Rafaela Andrade de Vasconcelos1, Sarah Murphy2, Claudio Antonio Talge Carvalho3, Rajiv G Govindjee4, Sanjay Govindjee4, Ove A Peters5. 1. Department of Endodontics, University of the Pacific, Arthur A. Dugoni School of Dentistry, San Francisco, California; Department of Restorative Dentistry, Sao Jose dos Campos School of Dentistry, Institute of Science and Technology, Sao Jose dos Campos, São Paulo, Brazil. 2. Department of Endodontics, University of the Pacific, Arthur A. Dugoni School of Dentistry, San Francisco, California. 3. Department of Restorative Dentistry, Sao Jose dos Campos School of Dentistry, Institute of Science and Technology, Sao Jose dos Campos, São Paulo, Brazil. 4. Department of Civil and Environmental Engineering, University of California, Berkeley, California. 5. Department of Endodontics, University of the Pacific, Arthur A. Dugoni School of Dentistry, San Francisco, California. Electronic address: opeters@pacific.edu.
Abstract
INTRODUCTION: The purpose of this study was to evaluate the effect of 2 different temperatures (20°C and 37°C) on the cyclic fatigue life of rotary instruments and correlate the results with martensitic transformation temperatures. METHODS: Contemporary nickel-titanium rotary instruments (n = 20 each and tip size #25, including Hyflex CM [Coltene, Cuyahoga Falls, OH], TRUShape [Dentsply Tulsa Dental Specialties, Tulsa, OK], Vortex Blue [Dentsply Tulsa Dental Specialties], and ProTaper Universal [Dentsply Tulsa Dental Specialties]) were tested for cyclic fatigue at room temperature (20°C ± 1°C) and at body temperature (37°C ± 1°C). Instruments were rotated until fracture occurred in a simulated canal with an angle curvature of about 60° and a radius curvature of 3 mm; the center of the curvature was 4.5 mm from the instrument tip. The number of cycles to fracture was measured. Phase transformation temperatures for 2 instruments of each brand were analyzed by differential scanning calorimetry. Data were analyzed using the t test and 1-way analysis of variance with the significance level set at 0.05. RESULTS: For the tested size and at 20°C, Hyflex CM showed the highest resistance to fracture; no significant difference was found between TRUShape and Vortex Blue, whereas ProTaper Universal showed the lowest resistance to fracture. At 37°C, resistance to fatigue fracture was significantly reduced, up to 85%, for the tested instruments (P < .001); at that temperature, Hyflex CM and Vortex Blue had similar and higher fatigue resistance compared with TRUShape and ProTaper Universal. CONCLUSIONS: Under the conditions of this study, using a novel testing design, immersion in water at simulated body temperature was associated with a marked decrease in the fatigue life of all rotary instruments tested.
INTRODUCTION: The purpose of this study was to evaluate the effect of 2 different temperatures (20°C and 37°C) on the cyclic fatigue life of rotary instruments and correlate the results with martensitic transformation temperatures. METHODS: Contemporary nickel-titanium rotary instruments (n = 20 each and tip size #25, including Hyflex CM [Coltene, Cuyahoga Falls, OH], TRUShape [Dentsply Tulsa Dental Specialties, Tulsa, OK], Vortex Blue [Dentsply Tulsa Dental Specialties], and ProTaper Universal [Dentsply Tulsa Dental Specialties]) were tested for cyclic fatigue at room temperature (20°C ± 1°C) and at body temperature (37°C ± 1°C). Instruments were rotated until fracture occurred in a simulated canal with an angle curvature of about 60° and a radius curvature of 3 mm; the center of the curvature was 4.5 mm from the instrument tip. The number of cycles to fracture was measured. Phase transformation temperatures for 2 instruments of each brand were analyzed by differential scanning calorimetry. Data were analyzed using the t test and 1-way analysis of variance with the significance level set at 0.05. RESULTS: For the tested size and at 20°C, Hyflex CM showed the highest resistance to fracture; no significant difference was found between TRUShape and Vortex Blue, whereas ProTaper Universal showed the lowest resistance to fracture. At 37°C, resistance to fatigue fracture was significantly reduced, up to 85%, for the tested instruments (P < .001); at that temperature, Hyflex CM and Vortex Blue had similar and higher fatigue resistance compared with TRUShape and ProTaper Universal. CONCLUSIONS: Under the conditions of this study, using a novel testing design, immersion in water at simulated body temperature was associated with a marked decrease in the fatigue life of all rotary instruments tested.
Authors: Murilo Priori Alcalde; Marco Antonio Hungaro Duarte; Clovis Monteiro Bramante; Bruno Carvalho de Vasconselos; Mario Tanomaru-Filho; Juliane Maria Guerreiro-Tanomaru; Jader Camilo Pinto; Marcus Vinicius Reis Só; Rodrigo Ricci Vivan Journal: Clin Oral Investig Date: 2017-12-09 Impact factor: 3.573