The efficacy of different instruments combined with Nd:YAP in endodontic retreatment

To evaluate the efficiency of endodontic retreatment using different instruments and observe whether the Nd:YAP laser can assist.

Eighty premolars were selected, of which the root canals were prepared, and were filled with both gutta-percha and AH plus. The teeth were randomly divided into eight groups, respectively using and not using the Nd:YAP laser with the use of H files, Reciproc files, Mtwo R files, and Mtwo R + H files to remove the root-canal filling material. The retreatment time of each sample was recorded, and the amount of residual gutta-percha was calculated by Image J.

(I) In the four no-Nd:YAP laser groups, the Mtwo R group and Reciproc group took the least time, and there was no statistical difference between them (P>0.05). The Mtwo R + H file group took longer than the Mtwo R group and Reciproc group (P<0.05). The H file group took the longest time (P<0.05). (II) In the Nd:YAP laser group, the H file group took the longest time (P<0.05), and there were no significant statistical difference between the other three groups (P>0.05). (III) The Nd:YAP laser groups took a longer time than the no-Nd:YAP laser groups (P<0.05). (IV) All of the groups had residues. (V) The residues in the Mtwo R + H files group and the Reciproc group were the least among the four groups (P<0.05), and the residues in the Mtwo R group were the most (P<0.05). (VI) The residues in the Mtwo R and H file groups of the Nd:YAP laser groups were less than those of the no-Nd:YAP laser groups (P<0.05), and the residues in the Reciproc and the Mtwo R + H file groups of the Nd:YAP laser group showed no statistical difference with that of the no-Nd:YAP laser group (P>0.05).

None of the experimental methods could altogether remove the root-filling material. The Nd:YAP laser could assist, but the procedure still took a long time and the efficiency of endodontic retreatment was limited. Using the Mtwo R + H or Reciproc file was the most efficient.