Original Articles
Evaluation of Cutting Efficiency by Rotary and Hand Files in Oval-shaped Canals
2018 Volume 61 Issue 1 Pages 30-39
Details
2018 Volume 61 Issue 1 Pages 30-39
Purpose: The purpose of this study was to evaluate by micro-computed tomography (micro-CT) the cutting efficiency using a nickel-titanium rotary file (NiTi-r), a stainless steel rotary file (SS-r), and a hand file (Hand) for preparation of a root canal in extracted human maxillary premolars placed on the left and right sides of a dental model on a phantom.
Methods: Twenty-four extracted human maxillary premolars with a buccolingual canal diameter two or more times larger than the mesiodistal canal diameter at 5 mm from the root apex were used in this study. The teeth were placed in the left and right sides of a dental model attached to a training phantom. The operator worked on the phantom clinically in a 9-10 o’clock position. The teeth were divided into three groups of eight teeth each (left: four teeth, right: four teeth) the NiTi-r group (K3XF file), SS-r group (ERT file) and Hand group (K-file) according to the following preparation techniques. Root canal preparation was performed with a brushing stroke in the NiTi-r and SS-r groups, and with circumferential filing in the Hand group. The working time, cutting ratio, and volume increase ratio were calculated and evaluated between groups and the left and right sides by micro-CT.
Results: Hand had a significantly larger cutting ratio than SS-r, but the working time of Hand was significantly longer. NiTi-r and Hand had similar cutting ratios, but the working time for NiTi-r was significantly shorter. There were no significant differences in the working time, cutting ratio, or volume increase ratio between NiTi-r and SS-r. SS-r and Hand had larger volume increase ratios than NiTi-r, but it was not significant. There were no significant differences in the working time, cutting ratio, or volume increase ratio between the left side tooth and the right side tooth.
Conclusion: When preparing left and right maxillary premolars with oval-shaped canal on a phantom, NiTi-r can cut efficiently in a short time and with a reasonable shape, the same as Hand files.
