Difficulty levels of extracted human teeth used for pre-clinical training in endodontics in an Australian dental school.

This study aimed to determine the difficulty level of extracted teeth treated by undergraduate students for pre-clinical endodontic training. Two independent observers assessed a consecutive sample of 1000 periapical radiographs of extracted teeth used in endodontic pre-clinical training. Chi-square test was used to evaluate the adjustment of the distribution, and inter- and intra-examiner agreement were calculated. Minimal, moderate and high difficulty teeth represented 23.1%, 52.1% and 24.8%, respectively. The presence of curvature was the most common grading factor, with 'moderate curvature' reported in 28.7%, and 'extreme curvature' reported in 15.6% of the sample. A difference in the distribution of frequencies was found, favouring the moderate category (P < 0.001). The inter- and intra-examiner strength of agreement were 0.78 and 0.86, respectively. More than 50% of the teeth were categorised as moderate complexity. Almost one-quarter of the total sample, in particular molars, was classified as high complexity, thus unsuitable for undergraduate pre-clinical training.