25 June 2019
Smoking cigarettes causes serious diseases and adversely affects our health, including oral health. Smoking discolors teeth, and it can lead to gum disease, tooth loss, and can even cause mouth cancer in severe cases.
A smoker’s teeth are exposed to the thousands of chemicals found in cigarette smoke. This includes colored compounds in the smoke that can end up on the surface of the teeth or penetrate the hard dental tissues, causing discoloration. A recent survey in the United Kingdom indicated that the risk of severe tooth discoloration in smokers was 2.4 times higher than in non-smokers, though other things can also stain teeth, such as coffee, red wine, or soy sauce.
The process of combustion is eliminated in Platform 1. Not only does this cause the product to produce levels of harmful chemicals that are on average 95% lower than those measured in cigarette smoke (3R4F), but we also expect to see significantly reduced tooth discoloration compared to that caused by cigarette smoke.
2.4 times higher than in non-smokers
In a publication titled "Smoking and tooth discolouration: findings from a national cross-sectional study" published in BMC Public Health in 2005, Mhd N Alkhatib et al. found smokers have higher levels of self-assessed tooth discoloration compared to non-smokers. Smoking is a risk factor of a number of oral diseases; the extent to which tobacco products influence dental aesthetics has not been widely investigated. The aim of this study was to determine satisfaction with own tooth colour of smokers and non-smokers and to investigate whether smokers have higher levels of self-assessed tooth discolouration compared to non-smokers. Twenty eight percent of smokers reported having moderate and severe levels of tooth discolouration compared to 15% in non-smokers. As well as more often perceiving discolouration smokers were also more likely to be dissatisfied with their own tooth colour compared to non-smokers.
Both groups of teeth were exposed to smoke (equivalent to 10 cigarettes) or aerosol (equivalent to 10 Platform 1 tobacco sticks) for 28 minutes. These exposure sessions occurred twice a day, four days a week, for three weeks – a total of 24 exposure sessions for each tooth. The teeth were kept in artificial saliva between sessions.
Assessing tooth color using CIE Lab
At baseline and each week after exposure, the teeth were brushed following a strict protocol. Then, the color of the teeth was assessed in the Commission internationale de l'éclairage L*a*b (CIE Lab) color space. This color space defines color values on three coordinates: L* (dark to light scale), a* (red to green scale), and b* (yellow to blue scale).
At the end of the three weeks, cigarette smoke caused an overall larger color change compared with Platform 1, showing decreased lightness and increased redness of the enamel, dentin, and composite resin restorations. Platform 1 aerosol caused similar trends in color change, but to a much lesser extent. It also caused no measurable mismatch between the tooth and the dental resin, unlike cigarette smoke. Artificially aging the restorations had no effect on the discoloration.
The tooth’s structure. The inner pulp of the tooth, containing the soft connective tissue, is covered by naturally yellow dentin. Dentin is naturally softer than enamel, which is the hard, outer layer of the tooth. The natural color of dentin ranges from light yellow to grayish white.
Exposing teeth to aerosol and smoke
The goal of our study comparing the effects of cigarette smoke and heated tobacco aerosol on teeth was to compare the level of discoloration, if any, caused by Platform 1 with that caused by cigarette smoke and to examine whether product use would lead to any color mismatches between dental resins and teeth.
Our researchers* collected premolars that were extracted for orthodontic reasons, collected fresh from oral surgery, and sterilized them with ethylene oxide overnight before use. Next, cavities were created in 22 teeth, and dental resins were applied to restore them. The teeth were then evenly separated into two groups. One group was exposed to Platform 1 aerosol, and the other was exposed to cigarette smoke.
The color of the human premolar teeth and composite resin restorations were assessed in the CIE Lab space to establish baseline values. Each week after exposure to Platform 1 aerosol or cigarette smoke, the teeth were brushed with a toothbrush and toothpaste and assessed for color. When the teeth were not exposed to aerosol or being assessed, they were incubated in artificial saliva.
Comparison of the color change caused by Platform 1 (top) and cigarette smoke (bottom). After three weeks, Platform 1 aerosol caused no obvious discoloration to the teeth and no color mismatch between the teeth and dental resins, unlike cigarette smoke.
Lack of combustion is a major factor
Still, quitting smoking and other nicotine-containing products is the best choice smokers can make, including for oral health and teeth discoloration. Although the color changes caused by Platform 1 during this study could not be noticed by the naked eye, Platform 1 aerosol and cigarette smoke both increased the level of yellow color in the teeth. It's possible that this is a result of nicotine exposure. While nicotine in its original state is not colored, it becomes yellow when oxidized, which may be responsible for the slight yellow color change.
Considering that the lack of combustion is an important factor in the reduced impact of Platform 1 on tooth color, we would also expect that e-cigarettes and other smoke-free products should have similar outcomes. In fact, we’re in the process of exploring the effects of e-cigarettes on tooth color, including both composite resin and dental hard tissue. We’ve presented our work in progress at the 97th General Session of the International Association for Dental Research.
* This study was conducted by PMI researchers Dr. Filippo Zanetti, Prof. Manuel C. Peitsch, and Dr. Julia Hoeng, in collaboration with others working with Prof. Yangfang Ren of the University of Rochester.