Influência do tipo de retentor intra-radicular e da radioterapia na deformação, resistência e padrão de fratura de diferentes dentes tratados endodonticamente

Abstract

The aim of this in vitro study was to evaluate the influence of post type and the radiotherapy effect on strain, fracture resistance and fracture pattern for different teeth endodontically treated. 160 human teeth were selected (n=40): In, incisives; Ca, canines; Pm, pre-molar e Mo, molars. After the endodontically treatment, half of samples (n=20) was subjected to gamma Co irradiation. Subsequently the teeth of each group were restored with (n=10): PFV, fiber glass post and NMF, cast post and core, both were fixed with self-adhesive resinous cement. All roots were prepared with ferule of 2mm and restored with metal crowns. The interaction betwwen these 3 factors resulted in 16 experimental groups (n=10). For strain-gauge measurement (n=5), the samples of In, Ca and Pm were subjected to loading until 150N. Subsequently the fracture resistance test were performed (n=10). Data of fracture resistance were analyzed by two-way ANOVA (4x2) regarding of post type and radioteraphy, followed by Tukey test (α=0.05). Further it was realized two-way ANOVA (2x2) for the fracture resistance data, proximal and buccal strain of each tooth type in function of type post and radiotheray effect, followed by Tukey test (α=0.05). The fracture mode analysis was realized. The type post altered the fracture pattern. Despite the presence of irradiation or not, the post type did not statistically influenced the fracture resistance for all teeth. The In non-irradiated presented fracture resistance statistically lower that the other teeth. Ca e Mo presented the highest fracture resistance values, statistically similar among them. The irradiated Pm presented fracture resistance lower than Ca and similar to Mo. The irradiation significantly increased the proximal strain values of In, Ca and Pm. The PFV resulted in higher proximal strain of irradiated and nonirradiated Pm; for the others teeth no influence was verified for post type. Nonirradiated In and Pm presented higher buccal strain values when restored with PFV.