The Influence of Brushing Motion on the Cutting Behavior of 3 Reciprocating Files in Oval-shaped Canals

Introduction: The purpose of this study was to compare the cutting efficiency of 3 reciprocating single-file systems used with a brushing motion in oval-shaped canals. Methods: Sixty premolars with single oval canals were selected and randomly assigned to 3 groups according to the file used in canal instrumentation: R25 Reciproc (VDW, Munich, Germany), Primary Wave One ((Dentsply Maillefer, Ballaigues, Switzerland), and a novel prototype instrument (UFile; MicoMega, Besancon, France). Instrumentation was performed in 4 consecutive steps; according to manufacturers' instructions, 5 brushing strokes against the buccal wall with a nonworking instrument followed by another 5 and 15 brushing strokes with a working file. Cone-beam computed tomographic scans were taken after each step of preparation. Pre- and postinstrumentation images were superimposed at the apical and midroot levels and then evaluated in terms of changes in the maximum buccolingual (Delta BL) and mesiodistal dimensions (Delta MD). Results: Instrumentation with a brushing motion resulted in the following findings. At the apical levels, no significant difference was found in Delta BL for the 3 groups (P > .05). However, Delta MD was significantly less for the Reciproc (P = .006) and UFile (P = .03) groups. At the midroot levels, the UFile group showed the highest significance in terms of Delta BL (P < .0001) but the lowest in terms of Delta MD (P = .003). MD was significantly the highest for the WaveOne group at the midroot levels (P = .05). Conclusions: The prototype file was more efficient than the other files at the midroot levels, whereas all systems acted the same at the apical levels. The increase in the number of brushing strokes resulted in more dentinal cutting in the direction of those strokes.