Management of Severe Mental Illness in the Dental Setting: A Grey Matter?

Severe mental illness (SMI) is a term used to describe a mental health condition that has a significant, debilitating impact on quality of life.¹ Functional impairment and/or limitation are key features of a spectrum of conditions that include schizophrenia and bipolar affective disorder.¹ Schizophrenia and bipolar affective disorder are the main conditions referred to under the umbrella of SMI and are the focus of this review.

According to the Impact Mental Health Report produced by NICE, around 0.9% of the UK population have been diagnosed with an SMI.² Over 550,000 people registered with a general medical practitioner (GP) were diagnosed with schizophrenia, bipolar affective disorder, or other psychoses in 2017–2018.²

People with SMI have been reported to be at a higher risk of dying 15–20 years earlier than those without an SMI.³ While causation is not clear cut, there are a number of comorbidities that are more common in this demographic and are likely to contribute. In 2018, a Public Health England analysis conducted on patients registered with a GP, found 10 comorbidities present at a higher rate in people with SMI compared to those without SMI (Figure 1).³ Additionally, the data showed that those diagnosed with SMI were twice as likely to have four or more of the above-mentioned comorbidities.³

Multiple risk factors have been linked to the increased morbidity and mortality in this demographic. These include poor nutrition; smoking; substance abuse; and alcohol misuse.³ Notably these are all risk factors for poor oral health.

Schizophrenia

Schizophrenia is a complex and long-term mental health condition where patients usually experience hallucinations and delusions.⁴ Other symptoms may include disordered speech, catatonic behaviour and lack of motivation.⁴ Historically, schizophrenia was divided into subtypes: paranoid; disorganized; catatonic; undifferentiated; and residual. This was based on the Diagnostic and Statistical Manual of Mental Disorders (DSM) IV. However, these subtypes have now been removed from diagnostic criteria in the updated DSM V.⁵

It is estimated that 1 in 100 adults may have an episode of schizophrenia during their lifetime.⁵ Schizophrenia is commonly diagnosed between the ages of 20 and 30 years. Men are more likely to be diagnosed with schizophrenia than women, but the causation underpinning this difference is unknown. The aetiology is yet to be fully elucidated and thought to be multifactorial.⁶

There is, however, a strong familial tendency. A large-scale Danish study on twins found that there was a 33% risk of both identical twins being diagnosed with schizophrenia in their lifetime.⁷ This risk is 7% for fraternal twins.⁷ Overall, it was found that there was a 79% risk of schizophrenia being inherited.⁷

Another proposed risk factor for developing schizophrenia is cannabis use. A systematic review found that those already genetically predisposed to schizophrenia, received a diagnosis at an earlier age if they were a cannabis smoker.⁸ Additionally, there is evidence that cannabis use can worsen the symptoms of schizophrenia and lead to relapses.⁸ The review does however note that the mechanism of action is unclear.⁸

Other potential risk factors for schizophrenia include a traumatic life event, imbalance of certain chemicals in the brain, brain damage, low birth weight and alcohol or drug misuse.⁹

Treatment usually involves cognitive behavioural therapy as well as the prescription of antipsychotics.^6,9 These may be second generation antipsychotics, such as clozapine, or first-generation antipsychotics, such as haloperidol.^6,9

Bipolar affective disorder

Bipolar affective disorder is a mental health condition where a person's mood fluctuates between manic and depressive phases which can last days to weeks.¹⁰ The manic phase is characterized by an elated mood, hyperactivity, racing thoughts, poor judgement, and a reduced need for sleep.¹⁰ In contrast, the depressive phase results in a low mood, greater need to sleep, withdrawal from social activities and pessimism.¹⁰

According to the Adult Psychiatric Morbidity Survey (APMS), 1.3 million people in the UK have bipolar affective disorder and there is a lifetime prevalence of 1–2%.¹¹ Two main types of bipolar affective disorder have been identified.¹² Bipolar type I is when there is mania with or without depression and hallucinations and delusion are common. Bipolar type II disorder is diagnosed based on one hypomanic phase and one major depressive phase.¹²

The aetiology is thought to be multi-factorial and is not yet fully understood; however, both environmental and social factors have been implicated.¹⁰ The main causes identified include a stressful life event or trauma, chemical imbalance, and genetics.¹⁰ Many genome-wide association meta-analyses have found a genetic link with bipolar affective disorder.¹³ There is no clear predilection for either biological sex.¹³

As well as psychological supportive treatment such as cognitive behavioural therapy, patients are prescribed medications that include lithium, anticonvulsants and antipsychotics.¹⁰

Oral health and SMI

A meta-analysis conducted in 2021 found that people diagnosed with SMI were less likely to visit the dentist or brush their teeth than the general population.¹⁴ There is a growing body of evidence to show higher scores for decayed, missing or filled teeth (DMFT) in this demographic compared to peers without SMI.^15,16 Illness duration has been proposed as one of the most significant predictors of suboptimal oral health, second only to the patient's age.¹⁷ All of the above reinforce the importance of consistent, lifelong preventive care for this patient group.

Caries

A meta-analysis of case-controlled studies found that people with schizophrenia had higher scores of decayed, missing and filled teeth and overall poorer oral health.¹⁸ There are many reasons as to why people with SMI can be at a higher risk of developing caries. It has been suggested that they may have an overall poor nutrition profile and rely on food and drinks high in sugar, which are cariogenic in nature.¹⁹ The behavioural patterns in those with SMI can lead to lapses in personal care as well as oral hygiene.¹⁵ Motivation may fluctuate daily, resulting in days where toothbrushing may not take place.¹⁵ People with SMI will also be on multiple medications that can cause xerostomia and thus reduce the buffering capacity of saliva.¹⁴

Periodontal health

Periodontal disease is a common oral health issue in those with SMI. A meta-analysis found that 50% of patients with SMI had periodontal disease.¹⁵ A study conducted in outpatient psychiatric care clinics in London, found 93.9% of dentate patients required periodontal treatment and 54.5% required advanced periodontal treatment.²⁰ As previously noted, poorer oral hygiene, a higher prevalence of tobacco smoking and diabetes in this demographic could be suggested as aetiological factors.

A case series has also identified the prevalence of gingivitis artefacta among those with SMI.²¹ Gingivitis artefacta is self-inflicted injury to the gingiva.²² This can be as a result of ‘picking’ the gingiva using fingernails or repeated trauma using an object such as a pen.²¹ This can occur without an associated psychiatric disorder.²² It can result in permanent gingival tissue damage and lead to severe gingival recession.²²

Edentulism

Systematic reviews and meta-analyses have found that people with SMI are 2.8–3.4 times likely of being edentulous than the general population.^12,13 They were also found to have 4.2 less teeth than adults without SMI in the UK.²² This is due to the higher risk of developing caries, periodontal disease, and xerostomia, which inevitably increases the likelihood of eventual tooth loss.

Tooth wear

Those with SMI can exhibit excessive toothbrushing behaviours as well as bruxism which can contribute to severe tooth wear.^14,15 SMI can also be associated with other mental health conditions, such as bulimia, which contributes to tooth wear. Other potential causes could be chronic excess alcohol intake or substance misuse.^14,15

Xerostomia

Owing to the number of antipsychotic or antidepressant medications a patient with SMI may be prescribed, the risk of xerostomia is increased.¹⁴ This will in turn increase the risk of caries, periodontal disease as well as oral candidiasis.¹⁵

Oral cancer

A survey conducted in a secure mental health unit found that over 56% of those who had been diagnosed with SMI were smokers compared to 14% of the UK population who were smokers.²³ Alcohol misuse has also been found to be higher in those with SMI. The link between smoking and oral cancer has been long established.²⁴ Additionally, consumption of alcohol has been shown to act synergistically in increasing that risk.²⁴ Therefore, education and awareness of risk factor control in this patient group is vital.

Impact of medication used in the management of SMI

Lithium

This is a common drug used for patients with bipolar affective disorder and is a mood stabilizer.²⁵ It helps to reduce the number of depressive or manic episodes and reduces their intensity. Long-term use can induce lithium toxicity resulting in reduced kidney or thyroid function.²⁵ Lithium also has many drug interactions with drugs commonly prescribed by dental professionals. These are listed in the British National Formulary (BNF) and outlined in Table 1.²⁶

Oral side effects of antipsychotics used in the management of SMI

Antipsychotics are commonly used to help manage SMI. If the patient is on medication for other comorbidities, polypharmacy can increase the risk of xerostomia.²⁷ Antipsychotics can cause multiple systemic side effects, alongside those affecting the oral cavity, as outlined in Table 2.

Practical dental management

Access

Multiple factors can negatively affect the ability of those with SMI to access dental care. This patient group may experience dental anxiety, which can discourage contact with necessary services.²⁸ Additionally, patients with SMI may have previously felt stigmatized or had a negative dental experience. Homelessness, a lack of fixed abode or an erratic lifestyle can also be deterring factors in seeking treatment.¹ Dental professionals should make reasonable adjustments for people with SMI. Patient education around the services available and referrals to appropriate settings such as community dental services may be indicated.

Communication and capacity

Owing to the nature of the medication taken for the management of SMI, patients can appear distant, drowsy, and uninterested (Table 2). Capacity may be transient, but that does not mean it is not present. It may be necessary to seek a second opinion and/or to bring a patient back on an alternative day or at a different time to make an assessment. Mental capacity should be assessed on a case-by-case basis using up-to-date legislative frameworks as a guide. The five main principles, detailed in the Mental Capacity Act (2005), are outlined below: ²⁹

• Assume a person has mental capacity unless proved otherwise;
• Reasonable steps must be taken to help support the person to make a decision;
• A person with capacity can make an unwise decision;
• The least restrictive option should be chosen;
• Any decision taken on behalf of the person should be in their best interests

Conscious sedation

Owing to the high prevalence of dental anxiety, patients with SMI may request conscious sedation.³⁰ Although there is no direct absolute contra-indication for the use of intravenous sedation in people with SMI, care must be taken if the patient has multiple comorbidities that may render them unsuitable.³⁰ The patient may be on certain antipsychotics or benzodiazepines that may increase the sedative effect of midazolam.³⁰ Alternative methods, such as inhalation sedation with behavioural management, may be recommended.

Oral health advice

Owing to the high risk of caries, periodontal disease and oral cancer, patients with SMI should be on a frequent recall as per NICE guidance.³¹ It is important to follow the ‘Delivering Better Oral Health’ guidance and implement a high level of prevention, along with smoking cessation, where appropriate.³² As discussed previously, oral hygiene may be inconsistent, in line with fluctuating moods, and dental professionals should be mindful of this. A 12-month randomized controlled trial found that an intensive oral health promotion programme was effective.³³ This included group sessions twice a week. This highlights the need to provide a tailored oral health prevention plan for people with SMI.

Dental treatment

It is important to manage expectations for this patient group. Restorative treatment may need to exclude any complex prosthodontics owing to the high caries risk.¹⁵ Palliative periodontal treatment may be the only option if oral hygiene cannot be improved for patients in this group. If the patient has uncontrollable facial movements (tardive dyskinesia) (Table 2), denture work may not be possible. If the patient has a history of substance and alcohol misuse, it may be necessary to obtain blood test results from the patient's physician prior to dental extractions. This will help to assess the need for additional haemostatic measures. Those within this patient group may also require referral to specialist services or community dental services.

Conclusion

Practical and sustainable adaptation of care delivery in patients with SMI is vital to ensure the dental needs of this patient demographic are met. The ‘Five Year Forward View for Mental Health’³⁴ published in 2016, set out a framework for the NHS to improve services in this domain. Building on this, the 2022 ‘Right to Smile’ Oral Health Consensus statement focuses on more specific oral health needs to provide a thorough, evidence-based resource for dental professionals.³⁵

SMI is often associated with stigma, discrimination, socio-economic disadvantage, unemployment, reduced quality of life and poor physical health.¹ The recent introduction of integrated care systems within NHS England in July 2022 supports and encourages cross-team liaison in co-ordinating care for patients.³⁶ Therefore, greater collaboration is necessary between healthcare providers in order to improve the overall general health of people with SMI. The provision of consistent, appropriate and focused dental care in this demographic will continue to be a vital piece of the puzzle.