Fracture incidence of instruments from a single-file reciprocating system by students in an endodontic graduate programme: a cross-sectional retrospective study

Aim To assess the fracture incidence of instruments from single-file reciprocating systems when used by students in an endodontic graduate programme. Methodology Dental records and periapical radiographs of patients treated by students on an endodontic graduate programme using reciprocating systems were assessed. Data on tooth type, number of treated root canals, number of fractured instruments, fragment size, angle, radius, arc length and position of root canal curvature where fractures occurred were tabulated for analysis. The risk of fracture was calculated for each group of teeth, root canal and root thirds, whilst the incidence of fractures reported for the reciprocating systems was compared using the chi-squared test at 5% significance level. Results Overall, 2056 root canals (826 teeth) from 810 patients were included. The incidence of fractured files from single-file reciprocating systems in relation to a number of instrumented canals was 0.92%. Fracture rates of 0.84% and 0.93% were found in 830 and 1226 root canals instrumented with WaveOne and Reciproc systems, respectively. No significant differences were observed between the systems. The highest fracture rate was 52.6% in the mesiobuccal root of mandibular molars. The central angle, radius and arc length of the curvature of root canals where the instruments fractured ranged from 58 degrees to 84 degrees, from 1.7 to 7.2 mm and from 2.4 to 7.6 mm, respectively. Conclusion The use of WaveOne and Reciproc single-file reciprocating systems in an endodontic graduate programme was associated with a low incidence of instrument fractures.