The impact of smoking on periodontitis patients’ GCF/serum cytokine profile both before and after periodontal therapy: a meta-analysis

Background Smoking is an established modifying factor for the host immune response of periodontitis patients. However, its exact influence remains unclear. We aimed to compare the cytokine profile of periodontitis patients with and without smoking habits both before and after periodontal therapy to preliminarily explore its influence on the host immune response to periodontitis. Methods The protocol of the present meta-analysis was registered in the International Prospective Register of Systematic Reviews (PROSPERO) under the code CRD42021255656. Meta-analysis was performed for each cytokine if at least three studies were included. We synthesized the evidence to compare the cytokine profile of periodontitis with and without smoking both in gingival cervical fluid (GCF) and serum to explore the impact of smoking on periodontitis both locally and systemically. Moreover, we also compared the cytokine profile of the two groups of patients after periodontal therapy to explore the effect of smoking on the outcome of periodontal therapy. Results Fifteen studies were included in this meta-analysis. We found that there was no significant difference between the two groups of patients in the baseline cytokine profile. However, after periodontal therapy, smoking periodontitis patients showed significantly higher IL-1β levels in their GCF than nonsmoking patients. Discussion There was no significant difference between smoking and nonsmoking periodontitis patients in the baseline cytokine profile. However, after periodontal therapy, smoking periodontitis patients showed significantly higher IL-1β levels in their GCF than nonsmoking patients, which indicates that smoking may impair the response of periodontitis to periodontal treatment.