The pattern of association between early childhood caries and body mass index in pre‐school children within Aotearoa | New Zealand: a national cross‐sectional study

Abstract

AbstractObjectivesThe relationship between childhood anthropometric measurements and dental caries has an inconsistent evidence‐base. This study investigated dental caries experience and body mass index (BMI) measurements of children aged 4 years in a national cohort, after accounting for key confounding variables.MethodsA near whole‐population cross‐sectional study of children who had a health and developmental assessment, as part of the nationwide B4 School Check screening program, conducted in Aotearoa | New Zealand (ANZ) between 1 July 2010 and 30 June 2021 was studied. The extracted database included 582 820 children, of whom 572 523 (98.2%) had valid BMI and oral health records. Dental caries experience was derived from the ‘lift the lip’ oral health screening, and measured height and weight were used to calculate sex‐specific BMI‐for‐age z‐scores (BMIz). Analyses were adjusted for age, sex, ethnicity and area‐level deprivation. Modified Poisson regression models using 2‐degree fractional polynomial curves for BMIz were employed.ResultsIn the extracted sample, the median age was 4.3 years (interquartile range: 4.1–4.5 years), 283 565 (48.7%) were female, 135 734 (23.4%) and 74 237 (12.8%) were identified as Māori and Pacific, respectively, and 140 931 (24.4%) lived in the most deprived areas of ANZ. Overall, 81 926 (14.2%) had dental caries identified. In unadjusted analyses, a significant J‐shaped association was observed between dental caries experience and BMIz. However, in the adjusted analysis, a significant flattened S‐shaped association was found; those with lower BMIz had lower predicted probabilities of dental caries experience. Large differences in predicted probabilities were observed between different sex, ethnicity and area‐level deprivation groups.ConclusionsThis study found significant non‐linear associations between dental caries experience and BMI in 4‐year‐old children. However, the inclusion of confounders importantly changed the shape of this non‐linear association. Sex, ethnicity and area‐level deprivation inequalities had a greater impact on dental caries experience than BMI.