Biological and clinical impact of chlorhexidine on peri-implant tissues and early peri-implant healing: A combined in vitro and clinical evaluation

Objective: To evaluate the short-term biological and clinical effects of 0.12% chlorhexidine (CHX) on peri-implant tissues using a combined in-vitro and randomised clinical approach. Methods: An in-vitro study assessed the effects of 0.01%, 0.05%, and 0.12% CHX on cell viability and extracellular matrix (ECM) protein expression via MTT assay, immunofluorescence, and ELISA. In parallel, a clinical study randomised 40 patients receiving dental implants to either a 0.12% CHX mouthrinse group (twice daily, starting 24h post-op) or a control group (standard hygiene). Plaque index, bleeding on probing (BOP), and marginal bone levels were assessed at baseline, 1, and 3 months. Data were analysed using linear mixed-effects models. Results: In vitro, 0.01% CHX showed minimal effects, while 0.05% and 0.12% caused significant, concentration-dependent cytotoxicity and suppressed collagen I and fibronectin expression (all p<0.001). Clinically, the CHX group had significantly lower plaque scores at 1 month (mean difference −0.8; p=0.001) and 3 months (−0.7; p=0.002), and reduced BOP at 3 months (−17.7%; p=0.003). Marginal bone loss did not differ between groups (−0.05 mm; p=0.46). No serious adverse events occurred. Conclusion: Short-term postoperative 0.12% CHX use improved peri-implant plaque control and soft-tissue inflammation without short-term adverse bone effects, despite in-vitro cytotoxicity at higher concentrations. Larger, long-term trials are needed to confirm safety and efficacy.