Classification of surgical difficulty in extracting impacted third molars.

Few studies have attempted to analyse preoperative factors that complicate the surgical removal of impacted mandibular third molars. We studied this problem in two steps. We found that difficulty in extraction is associated with depth (depth is deep occlusal level: level C), ramus relationship/space available (ramus relationship/space available is no space: class 3), width of root (the width of the middle root is thicker than that of the neck and the roots do not separate, incomplete roots excluded: bulbous), or a combination of these factors. The index was tested in 20 patients whose extractions were difficult, and 24 in whom they were not. The new index has an odds ratio (relative risk) of 62.3 (95% confidence interval, 9.3-415.9), a sensitivity of 0.85 and a specificity of 0.92. We consider that the new index is superior to the conventional Pederson's index.