Feasibility Study of a Behavioral Oral Health Intervention for People With Mental Health Challenges: A Self‐Regulation Approach

ABSTRACT

Background and Aims

People with mental health disorders experience disproportionately poor oral health and face persistent barriers to maintaining oral hygiene. This study aimed to assess the feasibility of supporting oral hygiene routines in community‐dwelling adults using a self‐regulation‐based education approach informed by Self‐Determination Theory, to identify practical strategies for integrated mental and oral health care.

Methods

Thirty‐nine participants from two community mental health centers received single‐session oral health education at baseline (T1). Oral health status was assessed using the Oral Health Assessment Tool and the Silness and Loe Plaque Index. Oral health knowledge and motivation were measured at T1, 4 weeks (T2) and 8 weeks (T3) using a knowledge questionnaire, the Treatment Self‐Regulation Questionnaire, the Perceived Competence Scale and the Relative Autonomy Index (RAI). At T2 and T3, participants received plaque feedback, reinforcement of the key message and motivational support.

Results

Most participants were aged 50 years or older. At baseline, over half of the participants demonstrated poor oral cleanliness, and fewer than one‐third had healthy natural teeth. Plaque scores improved significantly from T1 to T2 (mean reduction 21%, p < 0.001), but plateaued by T3. Oral health knowledge improved across all domains, particularly in understanding oral‐systemic links and recognizing oral disease risk factors. Autonomous motivation was modest at T1 (RAI = + 0.15), declined at T2 (RAI = −0.93), and partially recovered at T3 (RAI = −0.57), indicating variability in motivational regulation over time.

Conclusion

Single‐session oral health education was associated with short‐term improvements in knowledge and plaque control; however, sustaining behavior change and motivation likely requires ongoing reinforcement, support and repeated engagement. Visual feedback, structured routines and collaboration between mental health and oral health services may facilitate the integration of oral care into routine community mental health practice.

1. Introduction

Mental health is a vital part of overall well‐being, influencing how individuals think, feel, behave, manage stress, build relationships, and make health‐related decisions [1]. Globally, one in eight people lives with a mental disorder, making it the leading cause of years lived with disability [2]. In Australia, 42.9% of people aged 16–85 years have experienced a mental health condition at some point in their lives [3]. These conditions can disrupt daily routines and self‐care activities, including hygiene, medication adherence, sleep and nutrition [4].

Among self‐care routines, oral hygiene is particularly susceptible to neglect [5]. Maintaining oral health requires consistent behaviors, such as toothbrushing, flossing, healthy dietary choices, and regular dental visits. However, individuals with mental health disorders often face challenges in sustaining these routines. Research consistently shows they experience significantly poorer oral health outcomes than the general population, including high rates of untreated caries, periodontal disease, tooth loss, oral pain and reduced oral health‐related quality of life [6, 7]. Contributing factors include side effects of psychotropic medications (e.g., xerostomia), substance use, high sugar intake, smoking, and diminished motivation or capacity for self‐care [8, 9].

Mental health conditions such as schizophrenia, bipolar disorder, and major depression impair executive functioning, including reduced capacity for planning, decision‐making, and initiating goal‐directed behavior [10]. Consequently, toothbrushing may be forgotten, deprioritised, or avoided due to fatigue or lack of motivation [11]. Cognitive overload, poor insight or tendencies toward self‐neglect may further interfere with oral hygiene [12]. These behavioral barriers are compounded by systemic challenges, including low income, unstable housing, limited dental access and stigma related to mental health illness and oral health problems [13, 14].

Despite this burden, oral health remains largely absent from routine mental health care [15]. Services often prioritize psychiatric symptoms and psychosocial rehabilitation, overlooking physical health concerns, such as oral health. Yet, behavioral support strategies can help improve self‐care in people with mental illness [16]. A promising approach is self‐regulation theory, which focuses on managing thoughts, emotions, and behaviors to reach long‐term goals. It is essential for maintaining health behaviors, including oral health [17], and has proven effective in interventions for physical activity, diet, smoking cessation and chronic disease management [18].

Self‐determination theory (SDT), a key framework within self‐regulation research, suggests behavior change is more likely to be sustained when individuals experience autonomy, competence, and relatedness. Autonomous motivation, which involves engaging in a behavior for personal meaning or value, is more likely to support long‐term change than controlled motivation driven by external pressure or obligations [19]. For people with mental health disorders, fostering autonomous motivation may be particularly important given cognitive and emotional challenges affecting routine behaviors [20].

This study aimed to assess the feasibility of supporting oral hygiene routines among community‐dwelling adults with mental health disorders through a brief, self‐regulation‐informed intervention. Specifically, it examined whether an educational session supported by visual aids, reinforcement tools and personalized feedback could support improvement in oral health knowledge, hygiene behaviors, and motivational orientation over time. By identifying practical strategies to promote engagement and sustain behavioral change, this study seeks to inform the development of integrated, person‐centered care models that advance oral health equity in this underserved population.

2. Methods

2.1. Study Design

This longitudinal, quantitative study evaluated the feasibility and preliminary outcomes of a self‐regulation‐based oral health intervention for community‐dwelling adults with mental health disorders. Data were collected at three time points: baseline (T1), 4 weeks (T2) and 8 weeks (T3). Outcomes included oral health status, oral health knowledge, plaque levels, motivation (measured using the Treatment Self‐Regulation Questionnaire, TSRQ), and perceived competence (measured using the Perceived Competence Scale, PCS). The intervention consisted of a single education session, followed by two reinforcement visits providing personalized feedback. This repeated‐measures design enabled the assessment of short‐term changes and behavioral trends over time.

Feasibility outcomes included recruitment, retention, and engagement with study procedures and measures, alongside descriptive trends in oral health and motivational outcomes rather than formal hypothesis testing. Consistent with feasibility study guidance, the sample size was determined pragmatically based on service capacity and recruitment feasibility, and an a priori power calculation was not undertaken.

2.2. Participants and Recruitment

Participants were adults with a diagnosed mental health disorder receiving care from two community mental health centers within the Northern Sydney Local Health District. While formal psychiatric diagnoses were not collected, participants were engaged with specialist community mental health services and were considered by Care Coordinators to have serious and enduring mental health conditions. Eligibility was based on the ability to communicate, follow basic instructions and demonstrate sufficient mental health stability at the time of recruitment to participate in group‐based education. Participants were enrolled in small groups of approximately 10. As this is a feasibility study, the recruitment target of 60 participants across both sites was determined pragmatically based on service capacity and anticipated recruitment over the study period, rather than a priori power calculations.

2.3. Questionnaire and Measures

The oral health knowledge questionnaire was developed to assess factors influencing oral health behavior, knowledge and motivation. It included questions on demographics (age, gender, education, living situation, smoking and alcohol use), oral health practices (brushing frequency, fluoride toothpaste use and last dental visit), and knowledge derived from the group education session, focusing on oral‐systemic links, tooth decay and gum disease.

Motivation for toothbrushing was measured using the Treatment Self‐Regulation Questionnaire (TSRQ) [21], adapted for oral hygiene behavior. Based on Self‐Determination Theory [22]. The TSRQ assessed autonomous motivation, controlled motivation and amotivation. To reduce cognitive burden, the original 7‐point Likert scale was modified to a 5‐point scale (1 = strongly disagree to 5 = strongly agree), accounting for attention, working memory and decision‐making difficulties common in this population [23, 24].

Perceived competence was assessed using the Perceived Competence Scale (PCS), developed within the Self‐Determination Theory framework [25]. The oral health knowledge questionnaire, TSRQ and PCS were administered at three time points to examine changes over time.

2.3.1. Oral Health Status and Oral Hygiene Assessment

The Oral Health Assessment Tool (OHAT) [26] assessed eight domains: lips, tongue, tissues, saliva, natural teeth, dentures, oral cleanliness and dental pain, scored on a three‐point scale (0 = healthy, 1 = changes and 2 = unhealthy). This tool is simple and reliable for use in community mental health settings.

Oral hygiene was evaluated using the Silness and Loe Plaque Index by examining two surfaces (buccal and lingual) of one representative tooth in each sextant (six teeth total). A disclosing agent was used to visualize plaque. Surface was scored as follows: 0 = no visual plaque, 1 = plaque at the gum margin, 2 = plaque on the middle third, and 3 = plaque on more than two‐thirds of the surface. Scores were converted to percentages to account for missing teeth, allowing consistent comparison across participants.

2.3.2. Oral Health Intervention

All oral health education, assessments and intervention components were delivered face‐to‐face by the same oral health clinician trained in oral health promotion and experienced in working with vulnerable population groups. The 8‐week intervention comprised an initial education session with baseline assessments, followed by two follow‐up visits. The initial session provided oral health education and baseline assessments, while the follow‐up visits focused on reinforcement through personalized feedback and motivational support to encourage sustained oral hygiene behaviors. A standardized protocol incorporating structured education, visual aids, and plaque feedback was used to promote consistency across sessions. Although a formal fidelity assessment was not conducted, fidelity was supported through protocol adherence and single‐clinician delivery across sites.

Baseline (T1):

• 1.Completion of pre‐intervention questionnaire, including demographic and baseline oral health knowledge
• 2.Group education on oral hygiene, oral–systemic links and self‐care strategies
• 3.OHAT assessment across eight oral health domains
• 4.Plaque disclosure and scoring via the Silness and Loe Index
• 5.Provision of individualized oral health advice based on assessments
• 6.Administration of the Treatment Self‐Regulation Questionnaire (TSRQ) and Perceived Competence Scale (PCS) to measure motivation and self‐efficacy
• 7.Distribution of oral care products and a brushing reminder calendar

Four‐Week Review (T2):

• 1.Plaque disclosure and reassessment using Silness and Loe Index
• 2.Reinforcement of personalized oral health advice
• 3.Re‐administration of the knowledge survey, TSRQ and PCS
• 4.Provision of further oral care supplies and a second brushing calendar

Eight‐week Review (T3):

• 1.Final plaque assessment using the Silness and Loe Index
• 2.Re‐administration of all evaluation tools (oral health knowledge, TSRQ, and PCS)
• 3.Review of progress, reinforcement of oral health messages, and distribution of additional oral care products to support ongoing hygiene beyond the study period.

This phased intervention provided structured education and behavioral reinforcement, tailored to the cognitive and motivational needs of individuals with mental health disorders.

2.3.3. Ethics Approval

This study received ethical approval from Norther Sydney Local Health District Ethics Committee (2024/ETH00817). All participants were provided with written and verbal information about the study and gave informed consent prior to participation.

3. Data Analysis

Quantitative data were analysed using IBM SPSS Statistics (Version 30). Descriptive statistics were used to summarize oral health knowledge, plaque scores, and motivation levels at three time points (T1, T2, and T3). Motivation was measured using the 15‐item Treatment Self‐Regulation Questionnaire (TSRQ), comprising three subscales: autonomous motivation (six items), controlled motivation (six items) and amotivation (three items). Subscale scores were calculated by averaging the responses within the subscale.

To evaluate overall motivation, a Relative Autonomy Index (RAI) was calculated at each time point using the formula:

$$\text{RAI}=(2\times \text{Autonomous}\text{Motivation})–(1\times \text{Controlled}\text{Motivation})–\left(2\times \text{Amotivation}\right).$$

This composite score reflects the degree of self‐determined motivation along the self‐determination continuum, with positive values indicating more autonomous motivation and negative values indicating more externally regulated motivation or amotivation [27].

Repeated measures ANOVA [28] was used to examine within‐participant changes in plaque scores, oral health knowledge, and RAI across time points. Post hoc pairwise comparisons with Bonferroni correction were conducted to identify significant differences. Statistical significance was set at p < 0.05. All statistical tests were two‐sided, and statistical reporting followed the SAMPL guidelines.

Analyses examining changes in oral health outcomes and overall motivation over time were prespecified as part of the feasibility objectives of the study. Additional descriptive analyses of motivation subscales were exploratory and intended to inform future hypothesis‐driven research. No formal subgroup analyses were conducted.

4. Results

4.1. Participant Characteristics

Table 1 presents the demographic and behavioral characteristics of the 39 participants in the study. Participants were nearly evenly distributed across two sites: Royal North Shore (RNS) Community Mental Health Centre (51.3%) and Ryde Community Mental Health Centre (48.7%). Most were middle‐aged or older, with 38.5% aged 50%–59% and 20.5% aged 60 or above. The majority were female (56.4%) and none identified as Aboriginal Torres Strait Islander.

Table 1.

Demographic and oral health characteristics of participants (N = 39).

Variable (n)	Value distribution
Location (n = 39)	Ryde: 20 (51.3%), RNS: 19 (48.7%)
Age distribution (n = 39)	18–29: 3 (7.7%), 30–39: 4 (10.3%), 40–49: 9 (23.1%), 50–59: 15 (38.5%), ≥ 60: 8 (20.5%)
Gender (n = 39)	Male: 17 (43.6%), Female: 22 (56.4%)
Aboriginal/Torres Strait Islander (n = 39)	0 (0%), 39 (100%)
Level of education (n = 38)	High school: 15 (39.5%), TAFE: 8 (21.1%), University: 11 (28.9%), Other: 4 (10.5%)
Living situation (n = 38)	Independent: 29 (76.3%), With family/friends: 9 (23.7%)
Oral dryness (n = 38)	13 (34.2%), Occasional: 17 (44.7%), Frequent: 8 (21.1%)
Snack habit (n = 38)	No snacks: 8 (21.1%), Once/day: 12 (31.6%), Twice/day: 12 (31.6%), Thrice/day: 4 (10.5%), ≥ 4/day: 2 (5.3%)
Smoking habit (n = 38)	22 (57.9%), 11 (28.9%), Quit: 5 (13.2%)
Vaping habit (n = 36)	7 (19.4%), 28 (77.8%), Quit: 1 (2.8%)
Alcohol consumption (n = 38)	Once/day: 1 (2.6%), Few/week: 5 (13.2%), Few/month: 6 (15.8%), Quit: 11 (28.9%), Never: 15 (39.5%)
Brush after meal (n = 38)	Everyday: 10 (26.3%), Sometimes: 12 (31.6%), 16 (42.1%)
Brush before bed (n = 38)	Everyday: 9 (23.7%), Sometimes: 17 (44.7%), 12 (31.6%)
Use fluoride toothpaste (n = 37)	31 (83.8%), 5 (13.5%), Not sure: 1 (2.7%)
Use floss (n = 37)	Everyday: 4 (10.8%), Sometimes: 11 (29.7%), 22 (59.5%)
Natural teeth present (n = 37)	34 (91.9%), 3 (8.1%)
Dentures present (n = 37)	6 (16.2%), 31 (83.8%)

Among 38 respondents, 39.5% had completed high school, 21.1% held a TAFE qualification, 28.9% attended university, and 10.5% had other education. Most participants (76.3%) lived independently, while 23.7% lived with family or friends.

Oral dryness was reported occasionally by 34.2% and frequently by 21.1%. Snacking was common, with 31.6% snacking once or twice a day, 10.5% three times daily and 5.3% more than three times per day.

Of 38 respondents, 57.9% were current smokers, 28.9% were non‐smokers, and 13.2% quit smoking. Vaping (n = 36) was less common: of 26 respondents, 19.4% currently vaped, 77.8% did not and 2.8% had quit. Alcohol consumption varied, with 39.5% reported never drinking, 28.9% having quit, 15.8% consuming alcohol a few times per month, 13.2% a few times per week, and 2.6% daily.

Oral hygiene routines were inconsistent. Only 26.3% brushed after meals daily, and 23.7% brushed before bed. More participants reported brushing sometimes (31.6% after meals, 44.7% before bed), while 42.1% and 31.6% did not brush consistently after meals or before bed, respectively. Fluoride toothpaste was used by 83.6%, 13.5% did not use it, and one participant (2.7%) was unsure. Flossing was infrequent: 10.8% flossed daily, 29.7% flossed occasionally, and 59.5% not at all.

Among the 39 participants, 91.9% retained their natural teeth, and 8.1% were edentulous. Denture use was reported by 16.2%, with 83.3% not wearing dentures.

4.2. Oral Health Status

Oral health status was assessed in 37 participants at baseline using the Oral Health Assessment Tool (OHAT) domains to characterize the clinical oral health profile of participants (Table 2).

Table 2.

Oral health status of participants (OHAT).

Domains	Healthy (0)	Changes (1)	Unhealthy (2)	Valid N
Lips	7 (18.9%)	26 (70.3%)	4 (10.8%)	37
Tongue	4 (10.8%)	33 (89.2%)	—	37
Gums and tissues	14 (37.8%)	17 (45.9%)	6 (16.2%)	37
Saliva	13 (35.1%)	19 (51.4%)	5 (13.5%)	37
Teeth present	34 (91.9%)	3 (8.1%)	—	37
Natural teeth	10 (28.6%)	20 (57.1%)	5 (14.3%)	35
Dentures present	6 (16.2%)	31 (83.8%)	—	37
Oral cleanliness	2 (5.6%)	15 (41.7%)	19 (52.8%)	36
Dental pain	34 (91.9%)	2 (5.4%)	1 (2.7%)	37

4.2.1. Lips and Tongue

Only 18.9% had healthy lips; 70.3% exhibited changes such as dryness or cracking, and 10.8% were unhealthy. Tongue health was more compromised, with 89.2% having visible changes like coating or patchiness; only 10.8% were rated healthy, and none were unhealthy.

4.2.2. Gums, Oral Tissues, and Saliva

Healthy gums and oral tissues were found in 37.8%; 45.9% showed early changes (e.g., dryness or shininess), and 16.2% were unhealthy, showing swelling or bleeding. Salivary flow was suboptimal: 35.1% had normal flow, 51.4% reduced flow, and 13.5% had thick, dry saliva, indicating xerostomia risk.

4.2.3. Teeth and Dentures

Most participants (91.9%) retained natural teeth, while 8.1% were edentulous. Among those with natural teeth (n = 35), 28.6% were healthy, 57.1% had one to three decayed or broken‐down teeth, and 14.3% had four or more. Denture use was reported by 16.2%, with 83.8% not wearing dentures.

4.2.4. Oral Cleanliness

Oral hygiene was poor for many participants: Only 5.6% had clean, healthy mouths, 41.7% had one or two areas with visible plaque, food debris, or tartar, and 52.8% had widespread poor oral cleanliness.

4.2.5. Dental Pain

Despite widespread oral health issues, 91.9% reported no dental pain, 5.4% reported mild discomfort and 2.7% significant pain.

Summary

Early or moderate changes were common across OHAT domains: lips (70.3%), tongue (89.2%), gums and tissues (62.1%), and saliva (64.9%). While most retained natural teeth, 71.4%, showed decay or damage. Oral hygiene was poor in over half the sample, though pain was uncommon.

4.3. Changes in Oral Health Knowledge and Beliefs

Changes in oral health knowledge and beliefs over time are summarized in Table 3, with key patterns highlighted below. The largest gains were observed in recognition of oral–systemic health links, with awareness of oral–stroke associations increasing from 41.0% at T1 to 76.0% at T3, oral–Alzheimer's disease from 15.4% to 68.0%, and oral–diabetes from 7.7% to 52.0%. Awareness of key signs of gum disease increased, including bleeding when brushing (56.4%–88.0%) and loose teeth (46.2%–76.0%), alongside improvements in recognition of tooth decay indicators such as toothache (41.0%–64.0%) and discolouration (56.4%–88.0%). Knowledge of selected risk factors improved modestly, including dry mouth and diabetes, while smoking was consistently identified by most participants across time points (approximately 75%–80%). Preventive beliefs strengthened for daily brushing and flossing (69.2%–84.0%), with mouthwash endorsement reaching 100% by T3; however, belief in drinking water after meals as a preventive strategy declined from 41.0% to 8.0%.

Table 3.

Changes in oral health knowledge and beliefs across three time points following educational interventions.

Knowledge/Belief item	T1 (first visit)		T2 (Review after 4 weeks)		T3 (Review after 8 weeks)
	Yes (Frequency and %)	No (Frequency and %)	Yes (Frequency and %)	No (Frequency and %)	Yes (Frequency and %)	No (Frequency and %)
Mouth affects general health ‐ Heart	21 (53.8%)	18 (46.2%)	19 (67.9%)	9 (32.1%)	16 (64.0%)	9 (36.0%)
Mouth affects general health ‐ Stroke	16 (41.0%)	23 (59.0%)	19 (67.9%)	9 (32.1%)	19 (76.0%)	6 (24.0%)
Mouth affects general health ‐ Alzheimer's	6 (15.4%)	33 (84.6%)	15 (53.6%)	13 (46.4%)	17 (68.0%)	8 (32.0%)
Mouth affects general health ‐ Diabetes	3 (7.7%)	36 (92.3%)	14 (50.0%)	14 (50.0%)	13 (52.0%)	12 (48.0%)
Signs of gum disease ‐ No symptoms	15 (38.5%)	24 (61.5%)	19 (67.9%)	9 (32.1%)	14 (56.0%)	11 (44.0%)
Signs of gum disease ‐ Swollen gums	28 (71.8%)	11 (28.2%)	22 (78.6%)	6 (21.4%)	23 (92.0%)	2 (8.0%)
Signs of gum disease ‐ Bleeding when brushing	22 (56.4%)	17 (43.6%)	21 (75.0%)	7 (25.0%)	22 (88.0%)	3 (12.0%)
Signs of gum disease ‐ Loose teeth	18 (46.2%)	21 (53.8%)	21 (75.0%)	7 (25.0%)	19 (76.0%)	6 (24.0%)
Signs of gum disease ‐ Jaw pain	15 (38.5%)	24 (61.5%)	16 (57.1%)	12 (42.9%)	14 (56.0%)	11 (44.0%)
Signs of decay ‐ Cavity	27 (69.2%)	12 (30.8%)	23 (82.1%)	5 (17.9%)	16 (64.0%)	9 (36.0%)
Signs of decay ‐ Sensitivity	25 (64.1%)	14 (35.9%)	21 (75.0%)	7 (25.0%)	17 (68.0%)	8 (32.0%)
Signs of decay ‐ Abscess	24 (61.5%)	15 (38.5%)	24 (85.7%)	4 (14.3%)	17 (68.0%)	8 (32.0%)
Signs of decay ‐ Toothache	16 (41.0%)	23 (59.0%)	16 (57.1%)	12 (42.9%)	16 (64.0%)	9 (36.0%)
Signs of decay ‐ Yellow tooth	22 (56.4%)	17 (43.6%)	18 (64.3%)	10 (35.7%)	22 (88.0%)	3 (12.0%)
Decay risk factor ‐ Poor oral hygiene	18 (46.2%)	21 (53.8%)	21 (75.0%)	7 (25.0%)	17 (68.0%)	8 (32.0%)
Decay risk factor ‐ Sugar	34 (87.2%)	5 (12.8%)	25 (89.3%)	3 (10.7%)	24 (96.0%)	1 (4.0%)
Decay risk factor ‐ Dry mouth	31 (79.5%)	8 (20.5%)	21 (75.0%)	7 (25.0%)	22 (88.0%)	3 (12.0%)
Decay risk factor ‐ Lack of fluoride	17 (43.6%)	22 (56.4%)	11 (39.3%)	17 (60.7%)	14 (56.0%)	11 (44.0%)
Gum disease risk ‐ Poor oral hygiene	20 (51.3%)	19 (48.7%)	12 (42.9%)	16 (57.1%)	12 (48.0%)	13 (52.0%)
Gum disease risk ‐ Smoking	30 (76.9%)	9 (23.1%)	21 (75.0%)	7 (25.0%)	20 (80.0%)	5 (20.0%)
Gum disease risk ‐ Diabetes	28 (71.8%)	11 (28.2%)	16 (57.1%)	12 (42.9%)	21 (84.0%)	4 (16.0%)
Gum disease risk ‐ Dry mouth	17 (43.6%)	22 (56.4%)	10 (35.7%)	18 (64.3%)	15 (60.0%)	10 (40.0%)
Gum disease risk ‐ Brushing hard	23 (59.0%)	16 (41.0%)	19 (67.9%)	9 (32.1%)	16 (64.0%)	9 (36.0%)
Oral cancer risk ‐ Smoking and alcohol	26 (66.7%)	13 (33.3%)	20 (71.4%)	8 (28.6%)	18 (72.0%)	7 (28.0%)
Oral cancer risk ‐ Poor nutrition/sugar	29 (74.4%)	10 (25.6%)	21 (75.0%)	7 (25.0%)	21 (84.0%)	4 (16.0%)
Oral cancer risk ‐ Poor oral health	23 (59.0%)	16 (41.0%)	13 (46.4%)	15 (53.6%)	13 (52.0%)	12 (48.0%)
Oral cancer risk ‐ Gender and age	20 (51.3%)	19 (48.7%)	11 (39.3%)	17 (60.7%)	13 (52.0%)	12 (48.0%)
Prevention ‐ Brush & floss daily	27 (69.2%)	12 (30.8%)	20 (71.4%)	8 (28.6%)	21 (84.0%)	4 (16.0%)
Prevention ‐ Use mouthwash	31 (79.5%)	8 (20.5%)	25 (89.3%)	3 (10.7%)	25 (100.0%)	0 (0.0%)
Prevention ‐ Drink water after meals	16 (41.0%)	23 (59.0%)	8 (28.6%)	20 (71.4%)	2 (8.0%)	23 (92.0%)

Overall, the results indicate improvements in participants’ oral health knowledge and beliefs over time, particularly in relation to systemic links, oral disease signs, and selected risk factors.

4.4. Plaque Score Changes

Plaque scores were analysed at three time points to examine changes over time following oral health education. Repeated‐measures ANOVA revealed statistically significant differences in both total plaque and percentage plaque scores over time (as shown in Table 4).

Table 4.

Effect of oral health education on total plaque and percentage plaque scores across education stages: ANOVA (Bonferroni) results.

Dependent variable	(I) Education stage	(J) Education Stage	Mean Difference (I‐J)	Std. Error	Sig.	95% Confidence Interval
						Lower bound	Upper bound
Total_ Plaque	1 (T1)	2 (T2)	9.477*	1.557	< 0.001	5.69	13.27
		3 (T3)	10.162*	1.495	< 0.001	6.52	13.80
	2 (T2)	1 (T1)	−9.477*	1.557	< 0.001	−13.27	‐5.69
		3 (T3)	0.685	1.507	1.000	−2.98	4.35
	3 (T3)	1 (T1)	−10.162*	1.495	< 0.001	−13.80	−6.52
		2 (T2)	−0.685	1.507	1.000	−4.35	2.98
%Plaque	1 (T1)	2 (T2)	21.00288*	5.14067	< 0.001	8.4387	33.5671
		3 (T3)	20.95011*	5.08338	< 0.001	8.5259	33.3743
	2 (T2)	1 (T1)	−21.00288*	5.14067	< 0.001	−33.5671	−8.4387
		3 (T3)	−0.05277	5.46552	1.000	−13.4110	13.3054
	3 (T3)	1 (T1)	−20.95011*	5.08338	< 0.001	−33.3743	−8.5259
		2 (T2)	0.05277	5.46552	1.000	−13.3054	13.4110

^*The mean difference is significant at the 0.05 level.

Total Plaque: A significant effect was found, F(2,103 = 27.70, p < 0.001, with a large effect size (η² = 0.35). Post hoc Bonferroni comparisons indicated a significant reduction from T1 to T2 (p < 0.001) and T1 to T3 (p <0.001), with no further change between T2 and T3.

Percentage Plaque: A significant effect was also observed, F(2,82) = 11.79, p < 0.001, with a moderate effect size (η² = 0.223). Significant reductions occurred between T1 and T2 (p < 0.001) and T1 to T3 (p < 0.001), with no difference between T2 and T3 (p > 0.00)

Overall, observed improvements in plaque scores occurred between T1 and T2, with no further change between T2 and T3. Individual‐level trends showed marked early reductions for most participants, followed by minimal change or slight increases by T3.

4.5. Motivation and Relative Autonomy Index (RAI)

Motivation was assessed across three time points using the Treatment Self‐Regulation Questionnaire (TSRQ) and the RAI. Results are shown in Table 5.

Table 5.

Changes in motivation and relative autonomy index (RAI) across educational stages.

Phase	Autonomous motivation mean	Controlled motivation mean	Amotivation mean	RAI Score	Overall interpretation
T1	4.21	3.57	2.35	+ 0.15	High intrinsic motivation with low variability. Brushing was perceived as important and aligned with personal values. Moderate external influence. Low amotivation indicated most participants understood their oral hygiene behaviors. Overall motivation leaned slightly toward autonomy.
T2	4.20	3.53	2.90	–0.93	Autonomous motivation remained high but showed increased variability. Controlled motivation declined slightly. A rise in amotivation suggests temporary uncertainty or reduced confidence. Motivation shifted toward less self‐determined patterns.
T3	4.26	3.55	2.77	–0.57	Autonomous motivation increased, reflecting stronger internalization after repeated reinforcement. Controlled motivation remained stable. Amotivation declined slightly, indicating improved clarity and engagement. Motivation remained mixed but showed partial recovery.

T1 (Post‐Education): Participants reported moderately high autonomous motivation (mean 4.21). Controlled motivation was also elevated (mean = 3.57), and amotivation was low (mean = 2.35). The RAI was slightly positive ( + 0.15).

T2 (4‐week): Autonomous motivation remained stable (mean = 4.2), while amotivation increased to 2.90. Controlled motivation decreased slightly (mean = 3.53). The RAI declined to −0.93. T3 (8‐week): Autonomous motivation increased slightly (mean = 4.26), and amotivation decreased to 2.77. Controlled motivation remained relatively stable (mean = 3.55). The RAI improved to −0.57, but did not return to T1 levels.

4.6. Subscale and Perceived Competence Trends

Item‐level motivation responses are presented in Table 6. Analysis of individual TSRQ items indicated stable autonomous motivation across time points. For example, the item “I personally believe it is the best thing for my health” (Q3) remained consistently high (T1 = 4.32, T2 = 4.26, T3 = 4.31), while Q13 (“It is important for being as healthy as possible”) showed a slight increase from 4.27 at T1 to 4.38 at T3.

Table 6.

Descriptive statistics of motivation and perceived competence scores across three time points (T1–T3).

Questionnaire content	T1				T2				T3
	Mean	Min	Max	Std Dev	Mean	Min	Max	Std Dev	Mean	Min	Max	Std Dev	n
The reason I would brush my teeth regularly or continue to do so (TSRQ):
Q1 Because I feel that I want to take responsibility for my own health	4.32	3	5	0.638	4.29	4	5	0.46	4.19	1	5	0.801	26
Q2 Because I would feel guilty or ashamed of myself if I did not brush regularly	3.85	2	5	1.019	3.81	2	5	0.694	3.81	1	5	0.981	26
Q3 Because I personally believe it is the best thing for my health	4.32	3	5	0.589	4.26	4	5	0.447	4.31	4	5	0.471	26
Q4 Because others would be upset with me if I did not	3.21	1	5	1.298	3.36	2	5	0.951	3.38	1	5	1.235	26
Q5 I don't think about it	3.18	1	5	1.086	2.77	1	4	0.951	2.95	1	5	1.322	21
Q6 Because I have carefully thought about it and believe it is very important for my aspects of my life	4.03	3	5	0.577	4.19	3	5	0.483	3.92	1	5	0.845	26
Q7 Because I would feel bad about myself if I did not brush regularly	3.85	2	5	0.972	3.86	2	5	0.756	3.88	2	5	0.864	26
Q8 Because it is important choice really want to make	4.38	4	5	0.493	4.22	4	5	0.424	4.15	2	5	0.732	26
Q9 Because I feel pressure from others to do so	2.88	1	5	1.175	3.15	1	5	1.167	3.08	2	5	1.055	26
Q10 Because it is easier to do what I am told than think about it	3.44	1	5	0.96	3.7	1	5	0.912	3.2	1	5	1.19	25
Q11 Because it is consistent with my life goals	3.97	2	5	0.717	4.04	3	5	0.662	4.21	3	5	0.588	24
Q12 Because I want others to approve of me	3.41	1	5	1.076	3.54	1	5	0.962	3.38	1	5	1.023	26
Q13 Because it is important for being as healthy as possible	4.27	3	5	0.517	4.25	4	5	0.441	4.38	3	5	0.571	26
Q14 Because I want others to see I can do it	3.62	2	5	0.954	3.7	1	5	0.869	3.65	2	5	0.846	26
Q15 I don't really know why	2.7	1	5	0.951	2.59	1	4	0.844	2.55	1	5	1.146	20
Perceived Competence Scale (PCS)
Q16 I feel confident in brushing my teeth regularly	3.85	2	5	0.958	4.14	3	5	0.448	4.31	3	5	0.549	26
Q17 I now feel capable of brushing regularly	3.97	1	5	0.904	3.93	2	5	0.874	4.27	3	5	0.533	26
Q18 I am able to maintain a regular oral health regime over the long term	4.21	3	5	0.538	4	2	5	0.861	4.27	4	5	0.452	26
Q19 I am able to meet the challenge of brushing regularly	4.09	3	5	0.514	4.04	2	5	0.759	4.04	2	5	0.72	26

4.6.1. Controlled Motivation

Controlled motivation remained moderate with minimal fluctuation. For example, Q2 (“I would feel guilty or ashamed”) maintained stable means across timepoints (3.85, 3.81, 3.81), while Q4 (“Others would be upset with me”) showed some variability.

4.6.2. Amotivation Items

Amotivation items (e.g., Q5 and Q15) remained relatively low but trended upward at T2 before stabilizing. Q5 increased from 2.77 to 2.95 between T2 and T3, while Q15 showed a slight decrease from 2.59 to 2.55.

4.6.3. Perceived Competence

Perceived competence, measured via the PCS, gradually improved over time. For instance, Q16 (“I feel confident I can brush regularly”) increased from 3.85 (T1) to 4.31 (T3), and Q18 (“I am capable of maintaining a long‐term oral health routine”) improved from 4.00 (T2) to 4.27 (T3). Standard deviations for these items decreased over time, indicating reduced variability in perceived competence scores.

5. Discussion

This study examined the feasibility of a self‐regulation‐informed oral health approach and short‐term changes in oral hygiene outcomes and motivational orientation among adults receiving community mental health support. The findings indicate that improvements in oral health knowledge and plaque scores were observed following education and reinforcement; however, maintaining behavioral change and autonomous motivation over time remained challenging. These patterns are consistent with previous research showing that sustaining self‐care behaviors can be difficult across populations, including individuals living with mental conditions, particularly in the context of cognitive, emotional and organizational barriers [4].

Although participants demonstrated improved oral health knowledge and reduced plaque scores after initial education and follow‐up support, the decline in autonomous motivation and increase in amotivation observed at the 4‐week review reflect a pattern commonly reported in health behavior change. Within SDT and other behavior change models, initial gains following education or intervention are frequently followed by reductions in motivation and partial reversion to previous behaviors when ongoing support is limited, even in the general population [29].

These findings also suggest the potential limitations of low‐intensity reinforcement strategies when used in isolation. While brushing calendars and plaque score feedback were provided, adherence to these tools is limited. Symptoms commonly experienced in this population, including low motivation, disorganization, and cognitive fatigue, may have reduced engagement and self‐monitoring resources. Consistent with prior research, passive educational materials alone may be insufficient and may require augmentation with more active supports, such as behavioral activation strategies, habit cues, peer involvement, or digital prompts, to sustain engagement over time [30, 31].

Psychosocial factors may further influence motivation and engagement with oral health behaviors. Individuals with severe mental illness often report feelings of shame, avoidance, and fear of judgment in dental care settings, which can undermine motivation and discourage help‐seeking [11, 32]. Such experiences may contribute to controlled or amotivational regulation, where behaviors are driven by external pressures rather than personal values. Interventions that explicitly support autonomy and competence, such as motivational interviewing, peer‐led initiatives, and integration within recovery‐oriented mental health care models, may help address these barriers.

Emerging evidence also suggests broader links between oral and mental health, including associations between oral microbiota and mood disorders, highlighting the potential value of integrated care approaches [33]. Embedding oral health promotion with mental health services may therefore offer benefits beyond oral hygiene outcomes alone.

To our knowledge, this is the first Australian feasibility study to examine changes in oral health knowledge, plaque outcomes and motivational orientation using SDT constructs across multiple time points in a community mental health population. As a feasibility study with a relatively short follow‐up period, the findings should be interpreted cautiously. While short‐term improvements were observed, the data do not support conclusions regarding long‐term or sustained behavior change. Instead, the results underscore the need for tailored, ongoing and integrated support strategies that address the psychological, cognitive and environmental challenges influencing oral health behaviors among people living with mental illness.

6. Limitations

This study has several limitations. First, the modest sample size drawn from two community mental health centers limits the statistical power and generalizability, and the feasibility design means the study was not powered to detect small effects. Findings should therefore be interpreted as exploratory. Recruitment via Care Coordinators may also introduce selection bias, potentially underrepresenting individuals with more severe symptoms.

Second, formal psychiatric diagnoses were not collected. Although participants were engaged with specialist community mental health services and represented individuals living with serious and enduring mental health conditions, the absence of diagnostic data limits condition‐specific interpretation of the oral health status, motivation, and intervention response.

Third, motivation was not assessed prior to the initial education session, limiting attribution of motivational change to the intervention. Nonetheless, given the well‐documented barriers to self‐care in this population, baseline motivation was likely low.

Fourth, adherence data were limited. With few participants returning completed brushing calendars, assessment of behavioral engagement was restricted. Attrition was also notable, with dropout commonly related to acute illness, hospitalization, or service disengagement, potentially biasing results toward more stable participants.

Fifth, incomplete data occurred in the real‐world clinical setting, resulting in small variations in sample size across measures and affecting internal consistency. Finally, the 8‐week follow‐up may have been insufficient to assess sustained behavioral change. Despite these limitations, the study provides valuable preliminary evidence supporting the feasibility of self‐regulation‐based oral health support within community mental health services and highlights the priorities for larger, longer‐term investigations.

7. Conclusion

This feasibility study provides preliminary evidence that a brief, self‐regulation‐informed oral health intervention can improve knowledge and hygiene behaviors among individuals with mental health disorders. However, sustaining behavioral change remained challenging without ongoing reinforcement. These findings support the application of Self‐Determination Theory to guide interventions that foster autonomy, competence, and relatedness. Integrating oral health promotion into routine mental health care while addressing the cognitive, emotional, and social challenges unique to this population may enhance outcomes and contribute to reducing health inequities.

8. Recommendations

To support long‐term behavior change, future interventions should extend beyond one‐off education sessions and incorporate reinforcement strategies such as personalized feedback, reminders, and peer support. Embedding oral health promotion into routine mental health services through interprofessional collaboration can enhance continuity of care and accessibility. Co‐designing interventions with mental health consumers is essential to ensure they are relevant, practical and responsive to real‐world needs. Larger‐scale studies with more diverse populations and extended follow‐up are needed to validate and refine effective oral health strategies for individuals with mental illness.

Author Contributions

Grace Wong: conceptualization, investigation, writing – original draft, methodology, visualization, validation, writing – review and editing. Kyle Cheng: conceptualization, methodology, investigation, visualization, validation, writing – review and editing. Mark Montebello: conceptualization, investigation, visualization, validation, writing – review and editing. Carolyn Fraser: investigation, project administration, resources, supervision, writing – review and editing. Zion Park: investigation, project administration, resources, supervision, writing – review and editing. Anna Cheng: conceptualization, methodology, investigation, project administration, writing – review and editing. Marija Saponja: conceptualization, methodology, investigation, project administration, writing – review and editing. Lauren Monds: investigation, visualization, validation, writing – review and editing. Wenpeng You: investigation, writing – original draft, software, data curation, formal analysis, visualization, validation, writing – review and editing.

Funding

The authors received no specific funding for this work.

Ethics Statement

Ethics approval for this study was obtained from the Northern Sydney Local Health District Human Research Ethics Committee (2024/ETH00817).

Conflicts of Interest

The authors declare no conflicts of interest.

Transparency Statement

The lead author Grace Wong affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

Data Availability Statement

The data supporting the findings of this study are available from the corresponding author upon reasonable request.