A bilinear elastic constitutive model applied for midpalatal suture behavior during rapid maxillary expansion

Introduction : This study aims to evaluate the influence of the biomechanical behavior of the midpalatal suture (MPS) during the rapid maxillary expansion (RME) when modeled by the Finite Element Method. Methods Four simulation alternatives are discussed and, for each analysis, the suture is considered as a functional unit with a different mechanical behavior: (i) without MPS elements, (ii) MPS with Young's modulus (E) equal to 1 MPa, (ii) MPS with E equal to 0.01 MPa and (iv) MPS with bilinear elastic behavior. Results The stress analysis showed that, when MPS is not considered in the model, stress peaks are reduced in magnitude and their distribution is restricted to a smaller area when compared to the model with the inclusion of MPS (E=1 MPa). The increased suture stiffness also has a direct influence on MPS displacements after 30 expander activations. Conclusion The consideration of the MPS in RME computer models influences greatly the calculated displacements between the suture bone ends, even as the stress levels in maxillary structures. Furthermore, as proposed for the described model, the elastic bilinear behavior assigned to MPS allows coherent prediction of stresses and displacements results, being a good representation for this suture overall behavior.

Ancoragem esquelética ortodôntica: distalização de molares e fechamento de espaços com mini-implantes para correção da má oclusão Classe II sub-divisão esquerda / Skeletal anchorage: distalization of molars and spaces closure using miniscrews in the treatment of a Class II sudvision left

Os dispositivos intrabucais convencionais de ancoragem nem sempre são capazes de oferecer grande eficiência e resultam em movimentações dentárias indesejadas que podem comprometer o resultado final ou aumentar o tempo total de tratamento. A utilização de sistemas de ancoragem esquelética representa atualmente uma importante ferramenta na estratégia do tratamento ortodôntico por fornecer ancoragem estacionária, minimizando os efeitos indesejáveis em vários movimentos dentários e sem necessitar da cooperação dos pacientes. Neste relato de caso clínico é abordada a correção de má oclusão de Classe II subdivisão esquerda de Angle, com mecânica de distalização de molares por meio de Helical Bulbous Loop e com a utilização de mini-implantes para ancoragem. O objetivo do tratamento foi plenamente alcançado e, tanto as distalizações dos molares quanto o fechamento de espaço, foram ancorados em mini-implantes. Nenhum efeito colateral foi verificado durante o tratamento decorrente da ancoragem.

Conventional intraoral skeletal devices are not always efficient since they may cause undesirable dental movement that can compromise the final results and prolong the period of treatment. The use of skeletal anchorage systems represents an excellent tool for orthodontic treatment as it generates a stationary anchorage, with minimum unexpected dental movement and does not depend on patient compliance. The present study reports a clinical case of Angle Class II/2 malocclusion (subdivision left) treated with molars distalization using a Helical Bulbous Loop with the aid of iniscrews for anchorage. The aim of the treatment was fully achieved and both the distalization of molars and space closure were obtained through miniscrew anchorage. No side effect of anchorage was observed during treatment.