Quantitative Assessment of Long-Term Changes in Peri-Implant Bone Structure in Patients Using Fixed and Removable Prostheses

The aim of this study was to evaluate structural changes in peri-implant trabecular bone in patients with fixed and removable implant-supported prostheses over an average five-year period using panoramic radiography. Two consecutive panoramic images, one taken before implant placement and the other an average of five years after prosthodontic loading, of a total of 60 mandibular implants with either fixed or removable prostheses were included in the study. Measurements included fractal dimension, bone area fraction, and mean gray value of three peri-implant regions (mesial, distal, apical) and three control regions (inferior to the mental foramen, angle, and condyle). The paired samples t-test was used for statistical analysis (p<0.05). In patients with fixed prostheses, significant reductions in bone area fraction and mean gray value were observed after loading. Conversely, patients using removable implant-supported prosthesis exhibited increased fractal dimension values. Control regions in both groups exhibited age-related declines in bone area fraction and mean gray value over the five-year period. Our results demonstrated that fractal dimension is a useful method for monitoring structural bone alterations around implants with removable prostheses during post-loading follow-up periods. In addition to functional forces, long-term peri-implant bone remodeling may also be influenced by aging.