Gutta-percha retreatment: Effectiveness of nickel-titanium rotary instruments versus stainless steel hand files

This study compared the cleanliness of the root canal walls after retreatment using nickel titanium (NiTi) rotary and stainless steel (SS) files. Also compared were time of retreatment and canal deviation. Forty extracted canines were step-back prepared and obturated with gutta-percha and sealer. Retreatment was performed either by using chloroform and SS hand files or chloroform and NiTi rotary files. Time for retreatment was recorded. Radiographs of the root canal system before and after retreatment were made. Teeth were split longitudinally, photographed, and projected onto a screen. The amount of gutta-percha/sealer remaining on the canal walls was then traced and measured. The amount remaining was analyzed and compared statistically between NiTi and SS groups by t test. Results showed that the mean percentage of wall coverage by remaining obturating material in the SS group was 13.6% and was 15.2% for the NiTi group. There was no statistically significant difference (p = 0.361). No severe canal deviation occurred with either retreatment method. Mean retreatment time for the SS group was 6.3 min and 7.9 min for the NiTi group; the difference was statistically significant (t test p < 0.001). In conclusion, NiTi rotary and SS hand were similar in material remaining after retreatment, but SS hand was a bit faster.