Analysis of operator variability in standardized root canal preparation with Ni—Ti instruments

Objectives The aim of this study is to assess the influence of the operator variability during the preparation of standard resin blocks and the learning process with Ni-Ti instruments, the null hypothesis being that there are no significant differences regarding dentin removal, variation of the angle and radius of curvature, centering of the preparation, and time required by operator with different clinical experience. Materials and methods 100 standard resin blocks were used for this study. The blocks were divided into 4 groups of 25, and each group was assigned to a different operator. Operators 1 and 2 were 4th year DDS undergraduate students that had never performed endodontic treatments and as such could be considered as inexperienced operators. Operators 3 and 4 were 2 clinicians with 10 years experience and that were familiar with endodontic treatments and instrumentation (experienced operators). Many parameters were measured and compared. Result Differences could be detected between the 2 different level of clinical experience. Conclusions Under the experimental conditions of this study, experience of the operators can be considered as a crucial factor when all the other parameters are kept standard. In conclusion the null-hypothesis has to be rejected. Statistically significant differences exist in dentin removal, in the variation of the degree of curvature, in the centering of the preparation and in the time needed for the preparation when operators with different clinical experience where tested. © 2013 Società Italiana di Endodonzia.