Factors associated with root canal ledging during instrumentation.

The purpose of this study was to identify the presence of a ledge in 141 cases treated in an undergraduate clinic and in 103 cases treated by endodontists, and to identify the clinical factors associated with ledging. A total of 626 root canals were examined and the factors analyzed were canal location, tooth number and canal curvature. The results indicated that 51.5% of the canals treated by students had been ledged, whereas the percentage was 33.2% for intact pulp cavities treated by endodontists and 40.6% in cases of endodontic retreatment. Canal location was found to have an effect on the incidence of ledging as the mesiobuccal, mesiolingual and distal buccal root canals exhibited a significantly higher ledge incidence rate than the distal and palatal root canals. Canal curvature was the most significant variable affecting the incidence of ledging.