Análise não-linear do mecanismo de cimentação de pinos intra-radiculares utilizando o método dos elementos finitos

Abstract

The aim is to analyze a non-linear mechanism of the cementation of root posts considering the existence of gaps in cement-dentin and cement-post interfaces analyzing the correlation of mechanical test and computational model. Were selected 15 mandibular pre-molars, to receive root posts Exacto (Angelus®/Londrina - Brazil) fixed with chemical resin cement Cement-Post (Angelus®/Londrina - Brazil). The teeth were termocycled, radiographed and cuted themselves getting cervical, middle and apical discs of roots. These discs were treated and molded with addition of silicone and epoxy resin replics was obtained before and after the compression test (220 N-0, 2 mm / min). The replics were analyzed in MEV to observe the formation of gaps at the interfaces on the upper surfaces of the specimens, which were measured in the Image Tool program. For statistical analysis of the comparison between the mensures of gaps (μm) in the interface was used in the Wilcoxon test which showed that there were statistical differences between groups (p <0.0001). In the comparison between the mensures of gaps in the same interface of the cervical, middle and apical discs before and after the compression test, there was no statistically significant difference (p = 0.4304) and (p = 0.7766), respectively. In cement-post interface there was no gaps in most specimens. The dentin discs were photographed and their images obtained from three-dimensional models simulating the compression test using the Finite Elements Method, considering linear-elastic material with values of module of elasticity and Poisson's coefficient, and obtained in the mechanical test of the traction, compression and bending resistance in the post and/or the cement. There was the Poisson's effect and a low stress concentration in dentin-cement and cement-post interfaces promoted by the force application, geometry and materials properties. In assessing the match of the mechanical test with the computational model, met a difference because of the consideration of perfect adhesion in computational model of the cervical and middle discs, which does not occur clinically, as there was formation of gaps in some root regions of the dentin discs. The apical discs were modeled like non-linear and it was considered an area of contact between the faces.