Retrievability of Bioceramic Sealers Assessed using Micro-computed Tomography and Scanning Electron Microscopy: A Literature Review

Endodontic retreatment is a procedure to remove root canal filling material from the tooth, followed by cleaning, shaping, and obturation of the canals. Treatment outcomes may be influenced by incomplete removal of filling materials. The present literature review aimed to identify the techniques and materials used to remove Bioceramic Sealers (BCS) from the root canal system using Micro-Computed Tomography (Micro-CT) and Scanning Electron Microscopy (SEM). A search of the PubMed, Web of Science, Scopus, Science Direct, and Google Scholar databases using applicable keywords such as ‘‘BCS’’ and ‘‘calcium silicate-based sealer’’ and ‘‘retreatment’’ and ‘‘retreatability’’ and ‘‘micro-CT’’ and ‘‘SEM’’ identified studies on techniques and materials used to remove BCSs from the root canal system, as assessed by micro-CT and SEM. A total of 46 studies were included in the review. Of these, 32 studies used Nickel-titanium (NiTi) rotary instruments, 11 used reciprocating systems, and three compared continuous nickel-titanium rotary and reciprocating systems with rotary systems and reciprocation in removing filling materials. Apical patency and Working Length (WL) could be achieved in a canal obturated with gutta-percha and a BCS. The review revealed that removing filling materials using various instrumentation protocols can be successful but incomplete. Both rotary and reciprocating systems can efficiently remove root-filling material. Using supplemental techniques can improve the cleanliness of the root canal during retreatment. Solvents require less time to reach the WL and achieve patency; however, they leave a larger amount of residual root canal-filling material than non solvents. Additionally, the formation of dentinal microcracks remains controversial during the non surgical retreatment of canals filled using BCSs.