Comparative Assessment of Primary Stability, Secondary Stability, and Marginal Bone Loss in Immediate Post-Extraction Implants: A Retrospective Study of Three Implant Macro-Geometries

Background: Achieving predictable primary and secondary stability while preserving crestal bone in immediate post-extraction sockets remains technically demanding. This retrospective study compared stability progression, marginal bone loss (MBL), and early complication rates across three implant systems with distinct macro-geometries placed in fresh extraction sockets. Methods: Records of 120 immediate post-extraction implants allocated to Group A (C-Tech; n = 40), Group B (Straumann BLT; n = 40), and Group C (BTK IS+; n = 40) were reviewed. Primary stability was evaluated at implant placement (ISQ T0, Day 0), secondary stability was assessed at impression taking at 12 weeks/3 months (ISQ T1), and final stability prior to prosthetic loading was recorded at 16 weeks/4 months (ISQ T2). MBL was measured radiographically 1 year post-loading. Comparative assessments of ISQ at T1/T2 and MBL were conducted exclusively on surviving implants. Results: Overall 1-year survival rates were 100% (40/40) for Group A, 97.5% (39/40) for Group B, and 87.5% (35/40) for Group C. Group A demonstrated significantly higher ISQ values across all intervals (T0: 69.8 ± 10.6, T1: 81.5 ± 5.6, T2: 84.1 ± 4.6) relative to Group B (T0: 49.3 ± 8.6, T1: 71.3 ± 4.3, T2: 72.0 ± 4.1) and Group C (T0: 44.8 ± 8.3, T1: 64.1 ± 3.1, T2: 64.1 ± 3.1; p < 0.001). At 1 year post-loading, mean MBL was significantly lower in Group A (0.22 ± 0.38 mm) and Group B (0.29 ± 0.44 mm) compared to Group C (0.97 ± 1.25 mm; p < 0.001). Conclusions: Significant differences in initial stability, secondary stability trajectories, and 1-year marginal bone levels were observed among the implant systems evaluated in immediate post-extraction sites. Implants featuring double-lead or tapered configurations were associated with higher initial ISQ readings and enhanced crestal bone preservation.