At 25 years, peri-implantitis doubles — the lesson from the Bern cohort

Long-term data on dental implants beyond 10 years remain scarce, even though clinicians increasingly place implants in younger patients who will carry them for decades. This prospective cohort study from Bern followed partially edentulous patients rehabilitated with tissue-level implant-supported prostheses, re-examining them clinically and radiographically at 10 and 25 years to track implant survival, success, and the evolution of peri-implant mucositis (PM) and peri-implantitis (PI).

At the 25-year mark, 159 patients with 252 implants were assessed (down from 303 patients/511 implants at 10 years, reflecting expected attrition). Implant survival fell from 98.8% at 10 years to 94.0% at 25 years, and success rate from 97.0% to 90.8% — both still favorable outcomes over a quarter-century. Notably, implant failure attributable to loss of osseointegration nearly tripled between the two time points (0.6% to 3.6% at implant level), and occurred exclusively in premolar and molar sites, suggesting posterior implants deserve closer long-term surveillance.

Peri-implant mucositis, while still highly prevalent, actually declined over time (82.1% to 76.5% at implant level), possibly reflecting improved maintenance protocols as both patients and clinicians gained experience. Peri-implantitis, in contrast, more than doubled — from 3.5% to 9.1% at implant level and from 10.0% to 18.1% at patient level — confirming that peri-implantitis risk accumulates with time rather than plateauing.

Multivariate analysis identified two variables independently associated with peri-implant disease: a history of periodontitis (associated with over threefold higher odds of mucositis) and facial mucosal thickness, where thinner tissue was linked to both higher mucositis and higher peri-implantitis risk. These findings reinforce two well-established but still underapplied clinical principles: patients with a periodontitis history need more intensive, indefinite peri-implant maintenance, and soft-tissue thickness at placement is a modifiable risk factor worth addressing prophylactically rather than only after disease onset.

For clinicians counseling patients on implant longevity, this study offers rare, methodologically rigorous 25-year benchmarks: implant loss and peri-implantitis both continue to accrue well beyond the first decade, underscoring that osseointegration is not a permanent, "install-and-forget" outcome but a condition requiring lifelong monitoring — particularly in patients with a periodontal history or thin peri-implant soft tissue.