Dental Caries and Community Socioeconomic Status in Japanese and Chinese Children: An Ecological Study

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1 口腔衛生会誌 J Dent Hlth 66: 32 38, 2016 Information Dental Caries and Community Socioeconomic Status in ese and Chinese Children: An Ecological Study An LIU, Michiko FURUTA, Kenji TAKEUCHI and Yoshihisa YAMASHITA Abstract: Our aim was to compare the dental caries status between ese and Chinese children and to examine the association between the community socioeconomic status (SES) and dental caries. We made use of data collected in national surveys in and China. ese children aged 5 and 12 years old had more filled than Chinese children. As a result of this large number of filled, ese 5-year-old children had fewer decayed than Chinese children. ese 12-year-old children who lived in communities with a high SES had significantly fewer dental caries than those who lived in communities with a lower SES. Conversely, in China, dental caries was positively associated with the community SES. This suggests that the association between dental caries and the community SES differs among countries. Key words: Dental caries status, Socioeconomic status, Ecological study,, China J Dent Hlth 66: 32-38, 2016 (Received: March 10, 2015/Accepted: October 5, 2015) Introduction Dental caries is considered to be one of the most prevalent chronic diseases worldwide, to which people are susceptible throughout their lifetime 1). It is a multifactorial disease involving host, behavioral, and environmental risk factors 1). Because dental caries is associated with the lifestyle, oral health behavior, and socioeconomic status (SES), different countries would be expected to differ in caries status. In particular, the risk of dental caries in their children is influenced by the community SES, such as the average area income 2). is geographically and culturally close to China, and yet it has a distinctly different economic situation. It is speculated that the dental caries level in children is different between and China because of differences in economic development. A comparative study between these nations may provide further important evidence linking the community SES to dental caries of children in different populations. We compared the dental caries status between ese and Chinese children and examined the association between the community SES and dental caries in an ecological study. Methods 1. Data We made use of data collected in three national surveys to compare the dental caries status between and China at the national level: (1) the Survey of Dental Disease in, ), for 5-year-old children, (2) the School Health Survey in, 2006 *1, for 12-year-old children, and (3) the Third National Oral Health Survey in China, ), for both 5- and 12-year-old children. The Chinese survey contained data on children in only two age groups (5 and 12 years old,) and so these age groups were chosen to compare dental caries. The Chinese survey selected subjects randomly by stratified multistage cluster sampling with the size proportional to the population of each age group and province. Among all 31 provinces of China, 30 provinces were Section of Preventive and Public Health Dentistry, Division of Oral Health, Growth and Development, Kyushu University Faculty of Dental Science, Fukuoka, *1 Portal Site of Official Statistics of : School Health Survey. (Accessed July 15, 2014). 32

2 involved (Tibet Province was excluded) in the national survey. In the Survey of Dental Disease in, 2005, the subjects were members of households within 300 survey district units, which were selected by stratified random sampling out of the survey districts in the basic research on the living conditions of ese *2. In the School Health Survey in, 2006, the subjects were students at school selected by random sampling from the survey strata, which were decided by the school size in each prefecture and school type. 2. Dental caries experience The numbers of decayed, missing, and filled were examined as measures of the dental caries status in the ese and Chinese surveys. The criteria for classifying decayed were an unmistakable cavity, undermined enamel, or a detectably softened floor or wall in both ese and Chinese surveys. The criteria of filled showed some differences between the national surveys. In, abutment of bridges were counted as filled, while in China they were not counted as filled that were not caused by caries. However, the difference in the criterion of filled between ese and Chinese surveys could be negligible, because children focused in this study have little abutment of bridges. The criterion for missing in 12-year-old children was that had been extracted because of caries in both ese (the School Health Survey) and Chinese surveys. 3. Socioeconomic status To compare the association of dental caries and the community SES in 12-year-old children, prefectural economic accounts in, 2006 *3, and provincial income per capita in China, 2004 *4, were used for data on the community SES. 4. Sweet food intake To evaluate the association between the intake of sweet food and dental caries status, data on the monthly expenditure on sweet food per household in prefectural capitals from the Family Income and Expenditure Survey *5 in, 2006 and those on the percentage of 12-year-old children with a daily intake of sweet food in each province from the questionnaires of the Third National Oral Health Survey in China, ) were used. In the questionnaire, participants or their parents were asked about the intake frequency of sweet food such as candy, chocolates, desserts, carbonated beverages, and fruit juices with added sugar, and the response options were twice a day or more ; once a day ; two to six times a week ; once a week ; one to three times a month ; hardly or never. Then, twice a day or more and once a day responses were combined to create a dichotomous variable including daily intake. The percentage of daily intake of each sweet food was calculated in each province. 5. Dental care cost and dental insurance The dental care cost for outpatient treatment per person by prefecture or province was used to evaluate the association with the dental caries status. ese data on the dental care cost in 2006 were from a health insurance database *6. From the questionnaires of the Third National Oral Health Survey in China, ), data about the dental care cost per person for one year in two age groups, and year-olds, were used. Additionally, the percentage of Chinese with dental insurance in these two age groups per province was based on the same data sources. 6. Statistical analysis The non-parametric Spearman s rank correlation was calculated to assess the association of the dental caries status with the prefectural () or provincial (China) income per capita and the monthly expenditure on sweet food per household () or the percentage of 12-year-old children with a daily intake of sweet food (China). This correlation coefficient was also calculated *2 National Institute of Health and Nutrition: Section of the National Health and Nutrition Survey. project_nhns.html (Accessed September 29, 2015). *3 Cabinet Office, Government of : Prefectural economic accounts. main_h22.html (Accessed July 15, 2014). *4 National Bureau of Statistics of China: The annual statistics of Chinese household disposable personal income. index?m=fsnd (Accessed July 15, 2014). *5 Statistics Bureau, Ministry of Internal Affairs and Communications of : Family Income and Expenditure Survey, go.jp/data/kakei/2006np/index.htm (Accessed September 18, 2015). *6 Ministry of Health, Labour and Welfare: Health Insurance Database. (Accessed September 25, 2015). 33

3 口腔衛生会誌 J Dent Hlth 66(1), 2016 Table 1 Mean numbers of decayed, filled, and missing between and China by sex and age group 5 years old * 12 years old Number of survey subjects Decayed Filled Missing China China China China Boys 24 11, Girls 19 11, Total 43 23, Boys 11, Girls 11, Total (284218) 23, * Data from the Survey of Dental Disease in, 2005 and the Third National Oral Health Survey in China, Data from the School Health Survey in, 2006 and the Third National Oral Health Survey in China, ,654 (the number of survey subjects aged 12 to 14 years old: junior high school) / 3. The national survey included no data regarding missing in 5-year-olds. to assess the associations among the dental caries status, prefectural or provincial income, dental care cost, and dental insurance. The SPSS software (ver for Windows; IBM SPSS, Tokyo, ) was used for data analyses. Results The mean numbers of decayed, missing, and filled in ese and Chinese surveys are shown in Table 1. Most dental caries were evident in decayed in Chinese children, and the gap between decayed and filled in Chinese children was markedly larger than that in ese children. The major component of the decayed, missing, and filled for ese 12-year-old children was filled. Both countries showed little sex-related difference in decayed, missing, or filled, with the exception of the number of filled in ese 5-year-old children. The association between dental caries in 12-year-old children and the community SES in and China is shown in Fig. 1. The numbers of decayed and filled in China were positively associated with the provincial per capita income (Spearman rank correlation r=0.52, p=0.003 and r=0.68, p<0.001, respectively). In contrast, the numbers of decayed and filled in were negatively related to the prefectural per capita income (r= 0.52, p<0.001 and r= 0.51, p<0.001, respectively). When we evaluated the associations among monthly expenditure on sweet food per household, dental caries status, and prefectural per capita income, based on prefectural data in, expenditure on sweet food was significantly correlated with the prefectural per capita income, but not with dental caries in 12-year-old children (Table 2). To evaluate these associations in China, provincial data on the percentage of 12-year-old children with a daily intake of sweet food were used. The percentage of 12-year-old children with a daily intake of sweet food was 19.3% for candy/chocolate, 25.1% for desserts, 12.1% for carbonated beverages, and 10.9% for fruit juices with added sugar. The provinces with a higher percentage of 12-year-old children who ingested desserts, carbonated beverages, and fruit juice with added sugar everyday were more likely to show a high number of filled and high provincial income (Table 2). The association between the dental caries status in 12-year-old children and dental care cost per person by prefecture or province is shown in Table 3. The number of filled was negatively associated with the dental care cost per person in (Spearman rank correlation r= 0.48, p=0.001). Conversely, the number of filled was positively associated with the dental care cost per person in China (Spearman rank correlation r=0.43, p=0.019). The number of decayed was not significantly correlated with the dental care cost in and China. The percentage of Chinese with dental insurance was under 10% in 7 provinces, 10 20% in 12 provinces, 21 30% in 5 provinces, and over 30% in 6 provinces. The number of filled and decayed in Chinese children 34

4 China Decayed r = 0.52 p < Decayed r = 0.52 p = ,000 2,000 3,000 4,000 5,000 Prefectural per capita income of the year 2006 (thousand ese Yen) ,000 10,000 15,000 20,000 Provincial per capita income of the year 2004 (Chinese Yuan) Filled r = 0.51 p < Filled China r = 0.68 p < ,000 2,000 3,000 4,000 5,000 Prefectural per capita income of the year 2006 (thousand ese Yen) ,000 10,000 15,000 20,000 Provincial per capita income of the year 2004 (Chinese Yuan) Fig. 1 Associations between the number of decayed and filled with prefectural/provincial per capita income in ese and Chinese 12-year-old children Table 2 Spearman s rank correlation coefficient between sweet food, the mean number of decayed and filled in 12-year-old children, and prefectural () or provincial (China) per capita income based on prefectural or provincial data Monthly expenditure on sweet food per household Decayed Filled Prefectural or provincial per capita income * China (daily intake) Candy/chocolate Desserts 0.41 * 0.63 *** 0.58 * Carbonated beverages * 0.51 ** Fruits juice with added sugar * 0.40 * * p<0.05, ** p<0.01, *** p<0.001 Data on the percentage of 12-year-old children with daily intake of sweet food Table 3 Spearman s rank correlation coefficient among dental care cost, dental insurance, mean number of decayed and filled in 12-year-old children, and prefectural () or provincial (China) per capita income based on prefectural or provincial data Dental care cost per person Decayed Filled Prefectural or provincial per capita income ** 0.01 China Dental care cost per person * 0.36 * Percentage of individuals with dental insurance * p<0.05, ** p<0.01, *** p<

5 口腔衛生会誌 J Dent Hlth 66(1), 2016 at 12 years old was not associated with the percentage of individuals with dental insurance. Discussion ese children at 5 and 12 years old had more filled than Chinese children. As a result of this large number of filled, ese 5-year-old children had fewer decayed than Chinese children. The main reason for this difference may be the greater accessibility and availability of dental services in. The ratio of dentists to the population differs between and China. According to a WHO report in 2008, the number of dentists per 10,000 population was 7 in and 1 in China *7. Also, expenses for filled in are mainly covered by insurance provided by the government, while most Chinese do not have dental insurance and expenses for filled are self-paid in the majority of cases. Additionally, in, oral health examinations have been implemented for all 18-month infants and 3-year-old children according to the Maternal and Child Health Law, and annual dental check-ups are provided for all school children and students, except university students, according to the School Health and Safety Act. When decayed are found in an oral health examination, school teachers will suggest dental treatment to the students and parents. In contrast, there is no guarantee of such dental check-ups for school children in China. Thus, ese children have more opportunities for dental caries to be diagnosed than Chinese children. ese 12-year-old children who lived in communities with a high SES had significantly fewer dental caries than those who lived in communities with a lower SES, although this association was not analyzed in 5-year-old children because of a lack of data. This finding is consistent with a report by Gillcrist et al. 5). Many previous studies revealed that a low SES is a risk factor for dental caries 1,6-9). Conversely, in China, dental caries was positively associated with community SES. This result was similar to that of Huang s study 10) in Guangxi, a province in southwest China, where Chinese preschool children whose parents were employees in companies (i.e., higher SES) were more likely to suffer early childhood dental caries, than those whose parents were poor (i.e., lower SES), although this relationship was at an individual level. We showed that provinces with a high SES had more consumers of sweet food than those with a low SES (Table 2). Probably, Chinese children in higher-income families or areas had more access to high-sugar foods and drinks. In Chinese children, the number of decayed decreased from 3.4 in 5-year-old children to 0.5 in 12-year-old children, although the number of filled was the same. This result may be partially explained by the difference in the use of fluoride dentifrice. The percentage using fluoride dentifrice was 39% in 5-yearolds and 46% in 12-year-olds 4). With regard to fluoride, domestic water in some areas of China naturally contains some levels of fluoride. From the Third National Oral Health Survey in China 4), 51 of 180 survey areas underwent measurement of the concentration of fluoride in domestic water. Of these 51 areas, there was domestic water that naturally contains fluoride at concentrations 1.0 ppm in 4 areas, ppm in 5 areas, ppm in 8 areas, and 0.3 ppm in 34 areas. It is speculated that domestic water in most areas of China contains low concentrations of fluoride. Hence, fluoride water could not be considered as affecting the dental caries status in the subjects involved in this study. Dental care costs per person were negatively associated with the number of filled in ese 12-year-old children. In contrast, this association was positive in Chinese children. ese parents who live in communities with a high cost of dental care may be more likely to pay for preventive care for their children and Chinese parents may pay for the treatment of dental caries. The ecological design of this study had a number of inherent limitations. The effects of confounding factors could not be controlled due to the nature of an ecological study. Additionally, the association between dental caries and SES shown in our study, that is the observation of an association at a population level, does not necessarily suggest that the same association will hold at an individual level (i.e., ecological fallacy) 11). Future studies are necessary to assess the association between *7 World Health Organization: World Statistics (Accessed July 15, 2014). 36

6 dental caries and SES at an individual level on the comparison of and China. Despite these limitations, our study may play a certain role when considering a population approach for the prevention of dental caries in and China. In conclusion, ese children had more filled than Chinese children. The dental caries status in was negatively associated with the community SES, whereas the opposite association was seen in China. Acknowledgements The authors have no conflicts of interest to declare. This study was self-funded by the authors and their institutions. References 1) Selwitz RH, Ismail AI, Pitts NB: Dental caries. Lancet 369: 51 59, ) Aida J, Ando Y, Oosaka M, et al.: Contributions of social context to inequality in dental caries: a multilevel analysis of ese 3-year-old children. Community Dent Oral Epidemiol 36: , ) Statistics Analysis Committee on the Survey of Dental Diseases: Comprehensive guide to the survey of dental diseases, Oral Health Association, Tokyo, ) The National Committee for Oral Health of China: The third national survey of oral health in China, The People s Health Publishing House, Beijing, 1st-ed, ) Gillcrist JA, Brumley DE, Blackford JU: Community socioeconomic status and children s dental health. J Am Dent Assoc 132: , ) Reisine ST and Psoter W: Socioeconomic status and selected behavioral determinants as risk factors for dental caries. J Dent Educ 65: , ) Vargas CM, Crall JJ, Schneider DA: Sociodemographic distribution of pediatric dental caries: NHANES III, J Am Dent Assoc 129: , ) Dye BA, Arevalo O, Vargas CM: Trends in paediatric dental caries by poverty status in the United States, and Int J Paediatr Dent 20: , ) Tellez M, Sohn W, Burt BA, Ismail AI: Assessment of the relationship between neighborhood characteristics and dental caries severity among low-income African-Americans: a multilevel approach. J Public Health Dent 66: 30 36, ) Huang FX: The analysis of dental caries risk factors in 890 preschool children. Anthology of Medicine 19: , 2000 (in Chinese). 11) Morgenstern H: Uses of ecological analysis in epidemiologic research. Am J Public Health 72: , Reprint requests to Y. Yamashita, Section of Preventive and Public Health Dentistry, Division of Oral Health, Growth and Development, Kyushu University Faculty of Dental Science, Maidashi, Higashi-ku, Fukuoka ,. TEL: /FAX: yoshi@dent.kyushu-u.ac.jp 37

7 口腔衛生会誌 J Dent Hlth 66(1), 2016 日本と中国の児童におけるう蝕経験と社会経済状況の関係 劉安古田美智子竹内研時山下喜久 九州大学大学院歯学研究院口腔保健推進学講座口腔予防医学分野 概要 : う蝕は多要因性疾患であり, その発症には生活習慣, 口腔保健行動, 社会経済要因が関与し, 個人の要因だけでなく環境要因も関係する. 環境や社会経済状況が異なる国では, う蝕経験は異なることが予想される. 本研究では, 地域相関研究によって, 日本と中国の児童におけるう蝕経験と社会経済状況の関係について検討した. う蝕経験は, 日本の 2005 年歯科疾患実態調査および 2006 年学校保健統計調査, 中国の第三次全国口腔健康流行病学調査報告 (2005 年 ) の全国調査データから, 都道府県単位および省単位で 5 歳児 12 歳児の一人平均の未処置歯数と処置歯数を用いて評価した. 社会経済状況は, 日本は内閣府の県民計算から 2006 年一人あたりの県民所得のデータを用い, 中国は国家統計局のデータから 2006 年の一人あたりの年間総収入を省単位で評価した. 統計解析として, 日本と中国で, 未処置歯数, 処置歯数と社会経済状況の相関係数を 12 歳児のデータで求めた. 5 歳児と 12 歳児で処置歯数は中国に比べ日本のほうが多かった. 日本では, 未処置歯数, 処置歯数と社会経済状況の関係は負の相関であったのに対し, 中国では正の相関を示した. つまり, 日本では, 社会経済状況が良い地域では児童の未処置歯数や処置歯数が少ないが, 中国では未処置歯数や処置歯数が多かった. 児童のう蝕経験と地域の社会経済状況の関係は国によって異なることが示唆された. 口腔衛生会誌 66:32-38, 2016 索引用語 : う蝕経験, 社会経済状況, 地域相関研究, 日本, 中国 著者への連絡先 : 山下喜久 福岡県福岡市東区馬出 九州大学大学院歯学研究院口腔予防医学分野 TEL: /FAX: / yoshi@dent.kyushu-u.ac.jp 38