Results
Distribution of preoperative root canal curvatures.
The mean preoperative root canal curvature in the teeth of the Profile .04 group was 27.8 and in the Lightspeed group 28.4 .
Straightening.
Due to three instrument fractures during preparation of the unsectioned roots, the number of specimens in this Profile .04 group was only 22. The mean straightening after preparation to size 45 in the Profile .04 group was 0.2 in the unsectioned and 0.3 in the sectioned roots (SD: 0–5 ), in the Lightspeed group the mean straightening was 0.4 in the unsectioned and 0.2 in the sectioned roots (SD: 0–3 ). The difference was not statistically significant (Table 1).
Cross-sections.
The results concerning postoperative cross sections of the root canals are summarized in Table 2. Lightspeed produced slightly more irregular cross-sections in all parts of the root canal. Following the use of both Ni–Ti systems, the root canals in the majority of the cases showed round or oval root canal cross-sections and were rated acceptable. No statistically significant difference between the two systems occurred.
Table 1. Evaluation of root canal straightening.
Table 2. Evaluation of postoperative cross-section.
Table 3. Contact between pre- and postoperative cross-section.
Table 4. Assessment of root canal cleanliness.