Influence of temperature on the torsional properties of two thermally treated NiTi rotary instruments

• Autor(a) principal: Osaki, Roberto Barreto
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/25/25147/tde-26102021-101827/
• topic: Body temperature; Fadiga torsional; Heat treatment; Nickel-titanium; Níquel-Titânio; temperatura corporal; Torsional fatigue; tratamento térmico

Introduction: In this study, two experimental NiTi rotary instruments manufactured with Blue and Gold heat treatment and with the same design were used. The influence of temperature on the properties of torsional strength and angular deflection was evaluated. Methods: Forty experimental Niti instruments with Blue and Gold heat treatment were used (n= 20). Torsional strength and angular deflection to fracture at room temperature (21°C ± 1°C) and body temperature (36°C ± 1°C) were evaluated. Torsional testing was performed on the 3 mm tip of the instruments according to ISO 3630-1. The fractured surface of each instrument was observed by scanning electron microscope (SEM). The data were analyzed using the unpaired t test for inter and intra-group comparison and level of significance 5%. Results: The temperature at 21°C did not show significant difference in the comparison inter-groups the torsional strenght and angular deflection between Blue and Gold instruments (P> 0.05). The intragroup results, at 21°C and 36°C, showed that there was no significant difference in the torsional properties of the Blue and Gold instruments (P>0.05). In the intergroup comparison at 36°C, it was observed that the Blue instruments showed significantly less angular deflection than the NiTi Gold Instruments (P<0.05). Conclusion: The experimental instruments manufactured with heat treatment Blue and Gold were not affected by the temperature in the torsional properties. The angular deflection of Niti experimental instruments with Blue treatment was significantly lower than Gold instruments at 36°C.