A series of new studies investigates how e-cigarettes alter oral health and may be contributing to gum disease. The latest, published in mBio, finds that e-cigarette users have a distinctive oral microbiome that is less healthy than nonsmokers but potentially healthier than cigarette smokers, and measures worsening gum disease over time.
“To our knowledge, this is the first longitudinal study of oral health and e-cigarette use. We are now beginning to understand how e-cigarettes and the chemicals they contain are changing the oral microbiome and disrupting the balance of bacteria,” said co-lead researcher Prof Deepak Saxena.
While cigarette smoking is known to increase gum disease risk, much less is known about the impact of e-cigarette use on oral health, especially in the long term.
The researchers studied the oral health of 84 adults from three groups: cigarette smokers, e-cigarette users, and people who have never smoked. Gum disease was assessed through two dental exams six months apart, during which plaque samples were taken to analyse the bacteria present.
Gum health changes
All participants had some gum disease at the start of the study, with cigarette smokers having the most severe disease, followed by e-cigarette users. After six months, the researchers observed that gum disease had worsened in some participants in each group, including several e-cigarette users.
Clinical attachment loss is a key indicator of gum disease, measured by gum ligament and tissue separating from a tooth’s surface, leading the gum to recede and form pockets. These pockets are bacterial breeding grounds and can lead to worsening gum disease. In a study of the same participants published in Frontiers in Oral Health, the research team found that clinical attachment loss was significantly worse only in the e-cigarette smokers after six months.
A unique microbiome
Analysis of the bacteria in plaque samples showed that e-cigarette users had a different oral microbiome than smokers and nonsmokers, in line with their earlier results.
While all groups shared roughly a fifth of the types of bacteria, the bacterial makeup for e-cigarette users had strikingly more in common with cigarette smokers than nonsmokers. Several types of bacteria, including Selenomonas, Leptotrichia, and Saccharibacteria, were abundant in both smokers and vapers compared to nonsmokers. Several other bacteria – including Fusobacterium and Bacteroidales, linked to gum disease – were particularly dominant in the mouths of e-cigarette users.
When plaque samples were gathered and analysed in the six-month follow-up, the researchers found greater diversity in bacteria for all groups studied, yet each group maintained its own distinct microbiome.
“Vaping appears to be driving unique patterns in bacteria and influencing the growth of some bacteria in a manner akin to cigarette smoking, but with its own profile and risks to oral health,” said Fangxi Xu, study co-first author.
An altered immune response
The researchers found that the distinct microbiome in e-cigarette users was correlated with clinical measures of gum disease and changes to the host immune environment. In particular, vaping was associated with different levels of cytokines. Certain cytokines are linked to an imbalance in oral bacteria and can worsen gum disease by making people prone to inflammation and infection.
TNFα, a cytokine that causes inflammation, was significantly elevated among e-cigarette users. In contrast, cytokines IL-4 and IL-1β were lower among e-cigarette users; because IL-4 tends to be reduced in people with gum disease and increases after treatment, it suggests that certain bacteria in the mouths of e-cigarette users are worsening inflammation.
The researchers concluded that the distinct oral microbiome of e-cigarette users elicits altered immune responses, which along with clinical markers for gum disease illustrate how vaping presents its own challenge to oral health.
“E-cigarette use is a relatively new human habit,” said Scott Thomas, study co-first author. “Unlike smoking, which has been studied extensively for decades, we know little about the health consequences of e-cigarette use and are just starting to understand how the unique microbiome promoted by vaping impacts oral health and disease.”
Source: New York University
