Television radiographic evaluation of periapical osseous radiolucencies.

Periapical lesions were experimentally induced in forty-five teeth of seven beagle dogs by both septic and aseptic techniques. Preoperative and postoperative serial radiographs were produced with a specifically designed animal head x-ray device, at 30-, 60-, and 90-day periods. Four anatomic study areas, which consisted of the cervical, interradicular, proximal root, and periapical areas of each tooth, were evaluated by viewbox observation of radiographs, television subtraction radiographic imagery, and histologic examination. The findings obtained with the subtracted image and histologic examinations were correlated with viewbox observations. Diagnostic evidence of periapical pathosis was identified in the subtracted image 7 to 42 days before this same evidence was noted on the viewbox radiograph. The periodontal membrane space, lamina dura, bone trabeculae, and medullary spaces were markedly enhanced, with defined outlines of the periapical lesions noted in the subtracted image.