A series of new studies by researchers at the New York University College of Dentistry highlights how e-cigarettes alter oral health and may be contributing to gum disease. The latest study has just been published in in mBio, a journal of the American Society for Microbiology.
It finds that e-cigarette users have a unique oral microbiome – the community of bacteria and other microorganisms – that is less healthy than non-smokers but potentially healthier than cigarette smokers and measures worsening gum disease over time, according to a news release published by New York University on 22 February 2022.
“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 Professor Deepak Saxena, who led the research with Professor Xin Li. Both are professors of molecular pathobiology at NYU College of Dentistry.
Gum disease affects nearly half of United States adults over 30 years of age. Smoking cigarettes is a known risk factor for developing gum disease, but less is known about the impact of e-cigarettes – which vaporize nicotine and other chemicals – on oral health, especially the long-term consequences of vaping.
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.
Changes to gum health
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.
A key indicator of gum disease is clinical attachment loss, measured by gum ligament and tissue separating from a tooth’s surface, leading the gum to recede and form pockets. These pockets are breeding grounds for bacteria and can lead to more severe gum disease.
In a study of the same participants published last September in Frontiers in Oral Health, the research team found that clinical attachment loss was significantly worse only in the e-cigarette smokers – not non-smokers and cigarette smokers – after six months.
A unique microbiome
The researchers analysed the bacteria found in the plaque samples and determined that e-cigarette users have a different oral microbiome from smokers and non-smokers – building on findings the team previously reported in iScience and Molecular Oral Microbiology.
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 non-smokers.
Several types of bacteria, including Selenomonas, Leptotrichia, and Saccharibacteria, were abundant in both smokers and vapers compared to non-smokers. Several other bacteria – including Fusobacterium and Bacteroidales, which are known to be associated with 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, a junior research scientist in Saxena’s lab and the study’s 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 – proteins that help regulate the immune system. 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; IL-4 tends to be reduced in people with gum disease and increases after treatment, which suggests that certain bacteria in the mouths of e-cigarette users may be actively suppressing immune responses.
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 Dr Scott Thomas, an assistant research scientist in Saxena’s lab and the study’s 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.”
Study details
Electronic Cigarette Use Promotes a Unique Periodontal Microbiome
Scott C Thomas, Fangxi Xu, Smruti Pushalkar, Ziyan Lin, Nirali Thakor, Mridula Vardhan, Zia Flaminio, Alireza Khodadadi-Jamayran, Rebeca Vasconcelos, Adenike Akapo, Erica Queiroz, Maria Bederoff, Malvin N Janal, Yuqi Guo, Deanna Aguallo, Terry Gordon, Patricia M Corby, Angela R Kamer, Xin Li and Deepak Saxena.
Author affiliations: New York University and the University of Pennsylvania
First published by mBio on 22 February 2022
Abstract
Electronic cigarettes (e-cigs) have become prevalent as an alternative to conventional cigarette smoking, particularly in youth. E-cig aerosols contain unique chemicals which alter the oral microbiome and promote dysbiosis in ways we are just beginning to investigate.
We conducted a six-month longitudinal study involving 84 subjects who were either e-cig users, conventional smokers, or non-smokers. Periodontal condition, cytokine levels, and subgingival microbial community composition were assessed, with periodontal, clinical, and cytokine measures reflecting cohort habit and positively correlating with pathogenic taxa (eg Treponema, Saccharibacteria, and Porphyromonas).
α-Diversity increased similarly across cohorts longitudinally, yet each cohort maintained a unique microbiome. The e-cig microbiome shared many characteristics with the microbiome of conventional smokers and some with non-smokers, yet it maintained a unique subgingival microbial community enriched in Fusobacterium and Bacteroidales (G-2).
Our data suggest that e-cig use promotes a unique periodontal microbiome, existing as a stable heterogeneous state between those of conventional smokers and non-smokers and presenting unique oral health challenges.
Importance
Electronic cigarette (e-cig) use is gaining in popularity and is often perceived as a healthier alternative to conventional smoking. Yet there is little evidence of the effects of long-term use of e-cigs on oral health.
Conventional cigarette smoking is a prominent risk factor for the development of periodontitis, an oral disease affecting nearly half of adults over 30 years of age in the United States.
Periodontitis is initiated through a disturbance in the microbial biofilm communities inhabiting the unique space between teeth and gingival tissues. This disturbance instigates host inflammatory and immune responses and, if left untreated, leads to tooth and bone loss and systemic diseases.
We found that the e-cig user’s periodontal microbiome is unique, eliciting unique host responses. Yet some similarities to the microbiomes of both conventional smokers and non-smokers exist, with strikingly more in common with that of cigarette smokers, suggesting that there is a unique periodontal risk associated with e-cig use.
MBio journal article – Electronic Cigarette Use Promotes a Unique Periodontal Microbiome
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