Evaluation of torsional resistance and cyclic fatigue of endodontic instruments and rotational reciprocated: evaluation after 3 times of clinical use

• Grant number: 16/17823-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2017
• End date: March 31, 2018
• Field of knowledge: Health Sciences - Dentistry - Endodontics
• Principal Investigator: Rodrigo Ricci Vivan
• Grantee: Manoela Medola Marun
• Host Institution: Faculdade de Odontologia de Bauru (FOB). Universidade de São Paulo (USP). Bauru , SP, Brazil

Abstract

The aim of this research is to analyze the flexural strength (cyclic fatigue) Reciproc systems (M-wire), TF Adaptive (R Phase), Logic (controlled memory) and Medin (conventional), through mechanical testing; Torsional resistance Reciproc systems (M-wire), TF Adaptive (R Phase), Logic (controlled memory) and Medin (conventional) through mechanical test. Will be selected 10 instruments (n = 10) of each system, totaling 40 instruments, to be subjected to mechanical tests described below according to the specification ISO 3630-1 (International Organization for Standardization, 1992). The fatigue tests shall be carried out on a countertop device according to Bahia and Buono (2005), which enable the free rotation of the instruments in an artificial channel bow, simulating the geometric boundary condition of instrumentation in clinical practice, considering only the bending efforts in the area of maximum curvature. The artificial channel will be formed by a piece of tool steel ABNT H13, machined in the form of an arc whose curvature fits a guide cylinder, made of the same material, with radius of 5 mm. The artificial channel geometry, characterized by its angle and radius of curvature of 5 mm and 45, respectively, will be chosen on the basis of mean values of these parameters obtained in the literature. The placement of instruments in the artificial canal, in order to define the point of maximum curvature around 3 mm from the tip. The measurement of the distance from that region in relation to the tip of the instrument will be held in a profile projector. In this way, 10 instruments in each group will be tested to the break on fatigue bench, to establish the average number of cycles until the fracture (NCF) which each instrument can perform. For the study of the comparison between the time and the experimental groups will be applied to analysis of variance (ANOVA) followed by the Tukey test for multiple comparisons among them being adopted as significance level 0.05. (AU)