Statement of the problem: The complete removal of filling material is an important step to regain access to the entire canal and facilitate the disinfection of the root canal system. Rotary nickel–titanium (NiTi) instruments systems have been proposed as an effective removal technique for root canal retreatment.
Purpose: The aim of this study was to evaluate the efficacy of Neolix rotary system and ProTaper universal retreatment system in the removal of gutta-percha combined with two different sealers.
Materials and Method: Eighty extracted human permanent mandibular premolarswere prepared using the ProTaper universal rotary system to an apical size 30(F3/0.06). The specimens were randomly divided into 4 groups (n=20) and subsequently filled with lateral condensation of gutta-percha and two sealers: AH-26 and Sure-Seal Root. The teeth were stored for 4 weeks at 37 °C and 100% humidity and then retreated by one of the following rotary systems: Neolix or ProTaper universal retreatment system. Teeth were then grooved and monitored under a stereomicroscope with 8× magnification. The images were transferred to the computer and the amount of filling material that remained on the root canal walls was scored using AutoCAD 2017 version 1.1software. Results were analyzed using one-way analysis of variance test and post hoc Tukey-HSD test (p< 0.05).
Results: The mean percentage of remaining gutta-percha and sealer was significantly higher in apical third in all groups (P<0.01). Post hoc Tukey test showed that there is significantly higher residual filling material in the group filled with gutta-percha and Sure-Seal Root sealer and retreated by Neoniti rotary system compared with other groups in both coronal and middle third of the canal.
Conclusion: The Neoniti rotary system was as effective as Protaper universal retreatment system in retreatment of gutta-percha and AH-26 sealer but was significantly less effective in groups obturated with Sure-Seal Root sealer.