Influence of welding (laser or TIG) and mechanical cycling on marginal misfit (Bi and three-dimensional), detorque strength in prosthetic screws, and stress induced to abutment of implant-supported prostheses

Abstract

The aim of this study is to evaluate the influence of welding (laser - light amplification by stimulated emission of radiation e TIG- tungsten inert gas) and the mechanical cycling, about quantity of marginal misfit (bi and three-dimensional), detorque strength of the prosthetic screws and the stress induced to prosthetic abutment in multiple prostheses. Twenty frameworks will be casted in commercially pure titanium (cp Ti), simulating a three-element fixed prosthesis and two types of index models (n = 20) will be made, one in special plaster and another in photoelastic resin, simulating marginal misfit standardized of approximately 200 micrometers. Two analysis of marginal misfit will be made: one bi-dimensional through analysis in comparison optical microscope of precision and another three-dimensional through analysis in CAD/CAM. The test protocol of the screws single will is made to both analyses. This procedure will be made before and after the welding procedures (laser and TIG). The stress induced in analogs of prosthetic abutment will be made through extensometric analysis using strain gauges in the index models made of special plaster. Also will be made the simulation of masticatory cycles, through fatigue mechanical simulator (2Hz, 106 cycles) and evaluation of detorque strength in index models made of photoelastic resin. The evaluation of the detorque strength of prosthetic screws will be made through application of torque and retorque, using a digital torquemeter of precision. All evaluations will be made in two moments (before and after the welding). The results will be submitted to the Exploratory Analysis and made the statistical test for comparisons and correlations between the results. (AU)