An in-vitro evaluation of the influence of canal curvature on the sealing ability of Thermafil.

The sealing ability of lateral condensation and Thermafil were compared in root canals with curvatures either greater or less than 25 degrees. Forty-eight canals in roots of extracted human mandibular molar teeth were divided into four groups of 12. The root canals in two groups had curvatures of less than 25 degrees and the remaining two groups had canals with curvatures greater than 25 degrees. Four canals acted as positive and negative controls. All canals were enlarged to accept a size 30 file to the working length and flared using the step-back technique. Roth's sealer was used in all canals. Lateral condensation and Thermafil obturators thermoplasticized in an open flame were used to obturate two groups each of canals, one group with curvatures greater than 25 degrees and the other less than 25 degrees. After immersion in India ink, the teeth were rendered transparent and the linear penetration of dye measured. It was found that Thermafil sealed significantly better than lateral condensation in canals with curvatures greater than 25 degrees (P < 0.05). However, there were no significant differences between the techniques in the groups with canal curvature less than 25 degrees. There was no significant difference in the performance of each of the techniques when analysed with respect to canal curvature.