Peri-Implantitis and Soft Tissue Dehiscence in a Turkish Population: Risk Indicators, Diagnostic Parameters and Biomarkers Discovery

Aim: To assess (i) the risk indicators of peri-implantitis and peri-implant soft-tissue dehiscence (PISTD), and (ii) the accuracy of clinical parameters and peri-implant crevicular fluid (PICF) immunological markers in diagnosing peri-implantitis, within a Turkish university population. Methods: A total of 324 implants in 112 patients were included. The outcomes for the risk indicators analysis were the presence of peri-implantitis and PISTD, with peri-implantitis also serving as the reference standard for the diagnostic accuracy analysis. Several potential risk indicators—including demographic, medical, and dental history, clinical and radiographic parameters, and dental chart data—were assessed using multilevel logistic regressions. The diagnostic performance of clinical parameters and PICF immunological markers was evaluated using logistic regressions and reporting sensitivity, specificity, positive/negative predictive values, and area under the curve (AUC) values. Results: In the final multilevel logistic regression, the following indicators were associated with peri-implantitis: stage III-IV periodontitis (OR = 5.67), irregular maintenance (SPIC) compliance (OR = 7.71), history of implant loss (OR = 14.44), implant system, absence of keratinized mucosa (KM) (OR = 8.41), and clinical attachment loss in adjacent teeth (OR = 3.75). Risk indicators for PISTD included: mandibular location (OR = 0.22), implant system, absence of KM (OR = 5.95), and mucosal thickness < 2 mm (OR = 197.01). Peri-implant bleeding on probing (BoP) at 2 or more sites had the highest sensitivity for peri-implantitis (98.0%), while the highest specificity was observed for BoP severity (modified Bleeding Index 2–3 = 96.4%). The highest AUC was found for peri-implant probing pocket depth (PPD) ≥ 6 mm (0.88). Among PICF immunological markers, IL-2 and IL-10 exhibited the highest sensitivity (100.0%), while TNF-α had the highest specificity (92.9%). IL-8 and TNF-α had the highest AUC values (0.80). Conclusion: In this Turkish university cohort, several risk indicators were identified for peri-implantitis and PISTD. Among clinical parameters, only PPD ≥ 6 mm demonstrated strong diagnostic accuracy for peri-implantitis. Several PICF immunological markers, particularly IL-8 and TNF-α, showed promising diagnostic potential.