Oral health and dental caries experience among students aged 7–15 years old with autism spectrum disorders in Tehran, Iran

A descriptive/analytical cross-sectional survey was conducted in Tehran, Iran. All seven governmental special primary schools in the city of Tehran were selected for this study. None of the schools was a boarding school. Of 352 students with ASD aged 6–15 years old in the first to sixth grades, the parents of 265 students consented to their children's participation in the study by signing a written informed consent form after obtaining information about the purpose and process of the study via a letter sent to them along with the consent form by teachers (response rate: 75.2%). The inclusion criteria were parents’ consent, age between 7 and 15 years old, and an ASD level of 1 or 2 [19]. The exclusion criteria were the presence of other physical or developmental disabilities and lack of cooperation. All of the students were previously diagnosed with ASD by competent specialists of Tehran Exceptional Education Office and their medical records were made available to the authors.

A psychologist assessed the severity of autism (ASD level) according to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) [19]. These levels included level one (mild ASD), level two (moderate ASD), and level Three (severe ASD). Students assigned to ASD level three were excluded from the study. Finally, 217 students were included in the study.

An instrument was designed to measure oral health behaviors and barriers to tooth brushing in autistic students. The questionnaire items were derived from relevant articles and resources and then reviewed and revised to prepare an initial draft of the instrument. An expert panel including eight oral public health specialists, an epidemiologist, and a health education specialist assessed the content validity of the questionnaire in terms of relevancy, clarity, simplicity, and necessity. Content validity index (CVI) and content validity ratio (CVR) were calculated for each item. All of the items had acceptable CVI (≥ 0.83) and CVR value (≥ 0.75) [20]. To evaluate the face validity of the questionnaire, it was completed by 12 parents of autistic children. The respondents were asked about the clarity and comprehensibility of the items, and it was found they considered the questionnaire acceptable in these aspects. The reliability of the instrument was tested from two aspects of internal reliability and stability. Cronbach's alpha coefficient was measured and test–retest was done by twelve participants at an interval of two weeks, which were both within acceptable limits (Cronbach's alpha coefficient = 0.96, and ICC > 0.70) [21].

The questionnaire consisted of three parts. The first part was about demographic and basic characteristics of the students including age, sex, parents’ educational level, and household economic status. The second part consisted of four multiple choice questions to evaluate oral health behavior of autistic children (including 1- tooth brushing frequency, 2- routines of tooth brushing-brushing with/without help-, 3- using fluoride containing tooth paste, and 4- frequency of daily Sugary snack). The third part contained seven yes/no questions indicating which one of the seven possible barriers and challenges the student faced with while brushing their teeth. These items included 1- tooth brushing as an effort and a time-consuming task, 2- tooth brushing as a complicated task, 3- dislike oral entry, 4- dislike tooth brushing as a task, 5- unwanted movements appear while doing the task. 6-fear of tooth brushing. 7- difficulty in tooth brushing.

A pilot study was conducted in a private charity educational center for autistic children in Tehran. Eleven children with ASD who were not included in the main study participated in the pilot study. The inter-examiner agreement was assessed between the examiner and an oral public health specialist. First, the two examiners reviewed the examination method. They examined one child with ASD to observe the examination of each other and discuss coding issues. Accordingly, the 10 remaining children with ASD were examined by both examiners separately in the same room. (ICC = 1 for DI, CI and OHI-S and ICC = 0.83 for DMFT). For intra-examiner calibration, the examiner- a general dentist- examined 10 children to evaluate the Simplified Oral Hygiene Index (OHI-S) and DMFT (Decayed, Missing and Filled Teeth). The second assessment was after half an hour. (ICC = 1 for debris index (DI), calculus index (CI), OHI-S and DMFT).

Written informed consent was obtained from the parents. Subsequently, the questionnaire was completed by one of the parents and oral examination was done by the examiner. A week before the examination, a social story containing the pictures of the examiner and the steps of examination was given to the parents and they were asked to tell the story and show pictures to their children at least three times a day during the week.

On the examination day, the students entered the school health and care room one by one, accompanied by their teacher. Each student was requested to sit on the chair with help of the teacher. Before oral examination, two pictures were shown to the student, a picture of the examiner holding an examination mirror followed by a picture of a child undergoing oral examination by the examiner. The oral examination was carried out by the examiner sitting in front of the student. The examination was done under natural light using an intra-oral examination mirror. To assess the oral hygiene status, the OHI-S was recorded [22] including DI and CI. Accordingly, six index teeth [all 4 first molars [4], upper right and lower left central incisors [2] were considered and labial surfaces were examined except for the lower molars where the lingual surfaces were examined. Codes for DI were as follows: 0 = absence of soft debris or extrinsic stain, 1 = debris covering not more than one third of the tooth surface, 2 = debris covering more than one third but not more than two third of the tooth surface regardless of the presence of extrinsic stain, and 3 = soft debris covering more than two thirds of the examined tooth surface. The CI was scored as follows: 0 = no calculus present, 1 = supragingival calculus covering not more than a third of the exposed tooth surface, 2 = supragingival calculus covering more than one third but not more than two thirds of the exposed tooth surfaces or the presence of individual flecks of subgingival calculus around the cervical portion of the tooth or both, 3 = supragingival calculus covering more than two thirds of the exposed tooth surface or a continuous heavy band of subgingival calculus around the cervical portion of the tooth or both. In addition, Decayed, Missing and Filled Teeth in permanent dentition (DMFT), Decayed Teeth in permanent dentition (DT), Missing Teeth in permanent dentition (MT), and Filled Teeth in permanent dentition (FT) were recorded for each student. The cooperation level of the student with the dentist during examination was measured using the Frankle Index with a score range of 1–4 including 1: Definitely negative for refusal of examination, crying forcefully, fearful, or any other overt evidence of extreme negativism, 2: Negative for reluctant to accept examination, uncooperative, some evidence of negative attitude but not pronounced, sullen, withdrawn, 3: Positive for acceptance of the examination, at times cautious, willingness to comply with the dentist, but patient follows the dentist's directions cooperatively, and 4: Definitely positive for good rapport with the dentist, interested in the dental procedures, laughing and enjoying the situation [23]. A soft tooth brush was given to each student as a prize at the end of the oral examination.

Economic status was assessed according to relative poverty in urban areas of Iran, estimating that 360 USD provides the minimum subsistence needs for an urban family in Iran for a month. In this study, we asked the parents if their income was above or below this amount. An income of less than 360 USD per month was considered as low income and above 360 USD was considered as high income.

The education level of parents was assessed using their last academic certificate via a multiple-choice question ordinated in 6 levels of education including: 1- illiterate, 2- unfinished high school education, 3- high school diploma, 4- associated degree, 5- bachelor’s degree, 6- master’s degree or higher. Associated degree is an equivalent for a college education. Then, these levels were dichotomized according to our statistical distribution into two groups of associate degree or lower and above associate degree.

The data was analyzed using SPSS version 24 (IBM, Armonk, NY, USA). First, the whole data was scanned and cleared from false entries. Then, missing values were imputed by Expectation Maximization (EM) [24]. Descriptive statistics of demographic and basic characteristics of the students with ASD, oral health behavior, tooth brushing barriers and the results of oral examinations were produced. The distribution of the quantitative variables is presented as mean and standard deviation. Qualitative variables are reported as percentage and number.

We classified the participants into two groups according to their age. The first group was in the range of 7 to 11 years and the second group was in the range of 12 to 15 years old. This classification was done as the number of the participants in each group was almost equal. Additionally, the first age group had mix dentition while the second group had permanent dentition.

The oral hygiene status assessed by the OHI-S was categorized into two groups for data distribution analysis according to a previous study [25] (OHI-S ≤ 1.83 as good oral hygiene status and OHI-S > 1.83 as poor oral hygiene). The effect of different sociodemographic and oral health behavior factors on the OHI-S in students with ASD was assessed using logistic regression analysis. The relationship between different factors and DMFT in all students with ASD was assessed using generalized linear model regression (negative binomial identity link function). P-values less than 0.05 were considered significant.

Ethical clearance was obtained from the Research Ethics Committee of the School of Dentistry, Tehran University of Medical Sciences. Written informed consent was obtained from parents before the study and they were assured that their identity remained anonymous (IR.TUMS.DENTISTRY.REC.1398.153).

The students with ASD level 3 were excluded from this cross-sectional study due to the lack of cooperation during oral examination. Although there are special private centers and schools for children with ASD, we selected the study population from governmental schools since most of them had low to moderate severity levels of ASD and were relatively cooperative. In addition, significant comparisons between previous studies were limited because most of them were conducted in wider age ranges or in other countries with different conditions such as cross-cultural differences in living standards, dietary habits, genetics, etc.

Most of the studies on individuals with ASD are conducted in small populations or in wide age ranges. The present study evaluated an appropriate sample size of school students with ASD to assess their oral health status. Our study population included almost all of the students with ASD level 1 and 2 in Tehran, the capital of Iran and a multicultural city with a population of over 10 million with different socio-demographic characteristics, health beliefs, and races from all over the country. To the best of our knowledge, this descriptive study provides a great deal of basic information about oral health of children with ASD in Iran for the first time. Despite all limitations and high sensitivity of parents, educational authorities, and school staff, we managed to collect acceptable data for the study. Another advantage was the study setting. For autistic children, the school is the best place for examinations, since they are used to this environment. A change of location for dental examination would probably provoke negative behaviors in this group of children [5].