by Nancy W. Burkhart, RDH, EdD
Robert presents to your office for a regular maintenance appointment. Your practice has treated Robert for the past 15 years, and you have watched him grow from a child into adulthood. He is now 22 years old, recently graduated from college, and is searching for a first job. Robert tells you that he has had some difficulty in the transition from college life to his new responsibility.
Figure 1: Courtesy of Dr. C.D. Johnson, University of Texas Dental Branch at Houston
You begin your oral cancer detection exam and notice some oral tissue changes — leukoplakia — on the left lateral border of the tongue. Robert was in for a maintenance appointment about a year ago, and you do not remember any lesions or concerns that were noted. So you check your recorded history for any evidence.
You try to make a determination of what causes might produce such a lesion. With further questioning, Robert admits to using marijuana. He consumes no alcohol but tells you that he started using the marijuana in college on a regular basis with a group of friends. He reports smoking marijuana cigarettes daily (see Figure 1).
Overview: Marijuana has been described as the most commonly used illegal drug in the United States. However, a few states are relaxing laws and allowing medical usage of marijuana. Cannabis (marijuana, hashish, and hash oil) is also known as weed, pot, reefer, joint, Mary Jane, ganja, grass, sinsemilla, and dope (see Figure 2). Additionally, cigars may be emptied of some tobacco, refilled with marijuana and are called “blunts.”
Cannabis may be smoked as a cigarette or in a pipe, as well as added to foods. A favorite way to use marijuana is through a “bong” in which the smoke is sucked through a layer of water that cools and removes some of the tar and irritants.
Marijuana use is reported to have risen in recent decades in both adults and children. It is reported that as many as 60% of Americans have experimented with cannabis at some point in their lives. Cho et al. (2005) reported an upward trend in Australia with 40% of the population above age 14 having used the drug at some point in time.
Why is marijuana so widely used?
Reasons that have been reported for the use of recreational marijuana are a sense of euphoria, relaxation, heightened senses, appetite stimulation, and reduced nausea when used for chronic illness. The negative effects are cough, respiratory infections, slowed thinking and reaction time, impaired memory and learning, increased heart rate, panic attacks, and tolerance to the drug.
Withdrawal symptoms from marijuana have been reported to be anxiety, anorexia, dysphoric mood, and sleep disruption that may last several weeks. Even with unpleasant withdrawal symptoms, marijuana has continued to be used. The long-term side effects are not well established because of the absence of well-controlled large studies and nonstandardization of dosages. Many studies have not incorporated lifestyle factors and not considered important classifications of “ever users” (one time or several time users) vs. chronic long-term users. The length of time in usage and a reluctance to divulge usage make conclusions of the long-term effects variable and inconclusive.
Marijuana is less potent than hashish and prepared from the entire cannabis plant (C. sativa) (hashish is made from the resin in the tops of the hemp plant). Although cannabis is sometimes classified as a hallucinogenic agent (a schedule 1 controlled substance), very high doses are required in order for a patient to reach this state. The effects of cannabis are attributed to the main component in the product — THC (9-tetrahydrocannabinol). This agent affects primarily the respiratory, cardiovascular, and immune systems. THC has been shown to be passed through the breast milk of the mother to the nursing baby.
What is in the cannabis plant?
Cannabis has been reported by many as a harmless entity; however, components within the plant have been reported to be more carcinogenic than tobacco. Substances such as carbon monoxide, acetaldehyde, toluene, nitrosamine, naphthalene, vinyl chlorides, phenols, nitrosamines, and various polycyclic aromatic hydrocarbons, benzanthracene, and benzopyrene are commonly found within the final product.
Because of the high concentration of chemicals, smoking a marijuana cigarette has been reported to have the effect on the tracheobronchial epithelium of smoking 20 tobacco cigarettes (Fligiel, 1997). Someone who smokes five marijuana cigarettes a week may take in as much cancer-causing chemicals as someone who smokes a pack of cigarettes a day (Hale, 2007).
The contents of the marijuana will vary from location to location, from country to country, and state to state. The individual usage of marijuana is variable and often is combined with other lifestyle factors (such as other illicit drug use, alcohol use, medications, diet, and environmental factors). Added to the mixture is the person’s genetic makeup, and this renders the effect of usage different with each individual. Research studies often do not consider these factors in combination, and most documentation will rely on the person reporting these factors. Warnakulasuriya (2009) categorized cannabis use as having inconsistent, limited or no evidence for the promotion of oral cancers.
What do we know from research reports?
Heavy use of cannabis has been reported to cause respiratory problems, bronchial complaints, diarrhea, abdominal cramps, tachycardia, acute panic, acute paranoia, flashbacks, impairment of short-term memory and motor skills, along with immunosuppressive effects. Yamreudeewong et al. (2009) reported a probable interaction between warfarin, used for management of thromboembolic disease, deep venous thrombosis, atrial fibrillation, and marijuana smoking. Macrophages, natural killer cells, and both T and B lymphocytes are affected by the use of marijuana.
The most beneficial use of marijuana is its antiemetic properties in patients who are receiving chemotherapy and its ability to reduce intraocular pressure in the treatment of glaucoma. Cannabis may be used for cancer patients, AIDS patients, and other chronic disease states to produce a sense of euphoria. In recent years, synthetic oral cannabinoids such as dronabinol (Marinol) and nabilone (Cesamet) have been approved for control of chemotherapy-induced nausea and vomiting that does not respond to other antiemetic treatments. Cannabis spray has been used in the treatment of patients with multiple sclerosis (MS) for spasms with some adverse effects (in four out of nine patients) such as a stinging sensation and white lesions in the floor of the mouth (C. Scully, 2007). The base products of the solution were peppermint flavoring with a high alcohol component.
What do we know about the intraoral effects?
Heavy use may cause xerostomia in the mouth and dryness in the throat due to the parasympatholytic properties of the product, irritation of oral tissues, edema, and erythema of the uvula. As an added detriment, the xerostomia may enhance the rate of caries in the individual. The high temperature of the burning product on the oral tissues causes some tissue change and cellular disruption.
Thomson et al. (2008) reported a correlation of increased periodontal disease in a study population of 1,015 who were assessed at age 32. The researchers assessed the use of cannabis in the study population. They concluded that smoking cannabis may be a risk factor for the development of periodontal disease that is independent of the use of tobacco. Recent studies by Lopez and Baelum (2009) found no correlation in a group of adolescents and the use of cannabis. However, the study participants varied greatly in age and length of usage time from adolescents in the Lopez study and a 32-year-old age group in the Thompson study.
Additionally, oral leukoplakia/erythroplakia, leukoedema due to repeated irritation to the tissue, has been reported, and hyperkeratotic lesions have been documented. Candida (Candida albicans) has been reported to be higher in marijuana users compared with tobacco users.
The long-term effects of heavy use of marijuana have not been well-documented with regard to long-term cognition and the effects on pregnancy and the unborn child, although some childhood illnesses have been reported to be increased.
The association with oral cancer is not clear at this time, and a definite association has not been established.
In most studies, “ever users” may be affected much differently than those who would be considered “chronic, long-term users” and the interaction of tobacco products that are mixed with cannabis may greatly vary in composition and strength. Hashibe et al. (2005) points out that associations between marijuana use and cancer risk are often based on questionnaires, subject recall, subject honesty, and that confounders such as tobacco and excessive alcohol use must be assessed. Since these are not socially approved behaviors, there is reluctance on accurate exposure of these behaviors by the patient.
There is reported incidence of tachycardia and peripheral dilation associated with acute marijuana toxicity when an anesthetic is administered and anxiety in the patient may add to these symptoms. It is advised that the patient discontinue use for one week before having dental work completed when anesthesia is needed. Rosenblatt et al. (2004) makes the point that marijuana cigarettes do not contain filters as tobacco cigarettes do and that marijuana smokers may inhale more deeply and hold the smoke in their lungs longer. This is an explanation of why higher tar levels may be present and could also promote lung cancer. As the use of marijuana continues to increase with more states legalizing the use, we may see a rise in the numbers of individuals with both oral cancer and lung cancer.
Any lesion noticed in the mouth should be evaluated and an etiology should be determined. It is helpful to know that the oral effects of marijuana use have been documented and described. The dental clinician should be familiar with the possible signs of cannabis use whether it is used as a recreational drug or for medicinal purposes. This knowledge of the tissue changes associated with the use of cannabis assists the dental professional in determining a specific lesion etiology.
There is an old saying, “If you only have a hammer, you will only see nails,” and this may be true with regard to a dental clinician’s repertoire of possible lesion etiology. Unless the lesions associated with marijuana use have caused ulcerative or noticeable keratotic, leukoplakia, or leukoedema type lesions, there is no treatment suggested unless it is encouragement or support to discontinue the drug. Patient education for xerostomia and advice on the various products available to combat mouth dryness would be beneficial to the patient. Candida may be a factor as well and treatment may be necessary.
Perhaps counseling the patient about the effects of marijuana and the unknown ramifications that may be part of long-term use of the drug is warranted. In the case of medicinal use, benefits have been established for some disease states. As mentioned previously, the changes that occur in the tissue, the possible periodontal changes, and systemic changes should be considered in oral evaluations.
Keep asking good questions and listen to the answers!
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Nancy W. Burkhart, BSDH, EdD, is an adjunct associate professor in the department of periodontics, Baylor College of Dentistry and the Texas A & M Health Science Center, Dallas. Dr. Burkhart is founder and co-host of the International Oral Lichen Planus Support Group http://www.bcd.tamhsc.edu/outreach/lichen/ and coauthor of General and Oral Pathology for the Dental Hygienist. Her Web site for seminars is www.nancywburkhart.com.