NYU Researchers Discover a Unique Oral Microbiome in E-cigarette Users

Rising in popularity, e-cigarettes are used by more than 2 million school-aged adolescents. A recent study has discovered a unique connection to the oral microbiome in users.

By Dr. Shilpy Bhandari

E-cigarettes (electronic cigarettes) have been promoted as a safer alternative to traditional cigarettes, as the tobacco industry advertises them as a “breakthrough product” for people looking to quit smoking. While e-cigarettes have lower levels of carcinogens (nitrosamines) in comparison to traditional cigarettes, which contain 971 to 1806 times more carcinogens than their electronic counterparts, their impact on oral health is still being researched.

E-cigarettes have increased in demand among all age groups, especially among adolescents. According to research from U.S. Food and Drug Administration (FDA) and the U.S. Centers for Disease Control and Prevention (CDC), more than 2 million students in middle and high schools in the U.S. were using e-cigarettes in 2021. The global e-cigarettes market is estimated to reach 38.5 billion at a compound annual growth rate (CAGR) of 15.5% in 2026.

Recent Study Evaluates E-cigarettes

A recent study published in 2022, at the New York University (NYU) College of Dentistry discussed the effects of e-cigarettes on oral health and found a unique connection to the oral microbiome.

Researchers at NYU College of Dentistry conducted a longitudinal study with 84 participants. Participants with at least a mild form of periodontitis were selected for the study. These participants were divided into 3 groups: conventional cigarette smokers, e-cigarette users, and non-smokers. Subgingival (SGP) plaque samples were collected from all three groups twice, at the beginning and end of six months. These samples were taken to evaluate the severity of the disease, presence of different bacterial communities, and cytokine levels.

A sub-group of researchers, led by Fangxi Xu, also compared the clinical parameters and demographics of the same participants in a different study published earlier in 2021.

Below are the key findings of the study:

Finding One: Increase in Severity of Periodontal Disease

The e-cigarette group had a higher number of participants with severe periodontitis at both visits, in comparison to non-smokers. Meanwhile, all the participants in the cigarette smoking group had severe periodontitis in both visits.

Traditionally, the severity of periodontal disease is determined by the amount of clinical attachment loss. An increase in the clinical attachment loss signifies the destruction of the bone and other supporting tissues which hold the teeth in place.

The subgroup led by Fangxi Xu found that the progression of periodontal disease into severe form is higher only in e-cigarette users, versus the other two groups.

Research by Pushalkar et al. published in the journal of iScience (2020) supports these findings. The study found that 43% of people using e-cigarettes had gum disease and oral infections, compared to 73% among smokers and 28% among non-smokers.

Finding Two: Presence of a Unique Periodontal Microbiome

The bacterial composition of subgingival plaque in e-cigarette users shares more commonalities with cigarette smokers than non-smokers. For instance, bacterial groups such as Selenomonas, Saccharibacteria, and Leptotrichia were more commonly found in the microbiome of e-cigarette and cigarette smokers than non-smokers.

The study found a unique periodontal biome among e-cigarette users, with the presence of bacterial groups such as Fusobacterium and Bacteroidales, bacteria associated with periodontitis.

Finding Three: Exaggerated Host Immune Response

Researchers found that the presence of a unique microbiome in e-cigarette users was associated with periodontal disease and changes in the host immune system. The presence of disease-causing bacteria in gums causes the release of chemicals that trigger the host’s immune system. In response, cells of the immune system release several cytokines (proteins). These cytokines exaggerate the inflammatory reaction, contributing to further destruction of gums and bone loss.

Cytokines that worsen gum disease (such as Tumor necrosis factor-alpha (TNF-a)) were significantly higher in e-cigarette users than in cigarette smokers and non-smokers.

Cytokines such as Interleukin 1b (IL-1b) were significantly higher in cigarette smokers than the other two groups. Cytokines IL-4 and IL-1β were low in e-cigarette users. Levels of Interleukin-4 in the e-cigarette users decreased during gum disease and increased after the treatment. This signified the role of oral bacteria in suppressing the immune response in e-cigarette users.

In Conclusion

The results of the study concluded that the use of e-cigarettes creates a unique periodontal microbiome. While this microbiome was shown to be relatively healthier than those found in traditional cigarette smokers, it was still much less healthy than those in non-smokers. The unique features of the e-cigarette user’s periodontal microbiome point to the need for long-term research to study its full impact on overall health and disease.

References:

  1. Fangxi Xu, a Smruti Pushalkar, a Ziyan Lin, b Nirali Thakor, a Mridula Vardhan, a Zia Flaminio, a Alireza Khodadadi-Jamayran, b Rebeca Vasconcelos, a Adenike Akapo, a Erica Queiroz, a Maria Bederoff, a Malvin N. Janal, c Yuqi Guo, a Deanna Aguallo, a Terry Gordon, d Patricia M. Corby, e Angela R. Kamer, f Xin Li, a Deepak Saxenaa Scott C. Thomas, Fangxi Xu, and Smruti Pushalkar contributed equally to this work. Electronic Cigarette Use Promotes a Unique Periodontal Microbiome, mBio February 2022 Volume 13 Issue 1e00075-22.
  2. AUTHOR=Xu Fangxi, Aboseria Eman, Janal Malvin N., Pushalkar Smruti, Bederoff Maria V., Vasconcelos Rebeca, Sapru Sakshi, Paul Bidisha, Queiroz Erica, Makwana Shreya, Solarewicz Julia, Guo Yuqi, Aguallo Deanna, Gomez Claudia, Shelly Donna, Aphinyanaphongs Yindalon, Gordon Terry, Corby Patricia M., Kamer Angela R., Li Xin, Saxena Deepak, Comparative Effects of E-Cigarette Aerosol on Periodontium of Periodontitis Patients, Frontiers in Oral Health, Volume 2 2021.
  3. Smruti Pushalkar, Bidisha Paul, Qianhao Li, Jian Yang, Rebeca Vasconcelos, Shreya Makwana, Juan Muñoz González, Shivm Shah, Chengzhi Xie, Malvin N. Janal, Erica Queiroz, Maria Bederoff, Joshua Leinwand, Julia Solarewicz, Fangxi Xu, Eman Aboseria, Yuqi Guo, Deanna Aguallo, Claudia Gomez, Angela Kamer, Donna Shelley, Yindalon Aphinyanaphongs, Cheryl Barber, Terry Gordon, Patricia Corby, Xin Li, Deepak Saxena, Electronic Cigarette Aerosol Modulates the Oral Microbiome and Increases Risk of Infection, iScience, Volume 23, Issue 3, 2020, 100884, ISSN 2589-0042.

Author: Dr. Shilpy Bhandari is an experienced dental surgeon, with a specialization in periodontics and implantology. She received her graduate and postgraduate education from Rajiv Gandhi University of Health Sciences in India. She is also interested in evidence-based academic writing and has published several articles in international journals.

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