Efficacy of several rotary systems in removal of two different obturation materials during endodontic retreatment

Abstract

Background/Aim. In order to achieve good results in endodontic retreatment, satisfactory removal of filling material and adequate debridement of the root canal is necessary. The aim of this in vitro study was to evaluate the efficacy of three rotary systems in removing gutta-percha/AH Plus and RealSeal SE obturation materials during retreatment using scanning electron microscopy. Methods. A total of 72 freshly extracted mandibular first incisors were enlarged to a size #30 using iRaCe NiTi instruments. Teeth were randomly divided into 6 groups of 12 specimens each. 36 teeth (groups 1, 2 and 3) were filled with AH Plus?/gutta-percha and another 36 (groups 4, 5 and 6) with Resilon (RealSeal SE system), both using lateral condensation technique. In groups 1 and 4, the retreatment was performed using the ProFile System, in groups 2 and 5 using the ProTaper Universal Retreatment System and in groups 3 and 6 using the D-RaCe system. After retreatment the teeth were split vertically into halves and efficacy of retreatment techniques was evaluated by scanning electron microscopy. The assessment and comparisons of 3 parameters: smear layer, filling debris and surface profile irregularities were made using a predefined scale. These 3 parameters were evaluated in the coronal, middle and apical thirds of the root. Statistical analysis was performed using the Kruskal-Wallis test with the Bonferroni post-hoc test. Results. In the AH Plus/gutta-percha samples filling debris removal was significantly better when the D-RaCe and ProTaper System were used compared to the ProFile in the apical third. Less dentin irregularities were observed when the ProTaper was used compared to the ProFile system (p = 0.0139). In the RealSeal samples, no significant differences were found between the retreatment methods. Conclusion. None of the instrumentation technique completely removed filling material from the root canal, which implies the need for more research in this field. The apical third of the root canal was the most complicated area in terms of complete smear layer and filling debris removal and presence of surface profile irregularities regardless the filling materials.