How do periodontal indices compare among non-smokers, tobacco and e-cigarette smokers?

Design Systematic review and network meta-analysis.Data sources Medline (PubMed), ISI Web of Science and Scopus. Additionally, the following journals were hand-searched between 2000 and December 2021: Journal of Periodontology, Journal of Clinical Periodontology, Clinical Oral Investigations, International Journal of Periodontics and Restorative Dentistry. Citations of included articles and relevant systematic reviews were also screened.Study selection Cross-sectional and observational studies were included which compared periodontal indices in non-smokers, tobacco and e-cigarette smokers. A minimum sample of 25 patients in each group was required, as was reporting of bleeding on probing (BOP), plaque indices (PI) and probing depth (PD) outcomes.Data extraction and synthesis Two independent authors examined titles, abstracts and full texts of relevant articles against the inclusion criteria, with any disagreements resolved by discussion, or a third reviewer. Data was collected using an Excel spreadsheet and risk of bias assessed via the NIH quality assessment tool for observational cohort and cross-sectional studies. Results were pooled and checked for suitability before network meta-analysis for each separate outcome.Results In total, 279 studies were screened from electronic and hand searching with 28 full text articles assessed for eligibility. Twenty-three were excluded at full text, with five included for quantitative synthesis and review. The included studies incorporated a total of 512 patients encompassing 170 non-smokers, 176 tobacco smokers (mean duration 10.7 years) and 166 e-cigarette smokers (mean duration 3.7 years). All studies were based in Saudi Arabia only and 99% of patients were male with mean ages 37.8 (non-smokers), 39.5 (tobacco) and 33.5 (e-cigarette). No studies adjusted for key confounding variables, which limited risk of bias to fair or good in all cases. Meta-analysis suggested PD and PI were significantly worse in tobacco smokers compared to both non-smokers and e-cigarette smokers. BOP was significantly reduced in both smoking groups versus non-smokers.Conclusions Notwithstanding the limitations of this review, there is some evidence that supports accepted understanding that tobacco smoking can compromise periodontal health. E-cigarette smoking in this cohort showed no significant difference to non-smokers in terms of probing depth or plaque index and may be a safer source of nicotine for patients in terms of periodontal health. Greater understanding may be drawn from analysis of randomised controlled trials in wider populations that account for important confounding variables.