Bariatric dentistry: a review and clinical recommendations

Obesity is a chronic disease characterized by abnormal or excessive fat accumulation that poses a risk to health.¹ According to the Global Burden of Disease, obesity has reached epidemic proportions, with about 4 million deaths per year attributed to being overweight or obesity.² In the UK, the prevalence of obesity among adults was 63% in 2018–2019, which means that about 35 million UK adults are overweight or obese.³ The prevalence of obesity was similar between men and women, but severe obesity was more common among women.³

Being overweight or obese increases the risk of developing other medical conditions, such as hypertension, diabetes, liver cirrhosis, dysfunction of the respiratory and musculoskeletal systems, psychological impairments, and increased risks of some types of gastrointestinal cancer. Obesity is known to be a chronic disease.⁴

Several methods are available to assess overweight and obesity, such as neck circumference and body mass index (BMI). Neck circumference is a simple and inexpensive measure that reflects upper body fat distribution. The cut-off values for overweight or obesity based on neck circumference are ≥35.5 cm for men and ≥32 cm for women.⁵ BMI is another widely used indicator of overweight and obesity, calculated by dividing weight in kilograms by height in metres squared. The World Health Organization defines overweight as a BMI of 25 kg/m² or more, and obesity as a BMI of 30 kg/m² or more.⁶ The degree of overweight and obesity in adults can be classified according to the NICE obesity guidelines (Table 1).⁷

The American Society of Anesthesiologists (ASA) physical status classification system (2021) categorizes patients with BMI >30 but <40 kg/m² as ASA II, indicating mild systemic disease. Patients with BMI >40 kg/m2 are classified as ASA III, indicating severe systemic disease.⁸

BMI has some limitations as a measure of overweight and obesity. For instance, it does not differentiate between lean and fat mass, which may lead to misclassification of some individuals. However, BMI is useful for epidemiological studies owing to its simplicity and applicability.⁹

Waist circumference, along with the waist-to-hip ratio, is an alternative measure of abdominal fat mass, which is related to morbidity and mortality independently of BMI. Waist circumference also reflects the changes in the risk of obesity-related complications, such as cardiovascular disease. Therefore, the World Health Organization recommends combining BMI and waist circumference for a more accurate assessment of overweight and obesity.^6,10

Causes and risk factors contributing to obesity

Obesity is a multifactorial disease that results from the interaction of genetic, endocrine, environmental, behavioural, and social factors. Genetic causes of obesity include polygenic, monogenic, syndromic, and extragenetic variants that influence appetite, energy expenditure and fat distribution. Endocrine disorders such as Cushing's syndrome, polycystic ovary syndrome and hypothyroidism, can also contribute to obesity by altering hormone levels and metabolism. Some medications, such as antipsychotics, antidepressants, antidiabetics, antihypertensives, and steroids, can induce weight gain by affecting appetite, glucose homeostasis, and fluid retention. Excessive consumption of energy-dense foods and reduced physical activity lead to a positive energy balance and increased fat storage. Other factors that may influence obesity include sleep deprivation, health inequalities, and socio-economic status. Environmental factors, such as working hours, built environment, food availability, and social networks, can affect dietary patterns, physical activity levels, and stress coping strategies.¹¹

Treatment for obesity

The treatment of obesity requires a comprehensive approach that involves dietary therapy, physical activity, behavioural modification, pharmacotherapy, and surgery. Dietary therapy aims to create an energy deficit of about 500–600 kcal/day, which can result in a weight loss of about 0.5 kg/week for 12–24 weeks. The recommended energy intake ranges from 1200 to 1800 kcal/day depending on the individual's characteristics and needs. Physical activity enhances weight loss by increasing energy expenditure and improving cardiovascular health and muscle strength. Behavioural modification helps to change eating habits and lifestyle factors that contribute to obesity. Pharmacotherapy can be used as an adjunct to dietary therapy, physical activity, and behavioural modification in patients with BMI ≥30 or BMI ≥27 with comorbidities. The available drugs act by reducing fat absorption or suppressing appetite.¹⁴ Surgery is the most effective treatment for patients with severe obesity (BMI ≥40 or BMI ≥35 with comorbidities) who have failed to lose weight with other methods. The common surgical procedures include gastric bypass or banding, which reduce the stomach size and limit food intake. However, surgery also carries some risks and complications, such as oral acid reflux, tooth erosion and caries.¹⁴

Obesity is a growing public health problem that affects oral health and dental care. Dental practitioners need to be aware of the special needs and challenges of patients with obesity and provide them with appropriate care and guidance. This review provides an overview of bariatric dentistry, a new field that focuses on the oral health care of patients with obesity and offers some practical clinical tips for dental practitioners.

What is bariatric dentistry?

Bariatrics is a medical specialty that deals with the causes, prevention, and treatment of obesity.¹⁵ Patients with obesity are often referred to as ‘bariatric’ in literature. However, there is no established term for dentistry for this patient group. A possible term that could be used is ‘bariatric dentistry’, which implies the oral health care of patients with obesity.¹⁴

Bariatric dentistry training is essential for dental practitioners who encounter patients with obesity, as it can improve the quality of care and patient satisfaction.¹⁶ Bariatric dentistry is relevant because the prevalence of obesity is increasing, and patients with obesity have more oral health problems than the general population. Moreover, they often have other chronic medical conditions that require modifications in the dental treatment plan.¹⁴

Most common oral diseases affecting obese population

Figure 1 shows the most common oral diseases that affect patients who are obese.

Dental caries

Some studies detected a direct association between obesity and dental caries owing to the continued acidity of the mouth when the frequency of sugar intake is high, which may lead to an increase in the chance of tooth demineralization.^17,18,19 The development of dental caries and obesity are both likely to be influenced by dietary choices. For example, Taiwanese researchers discovered that decayed, missing, and filled teeth (dmft index) was not only associated with the degree of obesity, but also with the consumption of fried foods, potato chips, cookies, and fruits among children aged 6–12 years old in the study.²⁰

Periodontal diseases

Chronic periodontal disease destroys the periodontal ligament and alveolar bone supporting the teeth, so the initial gingival inflammation appears to be related to bacterial plaque accumulation, but the following progressive destruction appears to be dependent on a complicated plaque–host connection that is still being studied.²¹ For example, a Finnish survey of non-diabetic and non-smoking adults found a link between BMI and high scores of periodontal pocket depth.²² Moreover, although the causative processes behind the relationship between obesity and periodontitis remain unknown, the development of insulin resistance as a result of a chronic inflammatory state and oxidative stress could be implicated in the association between obesity and periodontitis.²³ Additionally, it is also possible that increased secretion of inflammatory mediators may modify the periodontal tissues’ response to the oral environment and that excessive adipokine production may produce this effect.²¹

Dry mouth

Dry mouth, or xerostomia, is explained by a change in the amount or quality of saliva produced, and can cause considerable pain and a burning feeling in the oral tissues, and increase the risk of dental caries.²⁴ An individual is diagnosed as having dry mouth when unstimulated flow rate is below 0.1 ml/min.²⁵ Saliva's role is frequently overlooked, and includes lubrication, which helps in daily oral functions such as speaking, chewing and swallowing, buffering action, removal of food debris, tooth integrity maintenance via self-cleaning activity, antibacterial action, taste, and digestion regulation.²⁶ Patients who are obese are more likely to experience dry mouth because they have a high risk of obstructive sleep apnea or have a polypharmacy regimen that reduces saliva flow rate (i.e. anti-hypertensive and/or anti-hypoglycaemic agents).²⁷

Most common medical diseases affecting those who are obese

Figure 2 shows the most common medical diseases that affect patients with obesity.

Cardiovascular diseases

High BMI is directly connected with many cardiovascular risks, such as increased risk for coronary heart disease, stroke and high blood pressure. For example, the rise of BMI by 1 kg/m2 increases the risk of heart failure by 5% for men and 7% for women.²⁸ Furthermore, excess weight leads to haemodynamic changes. For instance, an increase in BMI of 5 kg/m2 involves a 5mmHg rise in systolic blood pressure and cardiac output.¹⁹

Mental health illnesses

Research has found that those who are overweight are more likely to show symptoms of depression than those of normal weight, such as loss of energy, weight gain, and reduced routine daily activities.²⁹ Indeed, adults suffering from sadness and anxiety were more likely to lose their teeth, develop dental caries, and have poor periodontal and gingival health.³⁰ Adults with depression and anxiety were more likely to have at least one tooth extracted and accordingly more missing teeth, negatively affecting their quality of life and general health and wellbeing.³¹

Respiratory diseases

A meta-analysis of prospective epidemiological studies reported that obesity is a major contributor to obstructive sleep apnoea (OSA), which affects one in every five adults.³² OSA is linked to daytime sleepiness, car accidents, hypertension and premature death.³³ The link between the risk of OSA and self-reported dental health status has been investigated, such as difficulties opening the mouth, dry mouth, bad breath, gingival bleeding and swelling.³⁴

Diabetes

Obesity harms practically every aspect of health. Type II diabetes mellitus (DM) is strongly impacted by body weight, and it affects everyone who is overweight or obese.³⁵ DM type II is defined as a combination of decreased pancreatic β-cell insulin secretion and resistance of insulin uptake.³⁶ Insulin resistance causes an increase in fatty acids in the blood, resulting in decreased glucose transport into muscle cells and increased fat breakdown, which leads to an increase in hepatic glucose production.³⁶

In comparison to people with better controlled diabetes and non-diabetic subjects, adults with poorly controlled diabetes may have reduced salivary flow rate, which is a strong risk factor for increasing risk of dental caries and oral dysfunction.³⁷

Cancer

A meta-analysis and systematic review confirmed direct links between obesity and cancers of the breast, colon, rectum, endometrium, oesophagus, kidney, ovary, and pancreas.³⁸ People who are overweight or obese, or who have increased their BMI in maturity, are more likely to develop oral cavity cancer; however, the fundamental aetiology is still unknown.³⁹

Musculoskeletal problems

Obesity has been linked to an increase in musculoskeletal impairment that can impact soft tissue, such as cartilage and tendons, as well as with bones and joints (for example, osteoarthritis). The prevalence of overweight and obesity has increased along with the frequency of musculoskeletal illnesses.⁶

Dental management

The oral and medical diseases that affect patients with obesity, as discussed above, complicate routine dental management. Accordingly, dental treatment planning and/or treatment might require modification. Below are some related factors that should be discussed when managing patients with obesity in dentistry.

Dental chair

Many regular dental chairs are designed to treat patients with a maximum weight of 140 kg.¹⁴ Therefore, it is unsafe to use a normal dental chair for obese patients as this increases the risk of damaging the dental chair, which might unexpectedly fall on the dentist's knees or leg and indeed harm the patient, with negative consequences. Hence, a bariatric dental chair should be used because it can raise or recline a weight of up to 500 kg (Figure 3).¹⁴

Obtaining a thorough medical history

Obtaining a thorough medical history is vital for safe dental treatment. Therefore, dental care providers should obtain all medical history details using a validated and reliable questionnaire. As discussed above, many patients with obesity attend a dental clinic with several comorbidities, most commonly cardiovascular and diabetes diseases, hence liaison with the patient's physicians is crucial. It is also important to determine the timing of dental treatment, such as delivering dental care prior to or post insulin injections for diabetic patients, and morning appointments for cardiovascular patients to reduce risk of cardiovascular events.⁴⁰ Additionally, patients with obesity might require modification of their medications, such as insulin dose and/or anticoagulant medications; hence liaison with their physician is key.

Pain management and anxiety control

Local anaesthesia (LA)

LA is the primary means of pain relief. In dentistry, LA is a type of anaesthetic in which medications are injected into particular sites in the oral cavity to keep the patient awake and pain-free. LA can diminish the permeability of sodium channels in peripheral nerves and bind to Ca²⁺, blocking nerve impulse transmission to the brain and rendering patients painless.⁴¹ In clinical practice, the landmarks for an inferior alveolar nerve block (IANB) in the lower jaw of patients who are obese can be difficult to palpate through a thick fatty layer.¹⁶ Excess fat in the tissues can also interfere with a drug's pharmacological absorption.⁴² The Gow–Gates and Akinosi–Vazirani closed-mouth mandibular nerve block techniques are indicated if there is a history of IANB failure or if intra-oral landmarks for IANB are difficult to palpate.⁴³ Generally, the maximum recommended dose of LA differs depending on the LA agent and the patient's weight. For example, the maximum dose of 2% lidocaine is 4.4 mg/kg; however, that of 2% and 3% mepivacaine is 4.4 mg/kg max, and for 4% articaine, it is 7.0 mg/kg.⁴⁴

Conscious sedation (CS)

It is reported that obese patients have a degree of daily general anxiety,⁴⁵ which might manifest as dental anxiety and necessitate having some kind of behavioral management techniques such as CS.⁴⁶ CS has been defined as:

‘A technique in which the use of a drug or drugs produces a state of depression of the central nervous system enabling treatment to be carried out, but during which verbal contact with the patient is maintained throughout the period of sedation. The drugs and techniques used to provide conscious sedation for dental treatment should carry a margin of safety wide enough to render the loss of consciousness unlikely.’⁴⁷

The patient airway should be thoroughly evaluated before deciding which technique to use (i.e. inhalation sedation with nitrous oxide mixed with oxygen or intranasal/oral/intravenous sedation with midazolam) or general anaesthesia (GA). For example, for patient airway assessment, a tool such as ‘LEMON’ is one of the common airway assessment tools that is used to assess the airways of patients who are obese prior to starting dental treatment under conscious sedation or GA to hinder safe and effective dental care (Table 2).⁴⁸

Intravenous sedation (IVS)

Since its release in 1983, midazolam, a benzodiazepine, has been used for dental sedation.⁴⁷ It is appropriate for sedation in outpatient dentistry practice because of its quick onset, short half-life, and absence of active metabolites.⁴⁷ The use of a more dilute formulation (5 mg/5 ml) makes titration safer and easier.⁴⁷

Obesity is a condition where caution during treatment is required. Individuals with a BMI greater than 25 may not be suitable for treatment under IVS.³⁷ Furthermore, in dental surgery, patients who are obese frequently have problematic IV access.¹⁶ Also, in the event of a collapse, there may be airway management and patient handling problems.⁴² Since midazolam induces less respiratory depression than a combination of opiate analgesics or propofol, and because it is reversible, it is the drug of choice for dental sedation for patients who are obese and the usual dose is in the range 2–7.5 mg.^47,49

Inhalation sedation (IHS)

This is a long-established approach for managing mild to moderate anxiety in both children and adults that has a demonstrated safety record. Because oxygen levels are constantly above 30%, this is a safe procedure for medically difficult individuals.¹⁶ Recovery is quick, and patients are usually discharged shortly after treatment is completed.⁴⁷ Nitrous oxide mixed with oxygen for patients who are obese is the better choice as CS because of the low risk of any respiratory or cardiac complication.⁴⁷

General anaesthesia (GA)

The airway assessment is critical when assessing obese patients for GA. If GA is being considered, the patient will almost certainly need a pre-assessment with an anesthetist if their BMI is greater than 35, and bariatric trolleys may be required.⁴² Additionally, as patients with obesity have large tongues and difficult airways, GA does not always provide optimum operating conditions.⁴² According to the Royal College of Anesthetists' 4th National Audit Project, patients with obesity were twice as likely as patients without obesity to develop serious airway problems during a general anesthetic.⁵⁰

Post-operative dental pain control

Pain control is crucial for any successful dental treatment. However, it is important to understand that some pain control medications interact with anti-hypertensive and anticoagulant agents, which negatively affect their function. For example, multiple studies have demonstrated that nonsteroidal anti-inflammatory drugs (NSAIDs) raise blood pressure, cause new-onset hypertension, and worsen the blood pressure control of patients with existing hypertension.⁵¹ According to most studies, naproxen and celecoxib have only a minor effect on blood pressure, whereas ibuprofen, etoricoxib, and rofecoxib have significant effects.⁵¹ Patients taking angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) are likely to experience a more significant rise in blood pressure.⁵¹

A systematic review and meta-analysis found that when patients take warfarin and an NSAID or COX-2 inhibitor together, the risk of gastrointestinal haemorrhage is significantly increased compared to when taking warfarin alone. As a result, it is important to warn patients about taking these medications in combination.⁵²

Access to care

Patients with obesity tend to use dental services less than patients without obesity.⁵³ This may be due to several factors. First, patients with obesity may have other more urgent health issues that require their attention, and they may neglect their oral health. Second, most dental offices are not adequately equipped to accommodate patients with obesity, who may need special equipment such as bariatric dental chairs, comfortable waiting areas, ramps and toilets with handles, wheelchairs, large-size blood pressure cuffs, weighing scales, wheelchair tippers, and longer appointment times. Third, patients with obesity may experience higher levels of dental anxiety, which can deter them from seeking dental care.^53,55

Conclusion

Patients with obesity present various medical, anaesthetic, logistical, and surgical challenges that require careful perioperative risk assessment and management. To ensure the optimal care and safety of these patients, dental practitioners need to have adequate knowledge and skills in bariatric dentistry, a new field that focuses on the oral health care of patients with obesity. Therefore, bariatric dentistry training should be incorporated into undergraduate and postgraduate dental education programmes, which will enhance the quality of care and satisfaction of patients with obesity.