Association of maternal oral health literacy with dental caries status of 6-9-year-old children according to the caries assessment spectrum and treatment (CAST) index

Abstract

Objectives

This study aimed to assess the association of maternal oral health literacy (OHL) with dental caries status of 6-9-year-old children according to the Caries Assessment Spectrum and Treatment (CAST) index.

Methods

This cross-sectional study evaluated 223 mothers and their 6-9-year-old children who were selected by convenience sampling. The OHL of the mothers was evaluated by the Oral Health Literacy-Adults Questionnaire (OHL-AQ) while the dental caries status of the children was assessed by the CAST index. Data were analyzed by the independent t-test, linear and logistic regression, and Spearman and Pearson’s correlation coefficients (alpha = 0.05).

Results

Of 223 children, 51.6% were males. The mean age of the children was 7.25 ± 1.02 years. Mothers with a higher educational level (P = 0.01) and socioeconomic status (P = 0.02) had higher OHL. Optimal oral health behavior of the mothers was significantly associated with their higher OHL, and a lower rate of caries in their children (P < 0.05). The mean OHL score of the mothers was 12.42 ± 2.78, and their OHL had a significant inverse association with primary molar (P < 0.00) and permanent first molar (P = 0.01) caries in their children. Also, the rate of primary molar (P = 0.01 and P = 0.00, respectively) and permanent first molar (P = 0.02 and P < 0.00, respectively) caries was significantly lower in children of working mothers, and those with a higher educational level.

Conclusion

The maternal OHL was significantly associated with the dental caries status of 6-9-year-old children according to the CAST index.

Introduction

Despite numerous attempts, dental caries remains a public health dilemma worldwide [1]. High rates of caries have been reported in developing countries [2, 3]. The World Health Organization recommends periodic assessment of dental caries in different geographical regions [4]. Decayed, missed, and filled teeth (DMFT) index is extensively used for epidemiological assessment of dental caries and oral health status. Nonetheless, this index does not show the consequences and outcomes of untreated caries such as pain and infection. Thus, Frencken et al. [5], in 2011 introduced a new index known as the Caries Assessment Spectrum and Treatment (CAST) index to assess a wide range of teeth from intact to severely carious. This index includes a visual-tactile examination commonly used in epidemiological studies [6].

It has been well documented that parents are the main oral health mentors of their children during the early years and preschool period, and their behavior has a profound impact on oral health status of their children [7,8,9]. Also, the oral health-related quality of life of children has a close correlation with that of their parents [10]. Factors such as mothers’ level of education, occupation, age, knowledge level, attitude, and current health behaviors directly or indirectly affect the oral health of their children [11]. It has been reported that maternal oral health knowledge affects the oral health status and behavior of children during adolescence and adulthood, and preventive behaviors established early in life lead to better outcomes in adulthood [12].

In recent years, much attention has been directed to caries preventive measures in children, and the significance of oral health literacy (OHL) of the parents in this respect [13]. Health literacy is defined as the capacity of individuals to acquire, process, and comprehend information regarding their health status, the required health services, and proper health decision-making. Health literacy is evaluated in three levels: (I) functional health literacy with respect to the ability to read and write, understanding the prescriptions and drug dosage, and use of healthcare services, (II) communicative/interactive literacy that evaluates cognitive and social skills, and addresses the ability to extract data and acquire information from the media, and using the new information in personal situations, and (III) critical literacy which is the ability to critically analyze the information and use it to have greater control over the life events [14]. Health literacy is an important parameter in disease management [15], and is a predictor of health, hygiene behaviors, and health outcomes [16]. A review study reported that low levels of health literacy were correlated with poor health outcomes [16]. Moreover, it has been demonstrated that high level of health literacy of the parents has a direct correlation with optimal childcare, highlighting the necessity of assessment of health literacy level of the parents to identify their weaknesses and improve their performance [17]. OHL is a subtype of health literacy first introduced in 2000 [18]. It is defined as the “degree to which individuals have the capacity to obtain, process and understand basic oral health information and services needed to make appropriate health decisions” [19].

The OHL Adults Questionnaire (OHL-AQ), as a measure of functional OHL, was designed by Naghibi Sistani et al. [20], in 2013 for evaluation of OHL of the Iranian population. It also includes additional sections for evaluation of listening and decision-making skills. It was designed to assess the perception skills, knowledge about the correlation of oral and dental conditions with systemic diseases, basic calculations regarding the consumption of antibiotics and use of mouthwashes, and reading, writing, and decision-making about oral hygiene and common oral and dental problems [20].

A scoping review evaluated the effect of oral health literacy of the parents on oral health of children and showed that the majority of the reviewed studies had used the DMF index for assessment of dental caries [21]. Similar studies have also been conducted in Iran mostly using the DMF index [22,23,24].

Thus, this study aimed to assess the association of maternal OHL with dental caries status of 6-9-year-old children according to the CAST index. The null hypothesis of the study was that no association would be found between the maternal OHL with dental caries status of 6-9-year-old children according to the CAST index.

Materials and methods

This cross-sectional study evaluated 223 mothers and their 6-9-year-old children presenting to the Pediatric Dentistry Department of School of Dentistry, Alborz University of Medical Sciences in 2021–2022. The study protocol was approved by the ethics committee of the university (IRABZUMS.REC.1400.211). All procedures were conducted following the principles outlined in the Declaration of Helsinki.

Eligibility criteria

The inclusion criteria were children between 6 and 9 years, willingness of the mothers and children to participate in the study, and reading and writing literacy for the mothers.

The exclusion criteria were deaf or hard-of-hearing mothers, children with systemic disorders, generalized dental anomalies in children, and emergency cases e.g., dental trauma.

Sample size

The sample size was calculated to be 223 individuals assuming $\:{z}_{1-\frac{\alpha\:}{2}}^{2}=1.96$, $\:d=$ 5%, and $\:p=\:$17.6% according to a previous study [22], using the sample size calculation formula as follows:

$$\:n=\frac{{z}_{1-\alpha\:/2}^{2}\times\:p(1-p)}{{d}^{2}}$$

Data collection

Written informed consent was obtained from the parents prior to the onset of the study. One examiner (M.M) performed clinical oral examination for 20 children under the supervision of an expert (A.B) for the purpose of calibration (inter-examiner kappa: 87.9, intra-examiner kappa: 90.8). These children were not included in the study population. The children were selected by convenience sampling from March 2022 to June 2022 until the sample size was reached. The mothers were provided with the OHL-AQ, which has been specifically designed for the Iranian population, and its optimal validity and reliability have been previously confirmed [20]. It has 17 questions in four domains of reading comprehension, numeracy, listening, and decision-making [20]. The reading comprehension, numeracy, and decision-making domains were filled out by the mothers. For the listening domain, the interviewer repeated three sentences regarding post-tooth extraction instructions for a maximum of two times outload, and then the mothers responded to the respective questions in this domain. The oral health behavior, source of acquiring oral health information, and demographic information of the mothers (age, level of education, occupation, housing surface area, and number of family members) were also questioned. The socioeconomic status of the participants was determined by calculating the floor area per capita [25]. The questionnaire was distributed among the participants face-to-face. Filling out the questionnaire took approximately 20 min. The mothers filled out the questionnaire as self-report. However, questions of the listening part of the questionnaire were asked from the participants in a face-to-face interview. The listening questions were asked by the researcher from the mothers, and the mothers wrote their answers in the questionnaire. The OHL questions (17 questions) had dichotomous correct/wrong answer choices, and each correct answer was allocated one score. The total score of each participant was calculated and categorized as follows: scores 12–17: adequate OHL, scores 10–11: marginal OHL, and scores 0–9: inadequate OHL [20].

Next, the researcher examined the oral and dental health status of the children according to the CAST index and recorded the results in the respective form. The CAST index has 9 codes as follows: 0: sound, 1: sealant, 2: restoration, 3: enamel lesions, 4: primary dentin lesions, 5: advanced dentin lesions, 6: pulp involvement, 7: abscess/fistula, and 8: tooth loss due to caries; if a situation did not match any code from 0 to 8, the code 9 was assigned to it [5]. The maximum CAST score of each child was recorded, and a CAST score ≥ 3 indicated the presence of caries [6].

Statistical analysis

Data regarding the permanent first molars and primary molar teeth (Ds and Es) of the right and left quadrants of the maxilla and mandible were used for statistical analyses due to their greater significance. The t-test was applied to assess the association of OHL with the CAST index, and the linear regression analysis (enter method) was used to analyze the association of OHL with the demographic variables and oral health behavior of the mothers. The logistic regression was used to assess the association of the CAST index with the demographic variables and oral health behavior of the mothers. The Spearman’s correlation test was used to analyze the correlation between the number of dental information sources of the mothers and the CAST index score while the Pearson’s correlation test was used to analyze the correlation between the number of dental information sources of the mothers and their OHL. All statistical analyses were carried out using SPSS version 22 (IBM SPSS Statistics for Windows, Armonk, NY, USA) at 0.05 level of significance.

Results

Demographics

A total of 250 mother-child pairs were eligible for enrollment, and were initially enrolled; out of which, 27 were excluded since they did not fill out the questionnaire. Thus, the data of 223 mother-child pairs were analyzed, yielding a response rate of 89%. Table 1 presents the demographic information of the participants. Of all children, 51.6% (n = 115) were males, and 48.4% (n = 108) were females. There were 67 six-year-olds (30%), 63 seven-year-olds (28.3%), 64 eight-year-olds (28.7%), and 29 nine-year-olds (n = 13%). The mean age of the children was 7.25 ± 1.02 years. The mean age of the mothers was 36.08 ± 5.38 years (range 23 to 55 years); the majority of the mothers were between 30 and 40 years of age (67.3%).

Table 1 Demographic information of the mothers

OHL of the mothers

The mean OHL score of the mothers was 12.42 ± 2.78. Of all, 64.1% of the mothers had adequate, 17.1% had marginal, and 18.8% had inadequate OHL. Figure 1 shows the percentage of correct responses of the mothers to the OHL-AQ questions.

Fig. 1

Percentage of correct responses of the mothers to the OHL-AQ questions

Table 2 presents the frequency distribution of the mothers’ responses to the oral health behavior questions. Question 20 asked mothers to mark the sources from which they acquired their oral health information. The majority of the mothers selected “dentist” (70%) and “Internet” (59%) as their sources of information. Other sources from which the mothers acquired oral health information included magazines, newspapers, the media, and family and friends.

Table 2 Frequency distribution of the mothers’ responses to the oral health behavior questions

Dental caries status of the children according to the CAST index

Table 3 Frequency percentage of permanent first molar and primary molar caries in the children according to the CAST index (n = 223)

Table 3 presents the frequency of permanent first molar and primary molar caries in children according to the CAST index. As shown, in permanent first molars, code 0 (intact) had the highest prevalence (42.2-51.1%), and 27.8-35% of the teeth had code 1 (fissure sealant). Code 7 (abscess/fistula) and code 8 (lost due to caries) were not seen in permanent first molars of the children. In primary molars, the prevalence of dentin caries was < 16.6%. The percentage of pulp involvement, abscess/fistula, and tooth loss due to caries was < 24.7%, 1.8%, and 19.7%, respectively.

Association of maternal OHL and dental caries status of the children

The t-test showed that the maternal OHL had a significant association with dental health status of primary molars (P < 0.001, t = 5.08) and permanent first molars (P = 0.01, t = 2.84) according to the CAST index, such that the mean OHL score of the mothers whose children had intact teeth was higher (Table 4).

Table 4 Association of maternal OHL and dental caries status of the children according to the CAST index

Association of demographic variables of the mothers with dental caries status of their children according to the CAST index

As shown in Table 5, the logistic regression showed no significant association between the demographic variables of the mothers with the dental caries status of their children; however, independent assessment of the association of each variable with the CAST index score revealed some significant associations. Level of education of the mothers had a significant association with the CAST score of primary molars (P = 0.00) and permanent first molars (P < 0.00) such that the percentage of carious primary molars was significantly higher in children whose mothers’ level of education was below diploma (100%) or diploma (96%) compared to those whose mothers had university education (87.1%). Also, the percentage of carious permanent first molars was higher in children whose mothers’ level of education was below diploma (57.8%) or diploma (28.7%) compared to those whose mothers had university education (14.8%). Moreover, mothers’ occupation had a significant association with the CAST index of primary molars (P = 0.01) and permanent first molars (P = 0.02) of children such that the percentage of carious primary molars was higher in children whose mothers were housewives (95.5%) compared with the children of working mothers (81.1%). Also, the percentage of carious permanent first molars was higher in children whose mothers were housewives (29.2%) compared with the children of working mothers (11.3%).

Table 5 Association of demographic variables of the mothers with dental caries status of their children according to the CAST index

The linear regression showed that of different demographic variables, mothers’ level of education (P = 0.01) and socioeconomic status (P = 0.02) were significantly associated with maternal OHL, such that mothers with higher level of education acquired a higher OHL score, and mothers with a lower socioeconomic status had a lower OHL score (Table 6).

Table 6 Association of mothers’ demographic variables with their OHL

Table 7 shows the association of oral health behaviors of mothers with dental caries status of their children. As shown, the logistic regression revealed no significant association between the oral health behavior of the mothers and dental caries status of their children. Independent assessment of the association of each behavior showed no significant association with the CAST score of primary molars. However, frequency of toothbrushing by the mothers had a significant association with the CAST score of permanent first molars of their children (P = 0.05), such that the children of mothers who brushed their teeth at least once a day had a significantly lower percentage of carious permanent first molars. Also, a significant association was found between the time of most recent dental visit of the mothers and the CAST score of permanent first molars of their children (P = 0.02) such that the children of mothers who had visited a dentist in the past 6 months had a significantly lower percentage of carious permanent first molars (17.3%).

Table 7 Association of oral health behaviors of mothers with dental caries status of their children

The Spearman’s correlation test revealed significant inverse correlations between the number of dental information sources of the mothers and the CAST index score of primary molars (P = 0.04, r=-0.14) and permanent first molars (P < 0.00, r=-0.26) of their children, such that the children of mothers who had acquired their information from a higher number of sources had a lower rate of caries in their primary molars and permanent first molars.

As indicated in Table 8, the linear regression showed that of different oral health behaviors of the mothers, frequency of toothbrushing and time of most recent dental visit had significant associations with their OHL (P < 0.00). The mothers who brushed their teeth at least once daily and those who had visited a dentist in the past one year had a significantly higher level of OHL. The Pearson’s correlation test showed a significant correlation between the number of dental information sources of the mothers and their OHL (P < 0.00, r = 0.34) such that higher number of sources was associated with a higher level of OHL.

Table 8 Association of maternal oral health behavior and OHL

Discussion

This study assessed the association of maternal OHL with dental caries status of 6-9-year-old children according to the CAST index. Given that an association is found between the mothers’ OHL and their children’s dental caries, some interventional strategies may be designed to improve the mothers’ OHL to subsequently promote their children’s oral health. The OHL-AQ used for data collection has been previously validated for use on an Iranian population with a Cronbach’s alpha of 0.72 and intra-class correlation coefficient of 0.84 [20]. The current results confirmed that higher OHL of the mothers was associated with a lower percentage of dental caries in their children. Thus, the null hypothesis of the study was rejected. Similarly, Sheikhi and Moalemzadeh [22] evaluated the preschool children in Samirom City, Iran, and found a significant association between the maternal OHL and the dmft of their children. Adil et al. [26], also reported a significant association between the dmft of children and OHL of their parents. Yazdani et al. [27] found similar results in Tehran. Thus, maternal OHL may be considered as a determinant of oral health of children.

In the current study, over half of the mothers had adequate OHL. Similarly, Seyed Moalemi et al. [28], in their study in Isfahan reported that half of their participants had adequate OHL. Dieng et al. [29], in France demonstrated that less than half of their participants had adequate OHL. One possible reason for higher OHL of the participants in the present study is their higher level of education, compared with other studies. Calvasina et al. [30], in their study in Canada reported that a high percentage of their participants had adequate OHL, which can be due to their higher socioeconomic status and better access to dental care services. They reported that participants with an average family income of < $30,000/year were approximately four times more likely to have no dental visit within the previous year. They also declared that access to dental care services for Canadian adults highly depends on their socioeconomic status, employment benefits, and insurance coverage.

In the present study, caries status was evaluated by using the CAST index. Ribeiro et al. [31] used the CAST index for assessment of carious lesions and reported that the numerical value presented by this index enables general assessment of caries severity and its classification as mild, moderate, and severe. Castro et al. [32] compared the DMF index, International Caries Detection and Assessment System, and CAST index and reported that although the DMFT/dmft index is simple and easy to apply, it does not reflect the need for dental care as filling and decay have the same score in the total DMFT/dmft, and the burden of disease could not be estimated. The International Caries Detection and Assessment System provides comprehensive information about the severity of carious lesions; however, it is time-consuming and hard to interpret. The CAST index well describes the distribution of caries and reveals the severity of lesions as well as the preventive and therapeutic requirements of patients. Also, the time required for using the CAST index is the same as that for the DMF index. Adoption of the CAST index has several advantages. It encompasses a wide spectrum of tooth conditions from sound to pulp involvement, abscess/fistula, and tooth loss (as a severe consequence of caries). Thus, it appears that the CAST index is optimal for need assessment for both preventive care and restorative procedures. It can also aid the health policy-makers in budget al. location for management of high-risk children with advanced caries, dental pain, and infection [6].

Assessment of the dental caries status of the children in the present study by the CAST index revealed that half of their permanent first molars were sound, and one-third of them had a fissure sealant. However, in a study by Babaei et al. [6], over four-fifths of the permanent first molars were sound, and an insignificant percentage of them had a fissure sealant. In the current study, a higher percentage of primary molars were restored compared to the study by Babaei et al. [6], which may be due to differences in study populations and age groups of children since they evaluated 6-7-year-olds while 6-9-year-olds were evaluated in the present study. Higher number of sealed or filled teeth in the present study, compared with the literature, may be explained by the fact that the present study participants were selected among those presenting to a dental clinic.

A significant association was found between the level of education of the mothers and percentage of carious primary molars and permanent first molars of their children in the present study such that children of mothers with higher educational level had the highest percentage of sound teeth.

Similar results were obtained by Mahboobi et al. [33], Elamin et al. [34], and Babaei et al. [6]. Therefore, it appears that educated individuals have a higher level of oral health knowledge, are more concerned about the oral health status of their children, and pay more attention to the primary dentition and its impact on facial esthetics, masticatory function, and permanent dentition.

Naghibi Sistani et al. [20], in Tehran, Sheikhi and Moalemzadeh [22] in Isfahan, Adil et al. [26], in Malaysia, and Dieng et al. [29], in France reported significant association of maternal educational level and OHL, which was in agreement with the present findings. It appears that those with higher educational level acquire more information regarding oral health during their education and therefore have higher OHL.

The current results showed that children of working mothers had a lower CAST index score, which was consistent with the results of Alraqiq et al. [35], Kamiab et al. [36], and Adil et al. [26]. The possible reasons for this association may be fewer financial problems of working parents (to pay for oral healthcare of their children) and their better access to health information regarding preventive and therapeutic measures. Nonetheless, Abed et al. [37], in their study conducted in London reported that demographic information of the parents had no significant effect on incidence of caries in their children.

In the current study, socioeconomic status had a significant association with maternal OHL. Dieng et al. [29], and Calvasina et al. [30] reported similar results. It appears that limited access to correct sources of information regarding oral healthcare in low-income families is one reason for their lower OHL.

The present results revealed that children of mothers who brushed their teeth at least once a day had lower rate of carious permanent first molars, which was in agreement with the findings of Alraqiq et al. [35], Castilho et al. [38],, Elamin et al. [34],, Kamiab et al. [36], and Sheikhi and Moalemzadeh [22]. It appears that parents serve as a role model for their children, and their oral health behavior has a profound impact on formation of proper health behaviors and habits in their children. Mothers who brushed their teeth at least once daily had a higher level of OHL. The same results were reported by Sheikhi and Moalemzadeh [22], Naghibi Sistani et al. [20], and Seyed Moalemi et al. [28]. Proper oral health behaviors indicate adequate oral health knowledge.

Children of mothers who had visited a dentist in the past 6 months had a higher percentage of sound permanent first molars. Yazdani et al. [27] indicated a higher percentage of filled teeth in children whose parents had regular dental visits. It appears that regular dental visits of the parents can promote their own oral health status as well as that of their children. Maternal OHL had a significant association with the time of most recent dental visit of the mothers in the current study. Mothers who had visited a dentist in the past year had a higher level of OHL, which was in accordance with the findings of several previous studies [22, 30, 39]. Since dentists can be the best and most reliable source of oral health information, higher OHL of the mothers with recent dental visits can be justified.

In the present study, children of mothers who used a higher number of information sources (dentist, Internet, TV, etc.) had a higher percentage of sound permanent first molars and primary molars. Qu et al. [40] demonstrated that parents with a higher level of oral health information performed early preventive measures for their children and resultantly, their children had a lower rate of caries. Furthermore, mothers who used several sources to acquire oral health information had higher OHL, which was in agreement with previous findings [22, 28]. It appears that easy access to the media in addition to other methods of instruction plays a fundamental role in knowledge enhancement of the mothers regarding oral health.

Strengths

Adoption of the CAST index in the present study, which is a valid, accurate, and comprehensive index for detection of a wide range of lesions (non-cavitated to advanced) was a major strength of the present study. Also, a visual guide was used by the authors during calibration and dental examination which included the CAST index details to minimize the risk of misclassification of the lesions. Furthermore, a valid questionnaire was used for data collection.

Limitations

The present study had some limitations. Cross-sectional design was the first limitation of this study, which does not allow finding a causal relationship. Also, this study was a single-center study and only evaluated a specific age group. Thus, the results cannot be generalized to the entire population of Iranian children. Moreover, a self-report questionnaire was used for data collection, which is associated with the risk of social desirability bias. Poor cooperation of some parents in filling out the questionnaire and unwillingness of some children for study enrollment were among other limitations encountered in the course of the present study. Furthermore, several other factors such as diet, genetics, and environmental factors are involved in caries development in children that were not addressed in this study. Evaluation of only mothers was another limitation, which calls for further studies with inclusion of both mothers and fathers.

Recommendations

Future multi-center studies on a larger sample size are required to verify the present findings. Also, other factors involved in development of dental caries in children should be taken into account in future studies. Furthermore, similar studies on other age groups are recommended. Additionally, knowledge and OHL gaps should be discovered in order to plan future strategies to enhance OHL of families from diverse backgrounds, with the ultimate objective of reducing dental caries in children.

Considering the present results, educational programs are required for enhancement of OHL of the parents especially for those with low socioeconomic status to promote the oral health status of their children.

Conclusion

Maternal OHL had a significant association with dental caries status of 6-9-year-old children according to the CAST index. Higher socioeconomic status and educational level were associated with higher OHL. Also, the rate of dental caries was lower in children of working mothers and those with a higher educational level. Daily toothbrushing, visiting a dentist in the past one year, and using multiple sources of information by the mothers were associated with their higher OHL, and a lower percentage of caries in their children.