June 2020

Objectives: To establish the existence and directions of any associations between measures of body mass index (BMI) with caries levels using individual measures of each as derived from national surveys in England. Methods: The BMIs of five-year-old children calculated from the 2017 National Child Measurement Programme and caries measures from the 2016-17 Public Health England (PHE) National dental epidemiology survey were securely linked at a child level. Comparison at individual level of caries levels and BMI z scores was done using multivariable regression. Results: Records for 67,033 children were linked and allocated a deprivation quintile. An association between BMI Z score categories and caries levels was established. Caries prevalence was higher among overweight (24.4%) and very overweight (27.6%) children compared with those of average BMI (22.5%). Odds ratios were statistically significant at 1.08 and 1.14 for prevalence among overweight and very overweight children. Children of low BMI were found to have higher caries severity (1.2 d3mft) and extent (4.4 d3mft among those with any caries) compared to children of healthy BMI (0.7 d3mft, 3.3 d3mft) with statistically significant Incidence Rate Ratio of 1.24. Underweight children were more likely to have caries experience and more severe attack compared with children of healthy weight. Deprivation and ethnicity were confounding factors. Conclusions: There is some association between child BMI status and caries levels whereby caries prevalence among children of higher BMI is increased. The associations are over and above those of deprivation, ethnicity and water fluoridation individually, but these factors impact on the strength of the link between BMI and caries. Keywords: caries, height and weight measurements, BMI, associations, children