Histologic evaluation of three endodontic instrument/preparation techniques.

33 curved canals were prepared to quantify both the increase in canal area and predentin removal in the apical region. Compared were three different file designs/instrumentation techniques, that is "stepback" with K-flex file, "balanced force" with Flex-R file, and the Canal Master system. Following canal preparation and histological processing, cross-sections at 1 and 3 mm levels were examined using the Bioquant image analysis system. Results showed that, at the 3 mm leve, the mean increase in canal area and predentin removal showed no statistically significant difference (p > 0.05) between the techniques. At 1 mm, the step-back technique (with K-flex files) resulted in a significant increase in canal area and greater predentin removal than did the "balanced forces" (with Flex-R files) or the Canal Master system. However, although there were statistical differences, the actual differences were small; these may not translate to clinically significant differences in the 3 techniques.