THE USE OF FRACTAL ANALYSIS TO REVEAL REMODELING IN HUMAN ALVEOLAR BONE FOLLOWING THE PLACEMENT OF DENTAL IMPLANTS

In order to confirm the presence of adequate bone support for implants it is necessary to examine the surrounding bone at intervals. While t his may be attempted by looking for changes in serial radiographs, suc h comparisons are inaccurate unless standardized procedures are follow ed which allow subtraction of consecutive digital images. As image tex tures are less susceptible to magnification distortion, it was decided to examine the fractal dimensions of successive radiographs of bone a fter implant placement. All available panoramic radiographs for each o f 18 patients who had received fixed implant-supported prostheses were digitized. A window of bone adjacent and distal to the most posterior implant was defined as the region of interest; the fractal dimension of the image was calculated. Linear regression was used to investigate whether there were any significant shifts in fractal dimension during the recall period after implantation. A significant increase in fract al dimension was found during the period up to 2 yr after implantation (p < 0.001). The most pronounced increase was in the region of bone a round the neck of the implant. An increase in orientation of the image in a direction oblique to the implant was also found during the same period. These changes are consistent with models derived from finite-e lement analysis that predict the relation between trabecular architect ure and strain. One subject's radiographs had a significant negative r egression slope, which further monitoring may reveal was an early sign of implant failure. The satisfactory remodelling of bone in response to implant placement may be monitored using a texture analysis of rout ine orthopantomograms.