The detection of in vitro produced periodontal bone lesions by conventional radiography and photographic subtraction radiography using observers and quantitative digital subtraction radiography.

Changes in the periodontium produced by removal of bone cylinders at one interdental site of a dry human mandible, were recorded radiographically. These artificial lesions had diameters of 0.3 mm increasing to 1.4 mm in steps of 0.1 mm. Radiographs were obtained using 3 different X-ray tube potentials and 3 different amounts of radiation. These 9 exposure variables resulted in 9 series of radiographs from the artificial lesions. Observers were asked to determine the presence or absence of these periodontal bone lesions on conventional radiographs and on photographically subtracted images. The images were also evaluated by a quantitative digital subtraction technique. This study showed that the smallest periodontal bone changes were detected with the quantitative digital subtraction technique compared to the other methods using observers. On photographically subtracted images, smaller bone changes were detected by the observers than on conventional radiographs. Only the detection threshold of the quantitative digital subtraction technique was influenced by the 2 exposure factors: kVp and mAs.