Estudo da viabilidade do aparelho disjuntor suportado por mini-implantes para a expansão rápida da maxila

Abstract

Conventionally the breaker devices are supported by the posterior teeth associated or not to relative mucosal support. Currently, aiming to reduce the side effects on the supporting teeth, some studies have shown some alternatives using implants and/or mini-implants (MIs). However, there is great variability in the apparatus desing, mainly regards to the type and location of the anchorage used. The present work had aims to study the viability of palatal expander appliances supported by MIs placed in the palatal paramedian region. To accomplish this, the project was divided into 4 parts: (i) Descriptive survey of palatal bone thickness in the paramedian region in a wide age group; (ii) Evaluation of the total thickness (bone and soft tissue) in the paramedian region; (iii) Computational analysis by the finite element method of the MI diameter and length influence used as skeletal anchorage for palatal expander appliances; (iv) Computational analysis of facial bones during rapid maxillary expansion with bone supported appliances. The methodology adopted was: (i) Measurement of palatine bone thickness using Cone Beam Computed Tomography (CBCT) of 300 patients between 9 and 90 years; (ii) Measurement of soft and total tissue thickness (bone and soft tissue) using CBCT of 70 patients between 9 and 25; (iii) Analysis of the biomechanical behavior by the Finite Element Method (FEM) of the MIs and the surrounding bone, during the application of an activation of the palatal expander; (iv) Analysis by Finite Element Method (FEM) of the displacement of bone structures related to RME with different types of bone supported appliances. The results were: (i) the highest mean bone thickness found was 7.48 mm and the lowest mean was 1.46 mm. The linear regression model revealed a significant influence of gender, age, distance from the incisive foramen and from median palatal suture (MPS); (ii) the mean value of the thickness of the mucosa was 2.16 mm (+ 1.25) and the bone thickness was 3.66 mm (+ 2.40). Total thickness average found was between 2.17 and 9.47 mm; (iii) all MIs were resistant to expansion loads, however were observed stress and strain reduction for the increase in diameter and length; (iv) bone supported placed in the alveolar bone obtained a greater MPS openness, but showed a greater teeth inclination. With the present results it is concluded that the palatal expanders have the possibility of be supported by mini-implants placed in the palate.