Development of Innovative Contra-angle Handpiece Device with Piston Movement for Root Canal Preparation

The purpose of this study was to assess the optimal amplitude and weight of the newly developed contra-angle handpiece. The handpiece uses piston movement without using an endodontic motor and enables a safe, quick, and reliable canal preparation.

A prototype handpiece was designed. Instrumentation was performed on root canal resin blocks by 20 operators in 3 groups: the prototype handpiece with an H file (a stainless steel #25 manual H file, the piston group), a manually standardized technique with a K file (stainless steel #15-25 K files, the manual group), and a nickel-titanium (NiTi) reciprocating file with an endodontic motor (Reciproc Blue R25 [VDW, Munich, Germany], the NiTi group). Transportation of the canal center line and the time required for preparation were measured and statistically analyzed.

The optimal condition was an amplitude of 1.35 mm and a 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 the piston or NiTi group and the manual group, but no significant difference was found between the piston and NiTi groups. The least transportation was found in the NiTi and piston groups. The handpiece with a #25 H file demonstrated a good centering ability, similar to the NiTi file, which enabled speedy preparation. The time required for preparation between the piston or NiTi group and the manual group was statistically different. No significant difference was observed between the piston and NiTi groups (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.