Changes in the fractal dimension on peri-implant bone after surgical treatment of peri-implantitis: a retrospective study

Abstract

The aim of this study was to evaluate bony changes could be caused by surgical therapy for treatment of peri-implantitis around dental implants by fractal dimension analysis. Twenty subjects (12 males and 8 females; age range: 49 to 85 years; mean age: 63.2 years, 35 Implants) were selected from patients who were diagnosed with peri-implantitis at the Department of Periodontology, Gangnam Severance Dental Hospital between August 2007 and October 2012. Five different surface characteristics of implants were included in this study.Depending on clinical and radiographic outcomes of surgical treatment, subjects were assigned to two groups, treatment success and failure group. Fractal dimension was measured by comparing radiographs taken before and 3 months after the surgical treatment. The ROIs were set to a width of 100 pixels and a height of 200 pixels at the mesial and distal aspect of implant, and a fractal analysis was performed using the box-counting method of Image J 1.42 software. ROIs were created in same position. Wilcoxon signed-rank was used to analyze the differences in before and after surgery.There was a statistically significant difference in fractal dimensional changes after 3 months on both groups. In treatment success group, the median fractal dimension was 1.4878 before surgery and it increased to 1.5182 after 3 months surgery (p=0.001). This result could suggest increased mineralization of peri-implant bone structure around the implant as a result of bone remodeling. In treatment failure group, the median fractal dimension was 1.4675 before surgery and it decreased to 1.4334 after 3 months surgery (P=0.001).There was a correlation between increased peri-implant bone volume and density changes and successive outcome of surgical treatment for treating peri-implantitis as result of bone remodeling. As fractal dimension analysis could detect small trabecular mineralization changes, it could be used for early detection of trabecular bone changes in clinical situation.