Cannabis use remains highly prevalent in the US. Recently, youth cannabis use in particular has garnered public attention owing to favorable legality of recreational use across states, the increase in availability of potent cannabis-containing products, and the widespread media coverage of adverse health effects affecting young users [6,8,9]. Our study sought to preliminarily explore potential associations between cannabis use (both lifetime and current use) and measures of oral health and related behaviors among individuals aged 12–25. Where appropriate, findings are discussed with regard to orthodontic care, given that orthodontists commonly treat and interact with this age group on a near-monthly basis over an extended period of time.

Our findings demonstrate several potentially important associations between cannabis use and oral health, though a low prevalence of reported use (both current and lifetime) is a noted limitation. Firstly, patients who reported either current use or lifetime use of cannabis were more likely to report a history of oral lesions, defined as blisters, sores, or ulcers in the oral cavity, to their provider. Other studies have also suggested that cannabis use increases the risk of developing intraoral soft tissue or mucosal lesions [38]. However, significant heterogeneity exists between studies insofar as study designs and definitions of oral lesions are concerned [51,52], and most studies yielded inconclusive findings [53] or were limited to case reports [40,41,54]. Given our findings, it may be warranted for future studies to further assess the frequency and duration for which these lesions appear, as well as investigate the mode of cannabis consumption. Mucosal lesions such as traumatic ulcerations and erosions are known to be more common in children with appliances (e.g., braces or removeable retainers) than without [55,56], so documenting patient cannabis use and demonstrating additional vigilance is recommended for orthodontists.

In addition, our results show that patients who reported using cannabis in their lifetime were more likely to experience bruxism (adverse clenching and grinding of the teeth). This finding is potentially noteworthy as no previous studies have reported associations between bruxism and cannabis use. To the contrary, anecdotical sources have suggested that use of medical cannabis can alleviate bruxing [57]. The reason for our finding is currently unclear, but it is possible that there may be a confounding factor. For example, clinicians have long suspected psychosocial factors, such as stress, anxiety, and depression, to be predictors of bruxism [58,59,60]. It is possible that the cannabis users in this study—those who seek dental care at a university clinic—may be self-medicating with cannabis in order to cope with stress-inducing psychosocial factors in their lives [61,62,63].

A history of bruxism can have orthodontic implications insofar as the selection of treatment modality is concerned. Specifically, clear aligner therapy is often suggested by orthodontists as the appliance of choice in patients with bruxism since the occlusal coverage of aligners can produce a splint or “night guard” effect and prevent adverse enamel-wear [64]. However, some manufacturers of clear aligners suggest that severe bruxism may be considered a contraindication for clear aligner therapy since the extent of the occlusal forces can deform the plastic aligners and reduce treatment efficacy [65]. Nevertheless, studies supporting this claim are lacking and aligners are routinely changed on a weekly or bi-weekly basis, so it seems unlikely that a patient may structurally compromise their aligners that quickly even in the presence of bruxing.

Our findings also demonstrate that both current and lifetime users of cannabis are more likely to report frequent consumption of sugary beverages and snacks, which could affect their caries or periodontal risk. The dietary habits of cannabis users may foster a carious environment in the oral cavity since THC—the main psychotropic agent in cannabis—is an appetite stimulant that can drive consumption of cariogenic foods [66,67]. Other studies have also found increased consumption of sweet beverages among users [36]. While no association between cannabis use and caries or periodontal status were noted in this study, such knowledge may be of value to orthodontists because the use of common fixed appliances for orthodontic treatment, such as braces, are known to significantly increase caries and periodontal risk owing to the greater difficulty in maintaining adequate oral hygiene [68,69,70]. As such, orthodontists should demonstrate even greater prudence in monitoring the oral hygiene of cannabis-using patients. Moreover, the importance of documenting cannabis use during the initial medical review is again underscored.

While our findings did not demonstrate any significant associations between cannabis use and caries or periodontal disease, we would urge caution in prematurely concluding that no such associations exist. Indeed, an incidental finding in this study is that the prevalence of reported cannabis use (both lifetime and current) appears to be underestimated in this sample when compared to nationally representative samples of the same age range [45,71]. In fact, a recent study has demonstrated that the prevalence of current and lifetime use of several drugs, including cannabis, were markedly underestimated when derived from dental EHRs compared to data from the National Survey on Drug Use and Health [72]. While there are likely several patient-related and provider-related reasons for potential underreporting of use, the authors concluded by encouraging dental professionals to regularly ask patients about their drug use history at dental appointments [72]. From a research perspective, underestimated drug use represents a missed opportunity for furthering studies on oral health and drug use, due to the current lack of complete data that encompass both oral health metrics and drug use measures. Therefore, better EHR design and data collection methods are warranted for future research to build upon the present findings.

Routinely underestimated dental data can also have implications from a public health standpoint. Indeed, there remains a sizeable unmet need regarding treatment for individuals that engage in risky drug use behaviors in the US—an estimated 20.4 million Americans aged ≥12 had a substance use disorder in 2019, but only 2.1 million received any form of treatment [71]. Consequently, patient visits to healthcare providers, such as dentists, are increasingly being viewed as alternative opportunities for screening drug use [73,74]. While there have been general calls for dental professionals to demonstrate more diligence towards asking patients about their drug use history [72], orthodontic visits may represent a unique opportunity for providers to engage in discourse with younger patients about their potential drug use. The 12–25 age range is commonly seen by orthodontists, and the nature of typical orthodontic treatment necessitates regular interactions between provider and patient over a prolonged period. This typically facilitates patient-provider rapport in a manner that is different than that of a patient-physician or even patient-dentist. Consequently, orthodontists may represent an underutilized means of preliminary drug use screening among adolescents and young adults.

Finally, from a clinical standpoint, it is important for orthodontists to query patient cannabis use because the drug contains compounds that can influence physiology and affect treatment outcomes. For example, the non-psychoactive cannabidiol (CBD) compound has been shown to reduce inflammation and attenuate bone remodeling [75,76,77,78]. Orthodontic tooth movement is dependent on an inflammatory cascade to induce bone modeling/remodeling and subsequent tooth movement. Therefore, patients who use cannabis may be at risk for impaired tooth movement and longer treatment durations, the latter having been implicated in root resorption, bone loss, and increased risk of enamel demineralization [79,80]. Further studies in this area would be welcome, and better querying of drug use would only serve to increase the quality of data and facilitate research in this area.