Effects of clinical use of NiTi reciprocating instruments on cyclic and torsional resistance, and on roughness

The aim of the present study was to evaluate cyclic fatigue, torsional resistance and surface roughness Reciproc R25 instruments in four different situations, namely as new tested after clinical preparation one, two or three maxillary molars with root canals. total time required perform each canal recorded. Cyclic fatigue determined by fracture using a customized testing device (n = 10 per group). test evaluated torque angle rotation failure according ISO 3630-1 working parts used profilometer 5 Statistical analysis performed one-way ANOVA Tukey's test. level significance set at 5%. No fractures deformations were observed use. Higher needed during third use for all canals (p 0.05). Regarding measurements, groove depth higher on one- versus two- three-maxillary-molar-prepared < It can be concluded that increased decreased roughness. However, did not affect instruments.