Comparative evaluation of the shaping ability of WaveOne, Reciproc and OneShape single-file systems in severely curved root canals of extracted teeth

Aim: To compare the shaping ability of WaveOne, Reciproc and OneShape single-file systems in severely curved root canals in extracted human molar teeth. Methodology: Sixty mandibular molars with mesio-buccal canals with curvatures ranging between 25° and 35° and radii of curvature ranging between 4 and 9 mm were divided into three groups of 20 teeth each: group W (WaveOne), group R (Reciproc) and group O (OneShape). Using standardized pre- and post-instrumentation radiographs, straightening of canal curvatures was determined using the NIH Image J software. A double-digital standardized radiographic technique was used to determine apical transportation at 0.5 mm from the working length (1.5 mm coronal to the major foramen). Preparation time and instrument failures were also recorded. Data were analysed using one-way analysis of variance (anova) and post-hoc Tukey-test. Results: During root canal preparation, no instruments fractured but all OneShape instruments were deformed after preparation of four canals. The use of OneShape resulted in significantly greater canal straightening and apical transportation than WaveOne and Reciproc (P < 0.05), with no significant differences between WaveOne and Reciproc (P > 0.05). Instrumentation with OneShape was significantly faster than with WaveOne and Reciproc (P < 0.05), whilst Reciproc was significantly faster than WaveOne (P < 0.05). Conclusions: All instruments were safe to use. Reciproc and WaveOne instruments respected the original canal curvature better than OneShape files. The use of OneShape instruments required less time to prepare the curved canals compared with Reciproc and WaveOne.