Photodynamic Therapy as an Adjunct to Resective and Regenerative Surgical Treatment of Peri-Implantitis: A Prospective Cohort of 72 Patients Followed for 18 Months

Purpose: To evaluate the efficacy of photodynamic therapy (PDT) as an adjunct to resective and regenerative surgical peri-implantitis treatment (open flap debridement via scaling and smoothening of the implant surface [implantoplasty]) combined with guided bone regeneration (GBR) in a patient cohort of a university clinic. Materials and Methods: Seventy-two patients were treated with either conventional therapy (CON) or conventional therapy plus PDT. CON included mechanical debridement, implantoplasty, and GBR. Clinical parameters, including marginal bone level (MBL), probing pocket depth (PPD) and bleeding on probing (BOP) were assessed at baseline, 6, 12, and 18 months. The primary outcome was the resolution of the infection using a composite success criterion. Results: After 18 months, infection resolution rates were 75% for CON and 80% for PDT groups (p = 0.75). Kaplan-Meier survival analysis showed no statistically significant difference for the infection resolution between groups (log-rank test, p = 0.6221). Both groups demonstrated statistically significant MBL gain after 6 months (mean 2.59 mm +/- 1.25), with no statistically significant differences between groups throughout the follow-up. PPD was statistically significantly lower in the PDT group (two-way ANOVA, p = 0.018). BOP scores decreased initially but showed an increasing trend in both groups over time (chi-squared test, p = 0.045), with no statistically significant differences between groups. Conclusion: PDT as an adjunct to conventional peri-implantitis treatment with GBR resulted in statistically significantly lower PPD values. However, no additional benefits were observed for infection resolution, maintenance of infection-free status, MBL or BOP. Initial improvements in both groups followed by gradual recurrences in clinical parameters over 18 months.