Why Your Dentist Wishes You Wouldn't Smoke Pot

A new study suggests that smoking pot may not be particularly bad for your physical health — except when it comes to your teeth. The research, published in the June issue of JAMA Psychiatry , found that regular marijuana use negatively affects dental health; people who smoke pot have a higher risk of gum disease, a condition that can cause tooth loss and is associated with a number of other serious health problems. On the whole, however, the study reveals that cannabis use has relatively few long-term physical repercussions, and that these repercussions are much less severe than those associated with smoking tobacco.

The study looks at the long-term health of a group of 1,037 people born between 1972 and 1973 in Dunedin, New Zealand. The researchers began tracking their subjects' pot use when they were 18, in order to see how cannabis use would affect their health by the time they turned 38. Controlling for issues like health during childhood, childhood socioeconomic status, and tobacco use, the researchers found that regular pot use was not associated with physical health problems, except for those related to periodontal health. Just over 55 percent of people who used cannabis regularly for more than 15 years had periodontal disease (gum disease). Among subjects who didn’t use pot, only 13.53 percent had gum disease.

The researchers aren’t sure why cannabis use is associated with poor gum health. They found that people who used pot tended to have worse dental hygiene than those who didn’t, but heavy pot users’ questionable brushing and flossing habits still didn’t account for why cannabis use would have such a negative affect on gums and teeth.

“One thing that surprised me is that we didn’t see associations between cannabis use and poorer lung function,” lead author Madeline Meier, a psychologist at Arizona State University, told the Guardian. She and her colleagues found that tobacco use was associated with a much worse, broader spectrum of health problems than pot; in addition to gum disease, tobacco users experienced “worse lung function, systemic inflammation, and metabolic health.” The Washington Post hypothesized that tobacco’s extreme negative physical effects, and cannabis’s apparent lack of them, may have to do with how people consume these substances; even a heavy pot user is unlikely to smoke more than a limited number of joints each day, while a heavy smoker may go through multiple packs of cigarettes in the same period.

The researchers say that, although these results paint a fairly positive picture of pot’s influence on physical health, that doesn’t mean that marijuana use doesn’t come with negative consequences. “What we’re seeing is that cannabis may be harmful in some respects, but possibly not in every way,” study co-author Avshalom Caspi explained. Previous research has suggested that there may be some negative associations between pot use and health problems, and an earlier study by Meier using the same pool of subjects in New Zealand found a link between marijuana use and certain mental health issues. Caspi added, “We need to recognize that heavy recreational cannabis use does have some adverse consequences, but overall damage to physical health is not apparent in this study.”