- Review of 12 human studies found mixed and inconsistent results on oral bacteria in people who use vapes
- Some differences in oral microbiota were observed, but no consistent pattern linked to disease
- Evidence was rated “very low”, meaning current research cannot establish a clear link between vaping and oral disease
- Researchers say more long-term studies are needed to understand any real health impact
A new systematic review has found no clear evidence that vaping causes oral disease, despite identifying some changes in the bacteria found in the mouth.
The study, published in the Journal of Clinical Periodontology, analysed 12 human studies comparing the oral microbiota of people who use vapes, smokers and people who have never smoked.
Researchers set out “to examine whether the oral microbiota of e-cigarette users differs from that of never smokers and current smokers.”
What the study looked at
The oral microbiota refers to the community of bacteria and other microorganisms that live in the mouth. This system plays an important role in maintaining oral health but can be influenced by factors such as diet, hygiene and tobacco use.
While the harmful effects of smoking on oral health are well established, the researchers said the impact of vaping is still unclear, noting that “the long-term consequences of e-cigarette aerosol exposure and therefore safety-especially within the oral cavity-remain incompletely understood.”
To investigate this, the team reviewed studies that analysed saliva, plaque and oral tissue samples using molecular techniques.
Mixed and inconsistent findings
Across the studies, results were far from consistent. Some measures of bacterial diversity showed no clear differences between people who vape, smoke or have never smoked, while others varied depending on the type of sample analysed.
The review found that “alpha diversity findings were inconsistent across samples” – meaning there was no reliable pattern in the overall range of bacteria present.
There were also differences in the types of bacteria found, but again these varied widely between studies.
“Taxonomic differences were heterogeneous and sample-dependent,” the authors reported, with some increases in certain bacteria compared with non-smokers, but no consistent trend.
A distinct but unclear profile
One of the more consistent findings was that people who use vapes tend to have a different mix of oral bacteria compared with both smokers and non-smokers.
The researchers found that vaping was linked to “distinct microbial communities”, suggesting a unique oral microbiome profile. However, this did not translate into clear evidence of harm.
In fact, the review suggests that the microbiota of people who vape may sit somewhere between smokers and non-smokers, sharing some features of both without matching either group.
No clear link to disease
Crucially, the study did not establish a causal link between vaping and oral disease.
While some bacteria associated with gum disease were found in certain studies, the findings were inconsistent and often depended on factors such as existing oral health conditions or smoking history.
The authors stressed that current evidence does not support firm conclusions, noting that “the certainty of evidence is very low due to predominantly cross-sectional designs and methodological limitations.”
They added that this “underscor[es] the need for longitudinal studies with standardised exposure and protocols.”
Why the evidence is limited
A key issue is that most of the studies analysed were cross-sectional, meaning they only provide a snapshot in time rather than tracking changes over the long term. This makes it difficult to determine cause and effect.
Other limitations included small sample sizes, differences in how vaping was measured, and the inclusion of participants who also smoked cigarettes.
The review also highlighted the role of other factors – such as diet, oral hygiene and existing health conditions – which can all influence the oral microbiome.
What it means for consumers
For consumers, the findings highlight how little is still known about the long-term effects of vaping on oral health. While changes in oral bacteria have been observed, there is no clear evidence that these lead to disease.
At the same time, the risks of smoking are well established, particularly in relation to gum disease, tooth loss and oral cancers.
The study adds to a growing body of research suggesting that while vaping may affect the oral environment, its impact appears to be less clearly defined – and likely less harmful – than smoking.
Call for better research
The authors say more robust research is needed to provide clearer answers.
Future studies should follow people over time, use consistent methods and better account for confounding factors such as smoking history and oral health status.
Until then, the review concludes that while vaping is associated with changes in the oral microbiota, the evidence is not strong enough to draw firm conclusions about its impact on oral health.
