Almost a third of Americans have smoked or otherwise consumed marijuana five times or more. In 2000, almost a fifth of Americans were found to be marijuana users. It’s equally as consumed around the world, with almost a fifth of Australians having been found to use it within the past 12 months. Suffice to say, it’s popular — and not just for recreational reasons, but for medical purposes as well.

Here in Pennsylvania, marijuana has become a hot topic again. The relatively recent decision to legalize marijuana for some medical uses has fueled the debate.

I come to neither condone nor condemn. I don’t judge! 😊

As a dentist, I just want to talk about the role marijuana can play with regards to oral health and what a marijuana user can do about it.

First, let’s talk about the science:

What does science have to say about weed and oral wellbeing?

There are several ways cannabis can affect your dental health, some directly and some indirectly. It’s important to keep in mind that marijuana can be ingested several different ways and this can have an important impact on how it affects your health, so for the purposes of this discussion we’ll assume we’re talking about smoking it, specifically.

The first way marijuana can affect the state of your teeth, gums, and your oral anatomy in general is by causing “dry mouth,” which is a reduction in saliva production.

What does saliva do for you?

Saliva helps to protect the oral mucosa, which is a tissue that helps protect the inside of your mouth. It also helps to clean your teeth and gum from the bacteria that cause tooth decay and gum disease. Overall, saliva is one of the most important defenses your body has against oral complications. It makes sense, then, that anything that reduces the amount of saliva production can have an impact on your health.

In 2009, Schulz-Katterbach published a study that tracked 85 participants and split them into groups, one group with tobacco smokers only and the other with patients who smoked both tobacco and cannabis. He found that 69.6% of the second group (people who smoked both) had experienced extensive dry mouth, while only 18.6% of the first group (tobacco smokers only) reported similar experiences. A 1981 paper by Di Cugno and Tocci found that the rate at which cannabis users suffer from dental caries (tooth decay) is 2.5 times higher than the control group.

Similarly, in a 1993 paper, Darling and Arendorf found that the biggest, and perhaps only significant, difference between weed consumers and tobacco smokers was soft tissue lesions and disease — tooth decay and gum disease.

Are dental health issues related to marijuana use entirely due to restricted saliva production, though? Probably not.

This is where the indirect effects come into play.

The aforementioned Schulz-Katterback study also found that cannabis users are less likely to brush their teeth or visit the dentist than those who only use tobacco. What is that really saying? These studies don’t explicitly establish causation, so it doesn’t necessarily mean that marijuana smokers simply get lazy and don’t go to the dentist. It could be that people who don’t go to the dentist as often as others are just more likely to smoke marijuana. Still, the point remains that the relationship between marijuana use and poorer dental health, due to poorer dental hygiene decisions, has been established in the data.

Keep in mind I’m not approaching this from a doom-and-gloom angle. I’m not saying, “Stop smoking marijuana NOW or else your teeth will fall out!”

If you are conscious of your wellbeing and your dental hygiene is on point, then these studies don’t really address your specific habits. And I’ll offer some hygiene tips that cannabis users can keep at the back of their mind to avoid many of the problems that these academic papers bring up.

Before we delve into these tips, there’s another oral health problem that is relevant to marijuana use: oral cancer. This is a serious issue, so let’s cut straight to the chase here.

Marijuana and Oral Cancer

Cannabis smoke contains 50 percent more carcinogenic hydrocarbons than tobacco (!). You also retain a third more tar in your lungs than if you smoked cigarettes. Sounds terrible, right? Let’s see what the studies say.

In 2005, Hashibe, et. al. (a.k.a. a bunch of other authors), published a paper that specifically reviewed marijuana use and oral cancer. They found a positive correlation between weed use and two types of cancer — oral and laryngeal. HOWEVER, after controlling for tobacco, this relationship was no longer seen. Two more studies found no relationship, including one by Rosenblatt, et. al., and Llewyllin, et. al.

All this said, a study by Zhang and others did find a positive relationship between cannabis use and head and neck cancer.

The truth is, the jury is still out, as they say. This brings me to an important point about science:

The science is young

These studies suffer from drawbacks.

First, most of the time, sample sizes are small. What does this mean? We know there’s a 50-50 chance of a coin landing heads or tails. But if you toss a quarter four times, you might get heads all four times. We know the actual probability because we’ve flipped enough quarters throughout history to have a large sample size, and so on average coins do have 50-50 probabilities. That’s the thing, though. Sample size matters. Too small of a sample size, and the probabilities you experience may be off.

If the sample sizes on these studies are inadequate, then the results may be subject to biases that would be eliminated if the samples were larger (and therefore had a higher likelihood of being random and actually representative of the population at large).

Second, statistical methods matter. Sometimes scientists will use the same data sets and run the same tests and get different results. Just like with the toss of a coin, you really do need a large pool of studies, each with adequate sample sizes, that you can then aggregate and come out with an average.

When you interpret these studies, their drawbacks should always be at the back of your mind. This doesn’t mean it’s wise to discount them, it’s just smart to be skeptical in the sense of knowing that there’s more to the story.

Allow me to nerd out even more for a brief moment. We all have priors. They are the beliefs we start with. These studies shouldn’t replace our priors, they should cause us to adjust them. There’s a big difference. I would have thought there was a stronger relationship between cancer and marijuana, but several studies say otherwise. I’m not swayed that there’s no relationship at all, but so far the evidence has definitely caused me to adjust to what degree I think that relationship exists. Now I am a little bit less certain of my position.

That’s how I recommend you take these studies. You don’t have to buy them completely, you should just consider them.

Okay, back to the topic at hand. Let’s talk about what cannabis users can do to lower the likelihood of oral health complications due to marijuana use:

Oral Hygiene Tips to Keep in Mind When Smokin’ the Reefer

The studies show that cannabis users are less likely to visit the dentist and less likely to brush their teeth. Both of those things are easily solvable, right?

Brush your teeth at least twice a day (and floss)

Visit your dentist for a simple hygiene appointment, once every six months

Just like that, you’ve taken yourself out of the pool of people those studies address. And these habits aren’t specific to marijuana users. They apply to all patients, but the research says that cannabis users may be less cognizant of the need to do those things (although again, the causality is unclear).

Another thing I recommend is to use alcohol-free mouthwash. This is not an end-all, be-all, but it can help prevent oral diseases and infections. Why alcohol-free? Because alcohol also creates dry mouth, and that may decrease saliva production.

Saliva production was one of the main issues that the mentioned studies harped on. What can you do about that? One way to mitigate these problems is to drink more water when you smoke. Stay hydrated — water also helps to clean your teeth and it protects the various tissues that compose your oral anatomy.

Finally, a commonly mentioned indirect effect of marijuana is that it causes its consumer to eat more. There’s a tendency to eat carbohydrate heavy foods. Carbs are the elements that bacteria use to produce the acid that cause tooth decay and gum disease. By itself, and especially when paired with poor oral hygiene, the consequences can be drastic. This is something a marijuana consumer should be aware of. We already talked about the importance of hygiene and dental visits, but it’s also important to discipline ourselves on what we eat.

The Bottom Line

The research is still shallow, but it has shown that marijuana users tend to suffer from a higher risk of oral infection and other dental complications on average. Does this mean you should immediately stop smoking because otherwise your teeth will fall out?

As a dentist, I can’t say smoking marijuana is good for you. But, again, I don’t want to be that person who shakes their finger at you and your habits. Who am I to do that?

All I want to do is to make you aware of what the research has said, what it means to you, and what you can do about it. And I hope that to that end I’ve been helpful.