A new method to assess the results of instrumentation techniques in the root canal.

In the present study, the shape of the root canal was assessed with pre- and postinstrumentation silicone impressions. Curved root canals of 30 extracted molars were instrumented with the Canal Leader (CL), the ProFile System (PF), and hand instrumentation (HI). Photographs from each impression were digitized, and the enlargement of the canals was computed by substracting the preinstrumentation from the postinstrumentation images. Technical errors of preparation were also recorded. There was no significant difference in total dentin removal between the systems. However, CL removed significantly more dentin from the convex side of the root canal than PF. Instrument separation occurred in five cases, only with PF. Roughness of canal walls was recorded significantly more often with the use of CL than with PF or HI. CL also produced a significantly higher incidence of elbow formation, compared with PF or HI. With this method of assessment, it was possible to record details and differences between the tested instrumentation techniques.