Long-Term Socket Healing After Mandibular Third-Molar Extraction: Fractal Analysis and Clinical Parameters Comparing H-Prf and L-Prf

Objectives: To compare horizontal platelet-rich fibrin (H-PRF) and leukocyte-rich PRF (L-PRF) with no-PRF on long-term socket bone structure and periodontal parameters 12–18 months after impacted mandibular third-molar extraction. Materials and Methods: This retrospective follow-up analyzed a previously randomized three-arm clinical cohort (n=45; 15 per group). Panoramic radiographs obtained 12–18 months post-extraction were assessed by fractal analysis at the extraction site. Periodontal probing depths at six sites around the adjacent second molar and buccal keratinized tissue width were recorded with a UNC-15 probe. Group differences were evaluated at α=0.05. Results: Mean fractal dimension (FD) differed among groups (H-PRF 1.32±0.05; L-PRF 1.28±0.04; Control 1.26±0.06; overall p=0.005). H-PRF showed higher FD than Control (mean difference 0.062; 95% CI 0.018–0.105; p=0.004), whereas H-PRF vs L-PRF was not significant (p=0.101) and L-PRF vs Control was not significant (p=0.396). Keratinized tissue width tended to be greater with H-PRF (1.70±1.10 mm) than Control (0.84±1.00 mm) without significance (p=0.093). Site-specific probing depths showed no between-group differences (lowest p=0.051). Intra-examiner reliability for measures was good-to-excellent (ICC=0.895; p<0.001). Conclusion: At 12–18 months, H-PRF yielded a higher socket FD than no-PRF, while differences versus L-PRF were not significant. Periodontal indices at the adjacent second molar were broadly comparable across groups.