Body Mass Index and Early Childhood Caries in High Caries Risk Children: A Nested Case-Control Methodological Investigation.

Purpose: To evaluate body mass index (BMI) - early childhood caries (ECC) relationships with various BMI expressions.
Methods: Healthy eight- to 18-month children with unerupted molar(s) were conveniently sampled from Uniontown, Ala., USA, a high caries risk community (i. e., rural, poor, racial minority). Staff measured height/weight, dentists conducted oral exams, and parents completed questionnaires annually (from 2008 to 2014) for BMI, ECC (decayed, missing due to caries, filled primary tooth surfaces [dmfs] score), and sociodemographic values, respectively. Nationally recognized standard (underweight-normal-overweight-obese), crude (overweight/obese-not), and continuous BMI variables were evaluated. Logistic regressions (with restricted cubic splines) assessed BMI-ECC relationships, producing odds ratios (ORs) and 95 percent confidence intervals (95% CIs).
Results: Male and female ECC ORs supported positive and negative parabolic functions, respectively, for increasing standard BMI categories; underweight males were associated with ECC (OR=4.59; 95% CI=1.06 to 19.85). Crudely expressed, overweight/obese males and females had lower and slightly increased odds of ECC, respectively. A continuous BMI produced a similar OR across sexes, while spline models suggested nonlinearity for each.
Conclusion: BMI-ECC associations might be nonlinear; being underweight could be a male ECC risk factor. Studies should include extreme BMI values without collapsing BMI categories.