Cannabis smoking has become much more common (and acceptable) in recent years. Recreational marijuana is legal in twenty states, and medical marijuana is legal in thirty-six. According to the CDC, 18 percent of Americans used marijuana in 2019. 1 It is estimated that about 90 % of users smoke it. 2 Smoking may negatively affect the mouth, teeth, and gums. Negative effects include periodontitis (gum disease), caries (tooth decay), xerostomia (dry mouth), a decreased salivary pH (increased acidity), and an increase in the density of Candida albicans (yeast infection, thrush). 3 This post will only discuss dental problems associated with the legal smoking of marijuana by adults; I will not touch upon other routes of ingestion of marijuana or its effects on any other part of the body other than the mouth.

Tooth Decay

In one study of 85 individuals, smoking cigarettes versus cannabis smoking was compared. Both caused oral issues, but the cannabis users had significantly more surfaces of their teeth decay. 4 The primary difference is that cannabis users have dryer mouths (xerostomia, hyposalivation) which causes a higher incidence of decay on the smooth surfaces of teeth. 5 

Thrush

A review of 982 research papers revealed higher amounts of the oral yeast Candida albicans in cannabis smokers. 6 Candida is responsible for yeast infections, also called thrush. Another study reported that, although it is infrequently reported, oral candidiasis may occur in cannabis smokers. 7

Dry Mouth

The dry mouth associated with cannabis use can cause other problems in the mouth. Halitosis (bad breath) is common. One study of around 340 subjects demonstrated that the dryness caused traumatic ulcers and leukoedema, a mild inflammation of the oral mucosa. 8. Fiery red papilloma (benign growths) and uvulitis are common conditions and lesions among cannabis smokers, also secondary to dry mouth. Furthermore, dryness is associated with gum disease (periodontitis). 9 

General Anesthesia and Sedation

Patients who smoke cannabis within three days before general anesthesia experience a sustained increase in heart rate (tachycardia); this complication limits their ability to cope with intraoperative and postoperative stress. THC, the active ingredient in marijuana, causes a 24% increase in heart rate. The issue with general anesthesia and sedation is that the compensatory mechanism to correct arrhythmia is greatly diminished with cannabis intake. This causes a dangerous situation where death can result. 10 Compounding the issue is patients' reluctance to admit cannabis use.

Negative Dental Behaviors

Cannabis smokers reported brushing their teeth less frequently and failed to consult their dentist regularly. Cannabis smokers are also likely to use another substance with known harmful effects, making the combined effects of cannabis and other substances worse. When patients are impaired by cannabis use, dentists are sometimes reluctant to grant informed consent and postpone treatment until the patient is coherent enough to consent to treatment properly. 11

Green Tongue

Police officers have been under the false impression that cannabis use leads to a green tongue. A 1986 police handbook on recognizing marijuana users may be to blame. 12 However, there is no scientific literature on the subject, so green tongue is more than likely not caused by cannabis use.

Conclusion

Lifestyle combined with short-term hyposalivation after cannabis consumption is the most probable cause of the problems associated with its use. Smoke is an irritant and can also be blamed. Surprisingly, there is only a weak link between smoking cannabis and testicular cancer. Since cannabis is legal in many states, we will likely see more and more use. There are other methods of consuming cannabis, like eating it. However, hyposalivation and lifestyle issues will remain a consequence. It may be a more desirable method of consumption to avoid exposure to smoke. Limited evidence of an association between marijuana smoking and testicular cancer has been documented because the same toxins and carcinogens are found in tobacco and marijuana smoke.