Objectives: The purpose of this study was to evaluate the efficacy of steps, isolated or in cumulative means, in the endodontic retreatment of curved canals.
Methodology: Forty mesial roots of mandibular molars were divided into two groups. In the group 1 the filling removal was done with NiTi reciprocating M-wire and NiTi control memory wire rotary instruments followed by a passive ultrasonic irrigation solution agitation. In the group 2, the initial filling removal was done with NiTi reciprocating M-wire and conventional NiTi wire rotary instruments followed by a rotary plastic instrument for irrigation solution agitation. The results were analyzed through micro-computed tomography.
Results: The filling material was not completely removed for both groups. All steps did not statically differ between groups regarding to the filling removal. In the intragroup analyses, the results differed in some levels, mainly in the apical level, but did not statistically differ in all the different levels after each step. A statistical significant increase (P<.05), for both groups, in the volume of filling material in the isthmus was observed.
Conclusions: None of the protocols completely removed the filling material. The better results were found for the apical level and after passive ultrasonic irrigation. Vertical warm condensation filling technique enhanced the volume of filling material in the root canal system including the isthmus.
Clinical relevance: the control memory NiTi instruments could be considered a good choice for use as an additional step in the procedure of filling removal from curved mesial root canals.
Cone-beam computed tomography analysis of curved root canals after mechanical preparation with three nickel-titanium rotary instruments