn/pgs deg ns/no/pgs deg ul-e mm ll-e mm 0.1 0.8 0.7 ­0.7 ­0.6 ­1.1 ­0.7 ­0.5 ­0.1 ­2.5 0.4 1.0 1.1 3.1 1.0 ­1.3 ­0.3 p .05 p .01 p .001 p .0001 table 4 sagittal-occlusal analysis values in mm of hong kong and german samples german pretreatment posttreatment mean sd mean sd hong kong pretreatment posttreatment mean sd mean sd 7.1 1.1 78.8 80.9 89.8 82.7 60.4 59.2 2.0 1.3 4.0 6.8 4.1 4.8 5.2 5.0 1.9 ­3.2 78.9 82.1 89.6 87.7 59.7 63.0 0.6 1.8 4.2 6.7 4.6 4.5 4.9 3.8 overjet is/olp ­ ii/olp molar relation ms/olp-mi/olp maxillary jaw base a/olp mandibular jaw base pg/olp maxillary incisor is mandibular incisor ii maxillary molar ms mandibular molar mi 8.9 1.5 78.5 80.1 88.2 79.3 57.8 56.3 2.7 1.4 4.0 5.0 4.5 5.4 4.7 5.3 2.1 ­2.6 78.9 81.4 85.4 83.3 56.4 58.9 0.6 1.0 4.8 4.8 4.8 4.9 4.7 5.0 treatment changes of the hong kong sample showed significant snb and snpg increases of 1.1 degrees and 0.8 degree respectively reductions in anb 1.3 degrees anpg 1.1 degrees wits appraisal 3.6 mm and overbite 2.7 mm were significant these sagittal parameter changes were expressed as significant reductions in both hard and soft tissue convexity napg increased by 3.3 degrees while soft tissue profile convexity including and excluding the nose were reduced 1.4 degrees and 2.9 degrees respectively upper lip fullness also decreased 2.1 mm treatment changes for the german sample showed significant increases for snb 0.8 degrees and snpg 0.7 238 degrees and significant decreases for anb 0.7 degrees anpg 0.6 degrees and the wits analysis 1.1 mm regarding the ver tical parameters the mandibular plane decreased by 0.7 degrees and both the anterior and posterior facial height mean indices increased 0.4 mm and 1.0 mm respectively dentally the overbite was reduced 2.5 mm all 3 measurements relating to hard and soft tissue convexity increased resulting in a reduction in the profile convexity napg by 1.1 degrees soft tissue profile including the nose by 1.0 degrees and soft tissue profile excluding the nose by 3.1 degrees the retraction of the upper lip in the sagittal plane was 1.3 mm copyright © 2007 by quintessence publishing co inc printing of this document is restricted to personal use only no part of this article may be reproduced or transmitted in any form without written permission from the publisher

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volume 9 number 3 2008 purkayastha et al table 5 difference in pretreatment sagittal-occlusal analysis values of hong kong and german samples german pretreatment mm mean sd hong kong pretreatment mm mean sd 7.1 1.1 78.8 80.9 89.8 82.7 60.4 59.2 2.0 1.3 4.0 6.8 4.1 4.8 5.2 5.0 difference mm mean t 1.7 0.4 ­0.3 ­0.8 ­1.6 ­3.4 ­2.6 ­3.0 2.1 0.9 0.2 0.4 1.1 2.0 1.6 1.7 overjet is/olp ­ ii/olp molar relation ms/olp-mi/olp maxillary jaw base a/olp mandibular jaw base pg/olp maxillary incisor is mandibular incisor ii maxillary molar ms mandibular molar mi 8.9 1.5 78.5 80.1 88.2 79.3 57.8 56.3 2.7 1.4 4.0 5.0 4.5 5.4 4.7 5.3 p .05 p .01 p .001 p .0001 compared to the german sample the hong kong sample showed greater changes for some sagittal measures the cephalometric variables of anb wits and napg showed significant differences anb decreased an average of 0.6 degrees wits appraisal decreased 2.6 mm and napg increased 2.2 degrees more than in the hong kong sample table 3 when regarding the pretreatment sagittal-occlusal analysis variables the german patients had larger overjets by 1.7 mm tables 4 and 5 the treatment changes in the hong kong sample showed a mean overjet reduction of 5.2 mm molar relation correction was 4.4 mm on average the pogonion moved anteriorly 1.2 mm and the mandibular incisors 3.8 mm mean mandibular molar mesial movement was 2.1 mm the mean overjet reduction for the german sample was 6.8 mm molar relation correction was 4.1 mm average maxillary molar distal movement was 1.8 mm mandibular molar mesial movement was 1.4 mm on average a point and pogonion moved anteriorly 0.4 mm and 1.3 mm respectively the maxillary incisor moved distally 3.2 mm and the mandibular incisor moved mesially 2.7 mm when comparing the treatment changes for both groups the german sample exhibited greater maxillary incisor retraction by 2.9 mm and maxillary molar distalization by 1.1 mm table 6 discussion this study presented an additional modality for skeletal class ii correction in mature patients herbst therapy was shown to have reactivated condylar growth in this cohort these patients had a hand-wrist stage of r-i or r-ij and were considered to have little to no growth left.31 the reactivation of condylar growth led to a reduction in the severity of the skeletal class ii malocclusion as well as a reduction in soft tissue convexity sagittal correction occurred as a result of dental and skeletal changes the former involved mesialization of the mandibular dentition and distalization of the maxillar y molars the latter is achieved by the reactivation of growth in the adult condyle in the hong kong sample the skeletal contribution to the overjet reduction and molar relationship change was 22 and 26 respectively the skeletal component in the german sample was 13 for overjet and 22 for molar correction figs 6 and 7 both groups demonstrated that mandibular growth can be stimulated with consequent anterior movement of the b point what was remarkable was the higher skeletal component found in the hong kong sample this was reflected cephalometrically in the anb wits appraisal and napg for the hong kong patients however the hong kong group exhibited greater amounts of anchorage loss in the mandibular arch 239 copyright © 2007 by quintessence publishing co inc printing of this document is restricted to personal use only no part of this article may be reproduced or transmitted in any form without written permission from the publisher

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purkayastha et al world journal of orthodontics overjet correction h 5.2 mm 100 g 6.8 mm 100 skeletal h 1.1 mm 22 g 0.9 mm 13 dental h 4.1 mm 78 g 5.9 mm 87 mandible h 1.2 mm 24 g 1.3 mm 19 maxilla h ­0.1 mm ­2 g ­0.4 mm ­6 mandible h 3.8 mm 73 g 2.7 mm 40 maxilla h 0.3 mm 5 g 3.2 mm 47 fig 6 mechanism of overjet correction in hong kong and german samples h hong kong sample g german sample table 6 comparison of sagittal-occlusal analysis treatment changes in mm in hong kong and german samples mean german sd 2.6 1.5 0.7 1.3 2.1 1.9 1.1 1.1 t ­12.3 ­13.6 2.9 4.9 ­7.2 6.7 ­8.0 5.9 mean ­5.2 ­4.4 0.1 1.2 ­0.3 3.8 ­0.7 2.5 hong kong sd 2.2 1.8 0.7 0.5 2.1 1.7 2.1 2.3 t ­9.4 ­9.3 0.4 8.8 ­0.9 7.7 ­1.2 4.0 german hk mean t ­1.5 0.3 0.3 0.1 ­2.9 ­1.1 ­1.1 ­1.1 1.8 0.5 1.3 0.2 4.1 1.8 2.1 2.0 overjet is/olp ­ ii/olp molar relation ms/olp ­ mi/olp maxillary base a/olp mandibular base pg/olp maxillary incisor is/olp ­ a/olp mandibular incisor ii/olp ­ pg/olp maxillary molar ms/olp ­ a/olp mandibular molar mi/olp ­ pg/olp ­6.8 ­4.1 0.4 1.3 ­3.2 2.7 ­1.8 1.4 p .05 p .01 p .001 p .0001 compared to the german sample the maxillary incisors of the hong kong patients were retracted less this can be partly explained by the fact that the southern chinese population has more anteriorly placed incisors than do caucasians.34 the greater skeletal response found in the hong kong sample could be attributed to the clinical protocol used the german sample was treated by maximum jumping of the mandible to an 240 edge-to-edge position and the functional phase lasted 7 to 9 months the hong kong protocol differed in 3 key factors that are based upon the clinical integration of basic science research conducted by the hard tissue research team at the university of hong kong stepwise advancement 6-month duration for each advancement and initial advancement of at least 4 mm copyright © 2007 by quintessence publishing co inc printing of this document is restricted to personal use only no part of this article may be reproduced or transmitted in any form without written permission from the publisher

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volume 9 number 3 2008 purkayastha et al molar correction h 4.4 mm 100 g 4.1 mm 100 skeletal h 1.1 mm 26 g 0.9 mm 22 dental h 3.3 mm 74 g 3.2 mm 78 mandible h 1.2 mm 28 g 1.3 mm 32 maxilla h ­0.1 mm ­2 g ­0.4 mm ­10 mandible h 2.5 mm 57 g 1.4 mm 34 maxilla h 0.8 mm 17 g 1.8 mm 44 fig 7 mechanism of molar relation in hong kong and german samples h hong kong sample g german sample ruf and pancherz 5 showed conclusively via the use of mri that the use of functional appliances leads to remodelling of the glenoid fossa and condyle rabie et al demonstrated in rat experiments an increased condylar and fossa response to mechanical strain provided by a mandibular advancement appliance with a step-by-step advancement procedure compared to maximum jumping.20 stepwise advancement was shown to result in 100 and 50 more bone formation in the glenoid fossa and condyle respectively importantly while with 1step advancement the rate of bone formation fell to that of natural growth after an initial increase stepwise advancement resulted in a significantly greater amount of bone formed than natural growth throughout the entire experimental period the duration of the advancement is critical to the prognosis of the newly formed bone and the stability of the results 35 the matrix of newly formed bone is of the same nature as bone formed during development and bone repair accordingly we increased the duration of treatment in our samples to 12 months with 6 months for each advancement this allows the newly formed bone with type iii collagenous matrix to mature to more stable bone with type i collagenous matrix the amount of initial advancement is impor tant results of experimental research highlighted the fact that there is a minimum threshold of strain that needs to be exceeded to elicit a response 17 therefore we decided to determine such a threshold in our clinical research a 2-mm advancement elicited a much lesser response than a 4mm advancement on condylar growth unpublished data all of the hong kong patients had an initial advancement of at least 4 mm the magnitude of the subsequent advancements depended upon the size of the overjet to be corrected now let us consider the basic scientific evidence that explains the effects presented in this study rabie et al investigated the biochemical and genetic factors responsible for the response of the mandibular condyle to tensile strain produced by orthopedically advancing the adult mandible.7­27 results of a morphological study in adult rats revealed that the length of the condylar process and width of the condylar head were significantly increased.7 the ramus angle was reduced showing backward tilting of the ramus leading to forward movement of the body of the mandible.21 this morpho241 copyright © 2007 by quintessence publishing co inc printing of this document is restricted to personal use only no part of this article may be reproduced or transmitted in any form without written permission from the publisher

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purkayastha et al world journal of orthodontics logical data supported the concept that condylar growth could be reactivated in nongrowing individuals however we needed an explanation as to how the tensile strain produced by mandibular advancement could result or be translated into a cellular response that gave rise to the morphological changes observed the discovery of the indian hedgehog morphogen ihh8,25 in the condylar cartilage and its role as a mechanotransduction mediator of condylar growth was of great importance to the field of growth modification upon application of mechanical strain as a result of mandibular advancement the cells within the condylar tissues endogenously express ihh in turn ihh enhances cellular replication and cartilage formation in the condyle leading to reactivation of adaptive condylar growth furthermore we reported that mandibular advancement of the adult condyle led to the expression of angiogenic mediators and thus led to significantly more bone formed in these condyles.10,13,27,28 thus it is becoming evident that condylar growth and orthopedic mandibular advancement is not the preserve of children and young adolescents this information affords the clinical orthodontist an improved understanding of the responses to functional appliances the lynchpin is the demonstration of the critical role an individual s genetics play in the ability to stimulate growth by advancing the mandible and new bone are formed leading to an increase in condylar size such an increase was of clinical significance as it significantly reduced the patients profile convexity see figs 1 to 3 references 1 ruf s pancherz h orthognathic surgery and dentofacial orthopedics in adult class ii division 1 treatment mandibular sagittal split osteotomy versus herbst appliance am j orthod dentofacial orthop 2004;126:140­152 2 pancherz h ruf s the herbst appliance research-based updated clinical possibilities world j orthod 2000;1:17­31 3 pancherz h dentofacial orthopedics or orthognathic surgery is it a matter of age am j orthod dentofacial orthop 2000;117:571­574 4 ruf s pancherz h when is the ideal period for herbst therapy early or late semin orthod 2003;9:47­56 5 ruf s pancherz h temporomandibular joint remodeling in adolescents and young adults during herbst treatment a prospective longitudinal magnetic resonance imaging and cephalometric radiographic investigation am j orthod dentofacial orthop 1999;115:607­618 6 ruf s pancherz h dentoskeletal effects and facial profile changes in young adults treated with the herbst appliance angle orthod 1999 69:239­246 7 ng af yang yo wong rw hagg eu rabie ab factors regulating condylar cartilage growth under repeated load application front biosci 2006;11:949­954 8 ng tc chiu kw rabie ab hagg u repeated mechanical loading enhances the expression of indian hedgehog in condylar cartilage front biosci 2006;11:943­948 9 rabie ab hagg u factors regulating mandibular condylar growth am j orthod dentofacial orthop 2002;122:401­409 10 rabie ab leung fy chayanupatkul a hagg u the correlation between neovascularization and bone formation in the condyle during forward mandibular positioning angle orthod 2002;72:431­438 11 rabie ab she tt hagg u functional appliance therapy accelerates and enhances condylar growth am j orthod dentofacial orthop 2003 123:40­48 12 rabie ab she tt harley vr forward mandibular positioning up-regulates sox9 and type ii collagen expression in the glenoid fossa j dent res 2003;82:725­730 13 rabie ab shum l chayanupatkul a vegf and bone formation in the glenoid fossa during forward mandibular positioning am j orthod dentofacial orthop 2002;122:202­209 14 rabie ab tang gh hagg u cbfa1 couples chondrocytes maturation and endochondral ossification in rat mandibular condylar cartilage arch oral biol 2004;49:109­118 conclusion it is important to consider these results in light of the recent advances in basic molecular tissue responses when the adult condyle is subjected to mechanical strain as a result of mandibular advancement the condyle cartilage cells express ihh a mechanotransduction mediator this mediator reads and understands the mechanical forces and converts these forces into cellular responses that reactivate condylar growth this explains the reactivation of condylar growth seen in the 2 samples in response to reactivation of condylar growth new cartilage 242 copyright © 2007 by quintessence publishing co inc printing of this document is restricted to personal use only no part of this article may be reproduced or transmitted in any form without written permission from the publisher

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volume 9 number 3 2008 purkayastha et al 15 rabie ab tang gh xiong h hagg u pthrp regulates chondrocyte maturation in condylar cartilage j dent res 2003;82:627­631 16 rabie ab tsai mj hagg u du x chou bw the correlation of replicating cells and osteogenesis in the condyle during stepwise advancement angle orthod 2003;73:457­465 17 rabie ab wong l hagg u correlation of replicating cells and osteogenesis in the glenoid fossa during stepwise advancement am j orthod dentofacial orthop 2003;123:521­526 18 rabie ab wong l tsai m replicating mesenchymal cells in the condyle and the glenoid fossa during mandibular forward positioning am j orthod dentofacial orthop 2003;123 49­57 19 rabie ab xiong h hagg u forward mandibular positioning enhances condylar adaptation in adult rats eur j orthod 2004;26:353­358 20 rabie abm chayanupatkul a hagg u stepwise advancement using fixed functional appliances experimental perspectives semin orthod 2003;9:41­46 21 xiong h hagg u tang gh rabie ab robinson w the effect of continuous bite-jumping in adult rats a morphological study angle orthod 2004;74:86­92 22 xiong h rabie ab hagg u mechanical strain leads to condylar growth in adult rats front biosci 2005;10:67­73 23 xiong h rabie ab hagg u neovascularization and mandibular condylar bone remodeling in adult rats under mechanical strain front biosci 2005;10:74­82 24 tang gh rabie ab runx2 regulates endochondral ossification in condyle during mandibular advancement j dent res 2005;84:166­171 25 tang gh rabie ab hagg u indian hedgehog a mechanotransduction mediator in condylar cartilage j dent res 2004;83:434­438 26 van lam s rabie ab mechanical strain induces cbfa1 and type x collagen expression in mandibular condyle front biosci 2005;10 2966­2971 27 shum l rabie ab hagg u vascular endothelial growth factor expression and bone formation in posterior glenoid fossa during stepwise mandibular advancement am j orthod dentofacial orthop 2004;125:185­190 28 leung fy rabie ab hagg u neovascularization and bone formation in the condyle during stepwise mandibular advancement eur j orthod 2004;26:137­141 29 pancherz h the herbst appliance 1995 30 hagg u tse el rabie ab robinson w a comparison of splinted and banded herbst appliances treatment changes and complications aust orthod j 2002;18:76­81 31 hagg u taranger j skeletal stages of the hand and wrist as indicators of the pubertal growth spurt acta odontol scand 1980;38:187­200 32 pancherz h the mechanism of class ii correction in herbst appliance treatment a cephalometric investigation am j orthod 1982;82 104­113 33 dahlberg g statistical methods for medical and biological students br med j 1940;2 358­359 34 cooke ms wei sh cephalometric standards for the southern chinese eur j orthod 1988 10:264­272 35 chayanupatkul a rabie ab hagg u temporomandibular response to early and late removal of bite-jumping devices eur j orthod 2003;25 465­470 243 copyright © 2007 by quintessence publishing co inc printing of this document is restricted to personal use only no part of this article may be reproduced or transmitted in any form without written permission from the publisher

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