Heavy pot use was found to be strongly associated with gum disease at age 32 in a study published in the Feb. 6 edition of The Journal of the American Medical Association.
After controlling for other risk factors for gum disease, including tobacco use, the 32-year-old study participants who smoked the most marijuana were 60% more likely to show evidence of gum disease than 32-year-olds who had never smoked pot.
Almost one in three people had some evidence of gum loss.
"We found that about a fifth of the participants actually had adult gum disease in their mid-20s and by age 32 the number was just under a third," researcher W. Murray Thompson, PhD, tells WebMD. "It is clear that smoking -- whether it is tobacco or cannabis -- damages the gums."
Marijuana, Tobacco, and Gum Disease
The study included 903 young adults followed from age 3 as participants in a larger, ongoing New Zealand comprehensive health trial. All were born at the same hospital in Dunedin, New Zealand, between April 1972 and March 1973.
Study participants were asked about their use of marijuana at ages 18, 21, 26, and 32; dental examinations were conducted at ages 26 and 32.
About a third reported no exposure to marijuana, while slightly under half reported some exposure, defined as smoking marijuana between one and 40 times during the previous year.
The 20% of people who smoked more than this were considered heavy marijuana users.
Compared with people who smoked no pot at all, heavy marijuana users were three times more likely to have at least one gum site with evidence of severe gum disease and 60% more likely to show evidence of mild gum disease.
Infrequent marijuana users also had more evidence of gum disease than nonusers, but not as much as frequent users.
Earlier data from the Dunedin trial showed cigarette smoking to be a strong risk factor for gum disease in the study participants, who were then in their mid-20s. This was confirmed in the latest findings from the trial, but no interaction was seen between cigarette and marijuana smoking in terms of predicting gum disease.
One good piece of news: Cigarette smokers who gave up the habit before they reached their late 20s had no more evidence of gum disease by age 32 than people who had never smoked, Thomson says.
"With the gums there is a constant fine balance between destruction and repair," he says. "Smoking tips the balance toward destruction, and if you don't smoke the balance is tipped back toward repair."
'Canary in the Coal Mine'
Thomson and colleagues conclude that smoking may prove to be the "primary behavioral risk factor" for early gum disease.
In an editorial accompanying the study, University of Washington dental professor Philippe Hujoel, PhD, writes that evidence of gum disease in young smokers could also be considered the "canary in the coal mine" for other lifestyle-related diseases like diabetes and heart disease.
Hujoel tells WebMD that since young people tend to visit dentists more than doctors, dentists may be the first to recognize the early signs of an unhealthy lifestyle.
"The dental profession has an opportunity to detect the early clinical signs of unhealthy lifestyles, including potential drug abuse, and could play a role with physicians in addressing the challenges of reducing chronic [lifestyle-related] disease," he writes.