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In a prospective cohort study in the Journal of the American Medical Association (JAMA)1, a New Zealand-led research team found that young adults who were regular cannabis (marijuana) smokers had a higher incidence of periodontal disease by age 32. The study received online news coverage from Reuters,2 Bloomberg,3 HealthDay News4 and other agencies.

In the New Zealand study, scientists evaluated self-reported tobacco and marijuana smoking information from 903 participants in the Dunedin Multidisciplinary Health and Development Study, a long-term evaluation of a cohort of children born in 1972-1973. The participants were provided dental examinations, including periodontal measurements, at ages 26 and 32 years, and the authors compared data in three exposure groups: no exposure to cannabis, some use, or regular use.

After adjusting for potential confounders, including tobacco smoking, gender, dental plaque, socioeconomic status and others, the authors found that regular cannabis smokers (at least 41 occasions during the previous year) were three times more likely to have significant periodontal attachment loss than non-smokers of cannabis. Importantly, the authors identified a significant association between cannabis smoking and periodontal disease in regular cannabis users who had never smoked tobacco.

Smoking tobacco is strongly associated with numerous adverse health consequences, including periodontal disease, but the New Zealand study is reportedly the first to examine the relationship between cannabis smoking and periodontal health. The authors recommend further research to confirm their study finding in other populations. Their study was funded by the Health Research Council of New Zealand and the National Institute for Dental and Craniofacial Research (NIDCR). Another recent study, also from New Zealand,5 has reported an association between long-term cannabis use and increased risk of lung cancer in young adults.

According to the National Institute on Drug Abuse, marijuana is the most widely used illegal drug in the United States. Many cannabis smokers have poor oral health and also smoke tobacco, which is a known risk factor for numerous cancers and diseases. Previous studies have also reported similar carcinogenic properties in tobacco and cannabis smoke.
While the available research on cannabis use and periodontal disease is limited, it is not surprising that regular cannabis smoking could be a suspected risk factor for periodontal disease, independent of the use of tobacco. Dentists are encouraged to be aware of symptoms of substance abuse in their patients, educate patients in overcoming addictions to tobacco or illegal drugs, and promote intervention techniques to reduce the incidence of adverse health effects.


1. Thomson WM, Poulton R, Broadbent JM, Moffitt TE, Caspi A, Beck JD, Welch D, Hancox RJ. Cannabis smoking and periodontal disease among young adults. JAMA 2008; 299(5):525-531. Abstract available at: Accessed February 10, 2008.

2. Dunham W. Study links marijuana smoking to gum disease. Reuters, February 5, 2008. Available at: Accessed February 10, 2008.

3. Jinks B. Marijuana smokers have increased risks of gum disease. Bloomberg, February 5, 2008. Available at: 20601081&sid=a9JCfB5LANnI&refer=australia. Accessed February 10, 2008.

4. Marijuana bad for the gums. HealthDay News, February 6, 2008.

5. Aldington S et al. Cannabis use and risk of lung cancer: a case–control study. Eur Respir J 2008; 31:280-286. Abstract available at: cgi/content/abstract/31/2/280. Accessed February 11, 2008

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Science in the News is a service by the American Dental Association (ADA) to present current information about science topics in the news. The ADA is a professional association of dentists committed to the public's oral health, ethics, science and professional advancement; leading a unified profession through initiatives in advocacy, education, research and the development of standards. As a science-based organization, the ADA's evaluation of the scientific evidence may change as more information becomes available. Your thoughts would be greatly appreciated.

Document Posted February 2008