Efficacy of Different Nickel-Titanium Instruments in Removing Gutta-percha during Root Canal Retreatment

• We compared the cleanliness of root canal walls after retreatment using ProTaper Next, Twisted File Adaptive, Reciproc, and ProTaper Universal retreatment nickel-titanium (NiTi) systems and the time required for gutta-percha and sealer removal.
• The evaluation of gutta-percha removal was obtained from both halves under a stereomicroscope attached to a digital camera.
• This study has shown that the ProTaper Next and ProTaper Universal Retreatment groups showed significantly less gutta-percha and sealer on the canal walls than the Twisted File Adaptive and Reciproc groups.
• In light of these findings, it can be concluded that when the NiTi system's motion kinematics change from continuous rotation to reciprocating motion in nonsurgical retreatment, the remaining gutta-percha and sealer on the canal wall increases.

IntroductionThe aim of this study was to compare the cleanliness of root canal walls after retreatment using ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), Twisted File Adaptive (TFA; Axis/SybronEndo, Orange, CA), Reciproc (PRC; VDW, Munich, Germany), and ProTaper Universal retreatment (PTR, Dentsply Maillefer) nickel-titanium systems and the time required for gutta-percha and sealer removal.MethodsEighty human maxillary central incisors with single and straight root canals were instrumented up to #40.02 with manual K-files (Dentsply Maillefer) and obturated using the continuous wave of condensation technique. Removal of the gutta-percha and sealer was performed using 1 of the following nickel-titanium systems: PTN, TFA, RPC, or PTR. The teeth were sectioned, and digital images were captured. The photographs were analyzed using AutoCAD software (Autodesk, San Rafael, CA). Also, the total time required for gutta-percha removal was calculated by a chronometer.ResultsThe total retreatment time was significantly shorter in the PTR group compared with the other groups (P < .05). There was a significant difference between the groups according to the total residual gutta-percha and sealer (P < .05). The PTN and PTR groups left significantly less gutta-percha and sealer remnant than the TFA and RPC groups (P < .05).ConclusionsWithin the limitations of this study, the PTN and the PTR groups showed less residual gutta-percha and sealer than the TFA and RPC groups. The time required for gutta-percha and sealer removal was similar for all the groups, except for the PTR group.