Evaluation of periodontal indices among non-smokers, tobacco, and e-cigarette smokers: a systematic review and network meta-analysis

OBJECTIVES: The detrimental effect of tobacco smoking on periodontal health is well known, while the effect of electronic cigarette on periodontal parameters has been less investigated. The aim of the present systematic review was to compare periodontal indices in three categories of patients: traditional cigarette smokers (TS), e-cigarette smokers (ES), and non-smokers (NS). MATERIALS AND METHODS: An electronic search was conducted for studies published until December 2021 on MEDLINE (PubMed), ISI Web of Science, and Scopus. A hand search was additionally conducted. Clinical observational and cross-sectional trials investigating periodontal indices among tobacco smokers (TS), electronic cigarette smokers (ES) and non-smokers (NS) were included and selected by 2 independent reviewers. Data on probing depth (PD), plaque index (PI), and bleeding on probing (BOP) were collected. The risk of bias was evaluated according to the NIH quality assessment tool and a network meta-analysis (NMA) was undertaken. RESULTS: Five relevant studies, from 707 identified, were included. Overall, 512 patients were included, of them 170 were NS, 176 were TS, and 166 were ES. A significant difference in the comparison among TS vs NS: effect size (ES) = 3.297 (95%CI: [2.142–4.454], p = 0.001) and TS and ES ES = 2.507 (95%CI: [1.351–3.663], p = 0.001) was identified for PD. A significant difference in the comparison among TS and NS, ES = 21.34 (95%CI: [13.41–29.27], p = 0.001) and between TS and ES ES = 15.67 (95%CI: [7.73–23.62], p = 0.001) was identified for PI. The analysis of BOP values shows a significant difference in the comparison among ES and NS: ES = − 16.22 (95%CI: [− 22.85 to − 9.59], p < 0.001) and between TS and NS: ES = − 14.47 (95%CI: [− 21.103 to − 7.848], p < 0.001). Based on the SUCRA ranking, NS showed the most favorable outcome for PD and PI, followed by ES. Tobacco smokers were clearly in the last position. Dealing with BoP ES showed the most favorable outcome, followed by TS. NS were in the last position. CONCLUSIONS: Periodontal parameters were similar among NS and ES, while TS presented the worst indices. BoP was reduced both in ES and in TS. CLINICAL RELEVANCE: Results of the present review suggest a reduced effect on periodontal tissue of e-cig smoking compared to traditional cigarettes, despite recent studies proved that e-cig smoking increases oxidative stress, inflammatory responses, change in pulmonary cellular behavior, and stimulates DNA injury.