The effect evaluation of the curved oval root canal filling clearing by two kinds of nickel titanium files

To evaluate the efficacy of the curved oval root canal filling clearing by two kinds of nickel titanium instruments.

75 mandibular premolars with curved oval root canal were prepared with Heor642 and filled with warm vertical compaction technique. The teeth were randomly divided into three groups: ProTaper Universal Retreatment group (ProTaper UR), Mtwo group, and manual Hedström files group. The percentage of residual filling material from both buccolingual and mesial-distal direction were respectively calculated by X-ray photographs, and the operating time was recorded.

None of the groups completely removed the filling materials. Two groups of nickel titanium rotary instruments resulted in a smaller percentage of residual filling material compared with the manual Hedström files group from both bucco-lingual and mesial-distal direction, while no significant difference was found between the ProTaper Universal group and Mtwo group. Both of the operating time in the two nickel-titanium groups were less than Hedstrom files group, while no difference was found between the two nickel-titanium groups.

Both ProTaper UR and Mtwo rotary instruments were effective and efficient in removing filling material, but none of the instruments can completely remove filling material in curved oval root canals.