How e-cigarettes can ruin your smile

How e-cigarettes can ruin your smile

The health effects of e-cigarettes on the body, especially their impact on oral health, are not yet fully understood. Medical writer Maja Klys discusses what we currently know

Maja Klys

The use of e-cigarettes among young adults (18–25 years old) has become extremely widespread. Research has shown that between 2021 and 2022 alone, the number of young adults in Great Britain who vaped increased from 1.2% to 22.2%.

A major issue with young adults reaching for e-cigarettes is the high concentration of nicotine that is being inhaled. Nicotine is not only highly addictive, but it also affects the oral microbiome by disrupting the balance of microbes in the mouth.

Nicotine influences the activity of NMDA receptors involved in synaptic plasticity, a process thought to be the basis of memory formation. These affect cognitive development, mental health and addiction pathways in the brain. Exposure to nicotine has also been firmly linked with inflammatory responses in the lungs, increasing the risk of respiratory issues, such as e-cigarette or vaping product use-associated lung injury (EVALI). In 2020 over 2800 people were hospitalised due to EVALI, and the condition resulted in 68 deaths.

Gum disease

Disruptions to the oral microbiome can lead to oral health diseases, such as periodontitis, which causes inflammation of the gums (see Box 1). Longitudinal studies have shown that e-cigarette users have a 40% higher risk of periodontitis than non-users.

Periodontitis damages the soft tissue around the teeth. Without any treatment, this can destroy the bone that supports the teeth, leading to loosened or even lost teeth. Symptoms of periodontitis include swollen/bleeding gums, bad breath, painful chewing and/or pus between the teeth and gums (see Figure 1).

What is the oral microbiome?

The oral cavity contains the second largest microbiome in the human body, following the gut in both diversity and the number of microbial species present. This diverse community of microorganisms includes bacteria, fungi, viruses and protozoa. A healthy oral microbiome is characterised by the dominance of specific bacteria that contribute to the stability of the ecosystem, including Streptococcus species.

Disturbances in the oral microbiome, known as dysbiosis, can result from factors such as reduced saliva flow, frequent sugar intake and vaping. Vaping contributes to dysbiosis by drying the mouth, while nicotine, propylene glycol, glycerine and flavouring chemicals are harmful to the oral microbiome. These substances are routinely found in the vapour of e-cigarettes (see Box 2).

Dysbiosis in the microbial community caused by vaping allows opportunistic pathogens to proliferate, leading to oral infections. This imbalance can create environmental changes in the mouth, such as increased acidity or dryness, which further favours the growth of opportunistic pathogens. An example of an opportunistic pathogen in the oral microbiome is Porphyromonas gingivalis, a bacterium that contributes to oral infections, such as periodontitis. P. gingivalis can evade the host immune response, leading to chronic inflammation, which causes continuous tissue destruction and progression of periodontitis.

Vape users have high concentrations of IL-6 in their saliva, suggesting that they have an increased risk of chronic inflammation. Saliva serves as a vital defence mechanism against oral pathogens. It plays an essential role in the mouth, maintaining oral hygiene by neutralising acids produced by bacteria. Neutralisation of acids is helpful because acidic environments can erode the outer layer of teeth (enamel) and encourage bacterial growth. Saliva also washes away food particles and contains antimicrobial compounds that protect against infection. Disruptions to saliva flow, whether due to medication or vaping, can shift the oral microbiome and increase the risk of dental diseases.

Immunological dynamics in periodontitis

P. gingivalis colonises the periodontal pockets using fimbriae to attach to host gums and other bacteria. The bacteria contain or release virulence factors, including lipopolysaccharides and proteases, which trigger an inflammatory cascade (see Figure 2).

The interaction between P. gingivalis and the host immune system triggers the production and release of cytokines and inflammatory mediators from immune cells and infected tissue. These include IL-1, IL-6 and prostaglandin E2. These inflammatory molecules recruit and activate immune cells, such as neutrophils, macrophages and T cells, to the site of infection.

Oral epithelial cells are crucial in the defence against bacterial pathogens. These cells express pattern recognition receptors, including toll-like receptors, which recognise specific microbial components such as lipopolysaccharides. When toll-like receptors on oral epithelial cells are activated, they initiate intracellular signalling pathways, leading to the production of antimicrobial peptides and the release of pro-inflammatory cytokines.

Dysregulation in cytokine concentration, particularly an imbalance between pro-inflammatory and anti-inflammatory cytokines, is a hallmark of ongoing inflammation and tissue destruction in periodontitis. Chronic exposure to inflammatory mediators results in the breakdown of periodontal tissues, leading to the loss of connective tissue attachment and bone recession. Vaping increases blood pressure, the concentration of adrenaline in the blood and heart rate, all of which increase the chance of a heart attack.

Maja Klys wrote this as part of her final-year science media project at the University of Manchester, when studying for her BSc (Hons) in biomedical sciences. She is now a junior medical writer at Havas Lynx.