Background: While efficacy of the Forsus appliance has been shown, there are disagreements on its mechanism for Class II correction. Class II studies have been criticized for ignoring potential differences in results based on differing vertical facial phenotypes. The purpose of this study was to better understand the effects of Class II correction using the Forsus appliance and relate changes during and at the completion of treatment to initial MP-SN angles. Materials and Methods: Records of 59 patients obtained at 4 different time points were examined retrospectively. ANOVA was used to describe the cephalometric changes and Pearson’s correlation tested for any relationship between patients’ pretreatment MP-SN angle and other selected measures. Results/Conclusions: Class II correction was achieved by mesial movement of the mandibular dentition, differential mandibular growth, and clockwise rotation of the occlusal plane. There was no correlation between pre-treatment MP-SN angles and any selected cephalometric measure.

Este estudo foi realizado com o objetivo de investigar a atividade eletromiográfica (EMG) dos músculos temporal (porção anterior) e masseter em portadores de maloclusão Classe II de Angle, durante tratamento ortopédico funcional com a técnica “Reabilitação Dinâmica e Funcional dos Maxilares" (RDFM). Foram analisados dez pacientes com dentição mista, na faixa etária de seis a doze anos (média 8,6). Os registros EMG foram executados no ato da instalação da aparatologia (T1), após seis meses (T2) e um ano de tratamento (T3). Eletrodos bipolares de superfície eram posicionados bilateralmente na porção anterior do músculo temporal e na região média do músculo masseter. Um eletromiógrafo acoplado a um programa de computador (K6-I EMG Eight Channel Surface Electromyography da Myo-tronics), registrou a atividade muscular nas condições experimentais: 1 - Posição de Repouso (PR); 2 - Apertamento em Máxima Intercuspidação Habitual (AMIH); 3 - Apertamento Molar Bilateral com Rolete de Algodão (AMBA); 4 - Apertamento Máximo com o uso de Aparelho (AAPA) e 5 - Mastigação Habitual com Hiperbolóide (MH). As atividades médias dos músculos estudados foram analisadas estatisticamente pela Análise de Variância e teste complementar de Tukey. Pelos resultados conclui-se que: 1) na posição de repouso, a atividade dos músculos temporal (porção anterior) e masseter diminuiu significativamente após seis meses de terapia; não houve diferença estatística entre os músculos, apesar das alterações terem sido numericamente mais evidenciadas na porção anterior do temporal; após um ano de tratamento (T3) as médias EMG apresentaram valores maiores em relação ao período de seis meses (T2) e menores que o registro inicial (T1), demonstrando uma adaptação muscular durante o tratamento com RDFM; porém essas diferenças não foram estatisticamente significantes; 2) não houve diferença estatística entre as condições AMIH, AMBA e AAPA, porém essas foram significativamente diferentes da MH; 3) nessas condições a atividade EMG aumentou significativamente após um ano de tratamento (T3) e o músculo masseter apresentou atividade estatisticamente maior que a porção anterior do músculo temporal. / The aim of this study was to investigate the electromyographic (EMG) activity of the anterior portion of the temporal and the masseter muscles, in subjects with an Angle Class II malocclusion, during treatment with functional orthopedic appliance (Functional Dynamic Rehabilitation of Jaw - FDRJ). Ten patients with mixed dentition, age 6-12 years (mean 8.6), were evaluated. The EMG registrations were taken at just appliances insertion (T1), at the end of six months (T2), and after one year by therapy (T3). Bipolar surface disk electrodes were placed into the bilateral anterior portion of the temporal and media region of the masseter muscles. An electromyography, that was connected into a computer program (K6 I, EMG Eight Channel Surface Electromyography of Myo-tronics), has recorded the muscular actions in the experimental conditions: 1- rest position of the mandible (RP); 2– maximum intercuspal clenching (MIC); 3– bilateral molar clenching with cotton rolls (BMCR); 4– maximum clenching with appliance in the mouth (MCA), and 5– habitual chewing (HC). The mean values of the muscular activities were evaluated statistically through variance analysis and complement test of the Tukey. The results lead to conclude that: 1) in the rest position, the activity of the anterior temporal and the masseter muscles decrease significantly after six months of therapy; despite more numerical alteration was found in anterior temporal, there was no statistical difference among muscles; after one year of the treatment (T3), the EMG activity showed values greater than six months (T2), and lower than initial record (T1), that demonstrated a muscular adaptation, during the treatment with FDRM; but theses differences were not statistically significant; 2) there was no statistic difference among MIC, BMCR and MCA conditions, but these conditions were significantly different of the HC; 3) in these conditions, the EMG activity had significant increased after one year of treatment (T3), and the activity of the masseter muscle was statistical greater than the anterior portion of the temporal muscle.

Este estudo foi realizado com o objetivo de investigar a atividade eletromiográfica (EMG) dos músculos temporal (porção anterior) e masseter em portadores de maloclusão Classe II de Angle, durante tratamento ortopédico funcional com a técnica “Reabilitação Dinâmica e Funcional dos Maxilares” (RDFM). Foram analisados dez pacientes com dentição mista, na faixa etária de seis a doze anos (média 8,6). Os registros EMG foram executados no ato da instalação da aparatologia (T1), após seis meses (T2) e um ano de tratamento (T3). Eletrodos bipolares de superfície eram posicionados bilateralmente na porção anterior do músculo temporal e na região média do músculo masseter. Um eletromiógrafo acoplado a um programa de computador (K6-I EMG Eight Channel Surface Electromyography da Myo-tronics), registrou a atividade muscular nas condições experimentais: 1 - Posição de Repouso (PR); 2 - Apertamento em Máxima Intercuspidação Habitual (AMIH); 3 - Apertamento Molar Bilateral com Rolete de Algodão (AMBA); 4 - Apertamento Máximo com o uso de Aparelho (AAPA) e 5 - Mastigação Habitual com Hiperbolóide (MH). As atividades médias dos músculos estudados foram analisadas estatisticamente pela Análise de Variância e teste complementar de Tukey. Pelos resultados conclui-se que: 1) na posição de repouso, a atividade dos músculos temporal (porção anterior) e masseter diminuiu significativamente após seis meses de terapia; não houve diferença estatística entre os músculos, apesar das alterações terem sido numericamente mais evidenciadas na porção anterior do temporal; após um ano de tratamento (T3) as médias EMG apresentaram valores maiores em relação ao período de seis meses (T2) e menores que o registro inicial (T1), demonstrando uma adaptação muscular durante o tratamento com RDFM; porém essas diferenças não foram estatisticamente significantes; 2) não houve diferença estatística entre as condições AMIH, AMBA e AAPA, porém essas foram significativamente diferentes da MH; 3) nessas condições a atividade EMG aumentou significativamente após um ano de tratamento (T3) e o músculo masseter apresentou atividade estatisticamente maior que a porção anterior do músculo temporal. / The aim of this study was to investigate the electromyographic (EMG) activity of the anterior portion of the temporal and the masseter muscles, in subjects with an Angle Class II malocclusion, during treatment with functional orthopedic appliance (Functional Dynamic Rehabilitation of Jaw - FDRJ). Ten patients with mixed dentition, age 6-12 years (mean 8.6), were evaluated. The EMG registrations were taken at just appliances insertion (T1), at the end of six months (T2), and after one year by therapy (T3). Bipolar surface disk electrodes were placed into the bilateral anterior portion of the temporal and media region of the masseter muscles. An electromyography, that was connected into a computer program (K6 I, EMG Eight Channel Surface Electromyography of Myo-tronics), has recorded the muscular actions in the experimental conditions: 1- rest position of the mandible (RP); 2– maximum intercuspal clenching (MIC); 3– bilateral molar clenching with cotton rolls (BMCR); 4– maximum clenching with appliance in the mouth (MCA), and 5– habitual chewing (HC). The mean values of the muscular activities were evaluated statistically through variance analysis and complement test of the Tukey. The results lead to conclude that: 1) in the rest position, the activity of the anterior temporal and the masseter muscles decrease significantly after six months of therapy; despite more numerical alteration was found in anterior temporal, there was no statistical difference among muscles; after one year of the treatment (T3), the EMG activity showed values greater than six months (T2), and lower than initial record (T1), that demonstrated a muscular adaptation, during the treatment with FDRM; but theses differences were not statistically significant; 2) there was no statistic difference among MIC, BMCR and MCA conditions, but these conditions were significantly different of the HC; 3) in these conditions, the EMG activity had significant increased after one year of treatment (T3), and the activity of the masseter muscle was statistical greater than the anterior portion of the temporal muscle.

Background: The aim of this study was to compare the cephalometric changes in patients Class II division 1treated with Twin Block and MARA appliances. Material and Methods: The sample comprised 66 patients with Class II malocclusion divided into 3 groups: The Twin Block group consisted of 21 patients, the MARA group of 21 patients and the control group of 24 untreated subjects. Intergroup comparisons were performed at pre- (T1) and posttreatment (T2) stages. The initial and posttreatment measures concerning changes in angular and linear variables were compared using the analysis of variance (ANOVA) and Kruskal-Wallis tests. Results: Both appliances showed improvement of the relation Class II. MARA resulted in a significant increase in FMA and the occlusal plane, 1º more than control. Twin Block revealed significantly greater increase in LAFH than the others. MARA produced a significantly greater amount of labial tipping and protrusion of the mandibular incisors than the others groups. TB showed significant extrusion of the mandibular incisors compared to MARA and extrusion of the mandibular molars in relation to the control. Both treated groups showed improvement in the overjet, overbite and molar relationship. The treatment time for MARA almost was 1 year less than TB. Conclusion: The appliances were effective in the treatment of Class II malocclusion; however, the correction was mainly due to dentoalveolar effects. / Proposição: O objetivo deste estudo foi comparar as alterações cefalométricas em pacientes Classe II divisão 1 tratados com os aparelhos Twin Block e MARA. Material e Métodos: A amostra foi composta por 66 pacientes com má oclusão de Classe II divididos em 3 grupos: o grupo Twin Block composto por 21 pacientes, o grupo MARA constituído por 21 e o grupo controle com 24 indivíduos não tratados. Comparações intergrupos foram realizadas nos estágios pré (T1) e pós- tratamento (T2). As medidas iniciais e pós-tratamento referentes as alterações nas variáveis angulares e lineares foram comparadas pelos seguintes testes: análise de variância (ANOVA) e Kruskal- Wallis. Resultados: Ambos os aparelhos apresentaram melhora na relação de Classe II. O MARA resultou em um aumento significante do FMA e do plano oclusal em relação ao controle. O Twin Block revelou um aumento significantemente maior na AFAI em relação aos outros grupos. O MARA produziu um aumento significantemente maior na inclinação vestibular e protrusão dos incisivos inferiores em relação aos outros grupos. O Twin Block promoveu significativa extrusão dos incisivos inferiores em relação ao MARA e significativa extrusão dos molares inferiores em relação ao controle. Ambos os grupos experimentais resultaram em melhora no trespasse horizontal, vertical e relação molar. O tempo de tratamento do MARA foi próximo de 1 ano a menos em relação ao Twin Block. Conclusão: Os aparelhos foram eficazes no tratamento da má oclusão de Classe II, porém a correção ocorreu em sua maior parte por efeitos dentoalveolares.

In order to investigate growth modifications of the temporomandibular joint (TMJ) during dentofacial orthopaedic treatment, various functional appliances have been used to prompt the mandible into a protrusive position in various animal experimental models. The general purpose of this project was (i) to test the effectiveness of a functional appliance specially designed for sheep; (ii) to clarify whether or not forward mandibular displacement in sheep is associated with faster and/or redirected condylar growth; (iii) to evaluate the sheep as a model for dentofacial orthopaedic research by comparing the similarities of mandibular condylar growth in sheep and humans; (iv) to detail the position of the mandible during forward mandibular posturing and the effects of mandibular forward displacement on modelling and remodelling of the mandibular condyle. The specific purpose of this project was to reveal whether functional appliance treatment increases the quantity of bone formed during the treatment, or changes the distribution of the bone, or both. Eight, 4-month old, castrated male Merino sheep were randomly assigned to experimental or control groups with 4 in each group. Cast functional appliances were fabricated for the animals in the experimental group. The treatment period was 15 weeks. Calcein (day 1) tetracycline (13 weeks) and alizarin red S (3 days before sacrifice) fluorochromes were administered to all animals. Dental casts, endosseous implant markers and cephalograms were used to analyse the 3-D displacement of the mandible. Undecalcified mid-sagittal sections of TMJ were used to evaluate the tissue responses induced by the appliances. Dynamic parameters of bone formation, static indices of bone-forming and resorbing activity as well as structural indices of trabecular bone were estimated using histomorphometry. The trabecular bone was sampled from two regions: (i) a subchondral region; (determined by 2nd and 3rd labels), believed to comprise bone newly-formed during the experimental period; and (ii) a central region (labelled by all the three fluorochromes), believed to comprise bone which existed before the experiment. The cortical bone was divided into anterior and posterior regions for analysis. The weight of the animals was measured monthly to monitor their growth. Metacarpus growth was also evaluated. During the experimental period, the animals were found to maintain their weight within the normal range and grew normally. The appliance was found to displace the mandible to a downward and forward position with a net condylar displacement of 2.4 mm. The observed adaptive responses in the TMJ induced by the appliances included; the condylar process was less tapered and rounder in the experimental group than in the controls, and anteriorly thickened condylar cartilage and a thickened compact bone layer along the anterior surface of the posterior wall of the glenoid fossa. The mandibular condylar growth vector in sheep was found to be in a postero-superior direction. Condylar growth in the control sheep during the experimental period varied from 8.8 to 11.9 mm, with the mean being 10.6 mm, which is quantitatively similar to two years of condylar growth in human adolescents. In the experimental sheep, the condylar growth varied from 8.5 to 13.3 mm, with the mean being 11.4 mm. When metacarpal growth and weight gain were taken into consideration using multivariant analysis, the coefficients for growth in the postero-superior and posterior direction were found to be high, with adjusted r2 as 0.84 and 0.82 respectively. The induced condylar growth was estimated to be largest in the posterior direction (2.3 mm), which is also similar to previous reports in humans. Regional differences in adaptive response within the mandibular condyle were found in this study. In the experimental group, bone volume fraction (BV/TV) of the subchondral regions decreased, although the specific bone surface and bone formation rates increased. This low BV/TV was associated with decreased trabecular thickness and increased trabecular separation. In the central region of the experimental group's condyle, BV/TV was unchanged. However, an increased osteoid surface (OS/BS) was defined when the eroded surface (ES/BS) was taken into consideration. The sheep were found to cope well with the experimental procedures and the appliance used in this study has been effective in inducing adaptive responses in the TMJ. Consequently, it is believed that the sheep is an appropriate animal model for quantitative histological analysis of the responses to functional appliance treatment. The first null hypothesis, that functional appliance treatment has no effect on bone matrix mineralisation was rejected. The second null hypothesis, functional appliance treatment has no effect on the mineralisation lag time, was rejected. The results indicated that the treatment effects of functional appliances involve reorganisation of the TMJ through bone modelling and remodelling. An important mechanism of functional appliance treatment is, therefore, suggested to be a change in the distribution of bone rather than an increase in the quantity of bone. Posterior rotation of the principle tensile strain angle (Et) suggested an posteriorly altered direction of the condylar growth. Increased new bone formation in the glenoid fossa suggested an anterior re-positioning of the temporomandibular joint. / Thesis (Ph.D.)--Dental School, 2002.

Background and objectives: The control of anchorage is integral to successful orthodontic treatment. The objective of this research was to undertake three related projects to evaluate methods of increasing anchorage with the aim of adding to orthodontic knowledge and improve methods of treatment delivery. Methods: Two Cochrane systematic reviews were undertaken according to the methods published in the Cochrane Handbook for Systematic Reviews of Interventions, version 5.1.0. The influence of functional appliances on tooth position and the extraction decision was performed as a retrospective study using participants from a completed multicentre randomized trial. Results: 1- Statistically and clinically significant differences were found between the mean values of distal molar movement when surgical anchorage and conventional anchorage were compared. 2- Statistically significant differences were found between the mean values of distal molar movement and mesial upper incisor movement when intraoral distalising appliances and cervical headgear were compared.3- Fixed and removable functional appliances are equally effective in anchorage preparation. The type of functional appliance and time spent in Phase I treatment influenced the amount of lower incisor proclination. Conclusions: 1- Surgical anchorage is more effective than headgear without the inherent risks and compliance issues. However, intraoral appliances used in adolescence for distalisation of upper molars do not appear to have any advantages over cervical headgear. 2- Functional appliances reduce the anchorage requirements of a case primarily by reduction of the overjet, both fixed and removable functional appliances are equally effective in obtaining this. However, fixed functional appliances result in greater lower incisor proclination than removable functional appliances. 3- The type of functional appliance (removable or fixed) does not influence the extraction decision, however, this is influenced by overall space requirements.

Objectif : Évaluer les effets sur la croissance des maxillaires, ainsi que les effets dentaires, de l'utilisation du Forsus versus celle des élastiques de classe II. Matériel et méthode : Un échantillon de 30 patients a été traité sans extraction et a eu une phase d'alignement préliminaire avec appareillage orthodontique fixe complet. Vingt-trois (23) patients (14 filles, 9 garçons) ont été traités à l'aide de Forsus (âge moyen : 13,4 ans) et 7 patients (4 filles, 3 garçons) ont été traités avec des élastiques de classe II (âge moyen : 14,3 ans). Une radiographie céphalométrique a été prise à la fin de la phase d'alignement, juste avant la mise en place de l'appareil myofonctionnel choisi, et une autre au moment de l'enlèvement de l'appareil (temps de port moyen : 0,5 an). Les radiographies ont ensuite été tracées à l'aveugle et 17 mesures ont été sélectionnées pour évaluer l'effet des appareils sur les maxillaires (ANS-PNS, SNA, SNB, ANB, Go-Pg, Ar-Go, Co-Gn, axe Y, Ar-Gn, Ar-Go-Me, FMA, POF/FH, PP/FH, B-Pg(PM), 1/-FH, 1/-/1, /1-PM). Un questionnaire pour évaluer le confort face à leur appareil a été remis aux patients à environ la moitié du temps de port estimé. Résultats : Il n'y a aucune différence statistiquement significative entre les deux traitements sur la croissance du maxillaire (ANS-PNS p = 0,93, SNA p = 0,12). De façon générale, il n'y a pas non plus de différence significative entre les deux traitements sur la croissance de la mandibule (Ar-Gn p = 0,03, SNB p = 0,02 et pour les 6 autres mesures p > 0,05). Pour la composante dento-alvéolaire, les deux traitements proclinent les incisives inférieures et rétroclinent les incisives supérieures, le Forsus causant une plus forte rétroclinaison des incisives supérieures (1/-FH p = 0,007, /1-PM p = 0,10). Pour les changements angulaires des plans, le Forsus cause de manière significative une augmentation de l’inclinaison du plan occlusal (POF/FH p = 0,001). Pour le questionnaire sur l'évaluation du confort, il n'y a pas de différence entre les deux traitements en ce qui concerne la gêne face aux activités quotidiennes (p = 0,19). L'hygiène est plus facile avec les élastiques (p = 0,03). Le sommeil n’est perturbé par aucun des appareils (p =0,76). La différence entre le groupe «élastiques» et le groupe «Forsus» pour le confort en général n'est pas significative (p = 0,08). Conclusions : Le but de l’étude étant de vérifier l’efficacité des élastiques de classe II bien portés versus celle des Forsus, on peut conclure que leurs effets sont relativement similaires sur les maxillaires. Cependant, le Forsus cause de manière statistiquement significative une augmentation de l'angle du plan occlusal et une rétroclinaison plus importante des incisives supérieures. / Objective : To compare the effects on jaw growth of using Forsus Springs versus class II elastics. Material and Method : A sample of 30 patients was treated non extraction. Following a preliminary alignment phase with full fixed braces, 23 patients (14 girls, 9 boys) were treated with Forsus and 7 patients (4 girls, 3 boys) were treated with elastics (mean age : 14,3yo). Average wearing time : 0,5 y. Cephalometric radiographs were taken at the end of the alignment phase and at the end of the functional phase. Radiographic measurements were taken to assess the effects of both appliance types (ANS-PNS, SNA, SNB, ANB, Go-Pg, Ar-Go, Co-Gn, axe Y, Ar-Gn, Ar-Go-Me, FMA, POF/FH, PP/FH, B-Pg(PM), 1/-FH, 1/-/1, /1-PM). Questionnaires to assess comfort with the appliances were given to the patients approximately halfway through treatment. Results : No statistically significant differences in maxillary growth (ANS-PNS p = 0,93, SNA p = 0,12) or mandibular growth (Ar-Gn p = 0,03, SNB p = 0,02 and for the other 6 measurements p > 0,05) were noted between groups. Both treatments proclined lower incisors and retroclined upper incisors, with the Forsus causing more retroclination of the upper incisors (1/-FH p = 0,007, /1-PM p = 0,10). Forsus caused a statistically significant steepening of the occlusal plane (POF/FH p = 0,001). With respect to patient comfort, there was no statistically significant difference between the two treatments, although maintaining oral hygiene was easier in the elastics group (for daily activities p = 0,19, oral hygiene p = 0,03, sleep p =0,76, general comfort p = 0,08). Conclusions : The aim of this study being to assess the effectiveness of well worn class II elastics versus the effectiveness of Forsus, we can conclude that their effects are relatively similar on the maxillary bones. However, Forsus cause a statistically significant increase of the inclination of the occlusal plane and greater retroclination of upper incisor.

Objectif : Récemment, un nouvel appareil issu de la technologie du Forsus™ et visant à corriger les malocclusions de classe III a été mis sur le marché et se popularise dans la pratique orthodontique : le Tandem Forsus Maxillary Corrector (TFMC). L’objectif de la présente étude est de mesurer les effets squelettiques, l’influence réelle sur la croissance, et les effets dento-alvéolaires du port du TFMC. Matériel et méthodes : 14 patients présentant une malocclusion de classe III (âge moyen de 9 ans 6 mois) traités par le même orthodontiste ont participé à cette étude prospective. Le groupe consiste en 10 garçons et 4 filles. Le Tandem Forsus Maxillary Corrector est porté de 12 à 14 heures par jour jusqu’à l’obtention d’une surcorrection du surplomb horizontal et une relation dentaire de classe I. Le traitement est généralement d’une durée de 8 à 9 mois. Des radiographies céphalométriques latérales prises avant (T1) et après (T2) le traitement ont été analysées afin de déterminer les changements dentaires et squelettiques. Les résultats ont été comparés à un groupe contrôle composé de 42 enfants provenant du Centre de croissance de l’Université de Montréal. Les radiographies ont été tracées et analysées de manière aveugle à l’aide du logiciel Dolphin Imaging (ver 11.0, Patterson Dental, Chatsworth, California). L’erreur sur la méthode a été évaluée avec la formule de Dahlberg, le coefficient de corrélation intra-classe et l’indice de Bland-Altman. L’effet du traitement a été évalué à l’aide du test t pour échantillons appariés. L’effet de la croissance pour le groupe contrôle a été calculé à l’aide d’un test t pour échantillons indépendants. Résultats : L’utilisation du TFMC produit un mouvement antérieur et une rotation antihoraire du maxillaire. De plus, il procline les incisives supérieures et rétrocline les incisives inférieures. Une rotation antihoraire du plan occlusal contribue aussi à la correction de la malocclusion de classe III. Par contre, le TFMC ne semble pas avoir pour effet de restreindre la croissance mandibulaire. Conclusion : La présente étude tend à démontrer que le port de l’appareil TFMC a un effet orthopédique et dento-alvéolaire significatif lors du traitement correctif des malocclusions modérées de classe III. / Aim: Recently, a new appliance used to correct class III malocclusions, equipped with the Forsus™ technology, has been marketed and is gaining popularity in orthodontic practice: the Tandem Forsus Maxillary Corrector (TFMC). The purpose of the present study is to measure the skeletal and dento-alveolar effects, and the true influence on growth of the TFMC. Materials and Methods: A prospective study was done with 14 growing children (mean age of 9 years 6 months) who had a class III malocclusion and were treated with the TFMC by the same orthodontist. The group consisted of 10 boys and 4 girls. The «Tandem Forsus Maxillary Corrector» was worn 12 to 14 hours a day until a positive overjet and a class I dental relationship was obtained. For each patient, lateral cephalograms taken before (T1) and after (T2) the treatment were analyzed to determine skeletal and dental changes resulting from treatment. These results were compared to a control group randomly selected from the Growth Center of the University of Montreal. The cephalograms were traced and analyzed with the software Dolphin Imaging (ver 11.0, Patterson Dental, Chatsworth, California). Consistency and repeatability of measurements was evaluated with the intraclass correlation, the Dahlberg formula and the Bland-Altman test. The effect of treatment was evaluated with a paired T-test. The effect of growth for the control group was calculated with an unpaired T-test. Results: Use of the TFMC results in an anterior movement and a counterclockwise rotation of the maxilla. The upper incisors proclined and the lower incisors retroclined. A counterclockwise rotation of the occlusal plane also contributed to the correction of the class III malocclusion. Furthermore, the TFMC does not seem to restrain mandibular growth. Conclusion: The TFMC appliance seems to have a significant orthopedic and dento-alveolar effect when correcting a moderate class III malocclusion.

Objectif : Récemment, un nouvel appareil issu de la technologie du Forsus™ et visant à corriger les malocclusions de classe III a été mis sur le marché et se popularise dans la pratique orthodontique : le Tandem Forsus Maxillary Corrector (TFMC). L’objectif de la présente étude est de mesurer les effets squelettiques, l’influence réelle sur la croissance, et les effets dento-alvéolaires du port du TFMC. Matériel et méthodes : 14 patients présentant une malocclusion de classe III (âge moyen de 9 ans 6 mois) traités par le même orthodontiste ont participé à cette étude prospective. Le groupe consiste en 10 garçons et 4 filles. Le Tandem Forsus Maxillary Corrector est porté de 12 à 14 heures par jour jusqu’à l’obtention d’une surcorrection du surplomb horizontal et une relation dentaire de classe I. Le traitement est généralement d’une durée de 8 à 9 mois. Des radiographies céphalométriques latérales prises avant (T1) et après (T2) le traitement ont été analysées afin de déterminer les changements dentaires et squelettiques. Les résultats ont été comparés à un groupe contrôle composé de 42 enfants provenant du Centre de croissance de l’Université de Montréal. Les radiographies ont été tracées et analysées de manière aveugle à l’aide du logiciel Dolphin Imaging (ver 11.0, Patterson Dental, Chatsworth, California). L’erreur sur la méthode a été évaluée avec la formule de Dahlberg, le coefficient de corrélation intra-classe et l’indice de Bland-Altman. L’effet du traitement a été évalué à l’aide du test t pour échantillons appariés. L’effet de la croissance pour le groupe contrôle a été calculé à l’aide d’un test t pour échantillons indépendants. Résultats : L’utilisation du TFMC produit un mouvement antérieur et une rotation antihoraire du maxillaire. De plus, il procline les incisives supérieures et rétrocline les incisives inférieures. Une rotation antihoraire du plan occlusal contribue aussi à la correction de la malocclusion de classe III. Par contre, le TFMC ne semble pas avoir pour effet de restreindre la croissance mandibulaire. Conclusion : La présente étude tend à démontrer que le port de l’appareil TFMC a un effet orthopédique et dento-alvéolaire significatif lors du traitement correctif des malocclusions modérées de classe III. / Aim: Recently, a new appliance used to correct class III malocclusions, equipped with the Forsus™ technology, has been marketed and is gaining popularity in orthodontic practice: the Tandem Forsus Maxillary Corrector (TFMC). The purpose of the present study is to measure the skeletal and dento-alveolar effects, and the true influence on growth of the TFMC. Materials and Methods: A prospective study was done with 14 growing children (mean age of 9 years 6 months) who had a class III malocclusion and were treated with the TFMC by the same orthodontist. The group consisted of 10 boys and 4 girls. The «Tandem Forsus Maxillary Corrector» was worn 12 to 14 hours a day until a positive overjet and a class I dental relationship was obtained. For each patient, lateral cephalograms taken before (T1) and after (T2) the treatment were analyzed to determine skeletal and dental changes resulting from treatment. These results were compared to a control group randomly selected from the Growth Center of the University of Montreal. The cephalograms were traced and analyzed with the software Dolphin Imaging (ver 11.0, Patterson Dental, Chatsworth, California). Consistency and repeatability of measurements was evaluated with the intraclass correlation, the Dahlberg formula and the Bland-Altman test. The effect of treatment was evaluated with a paired T-test. The effect of growth for the control group was calculated with an unpaired T-test. Results: Use of the TFMC results in an anterior movement and a counterclockwise rotation of the maxilla. The upper incisors proclined and the lower incisors retroclined. A counterclockwise rotation of the occlusal plane also contributed to the correction of the class III malocclusion. Furthermore, the TFMC does not seem to restrain mandibular growth. Conclusion: The TFMC appliance seems to have a significant orthopedic and dento-alveolar effect when correcting a moderate class III malocclusion.

Objectif : Évaluer les effets sur la croissance des maxillaires, ainsi que les effets dentaires, de l'utilisation du Forsus versus celle des élastiques de classe II. Matériel et méthode : Un échantillon de 30 patients a été traité sans extraction et a eu une phase d'alignement préliminaire avec appareillage orthodontique fixe complet. Vingt-trois (23) patients (14 filles, 9 garçons) ont été traités à l'aide de Forsus (âge moyen : 13,4 ans) et 7 patients (4 filles, 3 garçons) ont été traités avec des élastiques de classe II (âge moyen : 14,3 ans). Une radiographie céphalométrique a été prise à la fin de la phase d'alignement, juste avant la mise en place de l'appareil myofonctionnel choisi, et une autre au moment de l'enlèvement de l'appareil (temps de port moyen : 0,5 an). Les radiographies ont ensuite été tracées à l'aveugle et 17 mesures ont été sélectionnées pour évaluer l'effet des appareils sur les maxillaires (ANS-PNS, SNA, SNB, ANB, Go-Pg, Ar-Go, Co-Gn, axe Y, Ar-Gn, Ar-Go-Me, FMA, POF/FH, PP/FH, B-Pg(PM), 1/-FH, 1/-/1, /1-PM). Un questionnaire pour évaluer le confort face à leur appareil a été remis aux patients à environ la moitié du temps de port estimé. Résultats : Il n'y a aucune différence statistiquement significative entre les deux traitements sur la croissance du maxillaire (ANS-PNS p = 0,93, SNA p = 0,12). De façon générale, il n'y a pas non plus de différence significative entre les deux traitements sur la croissance de la mandibule (Ar-Gn p = 0,03, SNB p = 0,02 et pour les 6 autres mesures p > 0,05). Pour la composante dento-alvéolaire, les deux traitements proclinent les incisives inférieures et rétroclinent les incisives supérieures, le Forsus causant une plus forte rétroclinaison des incisives supérieures (1/-FH p = 0,007, /1-PM p = 0,10). Pour les changements angulaires des plans, le Forsus cause de manière significative une augmentation de l’inclinaison du plan occlusal (POF/FH p = 0,001). Pour le questionnaire sur l'évaluation du confort, il n'y a pas de différence entre les deux traitements en ce qui concerne la gêne face aux activités quotidiennes (p = 0,19). L'hygiène est plus facile avec les élastiques (p = 0,03). Le sommeil n’est perturbé par aucun des appareils (p =0,76). La différence entre le groupe «élastiques» et le groupe «Forsus» pour le confort en général n'est pas significative (p = 0,08). Conclusions : Le but de l’étude étant de vérifier l’efficacité des élastiques de classe II bien portés versus celle des Forsus, on peut conclure que leurs effets sont relativement similaires sur les maxillaires. Cependant, le Forsus cause de manière statistiquement significative une augmentation de l'angle du plan occlusal et une rétroclinaison plus importante des incisives supérieures. / Objective : To compare the effects on jaw growth of using Forsus Springs versus class II elastics. Material and Method : A sample of 30 patients was treated non extraction. Following a preliminary alignment phase with full fixed braces, 23 patients (14 girls, 9 boys) were treated with Forsus and 7 patients (4 girls, 3 boys) were treated with elastics (mean age : 14,3yo). Average wearing time : 0,5 y. Cephalometric radiographs were taken at the end of the alignment phase and at the end of the functional phase. Radiographic measurements were taken to assess the effects of both appliance types (ANS-PNS, SNA, SNB, ANB, Go-Pg, Ar-Go, Co-Gn, axe Y, Ar-Gn, Ar-Go-Me, FMA, POF/FH, PP/FH, B-Pg(PM), 1/-FH, 1/-/1, /1-PM). Questionnaires to assess comfort with the appliances were given to the patients approximately halfway through treatment. Results : No statistically significant differences in maxillary growth (ANS-PNS p = 0,93, SNA p = 0,12) or mandibular growth (Ar-Gn p = 0,03, SNB p = 0,02 and for the other 6 measurements p > 0,05) were noted between groups. Both treatments proclined lower incisors and retroclined upper incisors, with the Forsus causing more retroclination of the upper incisors (1/-FH p = 0,007, /1-PM p = 0,10). Forsus caused a statistically significant steepening of the occlusal plane (POF/FH p = 0,001). With respect to patient comfort, there was no statistically significant difference between the two treatments, although maintaining oral hygiene was easier in the elastics group (for daily activities p = 0,19, oral hygiene p = 0,03, sleep p =0,76, general comfort p = 0,08). Conclusions : The aim of this study being to assess the effectiveness of well worn class II elastics versus the effectiveness of Forsus, we can conclude that their effects are relatively similar on the maxillary bones. However, Forsus cause a statistically significant increase of the inclination of the occlusal plane and greater retroclination of upper incisor.