INFLUENCE OF OPERATOR TRAINING LEVEL ON THE FRACTURE RESISTANCE OF RECIPROC R25 INSTRUMENTS

Résumé

Introduction: The fracture of an instrument is a major concern among dental surgeons in clinical practice because it can compromise the prognosis of endodontic treatment in cases with a periapical lesion. This study aimed to evaluate the influence of operator experience on the fracture strength of Reciproc R25 instruments when used on extracted molars. Materials and Methods:  Only extracted maxillary and mandibular molars with angulation between 30º and 45º were selected. Ten Reciproc R25 files, 25mm, were driven on the VDW Silver motor in the "RECIPROC ALL" mode used by odontology undergraduate students at Christus University Center, and 10 Reciproc R25 files, 25mm, driven on the VDW Silver motor in the "RECIPROC ALL" mode used by Endodontics professors at Christus University Center. The teeth were instrumented up to the apical foramen in all canals. The canals were irrigated with saline solution. Thus, we analyzed the durability of the instruments until the fracture occurred. The data were statistically analyzed by the Student’s t-test, being considered significant when P <0.05. Results: A total of 132 teeth and 410 root canals were instrumented. We observed that Reciproc R25 instruments, when operated by inexperienced operators, fractured after use in 19.3 ± 4.7 canals, and when operated by experienced professionals, fracture occurred after preparation of 21.7 ± 5.5 canals (P> 0.05). The mean number of instrumented teeth was 6.2 and 7.0 for the operators with little experience and the experienced professionals, respectively (P>0.05). Conclusion: We concluded that operator experience did not influence the fracture rates of Reciproc R25 instruments.