Angle class II correction with MARA appliance

Objective: To assess the effects produced by the MARA appliance in the treatment of Angle’s Class II, division 1 malocclusion. Methods: The sample consisted of 44 young patients divided into two groups: The MARA Group, with initial mean age of 11.99 years, treated with the MARA appliance for an average period of 1.11 years, and the Control Group, with initial mean age of 11.63 years, monitored for a mean period of 1.18 years with no treatment. Lateral cephalograms were used to compare the groups using cephalometric variables in the initial and final phases. For these comparisons, Student’s t test was employed. Results: MARA appliance produced the following effects: Maxillary growth restriction, no change in mandibular development, improvement in maxillomandibular relationship, increased lower anterior facial height and counterclockwise rotation of the functional occlusal plane. In the upper arch, the incisors moved lingually and retruded, while the molars moved distally and tipped distally. In the lower arch, the incisors proclined and protruded, whereas the molars mesialized and tipped mesially. Finally, there was a significant reduction in overbite and overjet, with an obvious improvement in molar relationship. Conclusions: It was concluded that the MARA appliance proved effective in correcting Angle’s Class II, division 1 malocclusion while inducing skeletal changes and particularly dental changes.Objetivo: avaliar os efeitos proporcionados pelo aparelho MARA no tratamento da má oclusão de Classe II, 1ª divisão. \ud Métodos: utilizou-se uma amostra de 44 jovens, divididos em dois grupos — Grupo MARA, com idade inicial média de \ud 11,99 anos e tratado com o aparelho MARA por um período médio de 1,11 ano; e Grupo Controle, com idade inicial média \ud de 11,63 ano e observado por um período médio de 1,18 ano, sem nenhum tratamento. Utilizou-se as telerradiografias em \ud norma lateral para comparar os grupos quanto às variáveis cefalométricas das fases inicial e final. Para essas comparações, \ud aplicou-se o teste t de Student. Resultados: o aparelho MARA proporcionou efeitos na restrição do crescimento maxilar, \ud sem nenhuma alteração do desenvolvimento mandibular, com melhora da relação maxilomandibular, aumento da altura \ud facial anteroinferior e inclinação anti-horária do plano oclusal funcional. Na arcada superior, os incisivos foram lingualizados \ud e retruídos, e os molares foram distalizados e inclinados para distal. Na arcada inferior, ocorreu vestibularização e protrusão \ud nos incisivos, e mesialização e inclinação mesial dos molares. Por fim, observou-se uma redução significativa nos trespasses \ud horizontal e vertical, e uma melhora evidente na relação molar. Conclusão: pode-se concluir que o aparelho MARA foi \ud eficaz na correção da má oclusão de Classe II, 1ª divisão, promovendo alterações esqueléticas e, principalmente, dentárias

Mechanical strength of stainless steel and titanium alloy mini-implants with different diameters : an experimental laboratory study

Background: The mechanical strength of mini-implants is a critical factor due to their small diameters. Currently, it is not possible to state whether there is a relevant difference between the mechanical properties of stainless steel (SS-MIs) and titanium alloy mini-implants (TA-MIs). The objective of this study was to test the null hypothesis that there is no difference in the mechanical strength of SS-MIs and TA-MIs, and to analyze, by scanning electron microscopy (SEM), the SS-MI, and TA-MI threads resistance to morphological damage after insertion. Methods: A standardized sample of 504 SS-MIs and TA-MIs with diameters ranging from 1.2 mm to 1.8 mm was used. Torsional fracture was performed in 154 MIs. Flexural strength of 280 MIs was evaluated at 1 mm and 2 mmdeflection. The threads of 70 MIs were morphologically analyzed by scanning electron microscopy (SEM), before and after their insertion in high-density artificial bone blocks. Comparisons between SS-MIs and TA-MIs were performed with t tests or Mann-Whitney U tests. A multiple linear regression analysis was used to evaluate the influence of variables on the ranging of MI mechanical strength. Results: SS-MIs had higher fracture torque. The mean difference between the SS-MIs and TA-MIs fracture torque was of 4.09 Ncm. The MI diameter explained 90.3% of the total variation in fracture torque, while only 2.2% was explained by the metallic alloy. The SS-MI group presented a higher deformation force during the 1mm and 2mmdeflection. The mean difference between the flexural strength of SS and TA-MIs at 1 mm and 2 mm-deflection was of 18.21 N and 17.55 N, respectively. There was no noticeable morphological damage to the threads of SS-MIs and TA-MIs. Conclusions: The null hypothesis was rejected. SS-MIs were 13.2% and 20.2% more resistant to torsional fracture and deflection, respectively. The threads of the SS-MIs and TA-MIs were not damaged during the insertion and removal process. Thus, the use of SS-MI can reduce the fracture risk without increasing the MI diameter

Orthodontic treatment alternative to a class III subdivision malocclusion

Class III malocclusions are considered one of the most complex and difficult orthodontic problems to diagnose and treat. Skeletal and/or dental asymmetries in patients presenting with Class III malocclusions can worsen the prognosis. Recognizing the dentoalveolar and skeletal characteristics of subdivision malocclusions and their treatment possibilities is essential for a favorable nonsurgical correction. Therefore, this article presents a nonsurgical asymmetric extraction approach to Class III subdivision malocclusion treatment which can significantly improve the occlusal and facial discrepancies