Prevalence and Risk Indicators of Peri-Implant Diseases and Buccal Soft-Tissue Dehiscence: A Cross-Sectional Study From a University-Based Cohort

Aim: To assess the prevalence of peri-implant diseases and buccal peri-implant soft-tissue dehiscence (PISTD) and to identify the associated risk indicators. Methods: Patients previously rehabilitated with implant-supported rehabilitations at the University of Turin Dental School were specifically recalled with a registry-based approach for this cross-sectional study. Data collection included medical and dental history, full-mouth clinical examination, and periapical radiographs. Moderate/severe peri-implantitis was diagnosed based on bone loss (direct criterion, when available) or bone level (indirect criterion) ≥ 2 mm and the presence of bleeding/suppuration. PISTD was defined as mucosal dehiscence on the buccal aspect of at least one implant site. Multilevel, multivariable logistic regression models were applied to identify factors associated with moderate/severe peri-implantitis and buccal PISTD. Results: Of the 397 patients contacted, 146 were included (mean age 61.1 ± 14.5 years; current smokers 34.3%; stage III-IV periodontitis 65.1%) with a total of 511 dental implants (mean function time: 13.3 years [2–31]). Implant survival rate was 96.5%. Moderate/severe peri-implantitis was detected in 56.8% of patients and 34.7% of implants. Prevalence of buccal PISTD was 54.1% and 40.5%, respectively. Protective indicators for moderate/severe peri-implantitis included supportive peri-implant care > twice a year (OR = 0.16; 95% CI: 0.03–0.95), > 2 mm of keratinized tissue height (OR = 0.44; 95% CI: 0.21–0.95), and correct mesio-distal implant positioning (OR = 0.54; 95% CI: 0.32–0.94). Risk indicators included stage III–IV periodontitis (OR = 2.82; 95% CI: 1.30–6.15), function time ≥ 10 years (OR = 3.02; 95% CI: 1.55–5.89), bisphosphonate use during follow-up (OR = 5.96; 95% CI: 1.33–26.66), and presence of a cantilever (OR = 5.51; 95% CI: 1.56–19.38). For PISTD, protective indicators were mandibular location (OR = 0.45; 95% CI: 0.25–0.81), thick buccal soft-tissue phenotype (OR = 0.18; 95% CI: 0.08–0.42), and > 2 mm of keratinized tissue height (OR = 0.05; 95% CI: 0.02–0.15). Risk indicators included peri-implantitis (OR = 2.21; 95% CI: 1.25–3.91), use of intermediate abutments (OR = 4.92; 95% CI: 1.92–12.58), and proximity to adjacent implants (OR = 3.35; 95% CI: 1.50–7.48) or edentulous spaces (OR = 3.38; 95% CI: 1.51–7.54). Conclusion: In this long-term, university-based cohort, peri-implant diseases and PISTD were highly prevalent. Multiple patient- and implant-level factors emerged as significant risk or protective indicators. Despite the widespread occurrence of peri-implant diseases, long-term implant survival remained high, challenging current diagnostic thresholds and underscoring the need for refined, progression-based definitions.