Is smoking associated with altered peri-implant trabecular bone microarchitecture as assessed by fractal dimension and lacunarity analysis?

This study aimed to investigate smoking-related alterations in peri-implant trabecular bone microarchitecture in the posterior mandible using fractal analysis (FA) of panoramic radiographs. This retrospective cross-sectional study analyzed standardized panoramic radiographs of 108 adult male patients who received posterior mandibular implants (premolar and molar regions) between January 2015 and January 2025. Patients were categorized as smokers ( n = 56) and non-smokers ( n = 52). All implants belonged to a single implant system (Bilimplant ® ) to minimize biomechanical variability. Quantitative fractal dimension (FD) and lacunarity values were obtained using ImageJ software from three standardized peri-implant regions of interest (mesial, distal, and apical). Intra-observer reliability and intergroup comparisons were statistically evaluated. Intra-observer reliability was high for all FD and lacunarity measurements (Spearman r = 0.827–0.982; ICC = 0.916–0.993; all p < 0.05). Smokers exhibited significantly lower FD values and significantly higher lacunarity values than non-smokers across all peri-implant regions (mesial, distal, apical, and mean; all p < 0.05), indicating reduced trabecular complexity and increased structural heterogeneity in peri-implant bone. No significant differences were detected between premolar and molar implant sites within either smoking group. Smoking was associated with differences in peri-implant trabecular bone microarchitecture in the posterior mandible on panoramic radiographs, characterized by lower FD and higher lacunarity values. These represent radiographic associations; because of the retrospective, cross-sectional design, causality cannot be inferred, and the findings should not be interpreted as evidence of impaired osseointegration or future implant failure. Combined FD and lacunarity analysis may have potential as a non-invasive adjunct for characterizing peri-implant trabecular bone, but larger prospective studies incorporating clinical outcomes and three-dimensional imaging are required to confirm these findings and clarify any clinical relevance.