Estudo comparativo do torque de remoção dos parafusos de conexão de pilares protéticos com cantilever sobre implantes hexágono externo e cone Morse após ensaio de ciclagem mecânica

Abstract

With the advent of osseointegration, the implantology brought a profound change in dentistry. Very well founded and consolidated, it is constantly looking for improvements and has been focused on the longevity and predictability of implant treatments. One of the scientific aspects is focused on improving the raw material of these implants, aiming at mechanical improvements, which results in new products, such as grade 4 Hard® titanium implants. The present study aims to measure the maintenance of the screw torque of the abutment of a two-element denture with cantilever on Ti cp4 implants. The experiment was composed of 3 groups (n = 60): G1 - Implants external hexagonal Ti grade 4 (n = 20); G2 - Implants external hexagon Ti grade 4 Hard® (n = 20); G3 - Morse Ti grade 4 Hard® implants (n = 20). All received simulated crowns of two cantilevered elements that were screwed by a digital torque wrench, receiving initial torque 30Ncm and after ten minutes another torque of 30 Ncm). Subsequently submitted to mechanical cycling (500,000 regular cycles, constant axial force of 120Ncm applied on the cantilever and 2Hz). At the end of the tests, the bolts were loosened and their torques checked. Statistical analysis was performed using the statistical program SigmaPlot, version 12.5, considering a level of significance of 5%. We can conclude that torque decreased significantly for all experimental groups (Wilcoxon test, p-value ranging from <0.001 to 0.002). There was no significant difference between the groups in relation to the torque at the time of loosening (Kruskal-Wallis test, p = 0.065). The same was observed in relation to the loss in torque, calculated by the difference between the tightening moment and that of the loosening moment (Kruskal-Wallis test, p = 0.065).