The purpose of this study was to assess the optimal amplitude and weight of the newly developed contra-angle handpiece. The handpiece employed piston movement without using an endo motor and enabled a safe, quick and reliable canal preparation.
A prototype handpiece was designed. Instrumentation was performed on root canal resin blocks by 20 operators in three groups: the prototype handpiece with H file (stainless #25 manual H file, Piston group), manually standardized technique with K file (stainless #15-25 K files, Manual group), and NiTi reciprocating file with endo-motor (Reciproc Blue R25, NiTi group). Transportation of the canal center line and time required for preparation was measured and statistically analyzed.
The optimal condition was the amplitude of 1.35 mm and weight of 61.0 g. Transportation of the canal center was observed in all groups. A statistically significant difference was found at 2.0-3.0 mm from the apical foramen between Piston or NiTi group and Manual group, but no significant difference was found between Piston and NiTi group. The least transportation was found in NiTi and Piston group. The handpiece with #25 H file carried a good centering ability as NiTi file which enabled speedy preparation. Time required for preparation between Piston or NiTi and Manual group was statistically different. No significant difference was observed between Piston and NiTi group (P<.05).
We concluded that the newly designed handpiece achieved efficient canal preparation and negotiation. The handpiece could avoid endodontic accidents including ledge formation, instrument separation, and perforation.

Copyright © 2021. Published by Elsevier Inc.

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