Avaliação das propriedades físico-químicas de instrumentos reciprocantes de níquel-titânio tratados termicamente

Abstract

Reciprocating nickel-titanium endodontic instruments have been developed to obtain a faster and safer preparation, however, these instruments have the disadvantage of fracturing during use. Facing this disadvantage, manufacturers have developed changes in instrument design and alloy finishes, as metallurgical characteristics are one of the factors that contribute to fractures. The aim of this study was to evaluate and compare mechanical properties of new nickel-titanium instruments with controlled memory. The WaveOne Gold (WOG; Dentsply Sirona, Ballaigues, Switzerland), WA1 File (WA1; TDKaFile, Mexico City, Mexico) and X1 File (X1; MK Life, Porto Alegre, RS, Brazil) systems were subjected to the torsional fatigue test, according to the ISO 3630-1 standard, flexural stiffness test, through the cantilever flexion test (45°) and buckling resistance test. The results were evaluated through analysis of variance (ANOVA), the F test and the Tukey test, considering a significance level of 5%. In the torsional fatigue test, the WOG instruments showed greater angular deflection, that is, greater resistance to torsional fracture and the WA1 instruments the lesser, and when comparing the maximum torsional torque, there was no statistically significant difference between the systems. In the flexural stiffness and buckling resistance tests, there was a statistically significant difference between the 3 systems, with the X1 instruments being the most rigid. In the first test, the WA1 instruments were the most flexible followed by the WOG instruments. In conclusion, the WOG, WA1 and X1 instruments showed differences in the mechanical tests, with the WOG and WA1 instruments being the most resistant to torsion fracture and the most flexible, unlike the X1 instruments that were more susceptible to torsion fracture and also the most rigid.