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Master's Dissertation
Full name
Roberto Barreto Osaki
Knowledge Area
Date of Defense
Bauru, 2020
Bramante, Clovis Monteiro (President)
Bernardes, Ricardo Affonso
Duarte, Marco Antonio Hungaro
Tanomaru Filho, Mario
Title in English
Influence of temperature on the torsional properties of two thermally treated NiTi rotary instruments
Keywords in English
Body temperature
Heat treatment
Torsional fatigue
Abstract in English
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.
Title in Portuguese
Influência da temperatura nas propriedades de torção de dois instrumentos rotatórios de NiTi tratados termicamente
Keywords in Portuguese
Fadiga torsional
temperatura corporal
tratamento térmico
Abstract in Portuguese
Introdução: Foi utilizado nesse estudo dois instrumentos rotatórios experimentais de NiTi fabricados com tratamento térmico Blue e Gold, apresentando o mesmo design. Foi avaliada a influência da temperatura nas propriedades de força de torção e deflexão angular. Métodos: Quarenta instrumentos experimentais de Niti com tratamento térmico Blue e Gold foram usados (n= 20). Foi avaliada a resistência torcional e a deflexão angular até a fratura na temperatura ambiente (21°C ± 1°C) e corporal (36°C ± 1°C). O teste torcional foi realizado nos 3 mm da ponta dos instrumentos de acordo com a ISO 3630- 1. A superfície fraturada de cada instrumento foi observada pelo microscópio eletrônico de varredura (MEV). Os dados foram analisados por meio do teste t não pareado para a comparação inter e intragrupos e o nível de significância à 5%. Resultados: Na temperatura de 21°C não houve diferença significativa na comparação intergrupo para a resistência à torção e deflexão angular entre instrumentos Blue e Gold (P>0.05). Os resultados intragrupo, à 21°C e 36°C, não mostraram diferença significativa nas propriedades torcionais dos instrumentos Blue e Gold (P>0.05). Na comparação intergrupo à 36°C observou-se que os instrumentos Blue apresentaram significantemente menor deflexão do que os Instrumentos de NiTi Gold (P<0.05). Conclusão: Os instrumentos experimentais fabricados com tratamento térmico Blue e Gold não foram afetados pela temperatura nas propriedades torcionais. Foi significantemente menor a deflexão angular dos instrumentos experimentais de Niti com tratamento Blue do que os instrumentos Gold à 36°C.
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