Endodontic retreatment of thermafil or lateral condensation obturations in post space prepared teeth

The purpose of this study was to quantify the amount of remaining gutta-percha/sealer after retreatment of post space prepared teeth obturated with a lateral condensation technique or with Thermafil with plastic and metallic carrier. The time required for retreatment was also recorded. Forty-five extracted mandibular premolars were prepared using a step-back flared technique and obturated. The post space was prepared and a 5-mm obturation was left in the canal. Retreatment of all groups was done using a solvent technique. The teeth were split longitudinally and photographed. The total area of the canal and the area of gutta-percha/sealer were traced on white paper. Both areas were quantified using a computerized image analysis system and the ratio of remaining obturation material to root canal periphery was derived and statistically analyzed. Statistical analysis (analysis of variance, p = 0.01) showed no differences among the techniques when the average percentage of remaining gutta-percha/sealer was compared. Results revealed that the Thermafil metallic retreatment group consumed significantly more time than the others (analysis of variance, Scheffe p = 0.01). The metallic carriers were not easily removed from the canals, six metal carriers could not be retrieved during the retreatment routine.