Thermafil retreatment with and without chloroform solvent.

A previous study reported that retreatment of Thermafil-obturated canals resulted in significantly more remaining gutta-percha than retreatment of those obturated with laterally condensed gutta-percha. The purpose of this study was to evaluate two retreatment methods in Thermafil-obturated canals. Thirty canals were cleaned and shaped. They were obturated with Thermafil and sealer. One-half were retreated using chloroform to aid in gutta-percha removal (group 1). The others were retreated without chloroform (group 2). The ease or difficulty of removing the metal carrier was assessed during each retreatment. The teeth were split longitudinally; the canal area and remaining gutta-percha area were measured in the coronal, middle, and apical thirds. The results were analyzed by analysis of variance. In each group, seven Thermafil devices were easy to remove and eight were difficult. No significant differences were found in comparing the two groups. However, when the factor of ease of removal was added there were significant differences. Group 2 had significantly less gutta-percha in the apical third (5.9%) when the device was easily removed than when it was hard to remove (54.2%). Group 2 canals were significantly cleaner in the apical third than group 1 canals whether the device was difficult (38.3%) or easy to remove (42.5%). Adequacy of Thermafil retreatment may be related more to the ability to easily remove the carrier than to the technique of gutta-percha removal.