The impact of smoking on non-surgical periodontal therapy: A systematic review and meta-analysis

Aim: Smoking is a risk factor for periodontitis. This study aimed to evaluate the impact of smoking on clinical outcomes of non-surgical periodontal therapy. Materials and Methods: Electronic databases were searched to screen studies published before May 2020. The included studies had to have two groups: smokers (S) and non-smokers (NS) with periodontitis. The outcomes evaluated were differences between groups in probing depth (PD) reduction and clinical attachment level (CAL) gain after non-surgical periodontal therapy. Meta-regressions were conducted to evaluate correlations between outcomes and other contributing factors. Results: Seventeen studies were included. The post-treatment PD reduction in the S group was smaller than in the NS group (weighted mean difference in PD reduction: −0.33 mm, 95% confidence interval (CI): [−0.49, −0.17], p <.01). The CAL gain in the S group was also smaller than in the NS group (weighted mean difference in CAL gain: −0.20 mm, CI: [−0.39, −0.02], p <.01). Additionally, baseline PD significantly affected the difference in PD reduction between two groups. Conclusions: Smoking negatively impacts clinical responses to non-surgical periodontal therapy. Smokers with periodontitis have significantly less PD reduction and CAL gain than non-smokers.