Removal of Thermafil root canal filling material.

The aim of this study was to evaluate if removal of Thermafil plastic carriers and reestablishment of working length were possible in single rooted teeth filled with the Thermafil system. Twenty freshly extracted maxillary central incisors were prepared and filled with #30 Thermafil plastic obturators according to manufacturer's recommendations. Teeth were divided in two groups: Group I: 10 teeth were retreated using dimethylformamide as a solvent. Group II: 10 teeth were retreated using chloroform as a solvent. Removal of filling material was performed manually using K files and H files alternately between carrier and dentinal walls. The average time needed to remove the plastic carrier was 7 min for group I and approximately 6 1/2 min for group II. No deformation of the plastic carrier was observed after removal from the canal. Removal of plastic carriers and measurement of the proper working length were easily performed using manual endodontic instruments. Chloroform greatly enhanced this procedure.