The use of electronic cigarettes (e-cigarettes) represents a significant and increasing proportion of tobacco consumption, posing a tremendous threat to oral health.

When compared to traditional tobacco use, an argument that e-cigarette use may be as dangerous to oral health—if not more dangerous—can be made.

Overview

Using e-cigarettes, referred to as vaping, works by heating a liquid to generate an aerosol that the user inhales. The liquid in the e-cigarette, called e-liquid, is usually made up of propylene glycol, glycerin, flavorings, water, and nicotine, although some users will substitute THC for nicotine. In practice, e-cigarette users tend to reach lower blood nicotine concentrations than tobacco smokers, although it is difficult to make a direct comparison because nicotine concentrations in e-cigarettes vary widely.

Reasons individuals vape include the following:

• Smoking cessation
• The thought that vaping is less harmful than cigarettes
• Circumvention of smoke-free areas
• Recreational enjoyment

Prevalence

Researchers and anti-tobacco advocates are especially concerned that irresponsible marketing has made e-cigarettes appeal to a younger population who does not have a history of tobacco usage. Tobacco use among middle and high school students has been steadily decreasing since 2014. However, since the introduction of the e-cigarette, that number is now increasing, and it is estimated that one in five high school students may now be using tobacco products. (2) E-cigarette use from 2017 to 2018 increased 78% among high school students and 48% among middle school students.

Propylene glycol

The first danger of e-cigarettes is associated with the carrier product known as propylene glycol (PG). PG is primarily used in the production of polymers and in food processing. It can be found in various edible items, such as liquid sweeteners, ice cream, and whipped dairy products. It can also act as a carrier for various inhalant pharmaceutical products, including nicotine. PG is a viscous, colorless liquid that possesses a faintly sweet taste and is one of the major ingredients of the e-liquid used in e-cigarettes. When used orally, the breakdown products of PG include acetic acid, lactic acid, and propionaldehyde, which are all toxic to enamel and soft tissue. (4) In addition, PG is a hygroscopic product, which means water molecules in saliva and oral tissue will bond to the PG molecules, leading to tissue desiccation. (5) The result of this is xerostomia, or "dry mouth," which has been shown to lead to an increase in cavities, gum disease, and other oral health issues.

Vegetable glycerin and flavorings

The second danger of e-cigarettes is due to other major component of e-liquid: glycerin and flavorings. Vegetable glycerin (VG) is a colorless, odorless, viscous, and sweet-tasting liquid. It has a myriad of applications, including medical, pharmaceutical, and personal care. In the food industry, it serves as a humectant, solvent, and sweetener. It is 60% as sweet as sucrose and is not metabolized by cariogenic bacteria, and is therefore thought not to cause cavities. However, studies have shown that the combination of VG with flavorings produces a fourfold increase in microbial adhesion to enamel and a twofold increase in biofilm formation. (6) In addition, a 27% decrease in enamel hardness was demonstrated when flavorings were added to e-liquid as compared to unflavored controls. The viscosity of the e-liquid also allowed Streptococcus mutans to adhere to pits and fissures. In other words, e-liquid allows more cavity-causing bacteria to stick to a softer tooth and can lead to rampant decay.

Nicotine

The final danger associated with e-cigarettes has to do with nicotine. Although the percentage of nicotine is much lower (0.3%–1.8%) than traditional tobacco products, one electronic cartridge (200–400 puffs) can equal the smoking of two to three packs of regular cigarettes. The dangerous effects of nicotine on gum tissue are well known. The literature suggests that nicotine affects gingival blood flow as it is a vasoconstrictor. It also affects cytokine production, neutrophil function, and other immune cell function. (7) In addition, nicotine decreases connective tissue turnover. All of this results a much higher chance of developing gum disease and tooth loss.