This review explores the field of retreatment strategies for the cases filled with calcium silicate-based root canal sealers. Since the introduction of calcium silicate-based materials in dentistry, calcium silicate-based root canal sealers have become popular among dentists because of their biocom- patibility, bioactivity, and sealing ability. Therefore, effective retreatment strategies are indispensable. This article aims to identify the challenges associated with the removal of calcium silicate-based sealers itself and gutta-percha with the sealers during retreatment, evaluate current techniques and materials, and provide future directions for research in this field. Regarding the strategies of removal of root canal sealers, calcium silicate-based sealers are still relatively new materials for clinicians compared with the traditional sealers such as epoxy- or eugenol-based sealers. First, no clinically established solvents have been reported. Second, calcium silicate-based sealers are currently utilized by clinicians in either cold sealer-based technique or warm vertical condensation technique. Third, the setting process of calcium silicate-based sealers generates byproducts primarily calcium hydroxide and secondarily hydroxyapatite, which could interact with dentine. Lastly, there is a lack of clinical studies evaluating the efficacy of retreatment protocols for teeth filled with calcium silicate-based sealers. Therefore, it is important to investigate chemo-mechanical properties of calcium silicate- based sealers itself and their reactions to solvents and/or mechanical instruments, and identify the interfacial properties of calcium silicate-based sealers in respect to dentine and gutta-percha. In addition, researchers in clinical field need to actively gather and report data on retreatments of teeth filled with calcium silicate-based sealers.

Aim: To compare the effectiveness of conventional and rotary NiTi files for Gutta-Percha (GP) removal in straight roots during retreatment root canal treatment (RCT), using manual Hedstrom files and ProTaper Universal System, respectively. Methods: It was an in-vitro experimental study using non-probability consecutive sampling. Sixty extracted single rooted maxillary and mandibular permanent teeth with straight canals were selected for this study. Following preparation, the root canals were filled with GP along with a sealer and kept for two weeks in a moist environment at room temperature. Thirty teeth were randomly allocated to the study and control groups each. GP removal was accomplished with Hedstrom files and Pro Taper retreatment files in group 1 and group 2, respectively. Digital radiographs were obtained using Kodak RVG digital radiography system software version VER.6.10.8.3-A and analyzed for the difference of opacities indicating residual GP. AutoCAD 2006 software was used to outline the root canal and the residual root filling. Independent sample t test was used to compare the total residual GP in both groups. Results: No significant difference in the residual root filling was observed following removal with conventional Hedstrom files versus ProTaper universal retreatment files. In both groups, the residual GP was confined to the apical third of the roots. Conclusion: ProTaper Universal Retreatment files and manual Hedstrom files are equally effective in the removal of GP in straight canals.