Prevalence and management of instrument fracture in the postgraduate endodontic program at the Dental School of Athens: a five-year retrospective clinical study.

The aim of the present clinical research was to investigate the prevalence and management of instrument fracture during root canal preparation by postgraduate students (Department of Endodontics, Dental School of Athens) and to determine the percentage of referred cases with fractured instruments managed by the same students of the program. A retrospective study was conducted by reviewing the dental notes of 1367 patients (2180 endodontic cases, 4897 root canals) treated between October 2001 and June 2006 by endodontic postgraduate students at the Dental School of Athens. Type of tooth and canal, type and length of fractured segments, level of instrument fracture, and management that followed were recorded. The overall prevalence of instrument fracture during root canal preparation by postgraduate students was 1.83%. The prevalence of endodontic cases with fractured instruments referred to the endodontic postgraduates was 7.41%. The prevalence of stainless steel hand and rotary nickel-titanium instrument fracture by postgraduate students were 0.55% and 1.33%, respectively. The prevalence of instruments fractured in the apical third (52.5%) was significantly higher when compared with coronal (12.5%) and middle (27.5%) thirds of the canals. The retrieval or bypass of fractured instruments was most successful in the coronal (100%) and middle (45.4%) thirds when compared with the apical third (37.5%) of the canals. The fracture frequency was higher in retreatment cases in relation to the respective rate of initial therapies. On the basis of the results of this study, the prevalence of endodontic instrument fracture by the postgraduate students was relatively low. The prevalence of fracture of nickel-titanium rotary instruments was more frequent than that of hand instruments. Retrieval or bypass of the fractured instruments in the apical third was less successful.