Relationship between Tooth Brushing and Hand Washing by Family Type among Adolescents: A 2020 Nationally Representative Korean Survey

Abstract

Habits formed during adolescence tend to persist into adulthood, and correcting poor habits or behaviors during this time is more effective than at other times. Particularly, parents and caregivers should encourage good hygiene habits in their adolescent children by setting a positive example themselves. Using logistic regression, we analyzed the association between brushing teeth after lunch and washing hands before lunch by family type among 54,848 adolescents from the 17th Youth Health Behavior Survey raw data in 2021. Four logistic regression models were used to adjust for confounders hierarchically. In all models, adolescents who practiced tooth brushing after lunch were 2.09 times more likely to practice hand washing before lunch than those who did not. With and without adjustment, we found that the association between adolescents’ tooth brushing and hand washing practices in two-parent households was stronger than the association between adolescents’ tooth brushing and hand washing practices in single-parent households. Associations were found between tooth brushing and hand washing practices, and these associations were higher among adolescents in two-parent households than among adolescents in single-parent households. The finding of a significant link between family type and personal hygiene habits indicates the need for interventions to enhance the oral health of children and adolescents. Such interventions should be customized to reflect the specific characteristics of the child’s household.

1. Introduction

Since the outbreak of COVID-19 in Korea in January 2020, public health measures such as social distancing, wearing masks, and vaccination have been strengthened. There has also been a surge of interest in hygiene practices such as hand washing and coughing etiquette, which continues to this day [1]. Disease can be prevented through good hygiene, and the first step in promoting personal hygiene is hand washing. Hand washing is the most effective preventive measure for stopping the transmission of many bacteria and viruses through the hands [2]. It is also an important health habit that helps promote and maintain the health of the community and reduces the risk of infection. The Korean Centers for Disease Control and Prevention recently conducted a survey on hand washing practices in Korea and found that 63.4% of Koreans wash their hands. However, this figure is significantly lower than the 82% hand washing rate in the United States, and 45.4% of Korean teenagers do not wash their hands [3].

According to the 2018 Korean Child Oral Health Survey conducted by the Ministry of Health and Welfare, the prevalence of caries in 12-year-old children was 1.84, which is higher than the average of 1.2 for countries that are members of the Organization for Economic Co-operation and Development (OECD). When analyzing the national policy target of ‘increasing the prevalence of tooth brushing immediately after lunch among 12-year-olds’, with a target of a 50% increase by 2020, the prevalence of tooth brushing immediately after lunch among 12-year-olds was 33.3%, with 25.9% for males and 41.3% for females. This was lower than 68.2% for ‘after breakfast’, 55.3% for ‘after dinner’, 6.2% for ‘after snack’, and 60.3% for ‘before bedtime’, and the average number of times per day 12-year-olds brushed their teeth was 2.5 [4]. In addition, the oral health of Korean adolescents has improved over the past 20 years, but the trend has stalled in the past 10 years or so [4].

Adolescence is a period of physical, mental, and social transition in human development and a time of health education. According to previous studies, it has been reported that parental characteristics, such as parents’ lifestyle habits and parenting attitudes, have a significant impact on the health of their children and the formation of health-related lifestyle habits. Parents’ unhealthy lifestyle habits can affect their children’s health through their children’s lifestyle habits [5]. Parents generally share the same environment as their children, as well as genetic predispositions. Because children form their lifestyle habits by imitating their parents’ behavior, the parents’ lifestyle habits directly affect their children [6]. Adolescents in Korea are at high risk for infectious diseases because they spend most of their time in a group in a certain place. Droplets emitted from coughs and sneezes can settle on fomites at a distance of 1–2 m from the emitter. These droplets can project huge numbers of virus particles to nearby targets. The virus can contaminate an individual’s hands and then deposit virus particles on the face, making hands a major vector for transmission of healthcare-related infections [7]. In the case of oral health, the eruption of permanent teeth is completed during adolescence, so it is necessary to manage dental caries; the most basic way to prevent dental caries is to manage the gingival bacterial film, and the primary prevention method is tooth brushing. Therefore, it is very important to develop good hygiene concepts and practices during adolescence, a transitional period that determines a person’s health for the rest of their life [8,9]. Parents and caregivers, who are the foundation of their children’s behavior, should help them form good hygiene concepts and habits during adolescence. Habits formed during adolescence tend to persist into adulthood, and correcting poor habits or behaviors during this time is more effective than at other times [10]. In particular, parents and caregivers should work to encourage good hygiene habits in their adolescent children by example. These parental efforts have a positive impact on the healthy growth and development of adolescents.

Recently, in Korean society, the number of single-parent families has been rapidly increasing due to the same reason as the divorce rate. According to previous research, there are studies showing that children from two-parent families and single-parent families show many differences in parenting style and level of development [11]. There are reports that these differences in family type also affect children’s health behaviors. Adolescents from single-parent families had higher smoking and drinking experiences, stress, sadness and despair, and suicidal thoughts than adolescents from two-parent families. Therefore, in order to improve the health of adolescents from single-parent families, it was suggested that community interest and policy support should be provided simultaneously for economic problems caused by incomplete family structures, gaps in children’s care, and emotional problems [12].

Although differences in family type can be a very important factor in the health of adolescents, there is no research that considers family type in research on hygiene habits. Therefore, this study was conducted to investigate the association between tooth brushing, represented by oral hygiene, and hand washing, represented by personal hygiene, and to identify differences between two-parent families based on family type, in order to provide a basis for health education and health promotion interventions.

2. Materials and Methods

2.1. Study Subjects and Data Collection

This study was conducted using raw data from the 17th Youth Health Behavior Survey conducted in 2021. The survey was conducted among 54,848 secondary school students in 800 schools across the country. The data collection method was based on online registration of information such as overall class characteristics and the number of male and female students in the sample schools, and the sample classes were selected based on these data. These data were used to calculate the weights. The 17th survey was conducted in a total of 800 schools, including 400 junior high schools and 400 senior high schools. The sampling frame for the sample design used national secondary school data as of April 2020, and the type of high school was divided into general and specialized high schools based on the classification of the sampling frame. Stratified cluster sampling was used, with schools as the primary sampling unit and classes as the secondary sampling unit. For the first sampling, the sample schools were selected by stratified permanent random number sampling. For the second sampling, one class per grade was randomly selected from the selected sample schools. All students in the lower grades selected as sample classes were surveyed, and students with long-term absenteeism, disabled children who could not participate in the survey on their own, and students with reading and writing disabilities were excluded from the sample.

2.2. Survey Methods

General characteristics included gender, grade, type of school, city size, economic level, grade, academic performance, frequency of consumption of sugary drinks in the past 7 days, perceived stress, father’s education, mother’s education, experience of personal hygiene education at school in the past 12 months, and gum pain and bleeding in the past 12 months, for a total of 13 questions. The oral hygiene item, represented by tooth brushing habits, consists of a dichotomous question about the frequency of tooth brushing after lunch: brushing or not brushing. The personal hygiene component, represented by hand washing practices, consists of a dichotomous question about the frequency of hand washing before eating at school. Family arrangements are defined as ‘two-parent households’ for those who answered ‘live with’ both mother and father in the original survey of caregivers, and ‘single-parent households’ for those who answered ‘live with’ one or the other.

2.3. Statistical Analysis

Complex sampling design analysis was performed to determine the distribution of study participants according to demographic characteristics. Multivariate logistic regression analysis was conducted to determine the association between hand washing and tooth brushing practices by general characteristics. Multivariate logistic regression analysis was conducted to determine the association between hand washing and tooth brushing practices by family type and general characteristics. Data were analyzed using SPSS 23.0 (IBM Co., Armonk, NY, USA), with a significance level of 0.05.

3. Results

3.1. General Characteristics of Subjects by Family Type

The general characteristics of the subjects by family type are shown in

Table 1. General characteristics of subjects by family type.

Variable		Family Type
		Living with Both Parents	Living with Single Parent	p-Value
Tooth brushing after lunch	Yes	13,708 (48.2)	1448 (40.8)	<0.001
	No	21,005 (51.8)	2040 (59.2)
Hand washing before lunch	Yes	29,505 (84.7)	2875 (81.9)	<0.001
	No	5208 (15.3)	613 (18.1)
Gender	Male	16,672 (47.8)	1629 (42.1)	0.123
	Female	18,041 (52.2)	1859 (53.9)
Grade	Middle school, 1st grade	7315 (19.8)	636 (16.2)	<0.001
	Middle school, 2nd grade	7025 (19.6)	588 (15.7)
	Middle school, 3rd grade	6186 (16.3)	653 (16.9)
	High school, 1st grade	5120 (15.0)	561 (16.4)
	High school, 2nd grade	4876 (14.9)	533 (16.8)
	High school, 3rd grade	4191 (14.4)	517 (17.9)
School type	Coeducation	23,754 (70.3)	2284 (66.6)	<0.001
	All-boys schools	4980 (13.0)	516 (13.3)
	All-girls schools	5979 (16.7)	688 (20.0)
Residence type	Rural area	2467 (5.3)	296 (5.5)	<0.001
	Metropolis	15,079 (41.6)	1453 (41.1)
	City	17,167 (53.1)	1739 (52.5)
Income level	High	3992 (11.5)	198 (5.6)	<0.001
	Mid-high	10,844 (32.0)	654 (19.7)
	Medium	16,998 (48.4)	1757 (50.1)
	Mid-low	2515 (7.0)	726 (20.5)
	Low	364 (1.0)	153 (4.0)
School level	General high schools (GHSs)	12,001 (37.9)	1174 (38.0)	<0.001
	Middle schools	20,526 (55.8)	1877 (48.9)
	Specialized vocational high schools (SVHSs)	2186 (6.3)	437 (13.1)
Academic performance	High	4830 (13.6)	309 (8.3)	<0.001
	Mid-high	9239 (26.5)	722 (20.5)
	Medium	10,741 (31.1)	1021 (29.5)
	Mid-low	7187 (20.9)	936 (27.4)
	Low	2716 (7.9)	500 (14.3)
Frequency of consumption of sweet drinks in the last 7 days	0 times a week	5450 (15.9)	556 (16.5)	0.178
	1–2 times a week	12,873 (36.7)	1253 (35.2)
	3–4 times a week	9301 (26.9)	944 (27.4)
	5–6 times a week	3571 (10.4)	346 (10.2)
	Once a day	2158 (6.4)	234 (6.5)
	Twice a day	847 (2.4)	84 (2.3)
	3 times a day	513 (1.4)	71 (1.9)
Perceived stress	Very high	3416 (9.9)	459 (13.1)	<0.001
	High	9496 (27.9)	1086 (30.6)
	Moderate	14,957 (43.2)	1359 (39.9)
	low	5569 (15.9)	493 (13.7)
	Very low	1077 (3.0)	91 (2.6)
Father’s education level	Lower than middle school	418 (1.0)	85 (2.2)	<0.001
	High school graduate	7325 (20.4)	870 (25.1)
	College or university graduate or higher	20,741 (61.9)	1506 (44.9)
	No response	6229 (16.6)	1027 (27.7)
Mother’s education level	Lower than middle school	330 (0.9)	66 (1.9)	<0.001
	High school graduate	8463 (23.9)	1020 (29.3)
	College or university graduate or higher	20,260 (60.1)	1591 (47.3)
	No response	5660 (15.1)	811 (21.5)
Hygiene education experience at school in the last 12 months	Yes	19,275 (55.0)	1882 (52.7)	0.069
	No	15,438 (45.0)	1606 (47.3)
Gum pain and bleeding in the last 12 months	Yes	6583 (19.2)	770 (21.9)	<0.001
	No	28,130 (80.8)	2718 (78.1)

Obtained by complex chi-square test. Bold values denotes statistical significance at p < 0.05.

. Significant differences by family type were found for tooth brushing after lunch, hand washing before lunch, grade level, school type, city size, economic level, school grade, academic performance, perceived daily stress, parental education, and gum pain and bleeding in the past 12 months (p < 0.001).

3.2. Association between Tooth Brushing and Hand Washing Practices

Analyses of the association between post-lunch tooth brushing and pre-lunch hand washing are shown in

Table 2. Multivariable association between tooth brushing practice and hand washing practice.

Independent Variable	Dependent Variable	Odds Ratio (95% Confidence Interval)
		Model 1	Model 2	Model 3	Model 4	Model 5
Tooth brushing practice	Hand washing practice (ref. no)	1.57 (1.45–1.70)	2.03 (1.88–2.18)	2.08 (1.93–2.24)	2.09 (1.93–2.25)	2.09 (1.93–2.25)

Model 1 was unadjusted association. Model 2 was adjusted for gender, grade, and school type. Model 3 was adjusted for all variables in model 2 and city size, economic level, and specialized school. Model 4 was adjusted for all variables in model 3 and academic performance, frequency of consumption of sweet drinks in the past 7 days, and perception of stress. Model 5 was adjusted for all variables in model 4 and parents’ level of education, personal hygiene education experience at school in the past 12 months, and gum pain and bleeding in the past 12 months. Bold values denotes statistical significance at p < 0.05.

. In all models, adolescents who engaged in post-lunch tooth brushing were more likely to engage in pre-lunch hand washing than those who did not, particularly in model 5, where adolescents who engaged in post-lunch tooth brushing were 2.09 times more likely to engage in pre-lunch hand washing than those who did not (p < 0.001), after adjustment for all variables.

3.3. Association between Tooth Brushing and Hand Washing Practices by Family Type

The results of the analyses of the association between tooth brushing and hand washing practices by family type are shown in

Table 3. Multivariable association between tooth brushing practice and hand washing practice according to family type.

Independent Variable	Dependent Variable	Family Type	Odds Ratio (95% Confidence Interval)
			Model 1	Model 2	Model 3	Model 4	Model 5
Tooth brushing practice	Hand washing practice (ref. no)	Living with both parents	1.79 (1.46–2.20)	2.21 (1.80–2.71)	2.33 (2.89–2.88)	2.37 (1.93–2.98)	2.39 (1.93–2.97)
		Living with single parent	1.54 (1.42–1.67)	1.99 (1.84–2.16)	2.04 (1.86–2.21)	2.04 (1.89–2.22)	2.04 (1.89–2.22)

Model 1 was unadjusted association. Model 2 was adjusted for gender, grade, and school type. Model 3 was adjusted for all variables in model 2 and city size, economic level, and specialized school. Model 4 was adjusted for all variables in model 3 and academic performance, frequency of consumption of sweet drinks in the past 7 days, and perception of stress. Model 5 was adjusted for all variables in model 4 and parents’ level of education, personal hygiene education experience at school in the past 12 months, and gum pain and bleeding in the past 12 months. Bold values denotes statistical significance at p < 0.05.

. Regardless of the adjustment, we found that the association between tooth brushing and hand washing among adolescents in two-parent families was higher than the association between tooth brushing and hand washing among adolescents in single-parent families. Among adolescents in two-parent households, those who brushed their tooth after lunch were 2.39 times more likely to wash their hands before lunch than those who did not (p < 0.001), after adjusting for all variables. Among adolescents in close-knit families, those who practiced tooth brushing after lunch were 2.04 times more likely to practice hand washing before lunch than those who did not (p < 0.001), after adjusting for all variables. Thus, we found differences in the association between tooth brushing and handwashing practices based on family type.

4. Discussion

Our hypothesis is that adolescents who maintain healthy habits will also exhibit good hygiene behaviors and that these behaviors are interconnected. Thus, our study examined the relationship between hand washing and tooth brushing, which are representative hygiene behaviors. This study was conducted to determine the association between tooth brushing and hand washing and family type among adolescent’s nationwide using raw data from the 17th (2021) Youth Health Behavior Survey. We found that adolescents in two-parent households had higher hand washing and tooth brushing practices than those in single-parent households. Hand washing and tooth brushing practices were significantly associated with family type.

This study found that teenagers in two-parent households were more likely to brush their teeth after lunch and also more likely to wash their hands before lunch. Gum pain and bleeding were also higher in single-parent households than in dual-parent households. These findings suggest that parental presence is an important factor influencing the practice of personal hygiene behaviors among young children. Children’s oral health habits are influenced by their parents’ physical, emotional, and parenting styles, so it is important to educate parents about oral health care at home, as active oral health care education can help build oral health knowledge, oral health attitudes, and behaviors to maintain a healthy mouth and improve quality of life [13,14,15]. Previous studies of children’s dental care by family type have found that children living with single mothers are 63% more likely to have unmet medical needs than children living with married parents, and children living with cohabiting parents or parents and step-parents are also more likely to have unmet medical needs [16,17]. Parental education and household income levels have a significant impact on children’s oral health [18]. In Korea, the poverty rate for single-mother families is 44.5%, six times higher than the 7.5% for two-parent families, and the poverty rate for single-father families is 18.8%, 2.5 times higher than for two-parent families [19]. In addition, the poverty rate for single-parent families has increased in recent years due to the rise in divorce [20]. The impact of these family types on income levels is thought to affect not only the oral health of children but also their health.

The study also found that adolescents living with their parents were less likely to have received hygiene education at school. In single-parent families, the father or mother may spend less time with their children than parents in dual-earner families because they are juggling work and childcare. It has been found that cohabiting families face great difficulties in raising children in poor living conditions and hygiene [21]. Therefore, it is necessary to solve the problem of medical neglect faced by vulnerable people in Korea.

According to previous studies, oral factors were reported as the main target of COVID-19 [22,23,24]. According to the survey, poor oral health was confirmed worldwide, and it was implied that this was mainly caused by lack of self-care and had a direct impact on overall health. Additionally, as the oral cavity acts as a reservoir for SARS-CoV-2, many studies have been conducted to the effect that oral factors are involved in the pathophysiology of COVID-19 [25]. Therefore, the strategy of managing oral health through good oral hygiene habits can be a very effective strategy to protect your health from unpredictable pandemics such as SARS-CoV-2.

There are several limitations to this study. First, the study was designed as a cross-sectional study, which allowed us to identify associations between tooth brushing and hand washing based on family type, but it is difficult to establish a clear causal relationship between them in a cross-sectional study. Second, the study did not identify whether participants had received education on personal hygiene (tooth brushing and hand washing) from their parents or caregivers. A systematic follow-up study that reflects the adolescents’ experience of health education at home and their parents’ health knowledge and attitudes is needed. Third, although there are many different family types, the variables used in this study were limited to two-parent and single-parent families. It is necessary to analyze different family types by subdividing multicultural families and cohabiting families. Fourthly, the step-father, biological father, step-mother, and biological mother of the children surveyed in this study were considered to be the same family members. As step-fathers, fathers, step-mothers, and mothers may have different attitudes towards parenting, it is necessary to analyze this aspect.

However, despite these limitations, this study is of great importance because it was conducted on a large scale at the national level and used data from the Youth Health Behavior Survey, which is representative, and the results were significant. In addition, in recent years, Korean society has been restructuring families and creating different family types [26], and the number of cohabiting families with divorced and single mothers has increased, which has become a social problem [27,28,29]. In line with these changes, the significance of this study is that it met the family factors influencing adolescents’ hygiene behavior and examined the influence of family type on oral health. The results are significant because we were able to identify differences in the association between oral hygiene and personal hygiene practices between two-parent and single-parent families, and this is the first study in Korea to investigate the relationship between tooth brushing and hand washing practices according to family type. It is expected that this study will provide evidence for the development of policies to promote oral health among adolescents.

The finding of a significant association between family type and personal hygiene habits suggests that interventions to improve the oral health of children and adolescents are needed. Interventions to improve the oral health of children and adolescents require tailored strategies that reflect the characteristics of the child’s household. In particular, children and adolescents growing up in environments where parental care and supervision is relatively absent, such as single-parent households, need more active education and direct support from schools and governments.

5. Conclusions

Associations were found between tooth brushing and hand washing practices, and these associations were higher among adolescents in two-parent households than among adolescents in single-parent households. Future studies should continue to investigate the health risk factors of vulnerable groups, and policies should be formulated based on these findings.