Cannabis Legalization and Oral Health

What Dental Hygienists Need to Know

by Roula Anastasopoulos RDH, BEd

The legalization of cannabis use in Canada dates back to 2001 when it became legal for medical purposes. It has since expanded to legalization for recreational use on October 17, 2018.

With this new expansion of legalization, there is a chance that the number of cannabis users may increase, and as such, dental hygienists need to be informed of the various forms of cannabis available, its effects on oral health, and implications to dental hygiene care.

What Is Medical Cannabis?

Medical cannabis is the use of the natural and unprocessed plant or chemical to help alleviate symptoms of certain conditions or diseases. The cannabis plant contains many chemicals known as cannabinoids, which influence your endocannabinoid system affecting mood, appetite, memory
and pain sensation.

The two main cannabinoids from a cannabis plant are:

  1. delta-9-Tetrahydrocannabinol or THC – this compound
    produces a psychoactive effect or a ‘high’.
  2. Cannabidiol or CBD – this compound does not produce
    any psychoactive effects and contains anti‑inflammatory
    and analgesic properties.

The cannabis used for medicinal purposes contains a higher CBD, which helps alleviate symptoms in some conditions but does not produce a psychoactive effect. Medical cannabis is currently being used to minimize symptoms in conditions such as: Alzheimer’s, cancer, Crohn’s disease, certain mental health conditions, multiple sclerosis, and chronic pain.

Currently there are two cannabis-based medications available
in Canada:

  • Nabilone – available in a capsule form, used mainly as an antiemetic in the prevention of chemotherapy-induced nausea and vomiting.
  • Nabiximols – available in an oromucosal spray, used
    mainly as an analgesic for cancer and multiple sclerosis

Possession and use of medical cannabis is legal in Ontario, provided a valid and current prescription is obtained from a medical doctor.

What Is Recreational Cannabis?

Recreational cannabis is used without medical justification. Often, recreational cannabis contains more THC, as this is what provides users with the ‘high’. Until recently, the possession and use of recreational cannabis was illegal, however, with the new legislation, people 19 years of age and older will be able to purchase, possess and use recreational cannabis legally.

“To ensure public safety, the Ontario Government has executed new laws surrounding how, where and who can buy, possess and consume cannabis in the province. These new laws are very similar to the existing laws in place for alcohol and tobacco and include the following:

  • The Ontario Cannabis Store website is the only legal option for purchasing recreational cannabis.
  • The use of recreational cannabis is permitted in areas stated by the legislation.
  • The use of recreational cannabis will continue to be illegal in the workplace.
  • The maximum purchase and possession limit is up to 30 grams of dried cannabis at one time for personal use.” (1)

Pharmacological and General Health Effects

Recreational and medicinal cannabis can be consumed by four different methods: inhalation, orally, topically and in suppositories/tampons.

The use of cannabis affects multiple body systems but has more profound effects on the cardiovascular, respiratory and central nervous system. Its effects will depend on the preparation and mode of transmission and will vary between individuals. Depending on mode of consumption, cannabis can reach the brain within seconds and its effects can be felt within minutes. Cannabis is metabolized in the liver and accumulates in adipose tissue. The tissue elimination of cannabis can take up to seven days, but total elimination of cannabis from the body can take up to thirty days.
The THC in cannabis will have an acute effect on the cardiovascular system that will cause tachycardia and widespread vasodilation. This consistent increase in heart rate will create an increase in oxygen demand requiring the heart to work harder. Long-term cannabis use increases one’s risk for cardiovascular diseases such as angina, stroke and myocardial infarction.
Cannabis use through inhalation directly affects the respiratory system. Cannabis contains many of the same carcinogens as tobacco, including carbon monoxide, bronchial irritants and tar. Smoking of cannabis is
associated with chronic inflammation of the airway causing increased airway resistance, compromising the respiratory system. Long-term cannabis smokers can present with symptoms such as coughing, wheezing,
bronchitis, emphysema, cardiopulmonary disorders and may be at greater risk for respiratory infections and pneumonia. (2)

The THC in cannabis enters the bloodstream and directly affects the central nervous system by binding to two main receptors. When THC binds to the CB1 receptors involved in brain function, the result can be cognitive impairment, memory loss, difficulty with attention, time distortion and euphoria. When THC binds to CB2 receptors involved in immune cell
function, it creates an immunosuppressive effect on macrophages, natural-killer cells, T and B lymphocytes, resulting in a decrease host resistance to bacterial and viral infections. (3)

Research studies have found that cannabis use may also be related to complications such as:

  • Acute kidney injury
  • Seizures
  • Psychiatric problems (psychosis, mania,
  • paranoia, self-harm and suicidal behaviours)
  • Hyperemesis
  • Nervous system disorders

In addition, studies have shown that cannabis use during adolescence and early adulthood is hazardous to the developing brain, affecting cognition, memory and increasing the risk of psychosis, depression and anxiety disorder. (4)

Oral Adverse Effects
With inhalation being the most common route of administration for recreational cannabis, it presents with the most oral effects. Generally, cannabis users who choose to smoke or inhale have poorer oral health than non-smokers. The most important side effect is xerostomia which has a direct relationship to the significantly higher prevalence of caries seen in smokers
of cannabis. In addition, the cannabinoid THC is an appetite stimulant which can lead to increased consumption of cariogenic foods. (3)
Cannabis users are also more prone to oral infections such as candidiasis. The immunosuppressive effect of THC could potentially allow opportunistic infections to proliferate and become clinically evident. Scientists believe that the hydrocarbons present in cannabis provide an energy source for Candida albicans resulting in an increase of oral fungal infections. (2)

Studies have shown a direct relationship between cannabis use and periodontal disease. Frequent users of cannabis presented with higher number of sites with pocket depths greater than 4mm and attachment loss when compared to non-users. In addition, periodontitis may occur at an earlier age in cannabis users than non-users. (5)

The use of cannabis through inhalation has also been found to have a direct effect on the oral soft tissues in higher and lower frequency. (6)

Dental Care Implications
A client that is ‘high’ or intoxicated by the use of cannabis may present difficulties for the dental hygienist. It is important to recognize signs of intoxication in order to determine and ensure that safe dental hygiene treatment can be provided.

Signs of potential intoxication might include:

If a client presents for dental hygiene care while intoxicated, the dental hygienist should consider postponing care since dental treatment can create heightened stress resulting in the client experiencing acute anxiety, dysphoria and psychotic-like paranoiac thoughts. (8) In addition, due to the increased heart rate and tachycardia experienced during intoxication, the use of local anaesthetic with epinephrine can seriously prolong these cardiovascular effects and create a potentially life threatening medical emergency. (8)

Finally, the dental hygienist should consider the legal implications surrounding the validity of informed consent obtained by an intoxicated client. Cannabis can impair the client’s decision-making capacity which would impact their understanding of the necessary information required for informed consent such as:

  • the nature of treatment,
  • the expected benefits of treatment,
  • the material risks of the treatment,
  • the material side effects of the treatment,
  • alternative courses of action, and
  • the consequences of not having treatment.

Dental hygienists are obligated to provide safe care and should use their professional judgment to determine if the client has the capacity to cognitively provide consent to dental hygiene treatment.

Things to Consider

  • Questions concerning cannabis use should be asked on the medical history.
  • Distinguishing between medicinal and recreational use can provide important information on possible comorbidities.
  • Verification of cannabis may require the need to assess vitals, capacity, etc., at every appointment.
  • Highlight the importance of regular dental hygiene care.
  • Include the management of oral side effects.

Examples of Questions to Add to a Health History

– Do you use cannabis?
– Do you use cannabis for recreational or medicinal purposes?
– If medical, what is the medical condition it is being used for?
– What is your mode of administration of cannabis?
– When was the last time you used cannabis?
– How frequently do you use cannabis?

With the legalization of cannabis in Ontario, dental hygienists are likely to encounter cannabis users more frequently. It is important to remain current with changes in applicable laws on recreational or medicinal cannabis and to be knowledgeable about cannabis use and its potential impact on general and oral health. To ensure safe and effective client care, dental hygienists should be cognizant of the oral implications and risks associated with cannabis use. They should remain free of judgment and promote open discussions in order for clients to feel secure in disclosing information related to cannabis use.


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  3. Joshi S, Ashley M. Cannabis: A joint problem for patients and the dental profession. Br Dent J 2016;220(11):597-601.
  4. Wang T, Collet J-P, Shapiro S, Ware MA. Adverse effects of medical cannabinoids: a systematic review. CMAJ : Canadian
    Medical Association Journal 2008;178(13):1669-78.
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    Use and Periodontitis in Adults in the United States: National Health and Nutrition Examination Survey 2011 to 2012.
    J Periodontol 2017;88(3):273-80.
  6. Rawal SY, Tatakis DN, Tipton D. Periodontal and oral manifestations of marijuana use. Journal of the Tennessee Dental
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