[Comparison of shaping ability of 4 nickel-titanium rotary instruments in preparation of curved root canals].

PRUPOSE

To compare the shaping ability of 4 nickel-titanium rotary instruments in preparation of curved root canals.

METHODS

Forty extracted human maxillary first or second molars with mesiobuccal root canal curvature ranging from 20°-40° were selected. The teeth were randomly equally divided into 4 groups(n=10). Mesial root canals were separately prepared using Protaper Universal, Protaper Next, TF, and S3 nickel-titanium instruments. A series of preoperative and postoperative images were taken by Micro-CT． Mimics 17.0 software was used to analyze the following parameters: canal transportation, centering ratio values, root canal volume, volume of removed dentin, and canal/root width ratio. Data analysis was performed by using SPSS 20.0 software package.

RESULTS

In terms of canal transportation after preparation at 1, 3 and 5 mm from the apex, Protaper Universal was more than the other three groups(P＜0.05). The centering ratio value of Protaper Universal was significantly smaller than that of the other three groups at 1 mm from the apex(P＜0.05). The amount of dentin removal was significantly different after instrumentation with the four test systems(P＜0.05). Protaper Universal had the highest mean volume of removed dentin. After preparation, all root canals had a diameter that was not larger than 39% of the root diameter at the coronal and middle segments.

CONCLUSIONS

Under the conditions of this study, Protaper Next, TF, S3 systems seem to be better choices than Protaper Universal system in preparing curved root canals.