Comparison of curved root canals preparation using reciprocating, continuous and an association of motions.

The aim of this study was to compare the rotary ProTaper Universal system, the single-file reciprocating WaveOne system and an association of motions assessing shaping ability, cleanliness, preparation time and instrument failures after preparation of curved root canals. Sixty root canals of extracted human molar teeth, with curvatures ranging between 20° and 40°, were divided into three groups, according with preparation system. Canals were prepared until apical size 25 using the ProTaper Universal system (G1), WaveOne (G2), or a hybrid technique (G3) associating reciprocating preparation with rotary glide path and cervical pre-enlargement. Teeth were scanned pre and post-operatively using computed tomography. Direction of transportation and centering ability of canals were measured using a computer image analysis program, and the results were analyzed statistically using one-way ANOVA. Preparation time was analyzed by one-way ANOVA and the Tukey post hoc test. Instrument failures were recorded. The amounts of debris and smear layer were quantified based on a numerical evaluation scale by scanning electron microscopy and were analyzed statistically using the Kruskal-Wallis test. No difference in transportation and centering ratio was found between the systems. Instrumentation with WaveOne was significantly faster than with other instruments (p < 0.05). During preparation, no instruments fractured and three suffered deformations. For debris removal and remaining smear layer, the results for the three groups were similar. The single-file reciprocating instrument was capable of providing faster root canal preparation with similar transporting, centralization and cleaning ability when compared with continuous and an association of motions in curved canals. SCANNING 38:462-468, 2016.