The association between children’s oral health behaviors, parents’ oral health knowledge and parents’ education level: a survey of 8446 families in Wuhan

Background: Children aged 6-7 years are in the early mixed dentition, which is a period of high prevalence of dental caries and other dental diseases, and a critical period for the formation of oral health behaviors. Therefore, good oral hygiene habits of children and oral health knowledge of parents are very important. This study sought to explore the relationship between children’s oral health behaviors, parental oral health knowledge, parental choices of pit and fissure sealants, and parents’ education levels based on a large scale sample size for the first time, and to compare the influence between parents. Methods: In this study, the families of the first and second graders of primary schools in Wuhan Hongshan District were selected as subjects. A total of 8446 questionnaires were collected to obtain comprehensive information on children’s oral health behaviors, parents’ oral health knowledge and parents’ pit and fissure sealants related choices. The relationship between these and parents’ education levels were studied through logistic regression analysis and chi-square test. Results: Families of parents who reported good education background had better children’s oral health behaviors and more favorable parents’ oral health knowledge than those of other parents. Four indicators of the children’s oral health behaviors were significantly affected by mother’s education levels, and three of them were correlated with the father’s. Moreover, seven indicators of the parents’ oral health knowledge were significantly related to mother’s education levels and four of them were affected by the father’s. In addition, parents with higher education attainment paid more attention to the quality of equipment, the professionalism of doctors, the proximity of the location, and paid less attention to the willingness and cooperation degree of children when choosing the pit and fissure sealants location. Conclusions: In the families of children with early mixed dentition, parents with higher education pose better oral health knowledge and have more for oral health care needs, such as pit and fissure sealants. As a result, their children tend to perform better on oral hygiene practices.


Introduction
The results of the fourth National Oral Health Epidemiology Survey of China conducted in [2015][2016][2017] found that the prevalence of permanent dental caries in children aged 12 to 15 years was 41.9%, the mean DFMT was 1.04, and the caries filling rate was 17.5% [1]. These data suggest that the prevention of dental caries in Chinese children is still a problem worthy of attention. This paper considers the age group of 6 to 7 years, since children of these ages are in the early mixed dentition that permanent incisors and molars start to erupt and the deciduous teeth remain [2].
In China, 6 to 7 years of age is especially important as it is generally the age at which children begin primary school, which makes reliable samples accessible through the school system. Also, children of these ages are able to acquire knowledge efficiently, which is a critical period for the development of oral hygiene habits [3]. The performance of adequate oral hygiene practices is not only important in the prevention of oral diseases [4], but also in children's physical and mental health [5]. School-based oral health education programs have been widely conducted in many countries, as these interventions are effective in increasing oral health knowledge, attitudes and behaviors among children [6]. It is notable that parental effects on children's knowledge, attitudes and behaviors towards oral health are also significant [7].
Previous studies have discussed the effect of the socio-economic status of parents on the prevalence of dental caries and oral health behaviors of children [8][9][10]. Socio-economic status are mainly measured by mother's education level [11,12] and household income [13,14]. Although parental education level has a certain correlation with the indicators of parental occupations and household income [15,16], their essences are distinct. The use of education level attempts to capture the knowledge and skills related assets of an individual, while the household income directly measures the material resources component of the family. Among previous researches, the relationship between children's oral health behaviors (COB), parents' oral health knowledge (POK), and parental education level has not been examined by research with large sample size.
Pit and fissure sealant (PFS) is a treatment that has been well proven to be effective in preventing dental caries [17][18][19]. It is suggested by the World Health Organization and health guidelines in the majority of countries [20]. Additionally, free PFS treatment is widely provided by governments over the world [21]. In this study, we collected information on parents' PFS-related choices and consider it as an extension of parents' attitudes towards oral health care.
The aim of this study was to explore the relationship between COB, POK, parents' PFS-related choices and patents' education levels, based on a large sample size for the first time, and to compare the influence of mother and father on COB, POK and PFS-related choices. An additional aim was to identify potential risk factors that might affect children's oral health, in order to provide evidences for stakeholders when planning and conducting public health programs. Methods

Study design
Funded by the Hongshan District Government, the Hongshan Longitudinal Study on Pit and Fissure Sealant Application (HoLSPA) aimed to provide free oral examination and pit and fissure sealants (PFS) for the first and second graders in Hongshan District, Wuhan, China. Families of the first and second graders in Hongshan District were all eligible for this study. Participants whose parents have psychiatric or cognitive dysfunctions were excluded. The HoLSPA consist of oral examinations, PFS and online surveys.
As part of the HoLSPA, survey data were collected through parental questionnaires issued by the Education Bureau. Electronic questionnaires were sent to parents of 11,000 eligible families through WeChat (a Chinese multi-purpose messaging and social media app) by head teachers. Each family was required to fill out one questionnaire and return it via WeChat. The survey was completed before the clinical part of HoLSPA project started. In the questionnaires, information on children's family situation, COB, POK and parents' PFS-related choice were collected.
The Medical Ethics Committee of Wuhan University Stomatological Hospital approved this study (2018. B13). All participants of this study gave written informed consent.

Questionnaire contents 2.2.1 Participant socio-demographic characteristics
The socio-demographic characteristics of the respondents included the number of children in the family, father's education level and mother's education level. Father's and mother's educational attainments were grouped into four categories: "Middle school and below", "High school", "College degree", "Undergraduate degree or above".

Children's oral health behaviors (COB)
We designed 5 questions to analyze the relationship between COB and parents' education level. The measures of COB included: (1) Does the child usually brush their teeth; (2) Does the child brush the teeth twice a day or more; (3) Has the child ever visited a dentist, (4) Was the last dental visit within past 12 months; (5) The main reason of the last dental visit. The first four questions were answered as "yes" or "no", and the last question defined as "treatment" or "consultation".

Parents' oral health knowledge (POK)
Eight items were focused on the relationship between POK and parental education level. POK was measured by the response to following true-false statements: (1) Gingival bleeding is normal when brushing teeth; (2) Gingivitis is caused by bacteria; (3) Tooth-brushing is useful for preventing gingivitis; (4) Bacteria can cause dental caries; (5) Eating sugar can cause dental caries; (6) Fluoride is useful in protecting teeth; (7) Pit and fissure sealant can protect teeth; (8) Oral diseases is related to general health. The answers were grouped into two categories: "correct" and "wrong and do not know".

Parents' pit and fissure sealants (PFS) related choices
Three questions explored the relationship between parents' opinions of PFS and their education.
Questions on parents' opinions of PFS included: (1) Whether you have heard of PFS ("yes" or "no"); (2) Where do you prefer to let your child receive PFS ("dental hospital" or "school"); (3) What are the determinants of choosing PFS location ("Treatment location distance", "Control of hospital crossinfection", "Therapeutic equipment perfection", "Emergency response measures", "Children's willingness and cooperation degree" and "Other reasons").

Statistical analysis
To begin with, the crude associations between family characteristics, COB, POK, parents' PFS-related choices and parental education level were analyzed through Chi-square tests. Then, logistic regression analysis was performed to examine the association between COB and parents' education level. In the univariate logistic regression model, we assessed the association between mother's and father's education level independently. In the multivariate model, mothers' education level and fathers' education level were added into the regression model simultaneously. Associations between children's oral health and parents' education level are not always consistent for the father and the mother [22]. Thus, we first conducted analyses separately for both parents, and then observe them together.
In the third part, we examined the association between POK and parental education level through logistic regression analysis. The choice related to PFS, as a proxy of parents' choices of oral health care, was assessed in the last part. We conducted logistic regression to examine the association between parental education and their understanding of PFS. EpiData 3.0 was used for data entry and SPSS 25.0 was used for data analysis. A significant level of 0.05 was used to determine statistical significance. Additionally, histograms drew by SPSSAU were used to demonstrate the relationship between the determinants of PFS location choice and parents' education separately.

Results
The distribution of family characteristics, oral health behaviors of children, oral health literacy of parents, and parents' PFS-related choices by parental education level were presented in Table 1. The response rates among families of first and second graders from 43 primary schools in Wuhan Hongshan District (n = 8,446) was 76.78%.
The proportion of families had only one child was slightly higher (50.82%) than that of families had two or more children (49.18%). As can be seen from the table, parents who received less education were more likely to have more than one child. A large number of fathers (36.06%) and mothers (29.12%) had education up to undergraduate degree or above. Less than one fifth of fathers (18.23%) and mothers (19.65%) had college degree. While some fathers (21.12%) and mother (25.04%) had only completed nine-year compulsory education or lower. According to the results of the chi-square test, the answers of all the questions were significantly related to the parents' academic background (P < 0.001). Overall, parents belonged to the higher education levels groups had better oral health knowledge and their children reported more favorable behaviors than their counterparts. Table 2 demonstrates logistic regression results of the effects of mother's and father's educational attainments on COB, respectively. In the univariate model, mother's and father's education level were all associated with children's tooth-brushing behavior. When adjusted for education level of counterpart parent, children's tooth-brushing behavior can be predicted by mother's education level rather than father's education level. Participants whose mother had college degree (Odds Ratio [OR] = 2.62, 95% Confidential Interval [CI] = 1.57-4.35) and undergraduate or above degree (OR = 1.72, 95%CI = 1.03-2.85) were more likely to brush their teeth than those whose mother with middle school education or below. A clear increased gradient in the effects of parental education level on tooth-brushing frequency was found, showing that participants whose parents with higher education level were more likely to brush their teeth twice a day or more. For example, children whose mother with university degree were 2.47 (95%CI = 2.01-3.02) more likely to brush teeth at least twice a day than those whose mother in the lowest education group, and the effect size of father's education (OR = 2.05, 95%CI = 1.68-2.51) was slightly smaller than that of mother's. Similarly, the proportion of children ever had dental visit was steadily increasing as the parental education level rose. The odds of children ever had dental visit was 1.79 (95%CI = 2.45-3.32) times and 1.52 (95%CI = 1.24-1.87) times higher among mothers with university degree and fathers with university degree than their counterparts with middle school education or lower, respectively. When further exploring the last dental visit, participants whose father ever attended university were 1.41 (95CI% = 1.09-1.83) times more likely to had dental visit in the past 12 months than those whose father with lowest education background. Additionally, those whose mother with higher education level were more likely visit dentists for dental treatment (OR = 1.28, 95%CI = 1.02-1.61 for high school degree; OR = 1.61, 95%CI = 1.22-2.11 for college degree; OR = 1.70, 95%CI = 1.35-2.37 for university degree). Reason for dental visit was associated with the father's education level in the univariate model, however, this association was eliminated after adjusted for mother's education level. Table 3 shows the answers of mothers and fathers with different education levels to oral healthrelated questions, as well as the correlation between the education levels and the correct answer rates obtained by binary analysis. The multivariate regression results showed that 7 of 8 oral healthrelated common-sense questions were significantly related to mother's academic qualifications, and 4 of them were significantly related to father's education level.

Parents' oral health knowledge
The accuracies of answers to "gingival bleeding is normal when brushing teeth", "tooth-brushing is useful for preventing gingivitis", "bacteria can cause dental caries", "eating sugar can cause dental caries", "fluoride protect teeth", "PFS protect teeth" and "oral diseases is related to general health" significantly lower among mothers with lower level of education as compared with those of higher education. Regarding to fathers' responses, the accuracies of answers to "fluoride protect teeth", "PFS protect teeth" and "oral diseases is related to general health" were significantly higher among fathers with undergraduate degree or above than fathers with lowest education background (OR = 1.30, 95%CI = 1.06-1.58; OR = 2.03, 95%CI = 1.49-2.76; OR = 2.03, 95%CI = 1.43-2.89, respectively). Moreover, fathers ever attended high school and college were 1.19 (95%CI = 1.01-1.40) and 1.26 (95%CI = 1.03-1.55) times more likely to report correct answer to "gingival bleeding is normal when brushing teeth" than those with lowest level of education. Table 4 presents the results of logical regression analysis between parents' education levels and their PFS-related choices. The odds of PFS awareness rate increased with both mother's and father's education level. Compared with mothers attended nine-year education, having high school, college and undergraduate or above degree yielded ORs of 1.29 (95% CI = 1.09-1.53), 1.65 (95% CI = 1.31-2.08), and 2.15 (95% CI = 1.67-2.78), respectively. The effect size of father's education level on PFS awareness is similar to mother's.

Parents' pit and fissure sealing related choices
Regarding to "the preference of PFS location for children", the proportion of choosing dental specialist hospitals were increased as the higher academic qualifications gained among both mothers and fathers. The effect size of education level on PFS location preference was stronger among fathers than mothers. Fig1 A and B present the distribution of parental education levels and the determinants that will be considered when selecting the location of PFS. The trends shown in the two figures were generally alike. As the figures demonstrate, with the rose of parental education level, the proportion of "therapeutic equipment perfection" and "treatment location distance" were increasing, while the proportion of parents considering "children's willingness and cooperation degree" was decreasing.

Discussion
This is the first study carried out in China to assess the relationship between COB, POK, parents' choice of PFS and parental education level among first and second graders' families.
The statistical results of this research demonstrated three aspects of information. Firstly, among households with lower parental education, children's oral health behaviors were poorer than those from well-educated families, specifically, no brushing teeth, brushing teeth less often, visiting the dentist less frequent, and have not check their teeth for a long time. These findings indicate that children were more likely to practice oral hygiene care with the increase of parental education levels.
Secondly, oral health knowledge was increased with education level among parents. Thirdly, parents with higher educational background not only had a better understanding of PFS, but also placed greater emphasis on the hospital's professionalism, equipment perfection and treatment location distance, while less consideration was given to children's wishes and cooperation.
When it comes to COB, mother's education level significantly affected 4 of 5 indicators, while father's education level only affected 3 of them. In terms of POK, mother's education was significantly associated with accuracies of 7 questions, 3 more than that of father's. Moreover, the PFS-related choices were significantly correlated to both mother's and father's education level. It appeared that the mother's education background may play a more important role than father's in the development of family's oral health knowledge and behaviors.
Previous studies have indicated that children dental caries is closely related to socio-economic [13] believed that mother's education level was the most important index that affect dental caries than household income and parents' occupation in Rotterdam, the Netherlands. In addition, Van den Branden et al. [25] found that 5-year-old children in Belgium whose mothers with higher education level were more likely to consume less sugary drinks, brush teeth more frequently, have more dental visits, and have lower prevalence of dental caries. In line with the study conducted by Khami MR et al. [35] showing that the Iranian children's smoking habits was associated with their father's education background, our findings demonstrate that father's education has a significant influence on COB.
Nunez L et al. [36] and Camargo MB et al.
[37] both suggested that higher parental education level was associated with the more frequent use of dental service, which was revalidated in our study.
Interestingly, our findings show that higher educated parents are more likely to visit dentist for the purpose of dental treatment rather than dental consultation. This might because of the higher internet use for health information acquisition among higher educated groups when encountering health problems. In disagreement with other studies, our project further investigated and analyzed parents' understanding and choices on PFS. AI Agili ED et al. [38] claimed that higher parental education and family income were independently associated with higher sealant prevalence. Our research adds that higher educated parents pay more attention to PFS location, quality of equipment, and doctors' professionalism. However, interestingly, they pay less attention to children's willingness and cooperation degree than the lower educated counterparts. It can be inferred that highly educated parents may be more uncompromising and autocratic as for dental health care.
The limitation of this study is that the survey was carried out in Wuhan Hongshan District, Hubei Province, where 38 high level colleges and universities are located in this district. Because of the great density and quality of educational resources, the local parents' education levels are generally higher than most other cities in China. Therefore, our sample cannot represent the Chinese population to certain degree.
Based on the findings of this study, concerted efforts to improve the Wuhan government's arrangement in HoLSPA project are recommended (1) to public more oral health knowledge through mass media, (2) to arrange the PFS location close to children's home address, to improve the integrity of PFS equipment, and to enhance the professionalism of the doctors.

Conclusions
In the early mixed dentition of children, the parent with higher education pose better oral health

Consent for publication
Not applicable.

Availability of data and materials
The patients' data will not be shared. However, the datasets used and analyzed during the current study are available from the corresponding authors on reasonable request.

Competing interests
The authors declare that they have no competing interests.

Authors' contributions
Liangwen Chen contributed to data analysis and manuscript drafting.
Jialan Hong contributed to data analysis and manuscript revision.
Dian Xiong and Luyi Zhang contributed to data collection.
Yuhong Li contributed to study design, and data collection.
Shengfu Huang congtributed to study design, data interpretation, and manuscript revision.
Fang Hua contributed to study design, data interpretation and manuscript revision.
All authors reviewed and approved the final version of the paper.  Tables   Table 1 Chi-square tests of the response to each question of participants' families (n=8446)   Significant associations (P < 0.05) are bold. Significant associations (P < 0.05) are bold. Significant associations (P < 0.05) are bold. Figure 1 Fig1 A and B present the distribution of parental education levels and the determinants that will be considered when selecting the location of PFS. The trends shown in the two figures were generally alike. As the figures demonstrate, with the rose of parental education level, the proportion of "therapeutic equipment perfection" and "treatment location distance"

Figures
were increasing, while the proportion of parents considering "children's willingness and cooperation degree" was decreasing.