Purpose: To evaluate the efficacy of adjunctive aids to scaling and root planing (SRP) on clinical outcomes in treating periodontal patients included in regular periodontal maintenance programs. Materials and Methods: The electronic databases MEDLINE (Pubmed), EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched for relevant articles published up to 1st January, 2020. Randomised controlled clinical trials of SRP with or without the use of adjuncts and published in English were included. A meta-analysis using the random-effects model was performed on the selected qualifying articles. Results: Nineteen studies were included in the systematic review and sixteen in the meta-analysis. The overall effect of adjunctive aids was statistically significant for reduction in probing depth (PD) (0.376 mm, 95% CI [0.144 to 0.609]) and clinical attachment level (CAL) gain (0.207 mm, 95% CI [0.0728 to 0.340]). No statistically significant differences were observed for changes in bleeding on probing (BOP) (p > 0.05). Among the different adjuncts, statistically significant positive effects were demonstrated for adjunctive photodynamic therapy (PD reduction 0.908 mm, 95% CI [0.227 to 1.589] and CAL change (0.457 mm, 95% CI [0.133 to 0.782]) and tetracycline fibers (PD reduction 0.534 mm, 95% CI [0.290 to 0.778] and CAL gain 0.280 mm, 95% CI [0.0391 to 0.521]). Conclusions: Despite high heterogeneity of the investigated data, based on the findings of a current systematic review, adjunctive aids (in particular, photodynamic therapy and tetracycline fibers) combined with SRP provide statistically significant clinical benefits compared to SRP alone. Due to the large number of included studies with high risk of bias, future studies should be based on adequate methodological procedures to improve the overall quality of reporting and to reduce the risk of bias. Keywords: periodontal maintenance, periodontitis, residual pockets, supportive periodontal treatment