Effect of experience on quality of canal preparation with rotary nickel-titanium files

Objective. The purpose of this study was to compare inexperienced third-year dental students and experienced dentists with respect to their ability to use rotary nickel-titanium files, specifically with respect to root canal shape and instrument fracture. Study design. A total of 102 simulated endodontic plastic blocks were used. Twelve untrained dental students and 12 practitioners prepared 3 blocks each, and an endodontist and a trained student completed 15 blocks each. Blocks were filmed before instrumentation and then prepared to ISO 35; they were filmed again after canal preparation. Before-preparation images and after-preparation images were then superimposed. The canal deviation during preparation was measured at 9 levels, beginning at the apex. Results. In total, 16 of 170 instruments fractured (9.4%). Nearly all preparations (98%) exhibited good taper, smooth walls, and definite apical stops. Material removal on the outer aspect of the canal was greatest near the apex (levels 1-4: 0.11-0.24 mm). The inner aspect of the canal was most instrumented at level 6 (0.23-0.27 mm). Conclusions. These findings show that both students lacking endodontic experience and experienced dentists used the rotary nickel-titanium files with success and achieved good root canal geometry.