Smoking & oral health
Smoking is a major cause of cancer affecting the oral cavity (mouth) and the oropharynx (part of the throat just behind the mouth). On average oral cancer occurs up to four times more frequently in smokers than in non-smokers(1). In men approximately 57%, and in women, approximately 51% of cancers of the oropharynx can be directly attributed to smoking(2).
The mouth can be a very visual reflection of the effects smoking has on the body. The results of smoking can range from something obvious and unsightly such as stained teeth, to leukoplakia, a harmless mucosal lesion that can sometimes develop into cancer. The presence and severity of these conditions depends on several factors including the form in which tobacco is used (cigarettes, pipes, cigars), as well as how often tobacco is used and how long the tobacco has been in use(3). The use of tobacco and alcohol together has also been found to markedly increase the risk of oral cancer (4,5,6).
How does smoking affect oral health?
If cancer is not already present and smokers quit, the risk of developing oral cancer halves after three to five years and continues to decline(1).
In 1996, 1982 new cases of cancer in the oral cavity and oropharynx were recorded in New Zealand(2). This is in comparison with 923 new cases recorded for cancer of the cervix(2). Only approximately 50% of those people affected with oral cancer will survive after five years, although early detection significantly increases the chances of survival(4,7,8).
Advanced oral cancers can cause chronic pain, loss of function and disfigurement(9). Oral cancer is more common in men than women, however the rate that women are developing oral cancer is increasing. This may be due to the increasing number of women who smoke and the greater numbers of women smokers in older age groups(7,9). The combined effects of smoking and alcohol are linked to between 75% and 90% of all cases of oral cancer(4). A male smoker of 40 or more cigarettes per day over 20 years is four times more likely to get oral cancer. A non-smoker who drinks four-alcoholic drinks per day is nine times more likely to get oral cancer. A person who is both a heavy smoker and heavy drinker is 37 times more likely to get oral cancer compared with those people who don't smoke or drink alcohol at all(6).
One of the reasons why tobacco and alcohol together are so damaging may be the possible effects on DNA. It is thought that tobacco damages the DNA of cells, causing havoc with the cell's instructions for repair and growth. This results in abnormal cells accumulating, causing a tumour to develop. It is not clear if alcohol causes direct damage to DNA but it is known that alcohol increases penetration of many DNA damaging chemicals into cells(7). Leukoplakia is a white patch or plaque on the lining of the mouth (oral mucosa). Leukoplakia is the most common mucosal lesion in the adult mouth and can go on to become cancerous(3). Leukoplakia occurs six times more frequently in smokers than in non-smokers and its occurrence can be related to the frequency and duration of tobacco use(3). However up to 75% of lesions regress or go away within a year if tobacco use is stopped(3).
Effects on the teeth and supporting structures
Periodontal disease is a major dental disease related to the gums and bones that form the supporting structures of the teeth. It is caused by bacteria in plaque producing toxins that seep down between the gums and teeth causing them to become inflamed. Problems can occur such as loss of jawbone that holds teeth in place, acute necrotizing ulcerative gingivitis (a painful infection that causes the gums to inflame and break down) and periodontal pockets (the formation of deep spaces around the teeth that harbour bacteria if plaque is not cleaned away)(10). Smokers are at between two-and-a-half and six times greater risk of periodontal disease compared with non-smokers(5). This may be because smoking affects the immune system by lowering the body's ability to inhibit bacteria that are associated with periodontal disease(10).
Other tobacco-induced conditions of the mouth:
- Smoker's Palate is a condition where heavy smokers develop a pale or white hard palate often combined with multiple red dots. This is caused by the narrowing of blood vessels and can disappear after cessation of smoking (4). This condition is most often seen in pipe and cigar smokers(3).
- Smoker's Melanosis is a condition where heavy smokers have an increased pigmentation especially on the cheeks and gums. It occurs in five to ten per cent of smokers(3). Although it is not associated with a risk of oral disease, it can be unsightly. However, stopping smoking can reverse this condition, although it usually takes more than a year after stopping for the colour to return to normal(4).
- Tobacco stains can penetrate into enamel, restorative materials and dentures creating ugly brown to yellow darkening of teeth(3).
- Bad breath (halitosis) and impaired taste is also commonly caused by smoking(3).
- Nicotine in cigarettes reduces blood flow to the gums. This means that smokers are more vulnerable to oral infection and take a longer time to heal after oral surgery(10).
Smoking can have devastating effects on the mouth. Stopping an addiction to smoking can reduce the risk of oral diseases associated with smoking and improve the health of the mouth, gums and teeth.
- US Department of Health and Human Services The Health Benefits of Smoking Cessation. A report of the Surgeon General., Rockville, Maryland: US Department of Health and Human Services, Public Health Service, Centres for Disease Control, Centre for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 1990.
- Australian Institute of Health and Welfare (AIHW) and Australasian Association of Cancer Registries (ACCR) 1999. Cancer in Australian 1996: Incidence and mortality data for 1996 and selected data for 1997 and 1998. AIHW cat.no. CAN 7. Canberra: AIHW (Cancer Series), 1999.
- Mecklenburg RE, Greenspan D, Kleinman DV, Manley MW, Neissen LC, Robertson PB, Winn DE. Tobacco Effects In The Mouth: A national cancer institute and national institute of dental research guide for health professionals, United States: U.S. Department of Health and Human Services, National Institutes of Health,1996.
- Watt R & Robinson M Helping Smokers To Stop: A guide for the dental team, London: Health Education Authority, 1999.
- Blot WJ, McLaughlin JK, Winn DM et al Smoking and Drinking in Relation to Oral and Pharyngeal Cancer, Cancer Research 1988, 48: 3282-3287.
- Blot WJ. Alcohol and Cancer, Cancer Research (Supp.) 1992, 52: 2119s-2123s.
- American Cancer Society, Oral Cavity & Oropharyngeal Cancer Resource Centre, URL: http:// www.cancer.org Accessed October 1999.
- Sugerman PB, Savage NW, Current Concepts in Oral Cancer, Australian Dental Journal 1999, 44: (3):147-156.
- Horowitz AM, Goodman HS, Yellowitz JA, Nourjah PA, The Need for Health Promotion in Oral Cancer Prevention and Early Detection, Journal of Public Health Dentistry 1999, vol 56, no 6.
- London WM, Whelan EM, Case AG, eds. Cigarettes: What the Warning Label Doesn't Tell You, the first comprehensive guide to the health consequences of smoking, New York: American Council on Science and Health, 1996.