Legality in Ontario

At the moment (September 2019) cannabis products in edible form (“edibles”) are illegal in Ontario. That will soon change however: on October 17 2019 new regulations will come into effect, paving the way for some forms of cannabis products — including edibles — as early as December 2019. At that time some other cannabis products, such as drinks, extracts, and topicals will also become legal. This is not to say that consumption of cannabis edibles does not already exist; however, the new legality of edibles means that some new users of edibles might also be created.

Whether legal or illegal (or whether recreational or pharmacological), edibles pose numerous significant challenges in dentistry, including some that are not well recognized.

What Make Edibles a Complex Issue in Dentistry?

Edibles introduce numerous complex issues into dentistry because they affect a variety of areas: pharmacological, legal, clinical, and oral health among them. Some of these areas relate to edibles specifically, while other relate to cannabis use more generally.

Differences between oral and inhaled cannabis: Unknowns and unpredictables

Ingesting cannabis orally and inhaling cannabis are quite different things, with different implications for dentistry. As the table below shows, orally ingested cannabis is metabolized through the liver, takes longer for its effects to be felt by the user, affects the user for a longer duration, is more difficult to assess dosage, and can be more variable in potency.

From the dental point of view, because orally ingested cannabinoids are metabolized through the liver, they can interact with other things, such as dental anaesthetics and antibiotics.

The characteristics of slower impact, longer duration, difficulty in assessing dosage, and variability in potency all amount to users being less likely to avoid being under the influence while visiting the dentist: a problem for both the dentist and the patient. Being high at the dentist can be accompanied by enhanced feelings of anxiety and paranoia, and a dentist will refuse to treat a patient they believe to be high.

The significantly long duration of ingested cannabis means that patients will need to allow a very substantial length of time between using and attending a dental appointment: estimate in term of days, not hours. Understanding one’s personal susceptibility to the effects of ingested cannabinoids is very important.

Cannabinoids and Dental Anaesthetics

Local anaesthetics

Dentistry often uses local anaesthetics that in combination with epinephrine (adrenaline) provide a suitable local anaesthetic experience.

“When epinephrine is mixed with local anaesthetic, such as bupivacaine or lidocaine, and used for local anesthesia or intrathecal injection, it prolongs the numbing effect and motor block effect of the anesthetic by up to an hour. Epinephrine is frequently combined with local anesthetic and can cause panic attacks.”

Source: Wikipedia entry “Epinephrine”.

However, when the effects of cannabis on the body’s production of adrenaline are added into the mix, both the duration and psychological experience of the anesthesia become unpredictable.

General anaesthetics

Under general anaesthesia, use of cannabis has been shown to potentially lead to cardiac arrythhmias and depressed breathing. For these reasons use of cannabis (in both inhaled or edible form) should be ceased at least 72 hours prior to general anaesthesia.

In addition, because oral cannabis is metabolized in the liver (as noted above), it has potential interaction with opioids and pain killers used in general anaesthesia:

“Oral cannabis is commonly used to deliver medicinal THC and results in high first-pass levels of cannabinoids in the liver, which could have effects on opioid metabolism different from those caused by vaporized cannabis. Therefore, further research is needed to determine how different cannabis delivery systems affect the metabolism of opioids and other drugs.”

Source: https://www.theroc.us/researchlibrary/Cannabinoid%E2%80%93Opioid%20Interaction%20in%20Chronic%20Pain.pdf

Other Adverse Effects of Orally Ingested Cannabis

While the negative aspects of edibles noted above are the most significant in the immediate, it should also be mentioned that edible cannabis is in many senses just another food, from the point of view of mouth care. Because many times edibles are packages as sweet treats or candies, they pose the same risks to oral health as other sugar-heavy foods. Users should be aware that sugars in the mouth are a primary cause of tooth decay, and in the case of edibles it’s possible that people eating them might not be inclined to clean their teeth promptly. In addition, edibles can, like other foods, cause dry mouth, another cause of tooth decay.

The Bottom Line on Edibles and Dentistry

For the reasons above, it’s clear that edibles and dentistry don’t mix. Users of cannabis edibles should allow a generous amount of time between consuming edibles and visiting their dentist, both for medical and psychological reasons. Moreover, remember that a dentist will dismiss a patient who appears under the influence of cannabis, whether oral or inhaled. The pharmacology of cannabinoids is not well enough understood, and the effects of edibles too long-lasting and unpredictable to risk a successful dental appointment.