Research Article: The bidirectional relationship between weight, height and dental caries among preschool children in China

Date Published: April 30, 2019

Publisher: Public Library of Science

Author(s): Anqi Shen, Eduardo Bernabé, Wael Sabbah, Frédéric Denis.


There is evidence of a bidirectional association between dental caries and anthropometric measures among children. This dual relationship has not been examined in the same population. The objectives of this study are (1) to examine the relationship between baseline caries and changes in weight and height; and (2) to assess whether baseline weight and height are associated with changes in dental caries in a sample of preschool Chinese children. Children were recruited from 15 kindergarten in Liaoning Province at baseline (8 in rural area and 7 in urban area), a total of 1,111 of children were included at baseline. The mean age of children at baseline was 50.82 months. Data were collected through clinical oral examination, assessment of anthropometric measures and structured questionnaire. Dental caries was assessed according World Health Organization (WHO) methods by one dentist. Sociodemographic and behaviour data were also collected. At follow-up, 772 children were included (attrition rate: 30%), dental caries and anthropometric measures were assessed again. Z-score for weight-for-age and height-for-age were calculated using the 2006 and 2007 WHO Child Growth Standards. The sum of decayed, missing and filled primary teeth (dmft) were used in the analysis. Multilevel analysis for longitudinal data was conducted to explore the relationship between z-score for weight-for-age and height-for-age, and dental caries among children. The median follow-up time was 10.12 months. There was a significant negative association between dmft at baseline and change in height-for-age. On the other hand, weight-for-age at baseline was negatively associated with change in dmft at follow-up. The findings suggest that dental caries impedes children’s growth indicated by height for age. Low weight children appear to be more susceptible to dental caries in the same population.

Partial Text

Dental caries is one of the most prevalent diseases in China affecting more than half of children and majority of adults [1]. With 97% of decayed teeth among 5-year-olds left untreated, the disease undoubtedly has implications on children’s wellbeing [2]. Undernutrition is another common and persisting problem in China. In 2011, approximately 19% of 2–6 years old children were underweight and 4% were stunted [3]. Although the rate of undernutrition in children is gradually declining, China is still facing a huge challenge of nutrition imbalance among children. On the other hand, the shifts in diet and activity led to an increase in children’s and adults’ obesity [4]. The prevalence of obesity increased to 10.1% in 2010, and then remained stable until 2014 among 5–6 years children [5]. Moreover, the rapidly changing lifestyles are highly associated with changes in disease patterns. The unhealthy lifestyles include excessive consumption of sugar and high fat diet [6].

Ethical approval for this study was obtained from King’s College London (KCL Ethics Ref: HR-15/16-2901). An oral consent was also given by Shenyang Dental Hospital (Ministry of Health of People’s Republic of China). A written consent was obtained from participants’ parents prior to baseline and follow-up data collection. The following formula was used to calculate the sample size: N = (zα + zβ)2 / (δ/σ) 2 (zα = significance, zβ = power, δ = difference between the baseline and follow-up means, σ = pooled standard deviation of means) [21, 22]. The sample size calculation is based on previous studies of the association between dental caries and anthropometric measurements among preschool Chinese children. Based on a study that examined the relationship between weight and height, and dental caries (outcome) among preschool children in Taiwan [23], the calculated sample size with 0.05 significance level and 80% statistical power was 278 and 176 for weight and height, respectively. Based on a study estimating weight and height (outcomes) among children with and without dental caries in Hong Kong [24], the sample size was 636 (significant 0.05, power 80%). The highest sample size of these three estimates was rounded up to 650. This number was increased to a minimum of 1000 to compensate for non-response and attrition at follow-up.

Among those who were lost at follow-up, mean age was 51.15 months, percentage of boys and girls were 51.10% and 48.94%, mean dmft was 3.17, means of actual weight and height were 18.56 and 106.26, respectively. There were minimal differences between those who were lost at follow-up and those completed the study in these parameters.

The findings of this study on the bidirectional association between anthropometric measures and dental caries indicated by dmft among preschool children in China showed that dental caries at baseline was negatively and significantly associated with children height over the follow-up time. The direction of the association between baseline caries and weight gain was also negative, but it was not statistically significant. On the other hand, children with higher weight-for-age at baseline had lower caries increment.

This is the first longitudinal study to examine the bidirectional associations between dental caries, height and weight among preschool children in China. The study demonstrated a significantly negative relationship between baseline dental caries and children growth indicated by height-for-age, and between baseline weight and caries increment. The findings highlight the importance of dental caries as a potential risk factor for children growth in China and the role of nutritional status in the development of caries.




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