Removal of Thermafil Obturators Using 2 Different Techniques: A Comparative Ex Vivo Study.

Introduction: The aim of this ex vivo study was to compare 2 techniques for removal of Thermafil obturators from curved root canals in mandibular molars.
Methods: Sixty mesial root canals in extracted mandibular molars were distributed into matched pairs according to degree and radius of curvature and were prepared to size 35/.04 and obturated with Thermafil obturators size 35. Each tooth was embedded in resin, mounted in a mannequin head, and isolated with rubber dam to simulate clinical conditions. Removal of obturators was undertaken under a dental operating microscope by an experienced endodontist using either the FragRemover loop device, or reciprocating NiTi instruments. Pre- and postoperative micro-CT scans were taken to compare the amount of remaining filling material and of removed dentin. Eventual problems during removal attempts were recorded.
Results: Using Reciproc, 24 carriers (80%) were removed, 16 in one piece, 8 in small pieces, and in 6 cases removal failed. The FragRemover removed 12 carriers (40%), all of these completely, but in 18 cases removal failed (P < .05). Reciproc left less remaining filling material than the FragRemover (P < .05) but removed significantly more dentin in the apical part of the root canal (P < .01). There was no significant difference concerning the total amount of removed dentin (P > .05) between both groups. Seven complications occurred in the Reciproc group. In 5 teeth, working length could not be reached; in 2 teeth, a Reciproc file R25 fractured. With the FragRemover, 64 complications occurred, in 36 cases, including second removal attempts, the loop slipped over the carrier, in 24 cases the top of the carrier was sheared off. In 9 cases, separation of the core occurred too far apically, not allowing further use of the FragRemover. In 4 cases, the wire loop tore.
Conclusions: Reciproc was more effective in removal of Thermafil carriers, whereas when using the FragRemover less dentin was removed in the apical part of the root canal and more obturation material was left.
(Copyright © 2023 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)