AVALIAÇÃO IN VITRO DA EXPANSÃO RÁPIDA DA MAXILA ANCORADA EM MINI-IMPLANTES: Comparação entre Dois Diferentes Diâmetros

Abstract

The aim of this study is to present a new system of rapid maxillary expansion supported by mini-implants, besides to evaluate the best screw diameter indicated for expansion, according to the strength achieved (Kgf) during an in vitro assay. Methods: 10 specimens were used, consisting of a metal frame and polyurethane 40 PCF (0,64 g/cc) artificial bone, in which Hyrax devices were adapted. Each device was supported on and anchored by four mini-implants, inserted with an angulation of 0 degrees related to insertion plane, in all of the specimens. The specimens were divided equally into two groups. Only the diameter of the mini-implants varied within the groups; all the mini-implants were 11 mm length: group 1: 1.6mm in diameter; group 2: 2.0 mm in diameter. The specimens underwent mechanical tests that simulated a palatal expansion, aiming to evaluate the loads of strength achieved by the system according to the activations and possible differences between the two groups. The results were obtained by the software Tesc Version 3.04 and then analyzed statistically. Results: Both groups achieved forces higher than necessary to rapidly expand the maxilla. Conclusion: There is a statistically significant difference at the level of 0.05%, between the strength achieved in accordance with the screw activation within the two groups. The 2.0 mm group showed higher values in comparison to the 1.6mm group. The new rapid maxillary expansion system, as much as the mini-implants of both diameters, showed its effectiveness and feasibility through these in vitro tests.