Scientists studying young adults in New Zealand have revealed that smoking cannabis (marijuana), independent of tobacco, is a potential risk factor for gum disease.
The study is published in the 6th February issue of the Journal of the American Medical Association (JAMA) and was the work of researchers based at the Dunedin School of Medicine in New Zealand; King’s College London, England; Duke University, Durham, North Carolina, USA; and the University of North Carolina, Chapel Hill, also in the USA.
Inflammation associated with periodontal disease (disease of the bone, gum or ligaments that anchor and support the teeth) can extend deep into dental tissue, weakening its supportive structure and resulting in loose teeth and eventually tooth loss as well.
Periodontal disease is one of the most chronic diseases in adults, wrote the researchers.
Scientists already knew that smoking tobacco was significantly linked to increased risk of periodontal disease, but there was no information on how cannabis smoking, with our without tobacco smoking, may or may not have the same connections.
In this study Dr Murray Thomson, of the Dunedin School of Medicine, and colleagues, put together a prospective cohort representative of the general population and examined cannabis use at ages 18, 21, 26 and 32 years.
They also did dental checks at ages 26 and 32 years, for which the most recent were completed in June 2005. The 1,015 participants were born in Dunedin, New Zealand, between 1972 and 1973. From these 903 (89 per cent) completed records were obtained for the duration of the study and used in the analysis.
The main outcome measure the researchers looked for was periodontal disease status at age 32 (including changes that had occurred since the previous exam at age 26). This was assessed from a measure known as periodontal CAL (combined attachment loss) which indicates how well or poorly the periodontal tissue is holding onto its teeth.
They defined cannabis exposure in three categories: no exposure, some exposure, and high exposure. No exposure was defined as not using cannabis during the period assessed, some exposure was defined as using cannabis on average between 1 and 40 times, and high exposure was 41 or more times.
The analysis showed that:
- 293, or 32.3 percent of participants fell into the no exposure group.
- 428, or 47.4 per cent of the participants had had some exposure.
- And 182, or 20.2 per cent of the participants had had high exposure.
- At the age of 32 years, 29.3 per cent (265) of the participants had one or more sites with 4 mm or greater amount of CAL, and 12.3 per cent (111) had one or more sites with 5 mm or more CAL.
- New CAL that appeared between the ages of 26 and 32 went up in line with cannabis exposure (ie higher cannabis exposure linked to worse gum disease).
- The no cannabis exposure group had an average of 6.5 per cent of new CAL.
- For the some exposure group this figure was 11.2 per cent.
- For the high exposure group it was 23.6 per cent.
- After controlling for tobacco smoking (using pack-years), gender, irregular attendance at the dentist, and amount of dental plaque, the high cannabis exposure group had a 60 per cent increased risk of having one or more CAL sites of 4 mm or more, a 3.1 times greater risk of one or more 5 mm CAL sites, and a 2.2 times greater risk of new CAL.
- Tobacco smoking was strongly linked to periodontal disease, but there was no interaction between cannabis use and tobacco smoking in predicting the condition’s occurrence.
The researchers concluded that:
“Cannabis smoking may be a risk factor for periodontal disease that is independent of the use of tobacco.”
They suggested that:
“The study’s demonstration of a strong association between cannabis use and periodontitis experience by age 32 years indicates that long-term smoking of cannabis is detrimental to the periodontal tissues and that public health measures to reduce the prevalence of cannabis smoking may have periodontal benefits for the population.”
Shoud these findings be comfirmed by other studies, they suggested that health authorities and practitioners start raising awareness that cannabis use damages teeth and gums.
“Cannabis Smoking and Periodontal Disease Among Young Adults.”
W. Murray Thomson; Richie Poulton; Jonathan M. Broadbent; Terrie E. Moffitt; Avshalom Caspi; James D. Beck; David Welch; Robert J. Hancox.
JAMA. 2008;299(5):525-531.
Vol. 299 No. 5, February 6, 2008.
Sources: JAMA article and press release.
Written by: Catharine Paddock, PhD