Investigation of the effects of two- and three-implant supported overdenture prostheses on peri-implant bone and mandibular trabecular bone using fractal analysis and radiomorphometric methods on panoramic radiographs

Abstract

Background: To compare the average values of fractal and radiomorphometric analysis measurements in patients using overdenture prostheses supported by two or three implants. Methods: This retrospective study analyzed panoramic radiographs of 40 patients (aged 40–90 years) treated with overdentures supported by either two or three implants (n = 20 per group). Baseline and 1–2-year follow-up radiographs were evaluated. Fractal dimension was assessed in mesial, distal, and apical peri-implant regions and averaged at the patient level to avoid clustering of implant-level observations. Radiomorphometric indices, including mandibular cortical width (MCW), mandibular cortical index (MCI), panoramic mandibular index (PMI), antegonial index (AI), and gonial index (GI), were measured bilaterally. Multiple linear regression analyses were performed to determine independent predictors of fractal dimension changes (T1–T0). Results: Fractal analysis showed no significant intergroup differences in overall trabecular bone structure. A significant increase over time was observed only in distal fractal measurements in the two-implant group, with higher follow-up values compared with the three-implant group (p < 0.05). At follow-up (T1), mandibular cortical width (MCW) and antegonial index (AI) values were significantly higher in the three-implant group (p < 0.05), whereas no differences were detected for PMI or MCI. Regression analysis demonstrated that baseline fractal values were significant predictors of fractal dimension changes in all regions, whereas implant configuration was significantly associated only with distal fractal change. Conclusion: Fractal analysis showed no significant difference in overall trabecular bone adaptation between two- and three-implant–supported overdenture groups. Radiomorphometric findings suggest a potential association between implant configuration and cortical bone characteristics; however, these findings should be interpreted with caution. Regression analysis indicated that baseline fractal values were the strongest predictors of subsequent changes, while the effect of implant configuration was limited to the distal region. These findings should be interpreted cautiously and considered hypothesis-generating rather than confirmatory.