Wide-diameter implants: failure risk shifts with time after placement

Clinical question: do wide-diameter implants (≥5.0 mm) fail for the same reasons regardless of when failure occurs, or do early and late failures follow different mechanisms?

Methodology: this retrospective cohort study analyzed 12,041 wide-diameter implants placed in 9,247 patients at a single center between 2014 and 2023. Implant survival was tracked with Kaplan-Meier curves and a multivariable Cox proportional hazards model clustered by patient. Because Schoenfeld residuals showed that penicillin allergy, implant length, and kidney disease had time-varying effects, the authors ran a landmark analysis at 365 days, fitting separate logistic regression models for early (≤1 year) and late (>1 year) failure.

Main findings: overall implant survival was 97.5%, with Kaplan-Meier estimates of 98.1% at 1 year, 97.8% at 3 years, and 97.6% at 5 years. Of 301 total failures, three-quarters (74.8%) occurred early. In the overall Cox model, short implants (≤8 mm, HR 1.94), maxillary placement (HR 2.13), male sex (HR 1.39), and self-reported penicillin allergy (HR 1.66) independently predicted failure, while older age was protective. The landmark analysis sharpened the picture: early failure was driven by penicillin allergy (OR 2.26), maxillary placement (OR 2.42), male sex (OR 1.40), and short length (OR 1.70) — largely perioperative and anatomical factors. Late failure, instead, was dominated by short implant length (OR 3.19) and kidney disease (OR 6.11) — systemic and mechanical factors that act over time.

Clinical relevance: wide-diameter implants perform very well overall, but the study's real contribution is showing that "implant failure" is not one phenomenon. Perioperative protocols — antibiotic choice, surgical technique in the maxilla — matter most for the first year, while length selection and screening for renal disease matter for long-term surveillance. This supports individualized risk stratification rather than a single follow-up protocol for every patient, and flags penicillin-allergic patients and those with reduced renal function as groups warranting closer monitoring at different phases of care.