A review of 52 human studies says e-cigarettes (vaping) and other tobacco harm reduction methods hurt adult oral health less than combustible cigarettes, but people who quit nicotine altogether had better oral health. German researchers went through cross-sectional and longitudinal papers published up to August 2024, dividing 199 separate findings into four broad categories of pre-cancerous changes, inflammation, everyday clinical signs such as plaque and bone loss, and shifts in the mouth’s microbiome. They focused on modern nicotine products including e-cigarettes, heated tobacco sticks, and nicotine pouches.They compared users with cigarette smokers and with people who used no nicotine at all.Across all measures, vapers scored an average of 0.37 on a scale where positive numbers mean worse outcomes than non-users and negative numbers mean better outcomes. In a comparison between cigarette smokers and vapers, cigarette smokers exhibited a score of -0.19, indicating that vaping generally resulted in fewer adverse effects compared to smoking cigarettes. Individuals who engaged in vaping exhibited significantly reduced negative effects in the oral cavity compared to those using combustible cigarettes. However, their levels of negative effects remained elevated when compared to non-users..Inflammatory markers told a similar result. In 76 comparisons between vapers and non-users, swelling and bleeding gums were more common in the vaping group. However, when the same indicators were stacked against smokers 69 times, vaping looked healthier. Everyday dental check-up items showed the clearest result. Bleeding on probing, plaque index, and probing depth all worsened in people who vaped versus never users. In a six month study, probing depth and bone loss deteriorated in the smoking group while remaining stable in the vaping group. Even the invisible ecosystem of bacteria was affected. Shifts in oral microbiome scored higher than 0.5, signalling frequent and significant changes among vapers compared with both smokers and non-users. .Scientists worry that upsetting that balance may set the stage for infection, gum disease, and even cancer down the road.The review’s authors stress that their meta-study is qualitative, not a traditional number-crunching meta-analysis. The 52 papers varied wildly in size, with anywhere from 30 participants to one million, and in design, duration, and test methods. That “mixing of apples and oranges” forced the researchers to treat the pooled scores as probabilities, not hard risk estimates. A bigger worry is “dual use.” Nearly 30% of American adults who vape also smoke cigarettes, yet many studies relied on self reporting or short term carbon monoxide breath tests to screen out smokers. The authors say some smokers could have slipped through and inflated the apparent harm of vaping. Time is another limitation. .E-cigarettes were first introduced to retail stores in 2007, followed by the introduction of heated tobacco devices and nicotine pouches in later years. That means no study in the review could track users for the two decades or more usually needed to see oral cancers emerge. Long term data may be scarce, but short and medium term signals are piling up. In one clinic, plaque, calculus, and gum disease still improved fastest in patients who had never used nicotine, while vapers landed in the middle, and smokers trailed behind both. Another six month cohort study showed each group’s mouth bacteria settled into its own stable pattern and was healthiest in non-users, most disrupted in smokers, and somewhere between for vapers.Propylene glycol and vegetable glycerin, the thick liquids that carry nicotine and flavours, soak up water and may dry the mouth, encouraging plaque build-up in vapers.The review underscores that prolonged and low level exposure to various irritants, including formaldehyde, acetaldehyde, and trace metals, may lead to chronic tissue inflammation over time. Nicotine itself constricts blood vessels, which can mask bleeding gums and delay healing even at the lower doses delivered by vaping and nicotine pouches. .Health Canada (HC) estimates that approximately five million Canadians continue to smoke. Federal data indicates that e-cigarette usage is experiencing the most rapid growth among young adults. HC promotes vaping as a quit smoking aid but warns non smokers not to start.This study will not settle the policy fight, but switching to e-cigarettes may lower some oral risks, yet leaving nicotine behind is safest. As lead author Gerhard Scherer said, “There is a need for further research into the long-term effects of these products … as well as the underlying biological mechanisms.” Researchers call for longer studies that track exclusive users of each product, verify nicotine exposure with biomarkers, and control for brushing habits, diet, and alcohol.
