Quantitative Digital Subtraction Radiography (DSR) as an approach for evaluating crestal alveolar bone density changes around teeth following orthodontic tooth movement.

Aim: The aim of the present study was to retrospectively evaluate changes in bone density using DSR  at the crestal and subcrestal regions of interproximal bone around posterior teeth (premolars and molars) before and after  orthodontic treatment using digital OPGs. Materials & Method : A total of 14 Pre and Post operative digital image pairs were obtained from the department of Orthodontics and 28 regions were sampled and analyzed. The selected patients were in the age group of 13-18 years. The mean duration of orthodontic treatment was 1.5 years. All pre and post operative radiographs were assessed at baseline and after completion of orthodontic treatment using DSR. All subtracted images were subsequently imported into The Image Tool® software to calculate the average density of Gray levels  in the areas that showed changes in subtraction. Results: Out of 28 test regions 23 regions (82.14%) showed an increase in bone density whereas 5 regions (17.85%) showed a decrease in bone density. The mean bone density of the  ROIs was 151.18 (gray level = 151.18 ± 19.97 SD). A one sample t test for statistical significance was carried out. The difference of the Mean values was found to be 23.18. The obtained p value was <0.001 at 95% confidence interval (15.44 to 30.92) Conclusion: In the present study, we have found that 23 out of 28 regions  (82.14%) showed significant increase in bone density whereas 5 regions (17.85%) showed a decrease in bone density. DSR is a valuable tool to assess subtle radiographic changes that occur in the alveolar bone during and after orthodontic therapy and can be used to monitor the bony changes over treatment period