Behavioral and social determinants of early childhood caries among Palestinian preschoolers in Jerusalem area: a cross-sectional study

Data for this study came from a cross-sectional survey carried out between June 2019 and January 2020 in the Jerusalem Governorate of Palestine, also referred to as the Occupied Palestinian Territories (oPt). The sampling frame included preschools registered in the Palestinian Government Ministry of Education (MOE) in the Jerusalem Governorate and located outside the Separating Wall. The separating wall built in 2002 by the Israeli side excluded Jerusalem's urban center from surrounding Palestinian villages and towns [28] (Fig. 1). The left-out towns and villages depended on Jerusalem as an urban center for health, education, recreational activities, and social services. This separation created two different healthcare systems operating inside (Israeli municipality supervision) and outside the separating wall (Palestinian Authority (PA) supervision). Therefore, the newly established Jerusalem governorates, outside the separating wall, are considered the weakest in health infrastructure among all governorates in the oPt [29].

The sampling frame of this study included preschools supervised by the PA Ministry of Education (MOE) in the Jerusalem Governorate and located outside the Separating Wall (n = 50 schools with 4122 children). Fifteen schools out of fifty met the study inclusion criteria. Inclusion criteria for the preschools were: (1) preschools located in Jerusalem governorates and situated outside the Separating Wall, (2) registered at the Palestinian Ministry of Education, (3) have both genders, and (4) have at least 100 children enrolled in the 2019/2020 academic year. A random sample of four preschools were selected and stratified based on the different geographic areas in the Jerusalem governate (North, Northeast, East and Southeast). A flow chart the demonstrate the recruitment process is presented in Fig. 2.

Based on sample size calculation, minimum of 352 subjects needed for this study. This number was based on an ECC prevalence of 50% (based on previous literature in oPt [25‐27], a marginal error of 5% and a target population of (n = 4122).

All children in the selected schools (aged 3–5 years) were invited to participate in the study via letters to the parents asking for consent for their children to be examined and explaining the study's purpose and methodology. Children who were absent on the day of the examination visit and those whose parents or main caregivers did not consent to their participation were excluded from the study.

A self-administered questionnaire was adapted from previous studies [30, 31] and translated to Arabic, the mother tongue of the Palestinians. The Arabic version was reviewed by a panel of 6 experts from the disciplines of Pediatric Dentistry and Public Health. Pilot testing of the Arabic version of the questionnaire was carried out on a sample of fifteen mothers in a preschool in Bethlehem Governorate. Modifications were added to make the questionnaire more readable, meaningful, and culturally appropriate.

The questionnaire was sent home to the mothers or the main caregivers in the family to answer before the day of the clinical screening visit to the preschool. The mothers/main caregivers were asked about feeding practices used for the children when they were infants, current dietary habits, oral hygiene habits, and their access to dental care. In addition, demographic and socioeconomic information about the parents was collected. Socio-psychological factors among the main caregivers were also collected through validated instruments [17, 21].

Demographic data included the child’s age, gender, and socio-economic status determined by parents’ level of education and family income. The child’s age was recorded as (a) 4-year-old, or (b) 5-year-old. Information regarding the level of education was requested separately for the father and mother using a five‐point scale ranging from less than eighth-grade education to 4 years of college and more. Father’s employment status (regular job, irregular job, unemployed) and the mother’s employment status (full-time job, part-time job, student, stay-at-home) were also assessed separately. The monthly household income was given in New Shekels (NIS) and ranged on a six-point scale from (1) less than 1000 NIS (285$) to (6) 4000 Nis (1700$) and more. The current residence of the family was assessed as a city, village, or camp. Children’s access to dental care was assessed by the following questions: the family has dental insurance (yes/no), the child’s last dental visit (yes/no), and the reason for the visit (preventive visit/checkup or restorative care/problem).

Questions about feeding habits covered the main method of feeding during infancy, breastfeeding duration if the mother used to breast-feed her infant for a limited number of meals or on-demand (after 6 months of age), bottle-feeding duration, the usual contents of bottle feeding, and if the mother added sugar to the bottle or use a sweetened pacifier. Another set of questions was asked about night feeding habits: such as what is done in case the child wakes up during the night, how many times mothers usually feed their child during the night, do they use to breast-feed their children at night after the age of 6 months, and if the child uses to fall asleep while breastfeeding at night.

Questions about the frequency of snacking between meals and daily soda/sweetened juices intake were measured on a 5-point scale (never, seldom, once/day, twice/day, more than three times/day). In addition, the type of snacks preferred (salty/sweet) was asked in the current questionnaire.

Oral Hygiene habits of the child were assessed by the following questions: (1) at which age did tooth brushing start (not yet, younger than 2 years, 2–3 years, 3–4 years, 4–5 years), (2) frequency of tooth brushing (no brushing, irregular, once/day, twice/day) and (3) if the mother or the main caregiver assists the child in tooth brushing (yes/no).

The questionnaire also assessed some psychosocial constructs that were measured by validated scales used in the literature that assessed ECC, namely, the Instrumental Social Support (ISS), Locus of Control (LOC), and Parental Stress Level (PSL). The PSL instrument [17] included six items scored on a Likert scale from 1 (“never”) to 5 (“almost always”). The final score of the scale was the sum of the rating of the six statements and ranged from 6 to 36. Higher scores indicated higher levels of stress.

The ISS instrument [17] comprised four items that scored “yes” or “no.” The social support instrument was calculated as a sum of the answers; each “yes” received a “2”, and each “no” received a “1”. This the ISS ranged from 4 to 8; the higher the summated result was, the more social support the mother received. The LoC scale that had been adopted by Lenčová et al. [21] was used in this study. Based on the Locus of Control theory, this scale measures the external locus of control, internal locus of control, and belief in bad luck and chance. Each item was measured on a five-point Likert multi-item scale [ranging from strongly disagree (1) to strongly agree (5)]. The coding for the negatively formulated items (items expressing more external LoC or relying on chance) was reversed so that for the overall LOC scale (ranging from 13 to 65), higher scores reflect more positive attitudes (stronger internal LoC).

Before the clinical dental examinations, three interns at the Ministry of Health were trained and their dental examinations were standardized by the study principal investigator (E.K). The standardizing session included a double examination of ten children; then an inter-examiner reliability of the diagnoses regarding the presence of decayed teeth (dt) was calculated. A kappa agreement of 0.8 and 0.85 were obtained among the three examiners. Dental examinations were carried out with the help of a headlamp and a disposable examination set containing a mirror and dental explorer. The decayed, extracted due to caries and filled teeth index (dmft) for primary teeth was used to quantify dental caries experience among preschoolers. The criteria for caries diagnoses conformed to the World Health Organization Oral Health Basic Survey recommendations [32].

Plaque accumulation was recorded using The Silness-Löe Plaque Index (PI) [33]. PI was categorized as follows: PI 0: no observable plaque; PI 1: a thin film of plaque detected at the gingival margin by running a probe or explorer across the tooth surfaces; PI 2: a moderate amount of plaque detected along the gingival margin, plaque clinically visible; PI 3: heavy plaque accumulation detected at the gingival margin and in the interdental spaces. This index was measured at 4 points on 6 teeth, then averaged as follows: < 1: excellent oral hygiene; 1–1.9: good oral hygiene: 2–2.9: fair oral hygiene; ≥ 3: poor oral hygiene [33].

Al-Quds University Human Subject Research Ethics Committee (74/REC/2019) reviewed all study aspects. The participation was completely voluntary. Mothers or main caregivers were asked to give informed consent to participate in the study. Identifiers data of the subjects were removed from exam sheets by the PI and were entered into the database anonymously with a numerical code only.

We first constructed scales to combine variables for children’s diet habits and children’s oral hygiene practices via principal component analysis. Specifically, we used the Factor Analysis of Mixed Data (FAMD), a principal component analysis for both continuous and categorical variables and identified principal components that explained 70–75% of the total variance of linear combinations of selected variables. For the scale of children’s current diet habits, we combined 3 variables (frequency of snacking between meals, type of snacks preferred, and daily soda/sweetened juices intake) into 2 scores (Children's diet habits #1 and #2) that explained 73% of the total variance of these variables. For the scale of children’s oral hygiene practice, we combined 3 variables (age at which tooth brushing started, frequency of Tooth Brushing, and helping children brush teeth) into 2 scores (Children's oral hygiene practice #1 and #2) that explained 76% of the total variance. We then calculated descriptive statistics for all study variables. In particular, for the outcome, we calculated the mean dmft (quantify the severity of dental caries), dt (untreated dental caries), and ft (dental treatment the children received) scores. The dmft score was further categorized into five levels (very mild, mild, moderate, severe, and extremely severe) according to the WHO classification of dental caries severity [32]. Lastly, we performed multivariable Poisson regression analysis to test the association between dmft scores and caregiver’s feeding habits, caregiver’s social and psychological characteristics, children’s oral hygiene practices, and children’s diet habits after accounting for demographic characteristics (caregivers’ and children’s age, children’s gender, caregivers’ education and employment, household income), dental insurance, and access to dental care, Fig. 3.

To address bias due to children clustered by schools, we used a generalized estimation equation with an exchangeable correlation structure. We also performed multiple imputations and generated 5 imputed data via multivariate imputation by chained equations. In this algorithm, missing data from one variable were predicted by regression models with all the other variables, and the imputation procedure was repeated multiple times to reduce the error of prediction of missing data [34].

Almost 48% of our sample were females (n = 217) and 67.5% were 5-year-old (n = 307). Out of 453 answered this question, 40.4% of mothers and 64% of fathers had a high school diploma or lower. Seventy-one percent of fathers had a regular job (n = 319) and 22.4% (n = 101) of mothers worked full-time. Almost 45% (n = 189) of the preschoolers had both parents work outside the house. Thirty-eight percent (n = 162) of preschoolers lived in a household with an income equal to or less than $850 (US dollars) a month. Seventy-eight percent of preschoolers pay $720 (US dollars) or less a year as tuition for kindergarten (Table 1).

Almost 45% (n = 199) of mothers in this sample reported that they exclusively breastfed their children and 11% (n = 49) used bottle feeding and 44% (n = 200) used both. Sixty-one percent of mothers (n = 279) in our sample used to breastfeed their children after 6 months of age at night and 27.7% used night bottle feeding (n = 121). Twenty-one percent (n = 84) added sugar to the bottle and 9% (n = 39) dip pacifiers in sugar or honey. Twenty-one percent (n = 81) of mothers who used bottle feeding added sugar to the bottle and 19% (n = 87) used to dip pacifiers in sugar or honey to soothe their babies.

Fifty-three percent of preschoolers (n = 231) snack twice a day, a sweet one (80%). Thirty-one percent of children in this sample (n = 138) reported to usually have one can of soda per day or more and 69% (n = 310) never or rarely have any (Table 2).

Regarding daily oral hygiene care, 52% (n = 237) of children started brushing with fluoridate toothpaste after the age of 3 years and 45% of them (n = 199) brushed their teeth irregularly. Seventy-six percent of the children (n = 335) brushed their teeth under their parents’ supervision (Table 3).

According to Table 4, most of the preschoolers in this sample fell in the “Good category” of the Oral Hygiene classification which ranged from poor oral hygiene to excellent oral hygiene.

Access to dental care was assessed by having a dental visit before. Forty-four percent (n = 203) answered yes. Seventy-one percent (n = 157) visited the dentists for therapy and 29% (n = 65) for routine and preventive care reasons. Among our sample, 72% (n = 317) paid out of pocket for their dental care, 5% (n = 22) had private insurance and 23.5% (n = 104) had public insurance.

For psychosocial factors reported by preschoolers’ mothers or main caregivers, social support in this sample (n = 457) ranged from 4 to 8 with a mean score of 6.1 ± 1.3 and a median of 6.0 and an interquartile range of (7–5). Mothers' Level of Stress (PLS) (n = 442) ranged from 6 to 28 with a mean score of 16.4 ± 4.2 and a median score of 16 and an interquartile range of (19–13). The Locus of Control measure ranged (n = 396) from 28 to 62 with a mean score of 48.3 ± 5.2 and a median of 49.0 and an interquartile range of (52–45). For all psychological scales, higher scores indicated higher, stress levels, a sense of locus of control, and higher social support (Table 5).

Among those who completed the clinical examination, 97% (n = 447) had at least one dmft, with an average score of dmft score of 6.6 ± 4. The main component of dmft scores was untreated dental decay (dt score of 6.2 ± 4.2) and filling (ft score of 0.34 ± 1.1). The severity of the dental experience was quantified by a dmfs score of 14.0 ± 13. A detailed description of preschoolers' dmft scores according to the WHO “Very Low” to “Extremely High” categories is shown in Table 6.

Bivariate associations between the prevalence of dental caries (dmft score) and study main exposure variables were tested (Fig. 3). Behavioral and psychological factors were significantly associated with the dmft scores (Table 7). Specifically, putting things other than water in the baby bottle and sleeping while naturally breastfeeding were related to higher dmft scores (IRR = 1.05, 95% CI = 1.01, 1.10, IRR = 1.14: 95% CI = 1.03, 1.25, respectively). On the other hand, not adding sugar to the bottle was associated with lower dmft scores (IRR = 0.80, 95% CI = 0.69, 0.92). Access to dental care was a significant factor in dmft scores. Having routine, preventive visits versus never seeing a dentist were associated with lower dmft scores (IRR = 0.44, 95% CI = 0.38, 0.51). For psychological factors, parents’ internal locus of control was associated with lower dmft scores (IRR = 0.97, 95% CI = 0.96, 0.98). Although PSL was not directly associated with dmft scores, it was correlated with LOC (r = − 0.133, p = 0.012) and SS (r = − 0.16, p = 0.001).

After accounting for potential confounding, parents’ internal locus of control was associated with lower dental caries among children (IRR = 0.97, 95% CI = 0.97, 0.98). When it comes to the burden of nighttime feeding, a higher burden (putting things other than water in the baby bottle at night, having children sleep while being breastfed at night) was positively associated with children’s dental caries (IRR = 1.06, 95% CI = 1.04, 1.09: IRR = 1.15, 95% CI = 1.03, 1.29, respectively). Not adding sugar to the bottle was negatively associated with children’s dental caries (IRR = 0.86, 95% CI = 0.74, 1.00). Lastly, after accounting for potential confounding, “having routine, preventive visits” versus “never seeing a dentist” was associated with lower dmft scores (IRR = 0.42, 95% CI = 0.33, 0.52). Bivariate and multivariable analyses can be found in Table 7.