Cannabis: A Joint problem for Patients and the Dental Team PDF

ARTICLE CPD: ONE HOUR...

ARTICLE CPD: ONE HOUR ©Nathan Griffith / Corbis Documentary / Getty Images Plus Cannabis: a joint problem for patients and the dental team By S. Joshi1 and M. Ashley1 Cannabis is one of the most commonly abused drugs in the UK. whereas 16.3% of young adults aged 16 to 24 used cannabis in the The debate about its legality has grown in recent times but the same period. Even though there has been a steady decline from health implication of cannabis use is an issue of today. It is a drug 20062015, cannabis still appears to be a favoured drug amongst commonly described as being ‘soft’ but its use has profound young adults aged 16 to 24.2 effects on many of the body’s systems, including the oral cavity. Cannabis is referred to by many different names but is commonly This is of particular importance to the dental clinician. This known as marijuana, hashish and hash oil. Its historic and current article aims to discuss the oral implications of cannabis use use extends from medicinal, recreational and religious purposes.3 and provide advice on ways in which dental professionals can It is derived from a plant called Cannabis sativa, which is grown in approach this sensitive topic and provide support. varying climates but usually indoors. The drug itself is extracted through drying and pressing of the plant.4 INTRODUCTION There are many different preparation methods for cannabis, the Cannabis is a plant-derived drug that has been used most common being in the form of dried leaves and flower, which extensively worldwide since 500 AD and is one of the most is referred to as marijuana. Marijuana is usually smoked in hand commonly abused drugs across the globe.1 It has been constructed cigarettes, known as ‘joints’. It can also be smoked reported that approximately 147 million people (2.5%) through a water pipe or vaporiser. Alternatively, the dried leaves worldwide use cannabis. and flowers are added to food and consumed to elicit intoxication.4 In England and Wales the most commonly used Hashish, on the other hand, is formed into small light brown to black illegal drug is cannabis.2 It is classified as a class B blocks, which consist of the resin extract from the flower head.5 Hash drug. Recent statistics show that approximately 6.7% oil, a more concentrated liquid is derived from hashish and is less of adults aged 16 to 59 used cannabis in 2014/2015, commonly used. 1 University of Manchester 21 BDJ Team www.nature.com/BDJTeam © 2 0 1 6 M a c m i l l a n P u b l i s h e r s L i m i t e d , p a r t o f S p r i n g e r N a t u r e. A l l r i g h t s r e s e r v e d.  ARTICLE Delta9-tetrahydrocannabinol (THC) Table 1 The average concentration of THC on three different preparations of Cannabis contains a total of 66 cannabinoids cannabis of which delta9-tetrahydrocannabinol (THC) Cannabis form Concentration (%) has been identified to be the most potent. This is also mainly responsible for eliciting the Marijuana 9.6 psychoactive effects.6 THC has a mimicry action similar to Hashish 14.8 a few endogenous compounds, namely Hashish oil 66.4 Narachidonylethanolamide (anandamide) and 2arachidonoylglycerol (2AG).7 Therefore, THC has a natural affinity for specific Table 2 The difference between tobacco and cannabis receptors found within the endocannabinoid Cannabis joints are usually smoked for a longer period of time than tobacco.4 system of the human body. There are two types of cannabinoid Cannabis joints are usually smoked to a shorter joint length, which results in a greater receptors, CB1 and CB2 on which THC number of toxins entering the mouth.4 interacts to produce its effect. They are found Cannabis has a higher combustion temperature compared to tobacco.4 in various locations but CB1 receptors are There is greater carboxyhaemoglobin concentration and tar retention in lower airway densely populated in the brain, whereas CB2 in cannabis smokers.4 receptors are found in larger numbers on immune cells and other tissues such as the Tobacco found in cigarettes is regulated. Cannabis is a non-regulated substance. gastrointestinal tract.8 Tobacco is usually smoked more frequently than cannabis due to the shorter half life The concentration of THC within a given of nicotine.4 preparation of cannabis varies considerably.9 The table below shows the average concentration of THC in three different The ingestion of cannabis with foods is and their effects on the body are hugely preparations of cannabis.10 It is clear that another route of administration, but the unpredictable.16 hashish oil, on average, contains six times as onset of the psychoactive effects are usually The manipulation of compounds to avoid much THC than marijuana (Table 1). delayed by 1-3 hours.1 This is primarily due the law has created a situation which poses to the longer absorption process via the new and rapidly changing challenges for Route of administration gastrointestinal tract. Therefore, the onset the Department of Health and other sectors Cannabis is most commonly smoked time is highly unpredictable and the duration within the UK. The acute and chronic in ‘joints’; this rapidly administers the of action has been found to be considerably psychological and general effects of these cannabinoid THC.6 During the smoking prolonged.5,13 NPS are unclear and strategies to tackle this process, approximately 50% of the available growing problem are being reviewed. THC is inhaled whilst the remainder is New psychoactive substances lost as heat or smoke.3 The effects of THC A growing concern for many is the emerging General effects of cannabis use are apparent within minutes and usually trend of new psychoactive substances (NPS) Cannabis use affects multiple bodily diminish after 2-3 hours.11 After the also referred to as ‘legal highs’, ‘designer systems, some more profoundly such as the experienced effects THC remains present drugs’ and ‘club drugs’. These substances are respiratory, cardiovascular and the central within adipose tissue for approximately 30 not regulated and may appear safe due to the nervous system. Its effects vary considerably days while it is slowly released back into loosely attached term ‘legal’ but a number of between individuals, and also depend on the the body.11 these drugs have been found to be controlled preparation and the mode of intoxication.17 Alternatively, cannabinoids in cannabis substances.14 can be inhaled through water pipes and These synthetic psychoactive drugs have Cardiovascular system vaporisers. Vaporisers have become a many similarities in their chemical structure, The THC found in cannabis has shown to growing trend and questions have been but not identical, to the drug they attempt consistently increase the heart rate, during raised as to whether its use can be a less to mimic. Therefore, they aim to produce a the initial period of cannabis use, through the harmful mode of intoxication. Many similar effect on the user. NPS can be defined inhibition of vagal stimulation via interactions vaporisers work via the passage of hot air to ‘stimulate or depress the CNS, or cause a with neurotransmitters such as acetylecholine.3,17 through the dried cannabis thus causing state of dependence, have a comparable level In contrast, bradycardia may be induced in some the active components such as THC to of potential harm to internationally controlled regular cannabis users further emphasising the essentially vaporise and become inhaled.3 drugs; and are newly available rather than complex effect of THC on the body.17 Despite limited studies having been newly invented’.15 conducted on these forms of inhalation Synthetic cannabinoids are intentionally Respiratory system techniques, recent studies have found that modified variants of the cannabinoids found Cannabis use, like tobacco smoking, has a vaporisers were shown to reduce toxins in cannabis. They are sprayed onto plant significant impact on the respiratory system. compared with cannabis ‘joint smoking’.12 material and have previously been marketed There have been studies which describe the Conversely, other studies have found that as ‘K2’ and ‘Spice’. The compounds interact similarities in carcinogenic chemicals between there may be some detrimental effects of with the same CB1 and CB2 receptors cannabis and tobacoo.18 However, there are vaporising cannabis such as a significant that THC interacts with but some of these many differences, some of which are shown production of neurotoxic ammonia.12 substances are much more potent than THC in Table 2. www.nature.com/BDJTeam BDJ Team 22 © 2 0 1 6 M a c m i l l a n P u b l i s h e r s L i m i t e d , p a r t o f S p r i n g e r N a t u r e. A l l r i g h t s r e s e r v e d. ARTICLE Oral impact of cannabis use an important hormone in regulating The combined use of cannabis and tobacco, appetite, a cannabis user is frequently hungry which is common amongst users, poses immediately after cannabis consumption.17 challenges for researchers who are interested The combination of reduced saliva production, in identifying the effects of cannabis alone. decrease in saliva pH and increased appetite Using the available evidence the effects of can leave teeth vulnerable to attack from cannabis on oral health will be discussed. potentially cariogenic foods and drinks. A survey carried out by Schultz-Katterbach10 Dry mouth and caries of his participants regarding their diet found Saliva is commonly known to protect the that 63% of those who felt hungry post underlying mucosa from frictional damage. It cannabis use had consumed foods and drinks is also an excellent buffering system involved categorised as being sweet. in protecting the oral cavity, especially the The study by Schulz-Katterbach10 found that teeth, from dental diseases such as caries. through a combination of poor oral hygiene, A study carried out by Schulz-Katterback10 less frequent dental visits and high cariogenic aimed to assess the implications of cannabis diets after cannabis use led to frequent use and the risk of developing dental caries. A identification of carious lesions, particularly sample size of 85 participants were used and on smooth surfaces. The test group had divided into two groups. The control group approximately six times as many decayed were tobacco smokers only and the test group surfaces compared to the control group.10 used cannabis and tobacco. Each participant Caries on smooth surfaces usually indicates was asked a series of questions regarding poor plaque control as these surfaces are easily their diet, attitudes and behaviour towards cleanable (Fig. 1). dental care. The results obtained showed A study carried out by Silverstein21 supports that cannabis users brushed their teeth less Schulz-Katterbach10 findings. The DMFT score frequently than the control group. In addition, of 77 subjects who had used recreational drugs the control group visited their dentist more was investigated. It is not surprising that 84% regularly whereas only 21% in the test group of the participants used cannabis. The DMFT visited their dentist annually. score for cannabis users was 11.99, of which This study also established that cannabis decayed teeth equated to 22% of the DMFT users generally experienced dry mouth score. Similarly, Di Cugno et al.20 found the Fig. 1 The oral presentation of a 22-year-old for approximately 16 hours after the use of number of decayed teeth amongst cannabis patient who smoked six cannabis ‘joints’ a day for the last eight years. Extensive cannabis. A study conducted by Darling users to be 2.5 times higher than that of caries present affecting multiple surfaces et al.19 which aimed to determine the oral controls, which made the overall DMFT index of numerous teeth. In addition, gross accumulation of plaque and calculus visible effects of cannabis found that dry mouth was in their study statistically significant. Even with inflammation of the gingivae experienced by 69.6% of its participants after though these studies have been conducted smoking cannabis, compared to 18.6% of the over 30 years ago, their findings highlight the cigarette smoking control group.19 Moreover, oral health status of cannabis users. Further alveolar bone loss in heavy cannabis users. the effects of dry mouth commenced studies are required to look specifically at the It is clear that cannabis has a higher immediately after the use of cannabis and the DMFT value of cannabis users today, whilst combustion temperature than tobacco and duration of the effects were variable between limiting the number of confounding factors. therefore, one would expect that a user is at participants. greater risk of thermal injuries to the oral In contrast, Di Cugno et al.20 found from Soft tissue diseases soft tissues. However, the evidence from their study of 198 young adult participants, Many drugs such as alcohol and tobacco have the studies available has not conclusively that cannabis did cause a decrease in parotid a direct effect on the soft tissues of the oral stated that particular soft tissue injuries have saliva flow rate, but this was statistically cavity and these are also commonly used by been identified as a result of cannabis use. insignificant as the cannabis using participants cannabis consumers.22 However, cannabis has Nonetheless, chronic thermal injury could also used amphetamines and none used been found to also have a detrimental impact cause hyperkeratosis of the oral mucosa.10 The cannabis alone. Interestingly, the results did on the oral soft tissues. frequency, duration and mode of intoxication reveal that the pH of the test group was 6.90, Periodontal disease has been found to of cannabis would possibly have an effect on whereas the pH of the control group was affect cannabis users. This could be closely the degree of thermal injury to the oral soft 7.51.20 These findings would suggest that a associated with the xerostomic effect and tissues. person who uses cannabis has a reduced saliva the subsequent accumulation of plaque and Darling et al.19 found the prevalence buffering capacity than someone who does calculus as a result of poor plaque control.22 of leukoedema amongst participants was not use cannabis. The study provides some Saliva plays an important role in protecting significantly higher in cannabis and tobacco information about the effects of cannabis on the periodontal tissues. Its reduction caused by smokers when compared to non-smokers. the oral environment, but the reliability of the inhibitory mechanisms activated by cannabis Leukoedema is a ‘bilateral, diffuse, translucent results can be questioned due to presence of can have damaging consequences. Gingival greyish thickening, particularly of the buccal confounding factors such as the concurrent enlargement has also been seen to affect heavy mucosa’.23 It has been described as a variation use of other recreational drugs. cannabis users.19 In addition, Darling et al.19 of normal, which is more common in Afro- Through the effect of cannabis on leptin, also found ‘painful fiery red gingivitis’ and Caribbean individuals. The presence of 23 BDJ Team www.nature.com/BDJTeam © 2 0 1 6 M a c m i l l a n P u b l i s h e r s L i m i t e d , p a r t o f S p r i n g e r N a t u r e. A l l r i g h t s r e s e r v e d.  ARTICLE leukoedema may be caused by many factors use and oral and laryngeal cancer. However, 116 cases in another, found there to be such as genetics, tobacco and cannabis this relationship was no longer observed no increased risk of oral cancer amongst smoking along with alcohol and other once confounding factors such as cigarette regular cannabis smokers. It is clear irritants.19 smoking were adjusted for. Caplan et al.29 that the results of the different studies The association between candida and described two cases where both individuals are conflicting and this could be due to tobacco smoking has been known for many who regularly smoked cannabis, but had no differing methodology of their studies. years. Therefore, a possible association past history of cigarette smoking or alcohol Moreover, participants are more prone to between cannabis smoking and candida may drinking, were found to have squamous cell under report the amount of cannabis used also be present. A separate study conducted carcinoma of the tongue. Dahlstrom et al.30 due to its illegal status. by Darling et al.24 showed that there was an conducted a study of 172 never smoker-never The concurrent intake of alcohol, tobacco increased prevalence of candida amongst drinker (NSND) participants who were newly and possibly other social drugs makes it cannabis users. The immunosuppressive diagnosed with squamous cell carcinoma of difficult to be certain if cannabis alone is a risk effect of THC via the CB2 receptors found the head and neck (SSCHN). Eleven percent factor for oral cancer. In order to reach a firm on immune cells could potentially allow of this group had regularly used ‘non-cigarette conclusion, rigorous clinical trials with robust opportunistic infections, such as candida to tobacco or marijuana’. It was concluded methods would be required. Hashibe et al.26 proliferate and become clinically evident. that there was an increased identification of outlines recommendations for future research A holistic approach must always be taken SSCHN of the oral tongue amongst NSND, which states that the amount of cannabis used when assessing patients, as there are many other immunosuppressive drugs and diseases that could also cause conditions associated ‘IT IS IN THE PATIENT’S BEST INTEREST THAT with candida. Darling et al.24 described the following: ¾ Increased density of candida seen in RECREATIONAL HABITS ARE UNCOVERED AND cannabis users when compared to tobacco smokers and non-smokers BRIEFLY DISCUSSED SO THAT PATIENTS CAN ¾ A combination of poor denture hygiene, deficient nutritional intake and cannabis use can contribute to the manifestation of BE DIRECTED TOWARDS SUPPORT’ candida ¾ Certain candidal species can utilise components of cannabis such as hydrocarbons to produce energy, which but no single aetiological factor could be by a participant should be clearly quantified, can be used for reproduction. responsible for these findings. the mode of intoxication established and to In contrast, a study carried out by conduct research projects in countries where Cannabis and oral cancer Rosenblatt et al.31 found no association cannabis is not illegal. This would allow more Cannabis, like tobacco, contains an array of between cannabis use and oral cancer. In accurate and reliable results to be obtained. carcinogens including ‘phenols, nitrosamines, support, another two studies carried out Uncertainty surrounding the possible link vinyl chloride and various polycyclic aromatic by Llewellyn et al.,32,33 which involved between cannabis use and oral cancer still hydrocarbons’.25 The quantity of tar inhaled the analysis of 53 cases in one study and remains, but a possible association should not and retained in the lower respiratory tract has been shown to be higher in cannabis Table 3 A summary of the oral implications of cannabis use smokers in comparison to tobacco smokers.26 Another difference between tobacco smoke Oral implications of Associated implications and cannabis smoke is that cannabis smoke cannabis use contains 50% more of the carcinogenic Dry mouth (xerostomia) - Increased risk of caries hydrocarbons.27 It is well known that there short term Increased risk of periodontal disease are many risk factors for oral cancer, some of which include the use of alcohol and Increased risk of frictional injuries tobacco. The combined use of both alcohol Halitosis and tobacco significantly increases the risk of Thermal injury Hyperkeratinisation due to higher combustion temperature developing oral cancer. However, the role of of cannabis cannabis in being a risk factor of oral cancer Leukoedema Normal variation is unclear. A case-controlled study conducted by Clinically detectable due to multifactorial reasons: genetics, Zhang et al.28 found an increased risk of head alcohol, tobacco and cannabis use and neck cancer amongst cannabis users. Candidal infection Increased risk of candidal infection – poor oral hygiene/ This had a dose dependent relationship even denture hygiene –nutritional deficiency after adjusting for possible confounding Oral cancer Cannabis contains similar carcinogens to tobacco. factors. Similarly, a study carried out by Hashibe et al.26 also found a positive dose Possibility of a link with cannabis use. However, more evidence required. dependent relationship between cannabis www.nature.com/BDJTeam BDJ Team 24 © 2 0 1 6 M a c m i l l a n P u b l i s h e r s L i m i t e d , p a r t o f S p r i n g e r N a t u r e. A l l r i g h t s r e s e r v e d. ARTICLE be disregarded. Table 3 summarises the oral use of a controlled substance. Patients Once a patient has been directed, implications of cannabis use. should be made aware that all information what can they expect? provided and discussed will remain There is an abundance of useful information How can recreational habits be confidential and any information will only available on NHS Stop Smoking35,36 and Talk uncovered? be shared out with the patient’s informed to Frank37 websites regarding many drugs As a health care professional it can be very consent. This would instil deeper trust in including cannabis. These websites, which challenging and daunting to discuss a the patient as they may be more likely to be are regularly updated, provide a great tool patient’s recreational habit. This is primarily open about their habits. for both patients and the dental professional. due to the illegal nature of many recreational The framework provided in section 7 in Talk to Frank is a dedicated organisation that drugs and patients’ reluctance to reveal their the Delivering better oral health34 document is available to be contacted at any time and habits. It is in the patient’s best interest that regarding smoking and tobacco use is an provide advice. Patients who use recreational recreational habits such as cannabis use excellent structure which could be used drugs should be strongly advised to visit their are uncovered and briefly discussed so that with cannabis consumers. The format of website. patients can be directed towards appropriate ‘Ask, Advice and Act’ could be used to give In brief, Talk to Frank advises cannabis care and support. ‘very brief advice’ on the use of cannabis. It users who are attempting to give up, to There are no fixed criteria or guidance is crucial that patients are not immediately identify reasons and trigger factors for using documents available which clearly state how warned about the dangers of cannabis use cannabis. Once these have been established, one can approach the topic of cannabis use. as this could ‘create a defensive reaction and diversions should be put in place to avoid However, it is clear that a set formulated raise anxiety levels’.34 This could potentially the trigger factors. An action plan should approach will not prove successful with all create barriers between the dental clinician be devised which states a clear stop date. patients and therefore flexibility is required. and the patient. In addition, a strong supportive network In order to open an avenue for discussion, It is best to leave the discussion towards of family, friends and professionals at Talk medical history forms can be adjusted, a dedicated period in the consultation to Frank should be present and available to contain a section where patients can where the patient can be educated on the to provide encouragement at all times. The simply tick a box if they have either never effects of cannabis on oral health. During journey is understandably difficult and used, previously used or currently use the ‘very brief advice’ period, it is essential withdrawal symptoms may be experienced recreational substances. Hashibe et al.26 that the patient’s motivation to stop using such as irritation, anxiety, anger, craving for cannabis and sleeplessness. However, these symptoms will eventually subside. During ‘IT IS IMPORTANT AS A DENTAL this period it is advised that nutritious meals are regularly eaten and exercise is carried out to help minimise the potential withdrawal PROFESSIONAL TO ACKNOWLEDGE IN A symptoms. NON-JUDGEMENTAL MANNER THAT A PATIENT Conclusion Cannabis is a very common recreational drug used around the world. The challenges faced HAS DISCLOSED SENSITIVE INFORMATION’ by healthcare professionals are increasing with the growing use of NPS. There is evidence to show that cannabis has a negative effect found that participants in their study were cannabis is gauged and the subsequent on oral health, however, further studies are more susceptible to underreporting their advice tailored to their desire to quit. It is required with reduced confounding factors in cannabis use when asked face-to-face than well known that habits are best broken and order to show more accurate findings. if they were asked through a questionnaire. cessation achieved via appropriate support As dental professionals we are likely A well laid out questionnaire will appear throughout the process. An engaging and to encounter cannabis users frequently general, standardised and not targeted motivated patient should be directed to throughout our working career. Therefore, one specifically at certain patients. Some patients their general medical practitioner, local must be prepared and confident in discussing may not initially disclose any recreational community NHS Stop Smoking Services35,36 the effects of cannabis use on oral and general substance use until they feel more confident and/or Talk to Frank.37 The use of leaflets, health and be able to either provide or direct in the dentist and able to trust them with the which are available from Talk to Frank, can towards a holistic support programme which information. This exemplifies how important be a very useful tool in conveying concise addresses the social habits. it is to be flexible in the approach when information to patients. The complexity of unravelling the specific gathering information. The patient should be educated on the effects of cannabis on an individual is importance of prevention of dental diseases extremely challenging, as discussed earlier, but What advice can I give once through improved oral hygiene techniques it can be said with certainty that cannabis use a recreational habit has been and regimes, but also on the benefits of does have an impact on oral health. This paper uncovered? fluoride. Furthermore, the patient’s diet should has aimed to enhance the dental professional’s It is important as a dental professional to be investigated and appropriate advice should armamentarium with regards to knowledge on acknowledge in a non-judgemental manner be given in reducing the amount of sugary cannabis and its general and oral effects, along that a patient has disclosed sensitive foods and drinks and to consider healthier with ways to uncover a recreational habit and information about their life regarding the alternative substitutes. give advice to patients. 25 BDJ Team www.nature.com/BDJTeam © 2 0 1 6 M a c m i l l a n P u b l i s h e r s L i m i t e d , p a r t o f S p r i n g e r N a t u r e. A l l r i g h t s r e s e r v e d.  ARTICLE Since this article was accepted for publication, cannabinoids with emphasis on man. 27. Hoffman D, Brunnemann K D, Gori G the Psychoactive Substances Act has been Pharmacol Rev 1986; 38: 21–43. B, Wynder E L. On the carcinogenicity of introduced into UK legislation on 26 May 2016. 14. Home Office. Annual report on the Home marijuana smoke. In Runeckles V C (ed). This makes it illegal to produce, supply and Office forensic early warning system. 2015. Recent advances in phytochemistry, 1st ed. possess psychoactive substances. Available online at https://www.gov.uk/ pp 63–68. New York: Plenum, 1975. government/publications/forensic-early- 28. Zhang Z F, Morgenstern H, Spitz M et 1. Versteeg P A, Slot D E, Velden U, Weijden warning-system-fews-annual-report al. Marijuana use and increased risk of G A. Effects of cannabis usage on the oral (accessed March 2016). squamous cell carcinoma of the head and environment: a review. Int J Dent Hygiene 15. Home Office. New Psychoactive neck. Cancer Epidemiol Biomarkers Prev 2008; 6: 315–320. Substances Review: Report of the expert 1999; 8: 1071–1078. 2. Home Office. Drug misuse: Findings from panel. 2014. Available online at www. 29. Caplan G A, Brigham B A. Marijuana the 2014/15 Crime Survey for England gov.uk/government/publications/new- smoking and carcinoma of the tongue. and Wales. 2015. Available online psychoactive-substances-review-report- Is there an association? Cancer 1990; 66: at https://www.gov.uk/government/ of-the-expert-panel (accessed March 1005–1006. statistics/drug-misuse-findings-from- 2016). 30. Dahlstrom K R, Little J A, Zafereo M E, the-2014-to-2015-csew (accessed 16. National Institute on Drug Abuse. Lung M, Wei Q, Sturgis E M. Squamous March 2016). DrugFacts: Synthetic Cannabinoids. 2015. cell carcinoma of the head and neck in 3. Borgelt L M, Franson K L, Nussbaum Available online at www.drugabuse. never smoker-never drinkers: a descriptive A M, Wang G S. The pharmacologic gov/publications/drugfacts/synthetic- epidemiologic study. Head Neck 2008; 30: and clinical effects of medical cannabis. cannabinoids (accessed March 2016). 75–84. Pharmacotherapy 2013; 33: 195–209. 17. Grotenherman F. Pharmacology of 31. Rosenblatt K A, Daling J R, Chen C, 4. Gates P, Jaffe A, Copeland J. Cannabis cannabinoids. Neuroendocrinology 2004; Sherman K J, Schwartz S M. Marijuana smoking and respiratory health: 25: 14–22. use and risk of oral squamous cell Consideration of the literature. Respirology 18. Moir D, Rickert W, Levasseur G et al. A carcinoma. Cancer Res 2004; 64: 2014; 3: 655–662. comparison of mainstream and sidestream 4059–4054. 5. Cho C M, Hirsch R, Johnstone S. General marijuana and tobacco cigarette smoke 32. Llewellyn C D, Linklater K, Bell J, and oral health implications of cannabis produced under two machine smoking Johnson N W, Warnakulasuriya K A A use. Aust Dent J 2005; 50: 70–74. conditions. Chem Res Toxicol 2008; 4: S. Squamous cell carcinoma of the oral 6. Gambhir R, Brar P, Anand S, Ranhawa A, 494–502. cavity in patients aged 45 years and Kakar H. Oral health aspects of cannabis 19. Darling M R, Arendorf T M. Effects of under: a descriptive analysis of 116 cases use. IndJ Multidis Dent 2012; 2: cannabis smoking on oral soft tissues. diagnosed in the South East of England 507–511. Community Dent Oral Epidemiol 1993; 21: from 1990 to 1997. Oral Oncol 2003; 39: 7. Devane W A, Hanus L, Breuer A et 78–81. 106–144. al. Isolation and structure of a brain 20. Di Cugno F, Perec C J, Tocci A A. Salivary 33. Llewellyn C D, Linklater K, Bell J, Johnson constituent that binds to the cannabinoid secretion and dental caries experience N W, Warnakulasuriya S. An analysis receptor. Science 1992; 258: 1946–1949. in drug addicts. Arch Oral Biol 1981; 26: of risk factors for oral cancer in young 8. Pertwee R G, Howlett A C, Abood M 363–367. people: a case-control study. Oral Oncol E et al. International union of basic 21. Silverstein S J. Relation between social 2004; 40: 304–313. and Clinical Pharmacology. LXXIX. drug use/abuse and dental disease in 34. Public Health England. Delivering Cannbinoid receptors and their ligands: California U S A. Community Dent Oral better oral health: an evidence- beyond CB1 and CB2. Pharmacol Rev Epidemiol 1973; 1: 89–93. based toolkit for prevention. 3rd 2010; 62: 588–631. 22. Rees T D. Oral effects of drug abuse. Crit ed. 2014. Available at: www.gov. 9. Pacifici R, Zuccaro P, Pichini S et al. Rev Oral Biol Med 1992; 3: 163–184. uk/government/uploads/system/ Modulation of the immune system in 23. Cawson, R, Odell E. Benign chronic uploads/attachment_data/file/367563/ cannabis users. J Am Med Assoc 2003; 289: white mucosal lesions. In: Cawson’s DBOHv32014OCTMainDocument_3. 1929–1931. essentials of oral pathology and oral pdf (accessed February 2016). 10. Schulz-Katterbach MS. Cannabis and medicine, 8th ed. p 252. Philadelphia: 35. NHS choices. Cannabis the facts. 2014. caries does regular cannabis use increase Elsevier, 2008. Available at: http://www.nhs.uk/livewell/ the risk of caries in cigarette smokers? 24. Darling M R, Arendorf T M, Coldrey N drugs/pages/cannabis-facts.aspx (accessed Zurick Open Repos Arch 2009; 119: A. Effects of cannabis use on oral candidal January 2016). 576–583. carriage. J Oral Pathol Med 1990; 19: 36. NHS. Local Stop Smoking Services. 11. Ashton C H. Pharmacology and effects 319–321. 2015. Available at: http://www. of cannabis: a brief review. Br J Psychiatry 25. Hoffman D, Brunneman D, Gori G, nhs.uk/smokefree/helpandadvice/ 2001; 178: 101–106. Wynder E. On the carcinogenicity of localsupportservices-helplines (accessed 12. Doblin R. The MAPS/California marijuana smoke. Recent Adv. Phytochem January 2016). NORMAL marijuana waterpipe/vaporiser 1975; 4: 63–81. 37. Talktofrank. Cannabis. 2009. Available at: study. Newsl Multidiscip Assoc Psychedelic 26. Hashibe M, Straif K, Tashkin D P, http://www.talktofrank.com/drug/cannabis Stud 1999; 5: 19–22. Morgenstern H, Greenland S, Zhang Z (accessed March 2016). 13. Agurell S, Halldin M, Lindgren J E et al. F. Epidemiologic review of marijuana Pharmacokinetics and metabolism of use and cancer risk. Alcohol 2005; 35: This article was originally published in the delta 1-tetrahydrocannabinol and other 265–275. BDJ (2016; Volume 220 pages 597-601). bdjteam2016146 www.nature.com/BDJTeam BDJ Team 26 © 2 0 1 6 M a c m i l l a n P u b l i s h e r s L i m i t e d , p a r t o f S p r i n g e r N a t u r e. A l l r i g h t s r e s e r v e d.