Failure of Wide‐Diameter Dental Implants (Predominantly 5.0 mm) Show Distinct Risk Profiles—A Large Cohort Study

AIM: To evaluate survival rates and identify temporally distinct risk factors for early and late failure of wide-diameter dental implants (≥ 5.0 mm) in a large real-world cohort using landmark analysis. MATERIALS AND METHODS: This retrospective cohort study analyzed 12 041 wide-diameter implants (≥ 5.0 mm), predominantly 5.0 mm, placed in 9247 patients at a single center between January 2014 and December 2023. Implant survival was defined as the fixture remaining in situ without clinical loss or replacement at the same site. Failures were classified as early (≤ 1 year) or late (> 1 year). Kaplan-Meier survival curves and a multivariable Cox proportional hazards model clustered by patient were generated. Schoenfeld residuals revealed time-varying effects for penicillin allergy, implant length, and kidney disease, prompting a landmark analysis at 365 days with separate multivariable logistic regression models for early and late failure. RESULTS: Overall implant survival was 97.5%. Kaplan-Meier estimates were 98.1% (95% CI: 97.9%-98.4%) at 1 year, 97.8% (95% CI: 97.5%-98.0%) at 3 years, and 97.6% (95% CI: 97.4%-97.9%) at 5 years. Of 301 failures, 225 (74.8%) were early and 76 (25.2%) were late. In the Cox model, short implants (≤ 8 mm; HR = 1.94, 95% CI: 1.43-2.62, p < 0.001), maxillary placement (HR = 2.13 vs. mandible, p < 0.001), male sex (HR = 1.39, p = 0.010), penicillin allergy (HR = 1.66, p = 0.014), and older age (HR = 0.84 per SD, p = 0.008) independently predicted failure; smoking was borderline (HR = 1.33, p = 0.065). Landmark analysis showed that early failure was driven by penicillin allergy (OR = 2.26, p < 0.001), maxillary placement (OR = 2.42, p < 0.001), male sex (OR = 1.40, p = 0.016), and short length (OR = 1.70, p = 0.007), whereas late failure was driven by short length (OR = 3.19, p < 0.001) and kidney disease (OR = 6.11, p = 0.003). CONCLUSIONS: Wide-diameter implants achieve excellent long-term survival. Early and late failures arise from distinct mechanisms: perioperative, anatomical, and sex-related factors predominate early, while short implant length and renal disease predominate late. These findings support tailored perioperative protocols, individualized risk stratification, and targeted long-term surveillance.