Radiographic absorptiometry method in measurement of localized alveolar bone density changes

Objective. The objective of this study was to measure the accuracy and prec ision of a radiographic absorptiometry method by using an occlusal density reference wedge in quantification of localized alveolar bone density change s. Study design. Twenty-two volunteer subjects had baseline and follow-up radi ographs taken of mandibular premolar-molar regions with an occlusal density reference wedge in both films and added bone chips in the baseline films. The absolute bone equivalent densities were calculated in the areas that co ntained bone chips from the baseline and follow-up radiographs. The differe nces in densities described the masses of the added bone chips that were th en compared with the true masses by using regression analysis. Results. The correlation between the estimated and true bone-chip masses ra nged from R = 0.82 to 0.94, depending on the background bone density. There was an average 22% overestimation of the mass of the bone chips when they were in low-density background, and up to 69% overestimation when in high-d ensity background. The precision error of the method, which was calculated from duplicate bone density measurements of non-changing areas in both film s, was 4.5%. Conclusions. The accuracy of the intraoral radiographic absorptiometry meth od is low when used for absolute quantification of bone density. However, t he precision of the method is good and the correlation is linear, indicatin g that the method can be used for serial assessment of bone density changes at individual sites.