Changes in the fractal dimension on peri-implant trabecular bone after loading : a retrospective study

Abstract

The aim of this study was to assess bony trabecular changes caused by loading stress around dental implants using fractal dimension analysis. Forty eight subjects (23 males and 25 females; age range: 33 to 77 years; mean age: 58 years) were selected from patients who were treated with dental implants for replacement of missing teeth at the Department of Periodontology, Gangnam Severance Dental Hospital between Januay 2007 and December 2010. Seventy-two internal-hexed implants (AstraTech OsseospeedTM, Astra Techs Dental Implant System; Astra Tech AB, Mölndal, Sweden) were used.Fractal dimension was measured by comparing radiographs taken immediately after prosthesis delivery to those taken one year after functional loading. Regions of interest were cropped, and a fractal analysis was performed using the box-counting method of ImageJ 1.42 software. Wilcoxon’s signed-rank test was used to analyze the differences in before and after delivery.The mean fractal dimension before loading (1.4213 ± 0.0525) increased significantly to 1.4329 ± 0.0479 at 12 months after loading (p < 0.05). Our results demonstrated that more increased fractal dimensions after loading, which could suggest an increased amount of bony microstructure around the implant. It may be concluded that there is an adaptive remodeling response of the surrounding bone to functional loading. Fractal dimension analysis might be helpful to detection of changes of peri-implant alveolar trabecular bone pattern in clinical situation.