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This study assessed the cutting properties of two Nickel Titanium file systems with different designs and manufacturing materials. ProTaper Next X1 and X2 (PTN; Dentsply Sirona) and ProTaper Universal S2 and F1 (PTU; Dentsply Sirona) instruments were employed. The cutting parameters, that is torque and apical forces, were determined using a specially designed bench-testing machine. Dimensional and geometric parameters were considered to evaluate the results. The average maximum torque values showed statistically significant differences (P < 0.05) among all instruments. Apical force for PTN X2 and PTU F1 instruments initially decreased and then experienced a rapid increase in the last 2 mm of the canal. For PTN X1 and PTU S2, apical force increased during the entire test. When compared to PTU files, PTN required higher torque and apical forces during the shaping procedure. The results lead us to conclude that PTN instruments demonstrated a lower cutting efficiency than PTU.

ResumoNeste trabalho, foi investigada a influência da textura de fitas de NiTi superelástico no início do processo de cristalização de um revestimento de TiO2 flexível. Foram utilizadas a calorimetria diferencial, cartografia Raman e difração de raios X para o estudo. Foi mostrado que existe uma influência significativa da textura do substrato no crescimento de grãos de anatase e rutila no filme de TiO2. Amostras com menor rugosidade apresentaram grãos mais desenvolvidos para todas as temperaturas de cristalização. Mostrou-se também que o substrato de NiTi promoveu a formação de TiO2 rutila em temperaturas abaixo daquelas observadas para a cristalização de pós. Palavras-chave: NiTi; TiO2; Sol-gel; Rutila INFLUENCE OF THE SUPERELASTIC NiTi ALLOY TEXTURE ON THE CRISTALISATION OF A TiO2 SOL-GEL COATING AbstractIn this work, the influence of the texture of a NiTi superelastic strip on the beginning of the crystallization process of a flexible TiO2 sol-gel coating was investigated. Differential scanning calorimetry, Raman spectroscopy and X-ray diffraction were used for the study. It was shown that there is a significant influence of the subtract roughness on grain growth of anatase and rutile TiO2. Smoother surfaces generated coarser grains for all crystallization temperatures. It was also shown that the NiTi substrate promoted a rutile phase transformation at lower temperatures than observed for powder crystallization.