ABSTRACT
The aim of this study was to evaluate the sealing ability of Thermafil root canal filling material as correlated with the shape of the prepared root canal walls, when instrumented with three different enlarging instruments. Fifty human central incisors were used in this study and were divided into three groups. Groups A and B, having 20 teeth in each, were prepared with square cross section K-type files and triangular cross section Flex-R files, respectively. These two groups were subdivided into two equal halves according to the mode of action used in mechanical preparation [filing or reaming action]. Group C consisted of 10 teeth prepared with triangular cross section K-type reamers using reaming action. Root canals were obturated using a standard size [50] of Thermafil with sealer. The extent of dye penetration was measured under stereomicroscope after clearing of teeth. When the results were subjected to an analysis of variance at P = 0.05, no significant difference in dye penetration existed between the three tested groups when compared as a whole. However, a significant difference existed between the subgroups prepared with different modes of action with better restriction of dye penetration in canals prepared using reaming action. Manufacturer discrepancies in Thermafil and sealer extrusion seemed to be main disadvantages