Efficacy of reciprocating instruments for removing filling material in curved canals obturated with a single-cone technique: a micro-computed tomographic analysis.

INTRODUCTION: The aim of this study was to evaluate the efficacy of nickel-titanium reciprocating instrument techniques and passive ultrasonic irrigation (PUI) for retreatment in curved canals and obturated with correspondent single cones. METHODS: Twenty molars were selected with mesial-buccal canals with curvatures between 20 degrees and 40 degrees , and they were instrumented with a Reciproc R25 instrument (VDW, Munich, Germany) in a reciprocating motion and obturated with single cones and AH Plus sealer (Dentsply Maillefer, Ballaigues, Switzerland). The teeth were divided into 2 groups (n = 10) according to the instrument used for the removal of filling material: group 1: Reciproc R25 instrument and group 2: WaveOne Primary instrument (Dentsply Maillefer). The analysis of the remnant filling material was made through micro-computed tomographic imaging after the use of reciprocating instruments and again after the use of PUI with xylene. The effective time of retreatment was registered. RESULTS: The filling material of the root canal was efficiently removed (P < .05) for both groups. The percentage of removal of filling materials was 93% for the Reciproc group and 92% for the WaveOne group. There were no statistical significant differences (P > .05) between the groups in relation to the removal of filling material ability and the time needed for the procedure. The effective time for the removal of filling material was 78.7 seconds and 89.5 seconds for the Reciproc and WaveOne groups, respectively. CONCLUSIONS: It was concluded that both instruments efficiently but not completely removed the filling material from inside the root canals. The use of xylene with PUI increased the removal of filling material a little, but it was not statically significant.