External root resorption: an experimental radiographic evaluation.

Radiographs of a human mandibular premolar, in which five holes (resorptive defects) of differing diameters were drilled before its replacement into a human mandible, were evaluated by 11 dental faculty members. The radiographs were made at various exposure times and angulations. The observers' results were evaluated statistically. It was found that small resorptive defects were significantly more difficult to identify than larger ones. Also, angulation, exposure time, and location of the defects as defined in this study had no significant effect on the ability of observers to accurately identify them.