Oral health behaviours and cariogenic food consumption in children with attention-deficit/hyperactivity disorder: a cross-sectional study

Abstract

Background:

Attention-deficit/hyperactivity disorder (ADHD) contributes to functional impairments in the performance of personal tasks such as oral hygiene. This study aimed to compare oral health behaviours and consumption of cariogenic foods in children diagnosed with ADHD and healthy control peers.

Methods:

In this cross-sectional study, 60 children with ADHD aged 6 to 11 years made up the study group, and 60 peers of the same age, sex, and from the same school, without a history of ADHD, made up the control group. To compare the parent-reported behaviours between the 2 groups, conditional logistic regression was used to obtain matched pairs odds ratios (ORs) and 95% confidence intervals (CIs).

Results:

Children with ADHD were 0.4 times less likely than their non-ADHD peers to brush their teeth at least once a day (OR = 0.40, 95% CI: 0.18–0.91, p = 0.028). Moreover, compared to the control group, children with ADHD were 4.71 and 9.67 times more likely to consume cariogenic foods (95% CI: 2.08—10.66, p < 0.001) and drinks (95% CI: 2.94–31.73, p < 0.001), respectively, at least thrice a day.

Conclusion:

In comparison to their non-ADHD peers, children diagnosed with ADHD were less likely to brush their teeth and simultaneously more likely to consume both cariogenic foods and drinks.

PRACTICAL IMPLICATIONS OF THIS RESEARCH.

• Children diagnosed with ADHD tend to brush their teeth less frequently and consume more cariogenic foods and beverages than their non-ADHD peers.

• Oral health promotion programs tailored to children diagnosed with ADHD may improve oral health outcomes.

• Parents of children diagnosed with ADHD need clear oral hygiene instructions to help their children develop good daily oral care and nutrition habits.

INTRODUCTION

According to the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-V), attention-deficit/hyperactivity disorder (ADHD) is a condition characterized by inattention and hyperactivity-impulsivity that impairs functioning or development.¹ The World Health Organization (WHO), in its International Classification of Diseases, tenth revision (ICD-10), offers similar criteria to diagnose this disorder.² Using either DSM or ICD criteria, meta-analytic studies estimate the worldwide prevalence of ADHD in children under the age of 18 years to be approximately 5% to 7%.^{3, 4} In children aged 6 to 11 years, the overall prevalence is estimated to be 11.4%.⁵ It has been recommended that ADHD be considered a major health concern in children that should be treated to prevent impairments.^6-8

The characteristics of inattention, hyperactivity, and impulsivity impair functioning in both social and academic contexts as well as in personal daily activities such as oral hygiene. Only a handful of studies have examined the oral health behaviours and cariogenic dietary habits of children with ADHD. The majority of studies found that children with ADHD brushed their teeth less frequently and for shorter periods of time.^9-12 Furthermore, compared to controls, children with ADHD were found to consume sweet snacks and acidic or sugary drinks more frequently.^{10, 13}

Several studies reported that children with ADHD had higher caries indices than non-ADHD children.^9-18 More periodontal problems such as gingival bleeding, debris, and calculus have also been found in children with ADHD.^{10-12, 16, 19, 20} Poorer oral health may result from less effective oral health behaviours and more cariogenic dietary habits among children with ADHD.

Although age, sex, and family socioeconomic status influence children’s oral health behaviours, there are a limited number of publications on oral health behaviours that compare these factors between children with and without ADHD to control selection bias.^{10, 12} This study aimed to assess the oral health behaviours and cariogenic dietary habits of children diagnosed with ADHD and compare the findings with healthy control peers of the same age, sex, and from the same school.

MATERIALS AND METHODS

This study adheres to the STROBE guidelines for cross-sectional studies. The Human Ethics Review Committee of the School of Dentistry at Shiraz University of Medical Sciences (Shiraz, Iran) reviewed and approved the research protocol for this study (IR.SUMS.DENTAL.REC.1400.115). Before answering the questions, the children’s parents or their guardians signed an electronic informed consent form.

Study samples

The study population comprised all children aged 6 to 11 years who had already been diagnosed with ADHD based on DSM-IV and V criteria and were referred to the psychological counselling centre at Shiraz University, Shiraz, Iran. In this cross-sectional study, 60 children with ADHD aged 6 to 11 years made up the study group, and 60 peers of the same age, sex, and from the same school, without a history of ADHD, made up the control group. The sample size was estimated using an unknown prevalence of daily tooth brushing in the non-ADHD population (P₁ = 50%), a 25% expected difference between the prevalence values of the 2 populations (P₁–P₂), significance level α = 0.05, and statistical power of 80%.

The children diagnosed with ADHD in the psychological counselling centre were selected based on the following inclusion criteria: age between 6 and 11 years and written consent from the guardian or one of the parents to voluntarily participate in the study. The exclusion criteria for children in the study group were as follows: invalid contact information; conditions that interfered with daily activities or changed lifestyles, such as chronic renal failure, diabetes, and asthma; other medical conditions that required treatment with medications affecting oral health; and other mental disorders such as autism spectrum disorder. After reaching the required sample size for the ADHD group, an age- and sex-matched peer was selected from the same school for each child in the ADHD group to form the control group. Along with any prior diagnosis of ADHD, the exclusion criteria for the children in the control group were the same as those for the ADHD group. The inclusion and exclusion criteria for the two groups are presented in Table 1.

The contact information of parents or guardians was extracted from the records at the psychological counselling centre or at the schools. The parents or guardians of both groups were contacted by phone and were informed of the objectives of the study. Then, those children whose parents or guardians approved their child’s participation in the study were recruited.

Table 1.

Inclusion and exclusion criteria

Group	Inclusion criteria	Exclusion criteria
Study (ADHD)	Children diagnosed with ADHD in accordance with DSM-V or DSM-IV diagnostic criteria in the psychological counselling centre of Shiraz University	The presence of other mental and central nervous system disorders such as autism spectrum disorder, schizophrenia, bipolar affective disorder, epilepsy, serious injuries, etc.
	Children of both sexes aged 6 to 11 years	The presence of medical diseases affecting lifestyle or the performance of personal tasks, such as chronic renal failure, diabetes, asthma, etc.
	Parental or legal guardian approval (signing the informed consent form)	Medications and hormonotherapy affecting oral health or the performance of personal tasks except for the conventional medications for ADHD
Control (non-ADHD)	Lack of ADHD and other mental disorders (parental report and lack of diagnostic document in the psychological counselling centre of Shiraz University)	The presence of any mental and central nervous system disorders such as ADHD, autism spectrum disorder, schizophrenia, bipolar affective disorder, epilepsy, serious injuries, etc.
	Children of both sexes aged 6 to 11 years	The presence of medical diseases affecting the performance of personal tasks or changing the lifestyle such as chronic renal failure, diabetes, asthma, etc.
	Parental or legal guardian approval (signing the informed consent form)	Medications and hormonotherapy affecting awareness or the performance of personal tasks

Oral health behaviours and cariogenic dietary habits

To evaluate the children’s oral health behaviours, the parents provided detailed information on how frequently their children used fluoride-containing toothpaste, flossed their teeth, and brushed their teeth per day. To evaluate cariogenic dietary habits, parents were asked to report on the frequency of their child’s daily consumption of cariogenic snacks and drinks such as chocolate, candy bars, chips, pastries or other similar foods, and sugary beverages.

A series of questions concerning the children’s oral health behaviours and cariogenic dietary habits as well as family sociodemographic characteristics was developed based on those used in similar previous studies. Additionally, the questions were assessed by 1 public health specialist and 2 pediatric dentists. The survey questions were then uploaded on the Porsline website (Porsline.ir), a widely used online questionnaire system in Iran. The web link for the study questionnaire, together with an informed consent form, was sent to the parents’ mobile phones. The questionnaire items are presented in Appendix A.

Table 2.

Demographic characteristics of members participating in personal interviews

	Gender (%)
Age (years)	na	Male	Female
6–7	11	8 (72.7)	3 (27.3)
7–8	7	4 (57.1)	3 (42.9)
8–9	12	6 (50.0)	6 (50.0)
9–10	13	9 (69.2)	4 (30.8)
10–11	7	5 (71.4)	2 (28.6)
11–12	10	8 (80.0)	2 (20.0)
Total	60	40 (66.7)	20 (33.3)

^aFrequency in each group; the study comprised 120 children (60 pairs)

Table 3.

Family sociodemographic characteristics

	Group (%)
Variable		ADHD	Non-ADHD	p value
Father’s education	Non-academic	15 (25.4)	20 (33.9)	0.307b
	Academic	44 (74.6)	39 (66.1)
Mother’s education	Non-academic	24 (40.7)	25 (41.7)	0.999b
	Academic	36 (59.3)	35 (58.3)
Father’s job	Medical services	7 (11.7)	14 (23.3)	0.353b
	Employee	24 (40.0)	18 (30.0)
	Private	29 (48.3)	28 (46.7)
Mother’s job	Medical services	7 (11.7)	16 (26.7)	0.295b
	Employee	13 (21.7)	9 (15.0)
	Private	3 (5.0)	2 (5.0)
	Housewife	37 (61.7)	32 (53.3)
Living with both parents	Yes	54 (90.0)	53 (88.8)	0.999b
	No	6 (10.0)	7 (10.2)
Family income (Riala)	<100 million	33 (55.0)	30 (50.0)	0.701b
	≥100 million	27 (45.0)	30 (50.0)
Number of children	–	3.63 ± 1.18	3.67 ± 0.99	0.821c
Child’s rank	–	1.83 ± 0.78	1.70 ± 0.69	0.070c

Categorical data were described using frequency and percentage; numeric data were described using mean ± SD.

^aRial: currency of Iran

^bMcNemar test

^cWilcoxon signed-rank test

Statistical analysis

Categorical data were summarized using frequency and percentage, while the numerical data were described using mean and standard deviation (SD). To assess the homogeneity of non-matched demographic variables in the 2 groups, McNemar and Wilcoxon signed-rank tests were used. To compare the parent-reported behaviours between the 2 groups, conditional logistic regression was used to obtain matched pairs odds ratios (OR) and 95% confidence intervals (CI). All statistical analyses were done using the R software, version 4.1.2.²¹ Conditional logistic regression analysis was specifically implemented using the survival package.²² P values less than 0.05 were considered statistically significant for all analyses.

RESULTS

Each matched group comprised 60 children aged between 6 and 11 years, including 40 boys and 20 girls. The mean (±SD) age of the children was 9.47 ± 1.69. The sex and age distribution of the 60 pairs of children is displayed in Table 2. In the study group, 51 of 60 (85%) children had received pharmacotherapy for ADHD.

Table 3 presents the comparison of the non-matched demographic variables between study and control groups. The results revealed no statistically significant differences between the 2 groups in any of the variables (all p > 0.05). The homogeneity resulted from the test results and descriptive indices similarities between the 2 groups.

The OR and CI derived from conditional logistic regression models for oral health behaviours are presented in Table 4. When compared to their control peers, children diagnosed with ADHD had an OR of 0.4 (95% CI: 0.18–0.91, p = 0.028) for toothbrushing at least once a day. In other words, children in the control group were 2.5 times more likely than children in the study group to brush their teeth at least once a day. However, there was no significant correlation between the presence of ADHD and the use of dental floss (OR = 0.67, p = 0.442), fluoride toothpaste (OR = 1), or having a regular dental appointment (OR = 1.13, p = 0.727).

Table 5 shows the OR and 95% CI for cariogenic dietary habits. Significant differences in the frequency of both cariogenic food and drink intake were found between the 2 groups. Children with ADHD were 4.71 and 9.67 times more likely to consume cariogenic foods (95% CI: 2.08–10.66, p < 0.001) and drinks (95% CI: 2.94–31.73, p < 0.001), respectively, at least 3 times daily compared to their control peers. Interestingly, significant OR were found for at least once daily consumption of cariogenic foods (OR = 4.5, 95% CI: 2.90–9.68, p < 0.001) and drinks (OR = 5, 95% CI: 2.10–12.01, p < 0.001) in the ADHD group compared to the control group.

Table 4.

Oral health behaviours

	Group
Variable		ADHD	Non-ADHD	ORa	95% CIb	p value
Toothbrushing	< once a day	22 (36.7)	10 (16.7)	0.40	(0.18–0.91)	0.028
	≥ once a day	38 (63.3)	50 (83.3)
Tooth flossing	< once a day	53 (88.3)	50 (83.3)	0.67	(0.24–1.87)	0.442
	≥ once a day	7 (11.7)	10 (16.7)
Fluoride toothpaste use	< once a day	35 (58.3)	35 (58.3)	1	–	–
	≥ once a day	25 (41.7)	25 (41.7)
Regular dental appointment	No	24 (40)	26 (43.3)	1.13	(0.57–2.70)	0.727
	Yes	36 (60)	34 (56.7)

^aOR: matched pairs odds ratio (ADHD/non-ADHD)

^bCI: confidence interval for OR

Table 5.

Cariogenic dietary habits

		Group
Variable	Daily intake	ADHD	Non-ADHD	ORa	95% CIb	p value
Cariogenic foodsc	<1	10 (16.7)	38 (63.3)	4.50	(2.90-9.68)	<0.001
	≥1	50 (83.3)	22 (36.7)
Cariogenic foodsc	<3	24 (40)	50 (83.3)	4.71	(2.08-10.66)	<0.001
	≥3	36 (60)	10 (16.7)
Cariogenic drinksc	<1	10 (16.7)	34 (56.7)	5.00	(2.10-12.01)	<0.001
	≥1	50 (83.3)	26 (43.3)
Cariogenic drinksc	<3	27 (45)	53 (88.3)	9.67	(2.94-31.73)	<0.001
	≥3	33 (55)	7 (11.7)

^aOR: matched pairs odds ratio (ADHD/non-ADHD)

^bCI: confidence interval for OR

^cDaily intake of food and drinks was analysed under 2 categorization scenarios: a) at least once versus less than once a day; b) at least thrice versus less than thrice a day

DISCUSSION

This cross-sectional study compared the oral health behaviours and cariogenic dietary habits of children diagnosed with ADHD and their non-ADHD peers aged 6 to 11 years. All participants were matched for age, sex, and school. In children with ADHD, daily toothbrushing was less prevalent, and at the same time, these children consumed more cariogenic foods and drinks than their non-ADHD peers.

The present study revealed that children with ADHD were less likely to brush their teeth than their peers in the control group. The results are consistent with the majority of the studies in this area of research.^{10, 12, 23} According to research by Blomqvist et al.²³ children with ADHD at age 13 had a significantly lower prevalence of toothbrushing in both evening and morning. Although no matching protocol was used, the results were adjusted for sex and the mother’s education level using a logistic regression model. In the study by Chandra et al.¹⁰ children with ADHD aged 6 to 14 years had a lower frequency of toothbrushing than healthy peers of the same age, sex, and socioeconomic status. Toothbrushing was included in the analysis as a variable with 3 categories (not every day, once a day, and twice a day). The discrepancy in percentages was particularly noticeable in the last category. Since both groups had a trivial and equal number of subjects who brushed their teeth more than once a day, the current study analysed toothbrushing as a dichotomous variable (at least once a day versus less than once a day). In another study with a matching design by Khobkham et al.¹² children not diagnosed with ADHD were significantly more likely than children with ADHD to brush their teeth after lunch. However, there were no significant differences between the groups for toothbrushing in the morning and at bedtime. In contrast to the current study’s findings, Pinar-Erdem et al.²⁴ found no significant difference in the frequency of toothbrushing between the 2 groups. None of the aforementioned studies reported OR as a measure of association. In line with the findings of the present study, earlier studies reported no significant association between ADHD and using dental floss and fluoride toothpaste.

The findings of the present study indicate that children diagnosed with ADHD are more likely to consume cariogenic foods and drinks regularly. According to Chandra et al.¹⁰ children with ADHD consumed more sticky carbohydrate foods such as chocolate, candy bars, chips, and pastries between meals 3 days or more per week. In the study by Paszynska et al.¹³ mentioned previously, children with ADHD had greater levels of overweight, prevalence of caries, and consumption of sugary foods or drinks than the control group.

Higher caries, plaque, and gingival indices have been reported in children with ADHD compared to children not diagnosed with ADHD.^{9-12, 14-20} In this regard, a meta-analytic review by Chau et al.¹⁶ reported a greater mean DMFS, decayed surfaces, plaque, and higher prevalence of caries in individuals with ADHD under the age of 18 years. In children with ADHD, higher caries indices could be attributed to poorer oral health behaviours and more risky food habits. Bimstein et al.²⁵ reported that the history of toothache, bleeding gums, bruxism, and oral trauma was more prevalent in children with ADHD compared to children without ADHD. Hidas et al.^{26, 27} stated that the higher levels of plaque combined with the lower salivary flow in children with ADHD in comparison to the control group might be a risk factor for caries at older ages. Paszynska et al.¹³ also found that children with ADHD had a higher prevalence of caries in both permanent and primary teeth than children in the control group. They conducted a dental examination using the International Caries Detection and Assessment System (ICDAS II)²⁸ criteria and found that the condition of the primary dentition of the study group was significantly worse than that of the control group. Staberg et al.²⁹ reported that the parents of children with ADHD faced challenges in mana,ging their children’s consumption of sugar as well as their toothbrushing routines.

There are no public health or school-based programs specifically including oral hygiene instructions in Iran. Therefore, children learn about the importance of good daily oral hygiene from their parents, in general. Based on the findings of the present study and previous research, some practical recommendations are presented for oral health promotion in children with ADHD (Figure 1). Children with ADHD had poorer oral hygiene habits, more oral health conditions, and increased intake of cariogenic foods and drinks implying the need for the implementation of specialized intensive oral health care and prophylaxis strategies including remineralization of early caries lesions. Moreover, it is essential to develop and implement clear instructions for parents of children with ADHD to emphasize the need for surveillance of oral hygiene habits and the reduction of cariogenic food consumption in these children.

There was no significant difference between the frequency of regular appointments with oral health professionals in the 2 groups. In both groups, approximately 60% of children visited a dentist for a checkup at least once a year. This finding is consistent with the findings of Pinar-Erdem et al.²⁴ who found no significant differences between children with and without ADHD aged 6 to 15 years. They also stated that there was no difference between the dental anxiety scores of the 2 groups based on the Dental Subscale of Children’s Fear Survey Schedule (CFSS-DS). However, in contrast to their findings, some studies have reported that children with ADHD had a higher level of dental anxiety and dental behavioural management problems (BMP) than their controls.^{9, 14}

Figure 1.

Recommendations to improve the oral health of children with ADHD

Strengths and limitations

Most research in this field has not used matching in the study design. Matching allowed the present study to decrease the potential selection bias by minimizing dissimilarities between groups and investigate the uncontaminated effect of ADHD on dependent variables. Children’s oral health behaviours and dietary habits might be influenced by age, sex, and family socioeconomic status. Matching the children from the same school resulted in the homogeneity of the 2 groups regarding the main socioeconomic determinants in this study. This homogeneity is probably due to Iran’s public education law limiting recruitment of students to schools located in their neighbourhoods.

The authors of the current study acknowledge that the findings can only be generalized to populations with comparable levels of oral health literacy and oral health values to those of the study population. Therefore, further studies in other countries are required to investigate population-specific behaviours of children with ADHD. The cross-sectional design of the study restricts the interpretation of the results and prevents casual conclusions. Due to restrictions on the oral health screening of students in schools during the COVID-19 pandemic, it was not feasible to record the oral health status of the children in the study. Moreover, the impact of the type and severity of ADHD on oral health behaviours has not yet been investigated by researchers in this area, even though it may play an important role in personal activities such as daily oral hygiene. It is recommended that cohort studies be conducted to investigate the incidence of new caries and demineralization changes in children with and without ADHD using more comprehensive matching criteria, including various determinants of family socioeconomic status. Another area of research may be to investigate the prevalence of obesity in those with ADHD given the results of this study regarding the consumption of cariogenic foods and drinks, which can lead to weight gain.

CONCLUSION

Consistent with previous research, this study confirms that children diagnosed with ADHD are less likely to brush their teeth at least once a day and have a higher daily frequency of consuming both cariogenic foods and drinks compared to their peers in the control group. These results strengthen previous findings by the use of matched groups.

Appendix A.

Questionnaire sent to the parents and guardians of study participants

Family sociodemographic characteristics	Response optionsa
Child’s sex	Female
	Male
Child’s age (year)	[open]
What is the father’s education level?	Under diploma
	Diploma
	Associate/bachelor’s degree
	Higher academic degrees
What is the mother’s education level?	Under diploma
	Diploma
	Associate/bachelor’s degree
	Higher academic degrees
What is the mother’s job?	Medical services
	Employee
	Private
	Housewife
What is the father’s job?	Medical services
	Employee
	Private
	Unemployed
Does your child live in the same house with both parents?	No
	Yes
What is the family’s income level (Rial)?	<50 million
	50 to 100 million
	100 to150 million
	150 to 200 million
	≥200 million
How many children do you have in your family?	[open]
What is the child’s birth rank in the family?	[open]
Oral health behaviours of children	Response optionsa
How many times does your child brush his/her teeth per day?	Once a day
	Two or more times a day
	Less than once a day
Does your child use fluoride toothpaste when brushing his/her teeth?	No
	Yes
Does your child use dental floss daily?	No
	Yes
Did your child have a regular dental appointment in the last 12 months?	No
	Yes
Consumption of cariogenic foods and drinks	Response optionsa
How many times does your child eat cariogenic foods? (including sugary and/or chewy foods such as chocolates, candies, candy bars, pastries, chips, snacks…)	Never
	Once a day
	Twice a day
	Thrice a day or more
How many times does your child eat cariogenic drinks? (including any sugary beverage such as non-diet soft drinks, lemonade, sports drinks, juices, fruit extracts, fruit leather, sweetened coffee or tea…)	Never
	Once a day
	Twice a day
	Thrice a day or more

^aThe response options were not necessarily the same as those used for the statistical analysis. Due to small frequencies, some responses were aggregated (see Table 3)

CONFLICTS OF INTEREST

The authors have declared no conflicts of interest.