Influence of operator’s experience in three different instrumentation techniques: an in vitro study

Aim: To evaluate the influence of operator’s experience comparing rotary and reciprocating shaping systems on simulated root canals. Methodology: Ninety resin blocks with simulated root canals were distributed to six groups (15 for each group); three groups of instrumentation were assigned to undergraduate students and three to specialists in endodontics. For each category of experience, the shaping was performed with Protaper Gold™, Wave One Gold™ and Stainless-steel K-File (Control). Resin blocks were inked, then pre- and post-instrumentation photographic images were taken to be superimposed by an imaging software (GIMP 2.10.10) and analyzed by ImageJ software. After the use of each instrument, a rinse with NaOCl 2,5% was made. The outcomes evaluated were the presence of apical zip, ledges, perforation, the centering ability and the amount of resin removed.  Results: The photographic analysis of the resin blocks showed a prevalence of apical zips within the undergraduate groups; the expert groups realized a higher number of ledges, while the number of perforations resulted to be higher in the inexpert Stainless-steel control group. The amount of resin removed was significantly higher in the undergraduate WOG group, as well as the centering ability. Conclusions: The rotary and reciprocating systems provides valid operative standards; by the way, inexpert operators showed major difficulties managing the reciprocating system. More studies are required to assess this parameter.