Cannabis is the most abused drug in most countries of the world. An estimated 147 million people use cannabis globally, mainly for recreational purposes. In Canada, 4.2 million people aged 15 and older reported using cannabis products in the previous three months, and a third of surveyed youths had consumed cannabis at least once by their 15th birthday. In addition, national consumption levels have risen annually since 1985, driven mainly by cannabis use among Canadians aged 25 years and older.
Smoking cannabis has adverse effects on multiple human organs including the oral cavity. The plant comprises over 400 chemical entities with the two main compounds, delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), shown to have opposing effects on many human organs. People who smoke cannabis usually experience an altered mental state (psychoactive feeling) that commences within a few minutes and can last up to three hours. The long-term effects of cannabis use include low birthweight, structural, functional and chemical changes in the brain, early onset psychosis, strokes, testicular cancer, suicide tendencies and deficiency in motor function and learning. It is estimated that up to 17% of people who start consuming cannabis as adolescents will develop cannabis use syndrome (irritability, anger, depression, difficulty sleeping, craving and decreased appetite). In the oral cavity, smoking cannabis has been associated with periodontal disease, dental caries and oral cancers.
Objectives: To summarize evidence relating cannabis smoking and oral disease and highlight any potential influence of cannabis smoking on clinical care and dental public health.
Methods: Using rapid evidence review, a librarian facilitated a systematic search of five electronic databases in August and September 2018 and updated it in March 2019, yielding 581 publications. Two researchers screened the documents using pre-established inclusion criteria: article was based on primary or secondary data; cannabis smoking was an exposure; at least 1 cannabis-related oral health outcome was reported; participants were humans; and the article was available in English or French. Data from retained articles were analyzed for themes without meta-analysis.
Results: We synthesized and summarized 23 articles in two broad categories: cannabis and oral disease; and cannabis, clinical care and dental public health. Current evidence shows that smoking cannabis is harmful to the health of the periodontium. The association between smoking cannabis and other oral disease (dental caries, soft tissue lesions and oral cancers) is sparse and inconsistent, although studies suggest that cannabis smoking is an underlying risk factor. Cannabis smoking can lead to an altered mental state that can delay dental treatment of the patient. Further, interactions between smoked cannabis and adrenaline-containing local anesthetics can result in life-threatening consequences.
Conclusions: Cannabis smoking is harmful to the periodontium. Further research is needed to fully understand how cannabis smoking affects oral disease and how dental professionals should integrate this knowledge into clinical care and dental public health.