ABSTRACT
ABSTRACT Introduction: The intra-oral skeletally anchored maxillary protraction (I-SAMP) has been found to be an effective treatment for skeletal Class III malocclusion. Objective: This in-silico study explored the influence of different force directions of intra-oral skeletally anchored Class III elastics on the changes in craniomaxillofacial complex, using finite element analysis. Methods: A 3-dimensional (3D) finite element model of the craniomaxillofacial bones including circummaxillary sutures was constructed with high biological resemblance. A 3D assembly of four miniplates was designed and fixed on the maxilla and mandible of the finite element model. The model was applied with 250g/force at the miniplates at three angulations (10°, 20°, and 30°) from the occlusal plane, to measure stress and displacement by using the ANSYS software. Results: The zygomaticotemporal, zygomaticomaxillary, and sphenozygomatic sutures played significant roles in the forward displacement and counterclockwise rotation of maxilla and zygoma, irrespective of the angulation of load application. The displacements and rotations of the zygomatico-maxillary complex decreased gradually with an increase in the angle of load application between miniplates from 10° to 30°. The mandible showed negligible displacement, with clockwise rotation. Conclusions: The treatment effects of I-SAMP were corroborated, with insight of displacement patterns and sutures involved, which were lacking in the previously conducted 2D and 3D imaging studies. The prescribed angulation of skeletally anchored Class III elastics should be as low as possible, since the displacement of zygomatico-maxillary complex increases with the decrease in angulation of the elastics.
RESUMO Introdução: A protração maxilar com ancoragem esquelética intrabucal (I-SAMP) tem sido considerada um tratamento efetivo para a má oclusão esquelética de Classe III. Objetivo: O presente estudo in silico avaliou, usando análise de elementos finitos, a influência de diferentes direções da força dos elásticos Classe III com ancoragem esquelética intrabucal nas mudanças no complexo craniomaxilofacial. Métodos: Um modelo de elementos finitos tridimensional (3D) dos ossos craniomaxilofaciais, incluindo as suturas circum-maxilares, foi construído, com alta semelhança biológica. Uma montagem 3D de quatro miniplacas foi projetada e fixada na maxila e na mandíbula do modelo de elementos finitos. O modelo foi aplicado com o uso de 250g/força nas miniplacas em três angulações (10°, 20° e 30°) em relação ao plano oclusal, para medir as tensões e os deslocamentos, usando o programa ANSYS. Resultados: As suturas zigomaticotemporal, zigomaticomaxilar e esfenozigomática desempenharam um papel significativo no deslocamento para anterior e na rotação anti-horária da maxila e do zigoma, independentemente da angulação na aplicação da força. Os deslocamentos e as rotações do complexo zigomático-maxilar diminuíram gradualmente com o aumento de 10° para 30° no ângulo de aplicação da força entre as miniplacas. A mandíbula apresentou deslocamento irrelevante, com rotação no sentido horário. Conclusões: Os efeitos do tratamento com I-SAMP foram corroborados, com um vislumbre dos padrões de deslocamento e das suturas envolvidas, que não existiam nos estudos com imagens 2D e 3D realizados anteriormente. A angulação dos elásticos Classe III ancorados esqueleticamente deve ser a menor possível, visto que o deslocamento do complexo zigomático-maxilar aumenta com a redução no ângulo dos elásticos.
ABSTRACT
OBJECTIVE: The purpose of this study was to evaluate treatment effects after distalization of the mandibular dentition using ramal plates through lateral cephalograms. METHODS: Pre- and post-treatment lateral cephalograms and dental casts of 22 adult patients (11 males and 11 females; mean age, 23.9 ± 5.52 years) who received ramal plates for mandibular molar distalization were analyzed. The treatment effects and amount of distalization of the mandibular molars were calculated and tested for statistical significance. The significance level was set at p < 0.001. RESULTS: The mandibular first molar distalization at the crown and root were 2.10 mm (p < 0.001) and 0.81 mm (p = 0.011), respectively. In the evaluation of skeletal variables, there was a significant increase in the Wits appraisal (p < 0.001). In the evaluation of the soft tissue, there was no significant effect on upper lip position, but the lower lips showed a significant retraction of 2.2 mm (p < 0.001). CONCLUSIONS: The mandibular molars showed a significant amount of distalization accompanied by limited extrusion and mesiobuccal rotation of the crowns. A ramal plate may be a viable device for mandibular total arch distalization in Class III patients who are reluctant to undergo orthognathic surgery.
Subject(s)
Adult , Female , Humans , Male , Crowns , Dentition , Lip , Molar , Orthognathic SurgeryABSTRACT
Nonextraction camouflage treatment in mild Class III malocclusion is achieved by backward movement of the lower dentition and forward movement of the upper dentition. Many camouflage treatment modalities have been used for distal tipping and distal movement of mandibular posterior teeth. The amount of distal movement of mandibular dentition can be improved in cases of severe crowding, even without the patient's cooperation, by using miniscrews for anchorage. However, miniscrew insertion may be unsuccessful, and it may contact the adjacent root because of the distal movement of dentition. Distal tipping of mandibular dentition can be achieved using multiloop edgewise archwires and intermaxillary elastics. However, the complexity of this wire design causes discomfort to patients. Recently, a new treatment using improved superelastic NiTi wires (ISWs) and intermaxillary elastics has been introduced. ISWs can deliver orthodontic force more effectively, and their use with molar tip-back treatment has several advantages-this approach is effective, simple, and easy to use and reduces patient discomfort. The aim of this study was to report a case of camouflage treatment using ISW with tip-back and intermaxillary elastics for distal tipping of mandibular posterior dentition and to evaluate the effectiveness of this treatment in a clinical setting.
Subject(s)
Humans , Crowding , Dentition , Malocclusion , Molar , ToothABSTRACT
OBJECTIVE: The purpose of this study was to evaluate the dentoskeletal and soft tissue profile changes after extraction of two lower first or second premolars in "borderline" adult skeletal Class III cases. METHODS: Twenty-eight patients with "borderline" skeletal Class III malocclusion were studied. All of them were treated by extraction of two lower first or second premolars. Lateral cephalometric radiographs taken at the start and end of treatment were analysed. Twenty-five cephalometric variables were calculated and paired t-tests were performed. RESULTS: After treatment, no significant changes were noted in the skeletal parameters (p > or = 0.05). Regarding the dental parameters, the L1-MP angle decreased by 8.1degrees, the U1-L1 angle increased by 7.7degrees (p < 0.01), the overjet distance increased by 5.7 mm (p < 0.01), the L1-NB angle decreased by 7.3degrees and the L1-NB distance decreased by 4.8 mm (p < 0.01). The soft tissue parameters of Li-E, Li-H and Li-RL2 distance decreased by 3.2 mm, 3.4 mm and 4.1 mm respectively (p < 0.01). CONCLUSIONS: Orthodontic camouflage treatment by extraction of two lower first or second premolars provides a viable treatment alternative for "borderline" skeletal Class III cases to achieve a good occlusal relationship.
Subject(s)
Adult , Humans , Bicuspid , Malocclusion , Tooth Movement TechniquesABSTRACT
A abordagem clínica não-cirúrgica da Classe III coloca-se entre os grandes desafios da Ortodontia e vem, desde sempre, gerando controvérsia entre clínicos e pesquisadores. Alguns defendem a tese de que o crescimento e o desenvolvimento do complexo craniofacial são determinados geneticamente e, portanto, inalteráveis. Para esses, a correção da grande maioria de casos de Classe III passará por intervenções orto-cirúrgicas, devendo a terapia ser realizada assim que cessar o período mais ativo do crescimento. Por outro lado, há aqueles que, mesmo concordando com o peso da hereditariedade na etiologia da Classe III, acreditam ser possível modificar o padrão e a direção do crescimento e, através de uma abordagem não-cirúrgica, minimizar a má oclusão ou até mesmo tratá-la com sucesso. Em face da controvérsia, quais seriam as possibilidades ortodônticas? Inúmeros são os relatos de que uma intervenção adequada, em momento adequado, acompanhada de um estudo do padrão familiar, pode, muitas vezes, minimizar o desenvolvimento de uma Classe III. Procedimentos selecionados com critério podem reduzir a indicação de intervenções cirúrgicas e proporcionar resultados positivos e duradouros. Há evidências clínicas e científicas de que algumas decisões terapêuticas podem mudar o curso de muitos prognósticos sombrios.
Orthodontic management of the Class III malocclusion has been a constant challenge to the orthodontic profession and remains a controversial issue among clinicians and researches. Some support the belief that growth and size of the craniofacial complex are genetically predetermined and cannot be changed. They assume that the great majority of Class III cases are "untreatable" and that they are due to surgical intervention after growth has been completed. Even agreeing that heredity plays a major role in this type os deviation, others support the contention that the pattern and direction of growth can be modified and that forces generated in orthodontic treatment are able to minimize and even successfully correct some Class III. The controversy is real and one question is still to be answered: How much can orthodontics really do? The literature provides enough support that appropriate interventions at the adequate time, accompanied by a family growth study may very well minimize or camouflage the Class III to acceptable and stable results without a surgical intervention. There are clinical and scientific evidences that selected procedures can change questionable prognosis.
Subject(s)
Humans , Female , Surgery, Oral , Surgery, Oral/methods , Malocclusion, Angle Class III , Clinical Protocols , Evaluation of Results of Therapeutic Interventions , Orthodontics, CorrectiveABSTRACT
The aims of this study were to investigate the differences in the early craniofacial morphology of Class III malocclusions with good, fair and poor occlusal stability and to elucidate a key determinant for distinguishing the cases. Lateral cephalograms of 30 subjects with Class III malocclusion in the mixed dentition were analyzed at the start of treatment (mean age of 8.58+/-1.47). All subjects were re-evaluated after a mean period of 7.50+/-1.94 years comprising active treatment and retention. At this time, the samples were divided into three groups: good (10 subjects), fair (10 subjects) and poor (10 subjects) occlusal stability groups. According to the results of ANOVA, there were significant morphological differences in the early stage among the good, fair and poor occlusal stability groups, especially in variables that represented the vertical skeletal relationships. As well, there were already more dental compensations in the poor occlusal stability group. Stepwise discriminant analysis on the measurements at the time of first observation identified only one predictive variable: AB to mandibular plane angle (AB-MP). With this discriminant function, 83.3% of the original grouped cases were correctly classified and the canonical correlation coefficient was 0.857. In conclusion, AB-MP can be a possible predictor for the eventual prognosis of early Class III treatment. If it is below 60, the prognosis of early Class III treatment is expected to be poor, while if it is above 65, a good prognosis is expected.