RESUMO
OBJECTIVE: Evaluate the effect of 5.25% NaOCl on the surface characteristics and fatigue resistance of ProFile. STUDY DESIGN: Eighty new ProFile instruments were divided into 1 control group (CG) and 3 experimental groups (EG1, EG2, EG3). Instruments of EG1 were immersed in 5.25% NaOCl for 24 hours. Instruments of EG2 and EG3 shaped 10 curved root canals, using, respectively, deionized water and 5.25% NaOCl as irrigants. Surface characteristics were observed by scanning electron microscopy. All instruments were then submitted to fatigue tests. Two-way ANOVA tests were employed to compare the results. RESULTS: Surface characteristics showed no alteration after the immersion tests. The fatigue resistance of instruments in EG2 and EG3 was significantly lower than in CG and EG1. CONCLUSIONS: Immersion of ProFile in 5.25% NaOCl for 24 hours had no influence on surface characteristics and fatigue resistance. Simulated clinical use was a decisive factor in the decrease of fatigue life.
Assuntos
Ligas Dentárias , Instrumentos Odontológicos , Níquel , Irrigantes do Canal Radicular , Preparo de Canal Radicular/instrumentação , Hipoclorito de Sódio , Titânio , Análise de Variância , Corrosão , Análise do Estresse Dentário , Falha de Equipamento , Reutilização de Equipamento , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Propriedades de SuperfícieRESUMO
OBJECTIVE: The changes in fatigue resistance of nickel-titanium rotary ProFile instruments after clinical use for shaping 10 curved molar root canals were evaluated in this study. STUDY DESIGN: Twenty-five sets of files #20, #25, and #30 and tapers .04 and .06 were divided into 2 groups, one with 10 sets of new files that were tested in a fatigue test bench device as a control. The other, experimental group, with 15 sets of clinically used files, was tested in the same device. The Student t test was employed to compare mean values of the measured parameters. RESULTS: A statistically significant decrease in the number of cycles to failure was determined for the clinically used files, as compared with the new ones. The fracture point was the same for all files tested. CONCLUSIONS: The clinical use of ProFile instruments for shaping curved canals reduces their fatigue resistance.