Application of heat-treated nickel-titanium files and new reciprocating motion in Tri Auto ZX2 for the development of apical patency

<p>Abstract : Purpose : The aim of this study was to evaluate the efficacy of heat-treated nickel-titanium (NiTi) files and an endodontic motor with reciprocating motion on the establishment of apical patency.</p><p> Materials and Methods : Seventy S-shaped root canal blocks were used in this study. Dentists with 6 to 11 years of clinical experience (Practician Group, n=7) and trainee dentists with 1 year of clinical experience (Trainee Group, n=7) tried to establish apical patency using the following five techniques. Group 1 : Manual operation with stainless steel (SS) files (#15/.02 K file). Group 2 : Tri Auto ZX2 Optimum Glide Path (OGP) mode with SS files (#15/.02 Superfile [SPF] ; OGP＋SPF). Group 3 : Tri Auto ZX2 OGP mode with heat-treated NiTi files (#16/.02-.08 ProGlider [PRG] ; OGP＋PRG). Group 4 : Tri Auto ZX2 new OGP (N-OGP) mode with Superfile (N-OGP＋SPF). Group 5 : Tri Auto ZX2 N-OGP mode with ProGlider (N-OGP＋PRG). The time required to establish apical patency was measured. The surface of the K file, Superfile, and ProGlider before and after the establishment of apical patency was observed by scanning electron microscope.</p><p> Results and Discussion : The rate of establishment of apical patency was 100% and 97.1% in the Practician Group and Trainee Group, respectively. One file fracture was observed in OGP＋PRG in the Trainee Group. KF required significantly more time than the other four groups in the Practician Group. This tendency was also observed in the Trainee Group, however there was no significant difference among the five groups. No significant difference was observed between the Practician Group and Trainee Group in the five methods. No morphological change was observed on the surface of the K file, Superfile, and ProGlider after the establishment of apical patency.</p><p> Conclusion : N-OGP＋PRG is a new treatment option that enables apical patency to be established in a shorter time than manual operation with a K file.</p>