Cross-cultural adaptation of Caregiver oral health knowledge questionnaire and its association with oral health status among Vietnamese children and adolescents with Autism Spectrum Disorder

Abstract

Background

Children and adolescents with autism spectrum disorder (ASD) often face oral health challenges and depend heavily on caregivers for daily oral care. In Vietnam, evidence linking caregivers’ oral health knowledge to children’s oral health remains limited. Therefore, this study aimed to cross-culturally adapt and validate a caregiver oral health knowledge questionnaire for Vietnamese use and investigate its association with oral health status among children and adolescents with ASD.

Materials and Methods

A questionnaire on caregivers’ oral health knowledge was validated through a pilot study using Cronbach’s alpha coefficient and exploratory factor analysis. A cross-sectional study included 170 children and adolescents with ASD and their caregivers. Participants received oral examinations assessing dmft/DMFT, and DI-S. Group differences were analyzed using nonparametric tests. Multivariable negative binomial regression models were applied for dmft and DMFT, and linear regression for DI-S. Significance was set at p < 0.05.

Results

The questionnaire demonstrated acceptable reliability (Cronbach’s alpha = 0.73) and mainly unidimensional structure. Higher caregiver knowledge was significantly associated with better oral hygiene (p < 0.001), no association with dmft, and inconsistent associations with DMFT. Age was strongly associated with DMFT (p < 0.001). Household income was the only sociodemographic factor significantly associated with outcomes.

Conclusion

A caregiver oral health knowledge questionnaire underwent cross-cultural adaptation and validation for use in Vietnam. Greater caregiver oral health knowledge and higher income were associated with better oral hygiene in children and adolescents with ASD, highlighting the relevance of caregiver and socioeconomic factors in oral health research for this population.

Keywords

autism spectrum disorder caregiver oral health knowledge dental caries questionnaire validation oral hygiene

1. Introduction

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition marked by impairments in social communication and interaction, as well as restricted and repetitive behaviors.¹ Children and adolescents with ASD often exhibit sensory sensitivities, behavioral rigidity, and compromised fine motor skills, which hinder daily self-care tasks, particularly oral hygiene.² Consequently, they face a higher risk of oral diseases than neurotypical peers. An umbrella review reported dental caries prevalence of 60.6% - 67.3% and periodontal disease prevalence of 59.8% - 69.4% in individuals with ASD.³ Moreover, although a recent systematic review and meta-analysis found no significant difference in DMFT/dmft scores between children and adolescents with ASD and controls, individuals with ASD exhibited higher DMFS scores, indicating greater caries severity.⁴

Given these challenges, parents and caregivers play a vital role in maintaining children and adolescents’ oral health with ASD, bearing primary responsibility for daily oral hygiene and access to preventive dental care.⁵ Previous studies have demonstrated that caregivers’ oral health knowledge, attitudes, and practices substantially influence children and adolescents’ oral hygiene habits and clinical outcomes.⁶ Additionally, caregivers’ perceptions and level of engagement have been associated with improved oral health–related quality of life and greater prioritization of preventive dental care.⁷ Therefore, evaluating caregivers’ oral health knowledge is crucial for understanding barriers to oral health outcomes in children and adolescents with ASD and for improving these outcomes.

Despite robust international evidence on oral health challenges in children and adolescents with ASD, data from Vietnam remain scarce. In the general pediatric population in Vietnam, dental caries is already highly prevalent. Among kindergarten children aged 2–5 years, one study reported an overall caries prevalence of 89.1% with a mean dmft of 9.32, and that caries in permanent dentition is also common among older schoolchildren, with a prevalence of 68.9% reported in a rural adolescent population.^8,9 A recent Vietnamese hospital-based study reported that 52.3% of children and adolescents with ASD aged 2–5 years had early childhood caries, with a mean dmft score of 2.97; however, it focused solely on clinical outcomes without examining caregiver-related factors.¹⁰ To date, no validated instrument exists for systematically assessing caregivers’ oral health knowledge in the Vietnamese context. This critical gap impedes the design and implementation of targeted, evidence-based interventions.

Therefore, this study aimed to: (1) validate a caregiver oral health knowledge questionnaire for the Vietnamese context, and (2) investigate the association between caregivers’ oral health knowledge and the clinical oral health status of children and adolescents with ASD.

2. Materials and methods

2.1. Study design and setting

This cross-sectional study was conducted in accordance with the STROBE guidelines at a specialized autism center in Hanoi, Vietnam, in November 2025.¹¹

2.2. Participants

Participants included children and adolescents aged 2 to 18 years diagnosed with Autism Spectrum Disorder (ASD) and their primary caregivers, who provided written informed consent. Exclusion criteria included children and adolescents with systemic illnesses that contraindicated dental examinations and those who exhibited severely uncooperative behavior (Frankl Behavior Scale scores of 1 or 2).¹²

2.3. Study size

The sample size was calculated using a standard formula for estimating a population proportion in a cross-sectional design:

n = z_{1 - \frac{α}{2}}^{2} \frac{p (1 - p)}{d^{2}}

Assuming a dental caries prevalence of 77%, as reported by MA Jaber (2011).¹³ With a 95% confidence level and a precision of 0.063, the minimum required sample size was 170. To account for a potential 15% non-response rate, 200 child–caregiver pairs were randomly selected from the center’s enrollment list, with replacements drawn from a reserve list as needed. Regarding the psychometric procedures, the final sample of 170 participants was considered acceptable for the initial exploratory factor analysis of the 10-item questionnaire. In this study, the participant-to-item ratio was 17:1, indicating that the sample size was adequate for an initial exploratory assessment of the questionnaire structure.¹⁴

2.4. Variables and measurements

The questionnaire used in this study was adapted from the validated instrument developed by Hamasha et al. (2019).¹⁵ It comprised ten knowledge-based items assessing fundamental oral health concepts, including primary dentition, toothbrushing practices and toothbrush replacement, timing of the first dental visit, dental plaque and calculus, fluoride use, and the relationship between oral and general health. Each correct response was scored as one point, and caregiver knowledge was classified as good (> 6/10 correct), average (4/10–6/10 correct), or poor (< 4/10 correct). The questionnaire also collected demographic information of caregivers, including educational attainment, household income, family size, and birth order. Children and adolescents with autism were categorized into three age groups: 6 years or younger, 7–12 years, and 13 years or older. This grouping was based on clinical relevance and dentition stages, broadly corresponding to the primary, mixed, and permanent dentition periods, respectively.¹⁶

2.5. Questionnaire translation and validation

The questionnaire was translated into Vietnamese using a forward–backward translation procedure to preserve the meaning of the original instrument and ensure cultural appropriateness. The Vietnamese version was subsequently pilot-tested with parents of children and adolescents with ASD to evaluate clarity, comprehensibility, and feasibility. Minor revisions were made after pilot testing to improve wording and contextual suitability before the questionnaire was used in the main study.¹⁷

2.6. Clinical examination and bias control

Children and adolescents’ oral health status was clinically assessed using the Simple Plaque Index (DI-S) and caries indices for deciduous (dmft) and permanent teeth (DMFT). Caregiver knowledge and socioeconomic characteristics were assessed using a validated questionnaire (see Supplementary material). To minimize bias, participants were selected using simple random sampling, and four well-trained pediatric dentists conducted oral examinations in accordance with standard procedures. Measurement and response biases were further minimized through the use of a pilot-tested, validated questionnaire and assurances of data confidentiality.

2.7. Data analysis

Incomplete or incorrectly completed questionnaires were excluded before analysis. The final analyses were conducted using only complete-case data, with no imputation for missing values.

Data were analyzed using appropriate statistical methods. Psychometric evaluation of the Caregiver Knowledge Questionnaire was conducted sequentially. Internal consistency was assessed using Cronbach’s alpha, while construct validity was evaluated using the Kaiser–Meyer–Olkin (KMO) test followed by Exploratory Factor Analysis (EFA). EFA was performed to examine the underlying factor structure once the KMO value exceeded 0.60.¹⁸

Associations between age group and caregiver knowledge with children and adolescents’ oral health indices (dmft, DMFT, and DI-S) were examined using the Mann–Whitney U test for two-group comparisons and the Kruskal–Wallis test for comparisons involving more than two groups. The Kruskal–Wallis test was also used to compare mean caregiver knowledge scores across sociodemographic characteristics, including family size, the child with ASD’s birth order, household income, and caregivers’ educational level. Multivariable regression analyses were performed to examine the associations of age group, gender, caregiver knowledge, and sociodemographic characteristics with oral health outcomes. Negative binomial regression was used for DMFT and dmft, while linear regression was used for the DI-S index. Statistical significance was set at p < 0.05.

3. Results

Among the 200 eligible child–caregiver pairs invited to participate, 22 caregivers declined participation, and 8 questionnaires were completed incorrectly; therefore, 170 pairs were included in the final analysis.

In Table 1, caregiver knowledge scores did not differ significantly by family size, the child’s birth order, or caregivers’ educational level (all p > 0.05). In contrast, household income was significantly associated with knowledge scores, with caregivers from higher-income households demonstrating markedly higher knowledge levels (p < 0.001).

Table 1.

Demographic characteristics of parents/caregivers of children and adolescents with ASD and their knowledge mean scores.

Category		n	%	Knowledge mean score	p-value
Family size	One child	15	8.8%	6.67 ± 1.66	0.876
	Two children	100	58.8%	6.52 ± 2.84
	≥ Three children	55	32.6%	6.38 ± 2.64
Child’s birth order	First	45	26.6%	6.71 ± 2.52	0.654
	Second	89	52.3%	6.27 ± 2.80
	Third	30	17.6%	6.90 ± 2.53
	Fourth	6	3.5%	6.00 ± 2.58
Educational level	Primary School	4	2.3%	5.00 ± 1.87	0.542
	Intermediate School	2	1.1%	5.50 ± 0.50
	High School	11	6.4%	6.64 ± 2.77
	University	141	82.9%	6.57 ± 2.72
	Postgraduate	12	7.3%	6.00 ± 2.42
Monthly income	Below average income	33	19.4%	2.30 ± 1.29	<0.001
Monthly income	Above average income	137	80.6%	7.50 ± 1.83	<0.001

Statistically significant p-values are shown in bold .

In Table 2, Item analysis demonstrated acceptable internal consistency of the caregiver oral health knowledge questionnaire. Item–test correlations ranged from 0.29 to 0.78, while item–rest correlations ranged from 0.17 to 0.67. Most items showed moderate to strong item–rest correlations, indicating good coherence with the overall scale. The overall Cronbach’s alpha coefficient was 0.73, reflecting acceptable internal consistency of the questionnaire.

Table 2.

Item analysis and internal consistency of the caregiver oral health knowledge questionnaire.

No	Questions	Item-test correltation	Item-rest correlation	Alpha
Q1	What is the number of primary teeth when all erupted?	0.4775	0.2995	0.7235
Q2	What is the ideal duration of brushing teeth?	0.5449	0.4618	0.7075
Q3	How often do you change your child toothbrush?	0.2894	0.1679	0.7343
Q4	What is the best age for the first dental visit of your child?	0.3883	0.1786	0.7472
Q5	What does plaque mean?	0.7558	0.6740	0.6692
Q6	What does calculus mean?	0.5888	0.4515	0.6986
Q7	What is the importance of adding fluoride to toothpaste?	0.7769	0.6282	0.6590
Q8	How does the plaque affect the mouth?	0.5581	0.3433	0.7236
Q9	Do primary teeth problems have an effect on permanent teeth?	0.5969	0.5031	0.6988
Q10	Do you think that the oral health of the child affects his general health?	0.5609	0.4686	0.7041

Test scale: average interitem covariance = 0.1490643, Cronbach’s alpha = 0.7296.

In Table 3, Exploratory Factor Analysis identified several factors with eigenvalues greater than 1, with most items loading above 0.30 on the first factor. Q3 and Q4 showed loadings below 0.30 or cross-loadings across factors, while the remaining factors included only one or a few items with notable loadings.

Table 3.

Exploratory factor analysis of the caregiver oral health knowledge questionnaire.

Questions	Factor 1	Factor 2	Factor 3	Factor 4	Factor 5	Factor 6
Q1	0.3895	-0.2908	0.3646	-0.0432	0.1188	0.0359
Q2	0.5180	0.4171	-0.3817	-0.1312	-0.0268	0.1289
Q3	0.1283	0.6692	0.3130	0.1179	-0.0450	-0.0883
Q4	0.2032	0.0048	0.1787	0.4467	0.0521	0.1334
Q5	0.7323	-0.0345	0.3401	-0.0230	0.1561	-0.0225
Q6	0.5916	0.1437	0.2920	-0.3946	-0.1444	0.0557
Q7	0.7038	0.3205	-0.1201	0.2805	-0.1252	-0.0498
Q8	0.4586	0.2251	-0.3131	-0.1063	0.2912	-0.0578
Q9	0.6883	-0.4151	-0.2447	0.1111	-0.0249	-0.0092
Q10	0.6473	-0.4519	-0.0711	0.0063	-0.1459	-0.0697

As shown in Table 4, caregiver knowledge was significantly associated with d (p = 0.010), dmft (p = 0.010), D (p < 0.001), F (p < 0.001), DMFT (p < 0.001), and DI-S (p < 0.001), but not with m (p = 0.370) or f (p = 0.470). Gender was significantly associated with D (p = 0.040) and DMFT (p = 0.040), whereas no significant differences were observed for other indices (all p > 0.05). Age group showed significant associations with d (p = 0.001), dmft (p = 0.001), D (p < 0.001), M (p = 0.020), F (p < 0.001), DMFT (p < 0.001), and DI-S (p = 0.003), but not with m (p = 0.210) or f (p = 0.130). No significant associations were identified between oral health indices and family size, child’s birth order, or caregivers’ educational (all p > 0.05). Monthly income was significantly associated with d (p = 0.040), dmft (p = 0.050), D (p < 0.001), F (p = 0.010), DMFT (p < 0.001), and DI-S (p < 0.001), whereas no significant associations were found for m (p = 0.690), f (p = 0.340), or M (p = 0.280).

Table 4.

The relationship between caregiver knowledge, gender, age group, sociodemographic factors, and the oral health status of children and adolescents with ASD.

Category		n(%)	d	m	f	dmft	D	M	F	DMFT	DI-S
Knowledge	Poor	26 (15.29%)	4.58 ± 4.75	0.50 ± 0.97	0.38 ± 0.49	5.46 ± 5.22	0.23 ± 1.15	0.08 ± 0.38	0.00 ± 0.00	0.31 ± 1.54	2.45 ± 0.65
	Average	50 (29.41%)	3.98 ± 4.24	0.54 ± 1.04	0.62 ± 1.15	5.14 ± 5.26	1.28 ± 1.78	0.14 ± 0.49	0.24 ± 0.55	1.66 ± 2.20	1.25 ± 0.58
	Good	94 (55.29%)	2.23 ± 3.17	0.31 ± 0.76	0.31 ± 0.62	2.85 ± 3.72	1.88 ± 2.52	0.09 ± 0.28	0.46 ± 0.75	2.43 ± 3.14	0.85 ± 0.42
	P - value		0.01	0.37	0.47	0.01	< 0.001	0.94	<0.001	< 0.001	<0.001
Gender	Male	141 (82.94%)	2.86 ± 3.62	0.42 ± 0.92	0.38 ± 0.72	3.65 ± 4.30	1.34 ± 2.19	0.10 ± 0.36	0.30 ± 0.64	1.74 ± 2.76	1.23 ± 0.78
	Female	29 (17.06%)	4.31 ± 4.90	0.34 ± 0.76	0.59 ± 1.13	5.24 ± 5.75	2.00 ± 2.33	0.10 ± 0.40	0.41 ± 0.72	2.52 ± 2.86	1.15 ± 0.59
	P - value		0.33	0.83	0.50	0.42	0.04	0.88	0.33	0.04	0.85
Age group	Under to 6 years old	99 (58.24%)	3.52 ± 4.02	0.43 ± 0.88	0.44 ± 0.79	4.39 ± 4.72	0.51 ± 1.19	0.1 ± 0.39	0.07 ± 0.29	0.68 ± 1.48	1.41 ± 0.85
	7-12 years old	35 (20.59%)	4.09 ± 4.44	0.54 ± 1.10	0.54 ± 1.02	5.17 ± 5.25	1.54 ± 1.42	0.2 ± 0.47	0.20 ± 0.52	1.94 ± 1.57	0.93 ± 0.49
	≥ 13 years old	36 (21.18%)	1.03 ± 1.71	0.19 ± 0.62	0.19 ± 0.52	1.42 ± 2.14	3.97 ± 2.97	0.0± 0.00	1.14 ± 0.82	5.11 ± 3.73	0.95 ± 0.47
	P -value		0.001	0.21	0.13	0.001	< 0.001	0.02	< 0.001	< 0.001	0.003
Family size	One child	15 (8.8%)	4.00 ± 5.26	0.07 ± 0.26	0.87 ± 1.36	4.93 ± 6.25	1.53 ± 2.77	0.1 ± 0.35	0.40 ± 0.91	2.07 ± 3.58	1.15 ± 0.76
	Two children	100 (58.8%)	2.98 ± 3.70	0.50 ± 1.05	0.34 ± 0.70	3.82 ± 4.42	1.52 ± 2.35	0.07± 0.33	0.37 ± 0.69	1.96 ± 2.97	1.19 ± 0.79
	≥ Three children	55 (32.6%)	3.09 ± 3.95	0.33 ± 0.64	0.42 ± 0.79	3.84 ± 4.58	1.31 ± 1.87	0.15 ± 0.45	0.22 ± 0.50	1.67 ± 2.24	1.27 ± 0.70
	P - value		0.98	0.29	0.29	0.96	0.94	0.77	0.62	0.99	0.55
Child’s birth order	First	45 (26.6%)	2.87 ± 4.22	0.24 ± 0.68	0.40 ± 0.89	3.51 ± 4.82	1.58 ± 2.48	0.07 ± 0.25	0.47 ± 0.79	2.11 ± 3.18	1.09 ± 0.78
	Second	89 (52.3%)	3.15 ± 3.69	0.55 ± 1.07	0.46 ± 0.87	4.16 ± 4.61	1.29 ± 2.18	0.12 ± 0.45	0.25 ± 0.61	1.66 ± 2.73	1.26 ± 0.76
	Third	30 (17.6%)	3.37 ± 4.44	0.20 ± 0.48	0.30 ± 0.53	3.87 ± 4.82	1.87 ± 2.15	0.10 ± 0.31	0.33 ± 0.61	2.30 ± 2.53	1.24 ± 0.69
	Fourth	6 (3.5%)	3.00 ± 2.76	0.50 ± 0.84	0.33 ± 0.52	3.83 ± 3.31	0.83 ± 1.60	0.00 ± 0.00	0.33 ± 0.52	1.17 ± 2.04	1.32 ± 0.95
	P - value		0.86	0.50	0.20	0.98	0.83	0.53	0.20	0.33	0.46
Educational level	Primary School	4 (2.3%)	2.25 ± 2.87	0.75 ± 1.50	0.25 ± 0.50	3.25 ± 3.77	0.50 ± 0.58	0.00 ± 0.00	0.75 ± 0.96	1.25 ± 1.50	1.55 ± 0.88
	Intermediate School	2 (1.1%)	3.50 ± 4.95	0.00 ± 0.00	0.50 ± 0.71	4.00 ± 4.24	0.00 ± 0.00	0.00 ± 0.00	0.00 ± 0.00	0.00 ± 0.00	1.32 ± 0.54
	High School	11 (6.4%)	2.91 ± 3.11	0.27 ± 0.65	0.36 ± 0.67	3.55 ± 3.64	1.18 ± 1.78	0.09 ± 0.30	0.09 ± 0.30	1.36 ± 2.01	1.35 ± 0.73
	University	141 (82.9%)	3.03 ± 3.93	0.40 ± 0.87	0.42 ± 0.85	3.84 ± 4.66	1.43 ± 2.12	0.11 ± 0.39	0.32 ± 0.64	1.86 ± 2.68	1.16 ± 0.76
	Postgraduate	12 (7.3%)	4.42 ± 4.85	0.58 ± 1.24	0.42 ± 0.51	5.42 ± 5.76	2.50 ± 3.83	0.08 ± 0.29	0.50 ± 1.00	3.08 ± 4.66	1.56 ± 0.82
	P - value		0.88	0.92	0.89	0.89	0.72	0.97	0.42	0.66	0.23
Monthly income	Below average	33 (19.4%)	4.39 ± 4.70	0.45 ± 0.94	0.39 ± 0.56	5.24 ± 5.11	0.52 ± 1.70	0.06 ± 0.35	0.09 ± 0.38	0.67 ± 2.20	2.23 ± 0.79
	Above average	137 (80.6%)	2.80 ± 3.66	0.39 ± 0.89	0.42 ± 0.86	3.61 ± 4.48	1.68 ± 2.30	0.11 ± 0.38	0.38 ± 0.70	2.17 ± 2.86	0.97 ± 0.50
	P - value		0.04	0.69	0.34	0.05	< 0.001	0.28	0.01	< 0.001	< 0.001

Statistically significant p-values are shown in bold .

Table 5 demonstrates that in multivariable regression analyses, gender was not independently associated with dmft (p = 0.469), DMFT (p = 0.822), or DI-S (p = 0.244). Age group was strongly associated with DMFT: children aged 7–12 years (IRR = 4.89, p < 0.001) and those aged ≥13 years (IRR = 13.37, p < 0.001) exhibited significantly higher scores than those aged under 6 years. Age group was not significantly associated with dmft (p = 0.121 for 7–12 years; p = 0.058 for ≥13 years) or DI-S (p = 0.968 and p = 0.308, respectively). Compared with poor caregiver knowledge, average knowledge was associated with higher DMFT (IRR = 3.11, p < 0.001) and lower DI-S (Coef = −0.432, p < 0.001). Good caregiver knowledge was associated with lower DI-S (Coef = −1.66, p < 0.001), but not with dmft (p = 0.057) or DMFT (p = 0.144).

Table 5.

Multivariable regression analysis of factors associated with the oral health status of children and adolescents with ASD.

Predictors		dmft		DMFT		DI-S
Predictors		IRR	p-value	IRR	p-value	Coef	p-value
Gender (Ref: Male)
Female	1.26	0.469	0.94	0.822	0.11	0.244
Age Group (Ref: Under 6 years old)
From 7 to 12 years	1.64	0.121	4.89	< 0.001	0.00	0.968
Above 13 years	0.50	0.058	13.37	< 0.001	0.11	0.308
Caregiver Knowledge (Ref: Poor)
Average	0.86	0.640	3.11	< 0.001	-0.432	< 0.001
Good	0.50	0.057	0.50	0.144	-1.66	< 0.001

Statistically significant p-values are shown in bold .

Table 6 indicates that household income was the only sociodemographic factor independently associated with oral health outcomes among children and adolescents. Compared with those from below-average income households, participants from above-average income households exhibited significantly higher DMFT (IRR = 3.34, p < 0.001) and lower DI-S scores (Coef = −1.27, p < 0.001). At the same time, the association with dmft was not statistically significant (IRR = 0.63, p = 0.105). Conversely, caregivers’ educational level, family size, and birth order showed no significant associations with dmft, DMFT, or DI-S. The corresponding p-values ranged from 0.196 to 0.997 for educational level, 0.191 to 0.835 for family size, and 0.124 to 0.992 for birth order.

Table 6.

Multivariable regression analysis of sociodemographic factors associated with oral health indices in children and adolescents with ASD.

Predictors	dmft		DMFT		DI-S
Predictors	IRR	p-value	IRR	p-value	Coef.	p-value
Household Income (Ref: Below average)
Above average	0.63	0.105	3.34	< 0.001	-1.27	< 0.001
Educational level (Ref: Primary School)
High School	1.25	0.815	1.21	0.856	-0.28	0.289
Intermediate School	1.45	0.780	-	0.997	0.09	0.838
University	1.36	0.714	1.21	0.856	-0.31	0.196
Postgraduate	1.80	0.529	2.44	0.381	-0.02	0.957
Family size (Ref: 1 child)
2 children	0.54	0.191	1.11	0.835	-0.23	0.203
More than 3 children	0.50	0.235	0.47	0.224	-0.15	0.499
Birth Order (Ref: First child)
Second child	1.63	0.132	1.02	0.944	0.14	0.244
Third child	1.47	0.450	2.45	0.124	0.09	0.607
Fourth child	1.53	0.558	1.34	0.723	-0.00	0.992

Statistically significant p-values are shown in bold .

4. Discussion

The Caregiver Oral Health Knowledge Questionnaire demonstrated acceptable internal consistency, with an overall Cronbach’s alpha of 0.73, indicating that the items were sufficiently related to measure a common underlying construct. However, this value also suggests that some items may still require refinement.¹⁹ Exploratory factor analysis supported a mainly unidimensional structure of the questionnaire, with most items loading on the first factor. In opposition, Q3 and Q4 showed lower factor loadings than the remaining items. This may suggest that knowledge about the timing of the first dental visit and toothbrush replacement is less consistently integrated into caregivers’ overall oral health knowledge than are more fundamental concepts such as plaque control or fluoride use. It is also possible that these items are more sensitive to differences in information sources or local practice recommendations, which may have contributed to less consistent responses. Future studies should consider refining or replacing these items with contextually more appropriate alternatives. Further validation with larger, more diverse samples is needed to confirm the factor structure and strengthen the questionnaire’s robustness. Taken together, these findings support the use of the questionnaire as an initial tool for assessing caregiver oral health knowledge in the Vietnamese context.

Caregiver oral health knowledge and household income appear to play an important role in the oral health of children and adolescents with ASD. Because this population often depends heavily on caregivers for daily oral hygiene, greater caregiver knowledge may contribute to more effective plaque control and a lower caries burden, particularly in the primary dentition. This interpretation is consistent with previous evidence showing that caregiver knowledge, attitudes, and practices are associated with oral hygiene behaviors and caries experience in this population.²⁰

In higher-income households, children and adolescents may have greater access to sugary snacks and drinks, which could contribute to a higher caries burden in the permanent dentition.²¹ At the same time, better access to dental services may increase the likelihood that diseased teeth are restored, which may explain the higher filled component observed in this group.^22,23 The higher DMFT observed in the average knowledge group may likewise be partly explained by age distribution, as older participants are more likely to accumulate caries in permanent teeth over time, rather than by caregiver knowledge alone. These findings extend previous literature by highlighting the relevance of caregiver knowledge and socioeconomic resources in shaping oral health outcomes in children and adolescents with ASD in Vietnam.

Previous studies have linked higher caregiver education to better oral health knowledge and more favorable oral health outcomes in children. A recent scoping review reported that low caregiver oral health literacy, often associated with limited education, was consistently associated with higher caries prevalence and poorer oral hygiene.^24,25 Conversely, no significant association between caregiver education and oral health knowledge was observed in the present study. This discrepancy may partly reflect the relatively homogeneous educational background of caregivers in our sample, which limited variability. It may also suggest that, in families of children and adolescents with ASD, formal education alone is insufficient to capture the practical challenges of oral health care. Factors such as high caregiving burden, time constraints, chronic stress, sensory sensitivity, behavioral difficulties, and limited access to dental services may play a more influential role in shaping oral health practices than educational attainment alone.²⁶ This suggests that greater emphasis should be placed on support programs for caregivers of children and adolescents with ASD, alongside the provision of oral health knowledge and practical guidance on daily care. Such approaches may be more effective in improving oral health outcomes than knowledge transfer alone, as they can better address the specific caregiving challenges faced in this population.

Pruckner et al. (2021) demonstrated that birth order can influence caregiver investment in health, primarily due to caregiver learning and updating of beliefs after experience with earlier-born children.²⁷ By contrast, our study found no significant association of birth order or family size with the oral health status of children and adolescents with ASD. This finding may indicate that family structure does not necessarily translate into more effective oral health care in the context of ASD, where caregiving demands and barriers to care may outweigh any experiential advantage gained from raising older children. Together, these findings suggest that caregiver-related barriers in this population are multifactorial and may not be adequately explained by education or family structure alone.

Although females showed higher permanent caries indices than males in the univariate analysis, this association was no longer statistically significant in the multivariable model, suggesting that confounding factors largely explained the apparent gender difference. In particular, female participants in this study were older than males, and the higher DMFT observed in females may therefore reflect greater cumulative exposure to caries in the permanent dentition rather than an independent gender-related effect. This interpretation is consistent with previous pediatric dental studies showing that gender differences in caries often become negligible after adjustment for age and other confounders.²⁸ Overall, these findings suggest that gender should not be regarded as an independent predictor of oral health outcomes in children and adolescents with ASD.

Our findings on age-related variation in oral health among children and adolescents with ASD reflect the well-recognized progression of dental caries across childhood. The higher dmft in younger children and in those aged 7–12 years may indicate that caries in the primary dentition can persist into the mixed dentition period before exfoliation.²⁹ This aligns with evidence on early childhood caries, which is driven by enamel immaturity, frequent exposure to sugar, and a heavy reliance on caregivers for oral hygiene.³⁰

In contrast, children and adolescents aged 13 years or older exhibited higher DMFT scores, reflecting the cumulative caries risk in permanent teeth as they erupt and are exposed to cariogenic factors for extended periods.³¹ This trend mirrors international surveillance data reporting stable or increasing rates of untreated decay in older children and adolescents.³² Contributing factors likely include early preventive care gaps, persistent unfavorable dietary habits, suboptimal hygiene, and irregular access to dental services.³² These results emphasize the value of age-tailored interventions for children and adolescents with ASD. Early childhood efforts should target caregiver education, fluoride application, and supervised brushing, while strategies for older children and adolescents should prioritize reinforced hygiene, routine dental visits, and prompt restorative treatment.³³

In interpreting these findings, it is important to consider the broader Vietnamese context, where dental caries is already highly prevalent in the general pediatric population. Some of the patterns observed in this study, particularly the age-related variation in caries and the influence of socioeconomic factors, are also seen in children and adolescents more generally.⁹ However, in children and adolescents with ASD, these patterns may be further complicated by greater dependence on caregivers for daily oral hygiene, behavioral and sensory difficulties, and challenges in accessing dental services.²⁰ Therefore, the oral health status observed in this population should be understood not only within the broader national burden of disease, but also in relation to the specific caregiving and service-related barriers associated with ASD.

This study has several limitations. First, although the final sample size of 170 was adequate for the primary analytical objective and acceptable for the initial exploratory factor analysis of the 10-item questionnaire, it was not specifically calculated for all multivariable regression analyses or for more comprehensive psychometric validation. Second, the cross-sectional design does not permit causal inference and only supports correlational interpretation of the observed associations between caregiver knowledge and oral health outcomes in children and adolescents with ASD. Reverse causality is also possible, as caregivers of children with greater oral health needs may have gained more oral health knowledge through previous dental visits and professional advice. Residual confounding from unmeasured factors cannot be ruled out, particularly because ASD support level or functional severity was not recorded; this factor may influence caregiver involvement in daily oral hygiene and access to dental services. Third, recruitment from a single urban center may limit the generalizability of the findings to the broader Vietnamese population, particularly rural families and those outside specialized service settings. Finally, caregiver knowledge was assessed by self-report and may therefore have been influenced by social desirability bias, despite the use of a validated questionnaire.

Future studies may benefit from sample-size calculations tailored to specific regression analyses and from more comprehensive psychometric validation. Longitudinal and multisite studies may help clarify temporal relationships, improve generalizability, and determine whether the observed associations persist across different care settings and populations. In addition, incorporating more objective measures and reducing reliance on self-report may help minimize potential reporting bias.

5. Conclusion

This study validated a caregiver oral health knowledge questionnaire with acceptable reliability and construct validity for use in Vietnam. Greater caregiver knowledge and higher household income were associated with better oral hygiene in children and adolescents with ASD. At the same time, age remained a strong determinant of caries in the permanent dentition. These findings suggest that caregiver knowledge and socioeconomic factors may be relevant considerations in future oral health research and preventive strategies for children and adolescents with ASD in Vietnam.

Supplemental material

Supplemental material - Cross–cultural adaptation of caregiver oral health knowledge questionnaire and its association with oral health status among Vietnamese children with autism spectrum disorder

Supplemental material for Cross–cultural adaptation of caregiver oral health knowledge questionnaire and its association with oral health status among Vietnamese children with autism spectrum disorder by Duc Long Duong, Dong A. Tran Luu, Van Anh Le, Tien Dung Nguyen, Manh Tuan Vu, My Hanh Tran Thi, Bach Duong To Thi, Huong Linh Pham Le, and Minh Hang Luong in Journal of Public Health Research.

Footnotes

Acknowledgments

The authors sincerely thank the children with Autism Spectrum Disorder and their caregivers for their participation and cooperation. We are deeply grateful to the staff of the Sao Mai Center, Hanoi, for their vital assistance with participant recruitment and data collection. We also acknowledge the pediatric dentists who performed the clinical examinations and the experts who contributed to the translation and cultural adaptation of the questionnaire. Their expertise was essential to this research.

ORCID iDs

Duc Long Duong

Dong A. Tran Luu

Minh Hang Luong

Ethical considerations

This study was approved by the Hanoi Medical University Institutional Ethical Review Board with the number 2129/GCN-HMUIRB. Before conducting the study, the school board approved it and granted permission.

Consent to participate

Additionally, children agreed to participate, and their parents provided informed consent.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data Availability Statement

The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.*

Supplemental material

Supplemental material for this article is available online.

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