Comparison of cleaning efficacy of root canal system by rotary instruments and Nd

Abstract

instrumentation methods leave a thin coating called a smear layer on the dentinal walls and are responsible for leakage between the canal walls and the obturation material and should be removed prior to the start of the obturation techniques. Different materials and methods have been introduced for this purpose. This study is aimed to evaluate the cleaning efficacy of canal system by Nd:YAG laser and rotary instruments. Materials & Methods: sixty single-root human teeth were divided into four experimental (n=15) groups. In the first group the teeth were prepared with step back technique using conventional K-files. In the second group, the tooth preparation was carried out using Nd:YAG laser and step back technique. Third groupEs teeth were prepared with rotary NiTi instruments. Finally the preparation in the fourth group was perfomed by combined laser and rotary methods. Then the remained smear layer was assessed by SEM in cronal, middle, and apical sections. Results: in all three sections, the combined laser and rotary methods remained the best results, and the step back was the worst. Evaluation of the x?? analysis revealed that the difference between four groups were statistically significant in apical and cronal thirds (P<0.05) but it wasnEt in middle third (P>0.05). Conclusions: the cleaning efficacy of combined laser and rotary was the best method. Keywords: smear layer, Nd:YAG laser, rotary instrument, SEM