Quantitative digital subtraction radiography for the assessment of peri-implant bone change

The purpose of this study was to develop a digital subtraction technique to assess peri-implant bone change. The method uses subtraction radiography to enhance visualization of the area of change that has occurred between radiographic examinations, and superimposes the area of change on the original radiographs. Furthermore, a reference wedge allows calculation of the mass of the lesion. The method was validated using 21 small bony chips placed on 3 different skulls prior to the first radiograph. The chips were removed, a second radiograph taken, and the images subtracted. A morphologic method was used to isolate the lesion and the change in bone mass calculated. Overall, there was excellent correlation between the calculated lesion mass (mg) and actual lesion mass (r2 > 0.90). The utility of the method was demonstrated using a case that experienced implant failure. These data indicate that quantitative digital subtraction radiography may be of value in measuring peri-implant bone change in root form implants.