Understanding the Oral Health Status and Factors Affecting Poor Oral Health in People Living With Severe Mental Illness: A Cross‐Sectional Study

ABSTRACT

Objectives

To assess the oral health status of patients with severe mental illness visiting the Collaborative Centre for Cardiometabolic Health in Psychosis clinics and examine the effect of demographic, medical and social factors on Oral Health (OH).

Methods

The cross‐sectional study included adults aged 18–65 years with severe mental illness who attended the clinics in Sydney, Australia between June 2016 and December 2020. As part of the OH assessment, information about their oral hygiene behaviours was recorded and participants underwent dental examination to assess their dental status.

Results

The majority of the 845 patients were male (63%), with a mean age of 43.4 years and a diagnosis of Schizophrenia (61%). Co‐morbidities included dyslipidaemia (93.3%), overweight/obesity (81%), and hypertension (47%). Gingival inflammation was noticed in 80% of participants. Caries experience was high, with 44% having active tooth decay requiring restoration or extraction. Age, smoking, schizophrenia, depression and cardiometabolic conditions like diabetes and hypertension were significantly associated with caries. Gingival inflammation was significantly associated with psychiatric diagnosis and antipsychotic medications, male gender, smoking and diabetes.

Conclusions

People with severe mental illness have a high prevalence of dental caries and gingival inflammation. A strong association between dental diseases and demographics as well as cardiometabolic conditions emphasises the need for a multipronged approach to improve the overall health outcomes of people with severe mental illness.

Summary.

• People living with severe mental illness (SMI) experience significant oral health disparities, including higher rates of dental caries, periodontal disease, and tooth loss. These issues stem from a combination of factors such as medication‐induced xerostomia, reduced ability for self‐care, and chronic systemic cardiometabolic conditions. Poor oral health in this population can adversely affect nutritional intake, social functioning, and overall quality of life. Furthermore, these oral health issues can exacerbate comorbidities such as diabetes and cardiovascular disease through bidirectional inflammatory pathways.

• The Collaborative Centre for Cardiometabolic Health in Psychosis (ccCHiP) Programme exemplifies the importance of collaborative, multidisciplinary care involving psychiatrists, oral health professionals, cardiologists, endocrinologists and nurses. This is the first large‐scale study looking at the oral health status of people living with severe mental illness in New South Wales, Australia. The findings of the study inform the burden of oral disease among this population and the need for early intervention in improving oral and general health outcomes. The ccCHiP integrated care model provides a one‐stop shop for these patients to assess and manage their cardiometabolic risk factors including poor oral health.

1. Introduction

Severe mental illness (SMI) (schizophrenia, schizoaffective disorders, depression and bipolar disorders) is chronic, typically involves progressive neuropsychiatric impairment, and reduces the ability of individuals to independently manage their own care, both medically and socioeconomically. People living with SMI experience worse health outcomes and shorter life expectancy than the rest of the population [1, 2, 3, 4]. Studies cited in the Australian Institute of Health and Welfare—Physical Health of People With Mental Illness report show similar findings in Australia [5]. In addition, this population has substantially high rates of potentially preventable hospitalisations for chronic physical health conditions like respiratory, particularly chronic obstructive airways disease, metabolic including diabetic complications, and cardiovascular disease (CVD) [6]. Obesity, diabetes, and smoking are important risk factors for CVD and premature mortality in patients with schizophrenia [7]. Despite the existence of national guidelines, up to 70% of people living with SMI are unscreened and untreated or undertreated for diabetes [8, 9], resulting in prolonged adverse effects on physical and mental health [10]. People with schizophrenia have four times the risk of abdominal obesity compared to the general population [11], and approximately 50% of public mental health service patients taking antipsychotic medication have a metabolic disorder [12].

Poor oral health (OH) is a significant problem in people living with SMI and is linked to systemic diseases such as cardiac disease, diabetes, stroke, and respiratory disease [13]. A decrease in mental health is associated with an increased need for dental care [14]. In a large national sample of patients in the Veterans Affairs (VA) health system, Kilbourne et al. [15] demonstrated that 61% of patients diagnosed with SMI reported poor OH. Higher risk of dental disease is due to several factors like poor nutrition, inadequate oral hygiene, high consumption of sugary drinks and comorbid substance misuse that may include tobacco, alcohol or psychostimulants. The main diseases that affect OH are dental erosion, dental caries, and periodontal disease. A systematic review and meta‐analysis [16] has shown that people with SMI have 2.8–3.54 times the odds of having lost all their teeth compared to the general community. They also have significantly higher decayed, missing, and filled surfaces (DMFS) and decayed, missing, and filled teeth (DMFT) scores, but most of the decayed teeth are unrestored. A Malaysian study [17] examining the OH status of a large cohort of people with schizophrenia reported significantly high DMFT in the participants compared to the general population (20.5 vs. 11.7). The prevalence of periodontal disease was high, but the severity was largely similar to that of the general population. The proportion of edentulism was significantly higher at 14.2% as opposed to 7.3% of the general population. An Australian study measuring the OH of psychiatric patients from two community mental health clinics in Queensland [18] reported a mean DMFT of 17.7, significantly higher than the state (13.1) and national (12.8) scores.

In the Australian health care system, there is a separation between primary and secondary care and between mental health and physical health care. This lack of integration often leads to poor communication between health care providers, role ambiguity, and reluctance to take on additional functions. Systematic reviews [19, 20] have demonstrated the effectiveness of primary health care for people living with mental illness and the critical enablers of effectiveness. However, evidence for the effectiveness of an integrated community care model is lacking. The 2016 Royal Australian and New Zealand College of Psychiatrists guidelines [21] advocate mandatory screening and intervention for cardiometabolic problems in people with schizophrenia from the first episode of psychosis. The paucity of long‐term data in the global literature provided the impetus for a multicentre study currently underway in New South Wales to examine cardiometabolic risks in first‐episode psychosis patients.

The Collaborative Centre for Cardiometabolic Health in Psychosis (ccCHiP) Programme [22] was established with a purpose to integrate primary care, mental health, and specialist services (including endocrinology, cardiology and OH) and aims to improve access to physical health care and health outcomes in people living with SMI. The model of care involves multiple medical and allied health specialists who provide a discipline‐specific assessment of the patient's cardiovascular risk and link them to appropriate services.

The aim of the present study was to determine the OH status of patients visiting the ccCHiP clinics and examine the relationship between OH and demographic, medical, and social factors.

2. Methods

The cross‐sectional study included adults with SMI, aged 18–65 years, who attended the ccCHiP clinic between June 2016 and December 2020 at one of two Sydney Local Health District sites—Concord Repatriation General Hospital (CRGH) or Charles Perkins Centre, Royal Prince Alfred Hospital (CPC‐RPA), New South Wales, Australia, and had an OH screening. Patients who had a primary International Classification of Diseases, 10th Revision (ICD‐10) psychiatric diagnosis of schizophrenia and related psychosis, bipolar and unipolar depression with psychosis, or a very small collection of other severe psychotic disorders (first episode psychosis, drug‐induced psychosis, or organic psychosis that are persistent), as recorded in their electronic medical records (eMR) by the treating mental health professional team, were eligible to be seen at the ccCHiP clinic. At the time of initial consultation, informed consent for examination and OH screening was obtained. Ethics approval was obtained from the Sydney Local Health District Concord Ethics Committee. A waiver of consent was granted by the ethics committee for use of patient data in this research project.

As part of the ccCHiP electronic form, demographic data like age, gender, body mass index, educational level, and living arrangements was noted. BMI of 18.0–< 25.0 kg/m² was defined as ‘normal’, ≥ 25.0–< 30.0 kg/m² as overweight, and ≥ 30 kg/m² as obese. Diabetes criteria have been explained in detail in an earlier paper [23]. A patient was diagnosed with hypertension if the diastolic was ≥ 85 or systolic was ≥ 130 or they were on medication for hypertension. Patients were classified as having dyslipidaemia if any one of the following targets was exceeded or they were on lipid‐lowering treatment—the total cholesterol targets were > 4.2 mmol/L or LDL cholesterol cut‐offs were > 2.59 mmol/L or triglycerides were ≥ 1.7 mmol/L, and HDL cholesterol was < 1.04 mmol/L for males or < 1.29 mmol/L for females.

Health behaviours recorded were smoking, diet, and consumption of sugar. Data on intake of food and added sugars from sugar sweetened beverages (SSB) was collected by the dietitian in the ccCHIP clinic. SSBs comprised of cola type soft drinks (Coca Cola/other carbonated sugar drinks), flavoured milk, tea/coffee, cordial, juice, and energy drinks. Clinical and medical comorbidities were routinely collected for patients who attended the ccCHiP clinic.

OH screening was done by one of two OH therapists (OHT) or an experienced dentist who trained the OHTs in screening protocol and standardised the examination to reduce inter‐examiner bias. Patients were seen in a consultation room, sitting in a normal chair under natural and artificial light using a disposable mirror and probe. The screening included recording the dental visiting patterns like time since the last dental visit and oral hygiene behaviours (brushing frequency, time of brushing, and cleaning aids used). History of dental issues that were asked included any pain, swelling, bleeding gums, broken teeth or denture and history of pain. More information like duration and severity of pain was recorded if present. Extra‐oral examination included the examination of facial structures including facial symmetry, lips, and extraoral lymph nodes. Intra‐oral examinations included the examination of soft tissues and hard tissues including dental charting and denture assessment. Gingival condition was assessed by visual examination and categorised into three—healthy and pink, edematous/inflamed with local redness (Localised), and edematous/inflamed with general redness (Generalised). During dental charting, dental caries was recorded as present or absent. It was marked as present if there was visible tooth decay. White spot lesions were not marked as dental caries. Filling was recorded if a tooth had any type of filling (amalgam, glass ionomer or composite). Any teeth absent, including wisdom teeth, were marked as missing. Tooth wear was defined as any tooth showing attrition, abrasion, or erosion. Denture assessment was done for those who wore dentures. The type of denture (partial or full denture in upper and/or lower jaw) was noted along with the stability of the denture and the health of the tissues under the denture.

Dental caries experience was calculated by adding the number of decayed, missing or filled teeth (DMFT score). OH findings were discussed with the patients and/or their carer along with OH advice and provision of oral hygiene products (toothpaste and toothbrush). Those with poor OH were referred with recommendations to have dental treatment in one of the public dental clinics (no cost) or their own private dentist. The national data on oral health status [24] and smoking [25] were compared with the study population.

Data were analysed using the SAS version 9.4 software (SAS Institute Inc., Cary, NC, USA). Descriptive analysis is expressed in frequencies and percentages for categorical variables and means and standard deviations for continuous variables. The statistical significance of bivariate associations between clinical outcomes and independent variables (sex, age group) was assessed by means of Chi‐squared tests. The Fisher exact test was used in place of the Chi‐squared test to analyse categorical data with insufficient expected cell counts. DMFT score and gingival inflammation were considered as the dependent variables. Socio‐demographic variables and factors predisposing individuals to OH problems, including SMI diagnosis, medication for SMI, oral hygiene habits, frequency of tooth brushing, smoking (previous smokers who reported having ceased smoking within 12 months were combined with the ‘current’ smokers, and those beyond 12 months with the ‘never’ category), and sugar‐sweetened beverages (SSB) intake habit were included as explanatory variables. A value of p < 0.05 was considered statistically significant. This paper was written following the ‘Strengthening the Reporting of Observational studies in Epidemiology (STROBE) statements’ (https://www.strobe‐statement.org/) [26].

3. Results

A total of 1058 patients were seen in the two main ccCHiP clinics. Of these, 845 patients (79.8%) had a baseline screening done by the dental team and tooth charting was undertaken for 733 (69.3%) patients. Over 60% of the patients (n = 515) were diagnosed with schizophrenia, followed by 14% with bipolar disorder (n = 117). The socio‐demographic characteristics of the group by SMI diagnosis are shown in Table 1. The mean age of the participants was 43.4 years (SD = 12.7) and the majority of them were male (63%). The education level was high with 95% having a secondary, post‐secondary, or tertiary qualification, but only 15% were currently employed. Just over a third lived alone and 28% lived with parents or siblings.

TABLE 1.

Socio‐demography and health status of the study participants.

Demographics	N = 845	%	Schizophrenia n = 515	Schizoaffective n = 65	Bipolar n = 117	Depression n = 38	Other n = 107
Male***	535	63.3	67.8	60	51.3	57.9	60.7
Age in years *
18–24	77	9.1	3.1	6.1	10.3	13.2	35.5
25–34	137	16.2	14.8	18.5	20.5	10.5	19.6
35–44	198	23.4	27.4	21.5	19.7	13.2	14.0
45–54	248	29.4	30.3	30.8	34.2	28.9	18.7
55–64	145	17.2	19.0	18.5	13.6	23.7	9.4
> 64	40	4.7	5.4	4.6	1.7	10.5	2.8
Education level *
Primary	16	2.0	2.6	1.6	0	5.6	0
Secondary	390	48.0	52.3	49.2	33.9	47.2	43
Post‐secondary	200	24.6	24.6	26.2	26.1	25	22
Tertiary	184	22.7	17.5	22.9	38.3	22.2	30
Unknown	22	2.7	3.0	0	1.7	0	5
Employment status *
Employed	125	15.6	11.4	16.7	29.7	13.9	21.2
Pension	508	63.4	74.8	66.7	41.4	44.4	37.4
Studying	39	4.9	2.4	3.3	8.1	2.8	13.1
Unemployed	129	16.1	11.4	13.3	20.7	38.9	28.3
Living status *
Alone	285	34.1	36.6	35.4	28.7	37.8	26.9
With Spouse/defacto	89	10.7	7.6	12.3	20.9	24.3	8.7
With Parents/siblings	237	28.4	27.2	29.2	24.4	13.5	42.3
With other family member	46	5.5	3.3	6.2	10.4	5.4	9.6
With one other not family	34	4.0	3.9	6.2	7	0	1.9
Group of others	39	4.7	5.5	0	4.4	2.7	4.8
Supported accommodation/hospital	45	5.4	6.5	4.6	2.6	10.8	1.9
Boarding house	60	7.2	9.4	6.2	1.7	5.4	3.8
Current smoker*	416	50.3	56.0	51.6	38.8	21.6	47.2
Never	331	40.1	33.9	37.5	49.1	67.6	50.0
Previous	79	9.6	10.1	10.9	12.1	10.8	2.8
Obese/overweight	650	81.3	81	87.3	82.6	80.6	77.8
Dyslipidaemia	788	93.3	94.2	92.3	95.7	92.1	89.7
Diabetes*	188	22.3	27.2	18.5	13.7	23.7	9.4
Hypertension**	384	46.7	48.6	54.7	42.2	65.8	31.4
Antidepressants*	264	31.4	26.5	32.3	25.6	86.5	16.7
Antipsychotics *
Clozapine or other	201	23.9	33.6	24.6	4.3	2.6	5.6
Olanzapine or other	151	17.9	16.1	29.2	22.2	13.2	16.8
Other	429	50.9	48.2	43.1	61.5	44.7	59.8
None	61	7.2	2.1	3.1	12	39.5	17.8

^* p ≤ 0.0001.

^** p < 0.001.

^*** p < 0.05.

Clozapine and Olanzapine were the two most common antipsychotics taken by patients, and almost a third of them were on antidepressants. The proportion of current smokers was 50% overall, but the prevalence of smoking was significantly lower in those with Bipolar (38.8%) and Depression (21.6%) compared to patients with Schizophrenia (56%) or Schizoaffective disorder (51.6%) (p ≤ 0.0001). A vast majority of them (81%) were overweight or obese, 22% had diabetes, 46.7% were hypertensive, and over 90% had dyslipidaemia.

More than half of the study subjects (55%) had seen a dentist in the last 2 years; 37% of them reportedly brushed their teeth once a day, and 32% brushed twice a day. Toothbrush and toothpaste were the most commonly used cleaning aids (76%), followed by mouthwash (15%) and floss (13%). Only 2% reportedly used interdental brushes. The overall gingival health of the study population was poor. Visible plaque was seen in over 90% of the participants, and almost a third (31%) had generalised severe plaque deposits covering over 2/3rd of the tooth surfaces.

Generalised gingival inflammation characterised by gingival redness and oedema was observed in 38% of the total participants, and 42% had localised inflammation. Patients with schizophrenia (83.8%), schizoaffective (78.9%), and bipolar (77.1%) disorders had significantly poorer gingival health (p < 0.05). Missing teeth were significantly more prevalent in patients with bipolar (85.5%) and schizophrenia (79.6%) (p < 0.05) (Table 2).

TABLE 2.

Oral health status of the study participants by the SMI diagnosis.

	Schizophrenia (%)	Schizoaffective (%)	Bipolar (%)	Depression (%)	Others (%)
Dry mouth	11.8	14.3	17.1	10.5	7
Last dental visit
0–12 months	12.1	19.4	15.6	12.5	11.7
13–24 months	39.8	43.6	52.3	37.5	39.8
> 24 months	33.1	27.4	25.7	31.2	29.1
Unknown	15	9.7	6.4	18.8	19.4
Brushing frequency
Infrequent	24	20.4	13.2	16.7	24.4
Once a day	40.8	40.7	40.6	40	34.4
Twice a day	35.2	38.9	46.2	43.3	41.1
SSB consumption
Yes	62.5	50.8	60.7	50	57.9
Location
L1 (CPC‐RPA)	49.1	53.9	53.9	42.1	48.6
L2 (CRGH)	48.2	41.5	41.9	52.6	51.4
Caries status
Decayed teeth	45.6	43.1	33.3	36.9	41.2
Filled teeth	65.4	67.7	76.9	71	57
Missing teeth***	79.6	72.3	85.5	73.7	68.2
Gingival status ***
Healthy gingiva	16.2	21.2	22.9	33.3	26.1
Localised gingival inflammation	42	38.5	50.5	36.7	37.5
Generalised gingival inflammation	41.8	40.4	26.6	30	36.4

^*** p < 0.05.

The dental caries experience of the study participants was high, with only 7.9% (n = 58) of participants having a DMFT of zero and 44% (318/720) having active tooth decay requiring restoration or extraction. Eighty percent of them had at least one missing tooth, and 568 patients had filled teeth (78.9%). The DMFT score for the study participants ranged from 0 to 28 (9.6 ± 8.0; mean ± SD). The number of decayed teeth ranged from 0 to 20 (1.7 ± 3.2; mean ± SD), and the number of filled teeth ranged from 0 to 24 (4.0 ± 4.3; mean ± SD). Only 13 participants had all teeth missing, and the mean number of missing teeth was 4.02 ± 6.5.

Denture status was available for the 577 participants and only 11% (n = 65) wore dentures; 32 had lower full, 27 had upper full, 21 had upper partial, and 13 had lower partial dentures. Some inflammation under the denture was noticed in 11 participants (27%).

The DMFT score was not significantly associated with gender, but there was a statistically significant association between DMFT score and age (p < 0.001). DMFT score increased with age, mainly the missing teeth (Table 3). Mean DMFT and mean number of missing teeth were significantly higher in smokers (p < 0.0001), patients with Schizophrenia and Depression (p < 0.0005), and participants with cardiometabolic conditions like diabetes (p < 0.0001) and hypertension (p < 0.005). DMFT scores were lower among those who did not take antipsychotic medications like Clozapine and Olanzapine (p < 0.05). There was no significant association between DMFT scores and BMI, Dyslipidaemia, dry mouth, dental visit, brushing frequency, and SSB consumption.

TABLE 3.

Factors associated with DMFT scores.

	N	Mean DMFT (95% CI)	Mean decayed teeth (95% CI)	Mean missing teeth (95% CI)	Mean filled teeth (95% CI)	p
Age in years
18–24	63	2.0 (1.4–2.5)	0.7 (0.3–1.04)	0.3 (0.1–0.4)	1.0 (0.7–1.4)
25–34	110	4.8 (3.9–5.8)	1.4 (0.8–1.9)	0.8 (0.5–1.1)	2.6 (2.0–3.2)
35–44	181	7.8 (6.8–8.7)	2.1 (1.5–2.7)	2.2 (1.6–2.8)	3.5 (3.0–4.0)
45–54	217	11.4 (10.3–12.4)	1.7 (1.3–2.1)	5.1 (4.2–6.1)	4.6 (4.0–5.2)
55–64	128	14.8 (13.5–16.2)	1.8 (1.3–2.4)	7.7 (6.3–9.1)	5.6 (4.7–6.4)
> 64	34	18.9 (16.2–21.6)	2.2 (0.6–3.8)	10.2 (7.0–13.3)	7.7 (5.1–10.3)	< 0.0001
Smoking status
Current	366	10.8 (9.9–11.6)	2.3 (1.9–2.7)	5.0 (4.3–5.8)	3.6 (3.2–4.0)
Never	354	8.5 (7.7–9.3)	1.1 (0.8–1.4)	3.0 (2.5–3.6)	4.4 (3.9–4.9)	< 0.0001
Psychiatric diagnosis
Schizophrenia	447	10.4 (9.6–11.2)	2.0 (1.7–2.3)	4.5 (3.9–5.2)	4.0 (3.6–4.5)
Schizoaffective	54	9.4 (7.4–11.5)	1.4 (0.6–2.1)	4.0 (2.2–5.7)	4.2 (3.0–5.4)
Bipolar	110	9.3 (7.8–10.7)	1.1 (0.6–1.6)	3.3 (2.4–4.2)	4.8 (4.0–5.6)
Depression	33	10.6 (7.6–13.5)	1.2 (0.3–2.1)	4.5 (2.1–6.8)	4.9 (3.0–6.7)
Others	87	6.1 (4.6–7.7)	1.3 (0.7–2.0)	2.3 (1.2–3.3)	2.6 (1.9–3.3)	< 0.0005
Diabetes
No	582	8.9 (8.3–9.6)	1.6 (1.3–1.8)	3.4 (3.0–3.9)	4.0 (3.7–4.3)
Yes	151	12.3 (10.9–13.8)	2.2 (1.7–2.8)	6.3 (5.0–7.6)	4.0 (3.3–4.7)	< 0.0001
Hypertension
No	387	8.4 (7.7–9.2)	1.7 (1.3–1.9)	3.2 (2.6–3.7)	3.7 (3.3–4.1)
Yes	346	11.0 (10.1–11.9)	1.7 (1.4–2.1)	5.0 (4.2–5.7)	4.4 (3.9–4.9)	< 0.005
Antipsychotics
Clozapine or other	173	10.2 (8.9–11.5)	1.8 (1.3–2.2)	4.7 (3.5–5.8)	4.0 (3.3–4.6)
Olanzapine or other	134	11.0 (9.6–12.4)	2.3 (1.6–2.9)	5.0 (3.7–6.2)	4.0 (3.3–4.7)
Other	379	8.9 (8.2–9.7)	1.5 (1.2–1.8)	3.4 (2.9–4.0)	4.1 (3.6–4.5)
None	47	9.3 (7.0–11.6)	1.5 (0.6–2.5)	3.9 (2.4–5.5)	3.9 (2.7–5.1)	< 0.05
Location
L1 (CPC‐RPA)	399	10.3 (9.5–11.2)	1.7 (1.3–2.0)	4.4 (3.7–5.1)	4.4 (4.0–4.9)
L2 (CRGH)	310	8.5 (7.7–9.4)	1.7 (1.3–2.0)	3.4 (2.7–4.0)	3.5 (3.1–4.0)	< 0.005

Gingival inflammation was significantly more prevalent among men (p < 0.0001), those who had not seen a dentist for over 24 months (p < 0.0001), and those who brushed infrequently (p < 0.0001) (Table 4). Psychiatric diagnosis and antipsychotic medications were also associated with gingival inflammation. Other significant risk factors for gingival inflammation included smoking (p < 0.0001) and diabetes (p = 0.001). No significant association was noted by age, BMI, dyslipidaemia and hypertension.

TABLE 4.

Factors associated with gingival inflammation.

	Healthy gingiva		Localised gingival inflammation		Generalised gingival inflammation		p
	N	% (95% CI)	N	% (95% CI)	N	% (95% CI)
Male	63	14.0 (10.7–17.2)	185	41.0 (36.5–45.6)	203	45.0 (40.4–49.6)
Female	77	30.0 (24.3–35.6)	113	44.0 (37.9–50.1)	67	26.0 (20.7–31.5)	< 0.0001
Smoking status
Current	53	15.0 (11.3–18.7)	141	39.9 (34.8–45.1)	159	45.0 (39.8–50.2)
Never	84	24.5 (19.9–29.1)	154	44.9 (39.6–50.2)	105	30.6 (25.7–35.5)	< 0.0001
Psychiatric diagnosis
Schizophrenia	69	16.2 (12.7–19.7)	179	42.0 (37.3–46.7)	178	41.8 (37.1–46.5)
Schizoaffective	11	21.1 (10.0–32.3)	20	38.5 (25.2–51.7)	21	40.4 (27.0–53.8)
Bipolar	25	22.9 (15.0–30.8)	55	50.5 (41.0–59.8)	29	26.6 (18.3–34.9)
Depression	10	33.3 (16.4–50.2)	11	36.7 (19.4–54.0)	9	30.0 (13.6–46.4)
Others	23	26.1 (16.9–35.3)	33	37.5 (27.4–47.6)	32	36.4 (26.3–46.4)	< 0.05
Diabetes
No	125	22.1 (18.7–25.5)	240	42.4 (38.3–46.5)	201	35.5 (31.6–39.50)
Yes	15	10.5 (5.5–15.6)	58	40.9 (32.7–48.9)	69	48.6 (40.4–56.8)	0.001
Antipsychotics
Clozapine or other	41	24.6 (18.0–31.1)	63	37.7 (30.3–45.1)	63	37.7 (30.4–45.1)
Olanzapine or other	23	17.1 (10.7–23.4)	52	38.5 (30.3–46.7)	60	44.4 (36.0–52.8)
Other	61	17.0 (13.1–20.8)	170	47.2 (42.1–52.4)	129	35.8 (30.9–40.8)
None	15	32.6 (19.0–46.1)	13	28.3 (15.2–41.3)	18	39.1 (25.0–53.3)	0.01
Last dental visit
0–12 months	97	32.2 (26.9–37.5)	121	40.2 (34.6–45.8)	83	27.6 (22.5–32.6)
13–24 months	14	14.9 (7.7–22.1)	47	50.0 (39.9–60.1)	33	35.1 (25.4–44.8)
> 24 months	23	10.7 (6.5–14.8)	85	39.3 (32.8–45.9)	108	50.0 (43.3–56.7)
Unknown	2	3.5 (0–8.3)	23	40.4 (27.6–53.1)	32	56.1 (43.2–69.1)	< 0.0001
Brushing frequency
Infrequent	7	4.9 (1.3–8.4)	40	28.0 (20.6–35.3)	96	67.1 (59.4–74.9)
Once a day	41	16.3 (11.8–20.9)	124	49.4 (43.2–55.6)	86	34.3 (28.4–40.1)
Twice a day	83	33.4 (27.6–39.4)	111	44.8 (38.6–51.0)	54	21.8 (16.6–26.9)	< 0.0001
SSB consumption
No	65	24.9 (19.6–30.2)	96	36.8 (30.9–42.6)	100	38.3 (32.4–44.2)
Yes	75	16.8 (13.3–20.3)	202	45.2 (40.6–49.8)	170	38.0 (33.5–42.5)	0.02
Location
L1 (CPC‐RPA)	112	29.7 (25.1–34.3)	124	32.9 (28.1–37.6)	141	37.4 (32.5–42.3)
L2 (CRGH)	27	8.8 (5.6–12.0)	166	53.9 (48.3–59.5)	115	37.3 (31.9–42.8)	< 0.0001

Table 5 compares the OH status of the participants with the Australian population. The median age and the proportion of males in the ccCHiP population were higher. They were more likely to be smokers (1 in 2) when compared to the prevalence nationally (1 in 7). The mean DMFT and in specific complete tooth loss were lower than the national average, but the prevalence of gingival inflammation was significantly higher in the ccCHiP patients.

TABLE 5.

Oral health status of ccCHiP patients, compared to national findings.

Variables	ccCHiP patient sample (%)	National (%)
No tooth decay	7.9	10.7
Untreated tooth decay	44	40.3
Filled teeth	77	77.4
Complete tooth loss	1.8	4.0
< 21 natural teeth	12.5	10.2
Mean DMFT	9.6	11.2
Gingival inflammation	80	28.8
Wearing U/L dentures	11.3	11.3

4. Discussion

The current study looked at the OH status of a large sample (n = 733) of people with SMI in an outpatient setting in Sydney, New South Wales. There have been very few previously reported Australian studies that have assessed the oral health of people with SMI. A study from Melbourne, Victoria [27] reported on the OH of people with a psychiatric disability (n = 273) who were part of the ‘Dental as Anything’ outreach programme. Another study interviewed and examined 50 psychiatric patients from two outpatient clinics in South‐east Queensland [18]. A third study from NSW was a retrospective analysis of a cross‐sectional study and included a survey and dental check‐up offered to all young people engaged with the Early Psychosis and Youth (At‐Risk Mental State) Programmes in the South Eastern Sydney Local Health District [28]. The distribution of participants by age, sex and psychiatric diagnosis in the current study was similar to the Queensland study than the other two studies.

The mean DMFT observed in the present study population was 9.6. This was significantly lower than studies published from Europe and the United States [16] where the reported mean score was close to 20 and the Queensland study with a score of 17.7 [18]. One of the reasons for this observation could be the effect of water fluoridation. Most of the study subjects were from the Sydney metropolitan region which has been fluoridated for over 50 years. The systemic and topical effects of fluoride may have had a preventative effect on dental caries. Positive OH behaviours and habits are shown to be associated with low caries prevalence [29]. A recent systematic review and meta‐analysis reported that individuals with a SMI were significantly less likely to access dental services or brush their teeth in comparison with non‐clinical controls [30]. In contrast, our study reported that the majority of the participants had seen a dentist in the last 2 years and almost 40% of them reportedly brushed twice a day. However, the positive dental behaviours in our study were not associated with DMFT scores. Psychiatric diagnosis and the use of antipsychotic medication along with smoking and diabetes were found to be significant risk factors for dental caries in the study. Hyposalivation, a side effect of the first‐generation antipsychotics and antihypertensive, has been shown to increase the risk of dental caries and could explain for the increased DMFT [31].

By contrast, the prevalence of gingival inflammation among the participants was substantially higher than the national average. This is of concern as chronic dental inflammation is shown to be associated with cardiovascular disease, and a bi‐directional link exists between periodontal disease and diabetes [32, 33] Gingival inflammation was associated with high‐risk behaviours such as poor oral hygiene, infrequent dental visits and smoking. A high proportion of participants reported brushing once or twice a day and using oral hygiene aids like a toothbrush and toothpaste. Similar findings were reported in the study among young people engaged with mental health services in Southeastern Sydney, who reported comparable positive oral health behaviours [28]. The high prevalence of plaque and gingival inflammation observed in our study could be due to the side effects of psychotropic medications such as xerostomia, lethargy, and movement disorders [34]. In addition, poor lifestyle and health habits like smoking and substance abuse can increase the risk of gingival inflammation. A longitudinal study looking at the prevalence of cigarette smoking in a sample of 1938 individuals with schizophrenia and bipolar disorder over a 17‐year period reported that 62% of individuals with schizophrenia and 37% with bipolar disorder were current smokers. This was very similar to the prevalence of smokers in our study, where 56% of individuals with schizophrenia and 38.8% with bipolar disorder were smokers. In comparison, the prevalence of smoking in the general population in Australia is 10% [24].

All the OH parameters in the study population except gingival inflammation were similar and comparable to the national averages [23]. This could be because the ccCHiP participants had a higher education level (97%), reported good oral hygiene practices, and were connected to dental services. Although most of the study subjects were male, it is unlikely that differences in the gender distribution between patients and the national sample would affect the comparison, given that the prevalence of dental disease does not vary greatly by gender. However, the high prevalence of plaque and gingival inflammation and the inability to look after their OH places the participants at high risk for periodontal disease and, therefore, for cardiometabolic diseases.

The study has a few limitations. The dental consultation did not allow for a detailed examination or periodontal charting and was undertaken in a non‐dental setting with the patient seated in a normal chair. No radiographs were taken and the gingival status was assessed visually. These factors will affect the accuracy of measurements and limit the ability to compare the findings with other studies of people with SMI undertaken in a controlled dental setting. The information on patients' oral hygiene practices, dental visits, or smoking behaviours was self‐reported. In addition, the clinicians were not blind to patients' psychiatric status. These may result in potential bias. The strength of the study, however, is its large sample size, which allowed for comparisons to be made by the SMI diagnosis. Most dental examinations were undertaken by only two clinicians who were trained by the principal author, thereby reducing potential inconsistencies and bias during the examination.

In conclusion, the study sheds light on the OH status of people with SMI. High prevalence of dental diseases increases the potential risk of cardiometabolic disease. However, the novel model of care offers to remove barriers to accessing care by providing free comprehensive dental treatment to ccCHiP patients in public clinics. Long‐term follow‐up studies will inform if the dental interventions alter the risk levels of people with SMI and impact their overall cardiometabolic outcomes.

Conflicts of Interest

The authors declare no conflicts of interest.

Supporting information

Data S1: adj70006‐sup‐0001‐DataS1.docx.

Data Availability Statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.