Cone-beam computed tomographic evaluation and fracture resistance of endodontically retreated teeth using hyflex remover, Mtwo, and ProTaper retreatment file systems: An in vitro study

Abstract

Introduction: One of the important factors contributing to the success of nonsurgical endodontic retreatment is the efficient removal of the obturating material from the root canal space. However, the fracture resistance of the tooth is likely to be affected by this procedure. Therefore, the study envisages assessing residual filling material in the root canals and the tooth’s resistance to fracture postretreatment using different retreatment files. Materials and Methods: Ninety extracted mandibular premolars with one root and a single canal were decoronated, followed by chemo-mechanical preparation, and thereafter, using the lateral compaction method, root canals were obturated. The samples were divided into three groups (n = 30) in accordance with retreatment file systems, namely Hyflex Remover, Mtwo, and ProTaper. All three groups were subjected to the cone-beam computed tomography evaluation to assess remnants of obturating material inside the canals postretreatment, and the same samples were further assessed for fracture resistance, respectively. The collected data were evaluated using the statistical analysis using the Kruskal–Wallis and post hoc Bonferroni tests. Results: There were significant differences in the volume of residual filling among the tested groups in the cervical thirds (P < 0.05). The HyFlex remover file showed the highest fracture resistance (427.30 ± 33.53 N), followed by the Mtwo R (396.90 ± 27.17 N) and ProTaper R (378.50 ± 36.82 N). Conclusion: All the tested nickel-titanium retreatment files performed satisfactorily. Hyflex remover left the least amount of filling material in the cervical third and displayed the highest fracture resistance among the respective groups.