Purpose: To evaluate the clinical efficacy of antimicrobial photodynamic therapy (aPDT) adjunctive to scaling and root planing (SRP) in the treatment of residual pockets for chronic periodontitis patients on supportive periodontal therapy (SPT). Method: Bibliographic databases of MEDLINE and Cochrane Library were thoroughly searched up to July 2016 for eligible randomized controlled trials (RCTs). Mean differences (MD) and the corresponding 95% confidence intervals (CI) were synthesized for probing depth (PD) reduction and clinical attachment level (CAL) gain. The I-2 test and Q statistics were employed to assess inter-study heterogeneity. Subgroup analysis was performed based on the enrollment of smokers. Result: Four RCTs fulfilling the eligibility criteria were included. Pooled estimates demonstrated statistically significant improvements in both PD reduction (MD=0.69, CI: 0.11-1.28, p = 0.02) and CAL gain (MD=0.60, CI: 0.11-1.10, p=0.02) for SRP + aPDT versus SRP alone. Meta-analysis of studies with smokers failed to produce a significant additional effect in PD (MD = 0.32, Cl: 0,30 to 0.94, p = 0.31) and CAL (MD=0.42, CI: 0.26 to 1.09, p=0.23) when SRP was associated with aPDT. However, significant enhancements in PD reduction (MD = 1.23, CI: 0.74-1.72,p<0.001) and CAL gain (MD = 0.96. CI: 0.31-1.62, p=0.004) were observed for studies excluding smokers. Conclusion: Pooled evidence indicates an additional clinical improvement in the maintenance of residual pockets in favor of SRP + aPDT compared with SRP alone. Subgroup analysis demonstrates an adverse impact of smoking on clinical effect of the combined therapy. Substantial heterogeneity and the paucity of included studies undermine the statistical power of this meta-analysis. Future well-designed and large-scale clinical trials evaluating the adjunctive efficacy of aPDT in periodontal maintenance phase are critically needed. (C) 2016 Elsevier B.V. All rights reserved.