The influence of different angles and reciprocation on the shaping ability of two nickel-titanium rotary root canal instruments.

PURPOSE: The purpose of the present study was to investigate and compare the effect of different reciprocating movements and angles on the shaping ability of the WaveOne and the single-fle ProTaper F2 using cone beam computed tomography (CBCT). MATERIALS AND METHODS: The mesiobuccal canals of 40 extracted maxillary molars, with curvatures of 20 to 45 degrees were coded and randomly divided into 4 equal experimental groups according to the instrument used (ProTaper F2 fle and Wa-veOne) and the reciprocation range, for both instruments, a 150 degrees angle was used for cutting and a 30 degrees angle was used for release. Group 1 - WaveOne primary 150 degrees CCW rotation angle and 30 degrees CW rotation angle; Group 2 - WaveOne 90 degrees CCW rotation angle and 30 degrees CW rotation angle; Group 3 - ProTaper F2 150 degrees CW rotation angle and 30 degrees CCW rotation angle; Group 4 - ProTaper F2 90 degrees CW rotation angle and 30 degrees CCW rotation angle. Canals were scanned before and after preparation using CBCT to evaluate the volumetric change, canal transportation and the canal centering ability at 2.6, 5.2 and 7.8 mm from the apex. The mean +/- standard deviation (SD) values were analyzed, and the significance level was set at p </= 0.05. RESULTS: There was no significant difference in the amount of dentin removed among the experimental groups, except that WaveOne 150 degrees CCW 30 degrees CW significantly showed the least volume of dentin removed (0.40 +/- 0.9) at 7.8 mm. All rotary systems tested in the different groups resulted in canal transportation in different directions at all examined levels. WaveOne 150 degrees CCW 30 degrees CW, demonstrated the lowest mean value of root canal transportation in both the mesial and furcal directions and in both the coronal and apical directions compared to the other groups. At the 7.8 level, WaveOne 150 degrees CCW 30 degrees CW yielded the highest mean centering ratio, whereas ProTaper F2 CW 150 degrees CCW 30 degrees yielded the lowest, statistically significant at p </= 0.05. CONCLUSION: The results of the present study demonstrated that differences among various reciprocating motions and angles could affect the shaping ability of a single-fle Nickel-titanium (NiTi) instrument.