This study was done to evaluate transportation of the apical foramen after 0.5 mm overinstrumentation by ProFile, ProTaper and K³ in simulated resin root canal.

Sixty simulated resin root canal with a curvature of J and S-shape were divided into two groups. Each group consisted of three subgroups with 10 blocks according to the instruments used: ProFile®, ProTaper™, and K^3TM. Simulated resin root canal was prepared by ProFile, ProTaper and K³ with 300 rpm by the crown-down preparation technique. Pre- and post-instrumentation apical foramen images were overlapped and recorded with Image-analyzing microscope 100X (Camcope, Sometech Inc, Korea). The amounts of difference in width and dimension on overlapped images were measured after reference points were determined by Image Analysis program (Image-Pro® Express, Media Cybernetic, USA). Data were analyzed using Kruskal-Wallis and Mann-Whitney U-test.

The results suggest that ProFile showed significantly less canal transportation and maintained original apical foramen shape better than K³ and ProTaper.