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Comparative analysis of cyclic fatigue between new and clinically used protaper next TM instruments

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Resumo:INTRODUCTION: NiTi instruments were introduced in endodontic instrumentation to overcome the disadvantages of stainless steel files. However, it seems that these files exhibit a higher risk of intra-operative fracture, compromising the outcome of endodontic treatment. The aim of this study is to compare cyclic fatigue resistance between clinically used and new files. MATERIAL AND METHODS: Twenty-six clinically used ProTaper NextTM files were analyzed. The sample was 9 files of X1, 8 of X2 and 9 of X3. A mechanical device was used to simulate the root canal system and, to compare our data with a previous study, the same parameters were followed. The testing time was registered with a digital chronometer until tip separation occurred. The number of cycles to fracture was calculated multiplying time by rotational speed. Data obtained was statistically analyzed by Mann-Whitney U and Kruskal-Wallis tests or t-student test taking into account the results of the normality tests previously applied. Significance was set at the 95% confidence level. RESULTS: X1 instrument proved to be statistically more resistant to cyclic fatigue than X2 and X3, respectively. X3 was the only file that showed a significant decrease in the resistance after clinical use. The local of fracture of used and new files was statistically different. DISCUSSION AND CONCLUSIONS: Within the limitations of this study, the results suggest that resistance to fatigue life diminish after various clinical uses and all instruments should be checked carefully before each use. A single use should be considered in more complex cases. A lower resistance to cyclic fatigue in larger instruments was also shown, so these files should be used with greater care. There is a need for standardization in cyclic fatigue tests of endodontic instruments to ensure the uniformity of methodology and comparable results for a safer clinical use.
Autores principais:Quaresma, Patrícia Simões
Assunto:Endodontia Materiais dentários Materiais dentários Fadiga Teses de mestrado - 2015
Ano:2015
País:Portugal
Tipo de documento:dissertação de mestrado
Tipo de acesso:acesso aberto
Instituição associada:Universidade de Lisboa
Idioma:inglês
Origem:Repositório da Universidade de Lisboa

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