Effect of canal drying methods on the apical seal

The purpose of this study was to observe the seal obtained in human root ca nals under different in vitro treatment conditions. Root canals of freshly extracted human maxillary incisors received traditional biomechanical prepa ration and irrigation with 10% NaClO, followed by a final rinse of distille d water. Teeth were divided into four groups. In group 1, each root canal w as dried with one paper point. In group 2, each root canal was dried with f our paper points. Group 3 was dried with four paper points, followed by a g entle burst of warm air. Group 4 was dried using four paper points, followe d by an internal 200 degrees C heat probe. Twenty canals in each group were filled with a gutta-percha cone and a zinc oxide-eugenol sealer, whereas 2 0 were filled with a glass ionomer sealer. All teeth were immediately immer sed in India ink for 1 or 4 wk. The teeth were cleared, and the dye penetra tion-leakage measured with an accuracy of +/-0.01 mm. Optimum sealing condi tions were observed when the canal was dried with paper points and a 200 de grees C probe. There were no significant differences between 1 and 4 wk imm ersion. Glass ionomer sealer appeared more susceptible to the wet condition of the root canal walls than zinc oxide-eugenol seater. An additional 40 t eeth were prepared in the same manner as the dye penetration tests to obser ve the drying conditions of the root canal walls, and the moisture inside t he canals was measured to an accuracy of 0.0001 g. The highest degree of in ternal canal wall dryness was found in group 4.