E-cigarettes and periodontal health: current evidence and research gaps.

Cigarette smoking is a well-established risk factor for periodontitis, contributing to increased clinical attachment loss (CAL), alveolar bone loss, and impaired treatment response. As electronic cigarettes (ECs) are increasingly used as alternatives to combustible tobacco, questions remain regarding their adverse effects on oral and periodontal health. This critical review integrated evidence from experimental, cross-sectional, longitudinal and interventional studies to evaluate the relationship between EC use and periodontal health. Experimental and molecular studies supported biological plausibility for periodontal harm, indicating that aerosols can induce oxidative stress, upregulate pro-inflammatory mediators, and disrupt host-microbial interactions. Cross-sectional studies generally reported poorer periodontal conditions among EC users compared with never-smokers, including higher plaque index and periodontal probing depth, although results for CAL and alveolar bone loss were inconsistent. Comparisons between EC users and cigarette smokers often showed more favorable clinical parameters among EC users. Longitudinal evidence continued to be limited. The only prospective cohort study reported higher CAL among EC users than never-smokers and observed an increase in CAL over time exclusively in EC users. Interventional studies assessing response to periodontal therapy have yielded inconsistent results, with some suggesting a poorer treatment response among EC users and others finding no significant differences. Overall, there were Well-designed longitudinal studies with clearly defined exposure groups, standardized periodontal outcomes, and longer follow-up are needed to clarify whether EC use independently contributes to periodontal deterioration.