Does smoking reduce the response to periodontal therapy?

Yes, smoking consistently and significantly reduces the response to periodontal therapy across multiple study designs and treatment modalities.

In a 6-year longitudinal study, smokers showed significantly less probing depth reduction and less clinical attachment level (CAL) gain than non-smokers following both non-surgical and surgical therapy, and these differences persisted at every yearly maintenance visit, with effects most pronounced in pockets of 7 mm or deeper ^[1]. A 2021 systematic review and meta-analysis of 17 studies confirmed this finding, reporting that smokers achieved 0.33 mm less probing depth reduction and 0.20 mm less CAL gain than non-smokers after non-surgical periodontal therapy ^[2]. At the biological level, smokers showed significantly higher GCF IL-1β levels after periodontal therapy compared to non-smokers, suggesting that smoking impairs the host immune resolution response even after treatment ^[3].

Importantly, cessation appears to reverse much of this impairment. Quitters achieved up to 0.2 mm greater CAL gain and 0.32 mm greater pocket depth reduction compared to non-quitters after 12-24 months, and their risk of periodontitis progression became comparable to that of never-smokers ^[4]. Former smokers also showed no increased risk of tooth loss compared to never-smokers, whereas current smokers had 2.6 times the risk ^[5]. Adding systemic antibiotics as an adjunct to scaling and root planing in smokers produced modest but statistically significant additional PD reduction and CAL gain, though the clinical relevance of these gains was considered limited ^[6]. Collectively, the evidence strongly supports integrating smoking cessation counselling as a routine component of periodontal care ^[4].