One of Dr. Caroline DeVincenzi’s first implant patients smoked marijuana to control the symptoms of a severe form of multiple sclerosis. If he had been a tobacco smoker, DeVincenzi, who is now a post-doctoral student in the periodontal program at Oregon Health and Science University, would have had a clear mandate. “At the time the school had a very firm policy with tobacco smokers,” she says. “We were required to tell them that we recommend they cease smoking six to eight weeks before surgery and continue to stop using tobacco for six to eight weeks after.” But she wasn’t sure if the same was true for marijuana smokers. She was also hesitant to recommend the patient stop using the drug when he needed it for medical reasons. DeVincenzi went to her mentors and asked for advice on what to tell the patient. “They all said, ‘I don’t know,’” she says. So she took it upon herself to research how marijuana affects oral health.
What she discovered is that very little evidence-based information exists. Marijuana is a hard thing to research because labs have a difficult time obtaining good samples of a drug that’s still illegal at the federal level, explains Dr. David Carsten, owner of Pacific Dental Anesthesia in Vancouver, Washington. In addition, since marijuana has been off-limits for so long, there hasn’t been much demand for information about its positive and negative impacts on the body.
But now that marijuana can be used recreationally and medicinally in Oregon, Washington and Alaska (and medically in Montana), more dentists are running into the same types of tough questions DeVincenzi faced. What should they tell patients who use marijuana and want to know how it will impact their oral and overall health? How does it affect the treatment of surgery patients or people who are in the office for something other than a standard cleaning? Is it even appropriate to discuss it during a visit?
Carsten is a firm believer that the answer to the last question is yes, especially if dentists will be prescribing painkillers or other pharmaceuticals. “Patients need to know this is not some herb,” he says. “It’s very pharmacologically active. It’s affecting your central nervous system. It can have some positive effects, but it can have some negative effects. [Questions about marijuana usage] need to be asked and they need to be straightforwardly asked.”
Marijuana’s effects on overall health
Cannabis sativa, more commonly known as marijuana, is a member of the Cannabaceae family of flowering plants. What sets it apart from its cousins (including hops, its best-known relative) is its psychoactive effects. Smoking it, consuming the leaves, or applying the oil through a topical cream or spray leads to an altered state that can include feelings of relaxation and euphoria.
Cannabis has over 100 compounds. The one that’s best known for causing the “high” is tetrahydrocannabinol or THC. The other well-known compound is cannabidiol or CBD. “CBD is what promotes what people think of as the therapeutic effects of marijuana,” says DeVincenzi. It can lower inflammation, decrease nausea, reduce anxiety and pain, and help with conditions such as seizures or peripheral neuropathy. If a cannabis strain has a high enough concentration of CBD it will block the high delivered by THC.
“Proponents say [marijuana] is completely harmless, but that’s not exactly true,” says Carsten. “What is true is that for the vast majority of people who are pretty healthy, it’s hard to point to any chronic disease or anything that would happen to them. They can use it and then they can stop and there’s no problem.”
One benefit to cannabis is that the scale of toxicity is relatively low. “It’s less toxic than caffeine. It’s less toxic than a lot of things you can think of,” Carsten says. “It is nearly impossible to ingest or smoke a fatal dose. There is no recognized LD50 for THC.
“Psychiatrists will tell you that about 20 percent of people could become addicted to this,” he adds. “But there are many things that are more addictive.”
However, THC is an anticholinergic, so it poses serious risks for people with heart problems. “If you’ve ever been around people who smoke pot, you know the pupils of their eyes get big and their heart races,” Carsten says. “That’s bad for people who have arrhythmias, atrial fibrillation or certain heart problems. If an older person wants to use THC they need to make sure they have their heart checked out.” The major risk for young people is an undiagnosed case of Wolff-Parkinson-White syndrome.
Marijuana can react badly when combined with alcohol and some prescription medications. They include the antiarrhythmic Amiodarone, antidepressants Fluoxetine and Fluvoxamine, and antifungals Fluconazole and Itraconazole.
Long-term users may develop medical conditions such as cannabinoid hyperemesis, which causes uncontrollable vomiting, and memory impairment. People can develop mental health problems such as anxiety, depression and suicidal thoughts. Negative side effects from marijuana use and addiction are often more pronounced in young people, whose brains and bodies are still developing.
What research does exists?
While there is some evidence-based research showing how marijuana impacts humans, there’s very little information about its effects on oral health. But there are a few things that dentists can share with 420-friendly patients.
One is that smoking it leads to many of the same negative consequences as inhaling tobacco smoke. “It causes dry mouth, which leads to caries,” says Dr. Barry Taylor, an assistant professor in the Department of Restorative Dentistry at Oregon Health and Science University. “It also stimulates your brain to eat sweet foods.” Frequent smoking can lead to tooth staining. It’s a good idea to emphasize the importance of good oral hygiene for these patients.
Dentists can also safely mention that the amount of marijuana a person consumes will impact how likely they are to experience the negative side effects. “People are always asking, ‘Is it bad or good?’” Taylor says. “A lot of it has to do with the amount you use it. There’s a difference between smoking one cigarette a month and three packs a day.” Frequent or sustained users are more likely to see changes in their oral health.
DeVincenzi is in the early stages of a research project to understand how smoking marijuana affects periodontal disease. Until her study concludes, she can only offer general advice. Referring back to that initial implant patient and what she told him, she says, “If it was me, I wouldn’t smoke for a month or two before my surgery and I wouldn’t start up right after. Use an edible form of cannabis if you have to have it. If you think about it, if you have a big open wound in your mouth after surgery, you don’t want smoke or heat in your mouth. You’re going to have a bad environment that will set you up for failure.
“The basic thing I go back to is that smoke in any form is not inherently good for you,” DeVincenzi continues. “I don’t care if it’s smoke from a campfire, tobacco, car exhaust or cannabis—the heat from the smoke and all the agents in the smoke are going to have a detrimental effect on the oral tissue and lung tissue.”
There is some evidence that smoking marijuana can cause an earlier or more serious onset of periodontal disease. Inhaling any type of smoke may worsen bronchitis and impair respiratory immunity.
“A common question and one thing we’re trying to find out is does cannabis affect whether a patient can get numb or not,” says Taylor. “The possibility exists that cannabinoids may affect sodium channel conductance directly, which may make local anesthesia ineffective. Peripherally, sensory neuron ending depolarization may be affected, potentiating AP conductance and rendering anesthesia useless. However, more research is needed in this area.”
Taylor also gets frequent questions about whether marijuana causes cancer. “There are two or three studies showing a possible link to laryngeal cancer,” he says. There have also been studies that indicate an increased risk of pharyngeal cancer and non-seminomatous testicular germ cell tumors, which are an aggressive form of testicular cancer found in some young men. None of these studies have provided definitive proof yet.
Just say no…
to avoiding the subject
Sometimes the bigger problem isn’t that dentists don’t know what to say about marijuana, but that they don’t say anything at all. There are circumstances where it’s critical to talk to patients about their cannabis use.
“If a person is going to use just cannabis that’s one thing, but if they start mixing it with some of the other pain medications it’s an entirely different animal and can cause them problems,” says Carsten. “We need to know because all of these things are pharmacologically active and can potentiate other drugs. Because it’s an anticholinergic, there’s a whole series of side effects. Dentists need to know that because they’re going to write prescriptions.”
Patients sometimes have a perception that weed is “all-natural” and there’s no reason to tell their dentist they’re using it. Remind them that many herbal supplements can be dangerous when combined with certain medications. They need to tell their medical provider about anything that might cause a drug reaction.
Another issue to consider is that medical providers can’t get informed consent from a person who is high. “If you smoked it in the morning, it’s not that different from drinking alcohol,” says Taylor, who points out that both are nervous system depressants. “If a patient came into your office and they’d had a couple beers, you wouldn’t take their consent because they’re under the influence. It’s the same for marijuana.” (Ways to tell if a person is high include red or dry eyes, poor muscle coordination, delayed reaction times, and a sudden onset of panic or anxiety.)
There’s a certain public health benefit to providing some basic education about marijuana and its potential dangers, especially those that exist for young people. DeVincenzi encourages dentists to remind parents that their children are more likely to experience the negative effects of the drug.
“The developing body and mind is not something to be tampered with,” she says. “It’s important to educate parents that there’s strong evidence to support that there are negative consequences to using alcohol or cannabis at a young age when your brain is still developing. Once you’re 25 and your brain is done growing, the effects aren’t going to be as deleterious to your future.”
Many dentists and hygienists are uncomfortable raising the subject of marijuana use with patients. Even though it’s legal, there’s still a stigma attached to it. Carsten encourages dentists to put aside those concerns and find positive ways to bring it up.
“The big takeaway is that dentists and patients need to trust each other,” he says. “Patients need to tell their dentist that they use cannabis. Dentists need to ask.” Not doing so can have consequences that range from inconvenient to downright dangerous.