Clinical efficacy of single and multiple applications of antimicrobial photodynamic therapy in periodontal maintenance: A systematic review and network meta-analysis

•Antimicrobial photodynamic therapy is a valuable adjunctive in periodontal maintenance•Single and multiple adjunctive applications of antimicrobial photodynamic therapy result in significant bleeding on probing reduction•Repeated applications of adjunctive antimicrobial photodynamic therapy do not result in superior outcomes compared to single applications At present the clinical efficacy of single (S) versus multiple (M) applications of antimicrobial photodynamic therapy (aPDT) is controversially discussed. To systematically evaluate the clinical efficacy of adjunctive S and M applications of aPDT to subgingival debridement (SD) in the treatment of residual periodontal pockets. An electronic search was carried out for randomized controlled clinical trials (RCTs) reporting on SD with the adjunctive use of S- or M-aPDT applications. Statistically significantly higher improvement in bleeding on probing (BOP) and probing depth (PD) reduction was found for SD + S-aPDT versus SD, with Mean difference (MD) = -16.8 (95% CI: -30.7 to -2.91; p = 0.02) and 0.4, (95% CI: 0.02 to 0.78, p = 0.04), respectively. Regarding BOP, there was also a statistically significant difference when SD + M-aPDT was compared with SD alone, with a MD of -5.13 (95% CI: −7.20 to -3.07; p < 0.00001). For all parameters, SD + S-aPDT demonstrated the best treatment ranking of probability results, followed by SD + M-aPDT and SD alone. Within their limits, the present data indicate that in periodontal patients enrolled in maintenance: a) single and multiple adjunctive applications of aPDT following SD resulted in statistically significant BOP reduction compared to SD alone, and b) repeated applications of aPDT did not seem to result in superior outcomes compared to single applications.