Prospective association of daily toothbrushing frequency and the prevalence of childhood functional constipation: the Japan Environment and Children’s Study

Functional constipation is the most common gastrointestinal disorder during childhood. Oral stimulation (mastication and toothbrushing) reportedly improves bowel movements, but the association between daily toothbrushing behavior and functional constipation remains unknown. Data (n = 83,660) from fetal records (n = 104,059) in the Japan Environment and Children's Study, an ongoing prospective birth cohort, were analyzed to investigate the impact of daily toothbrushing frequency on functional constipation during childhood, using ROME III diagnostic criteria. After multiple imputations of data acquired from self-reported questionnaires, a multivariable binomial logistic regression analysis was used with adjustments for several maternal and child-related variables. Functional constipation was observed in 10,123 (12.1%) and 8,820 (10.5%) participants at 3 and 4 years postpartum, respectively. Using the appropriate frequency of daily toothbrushing (twice or more) as a reference, the odds of functional constipation increased with decreasing daily toothbrushing frequency after covariate adjustments involving daily feeding frequency. The adjusted odds ratio (OR) for functional constipation in participants without daily toothbrushing behavior (less than once a day) at 4 years postpartum was 1.87 (95% confidence interval [CI] 1.34-2.61). Similarly, the adjusted OR (95% CI) for chronic functional constipation (at both 3 and 4 years postpartum) in participants without daily toothbrushing behavior (less than once a day) at 2 years postpartum was 1.62 (1.14-2.31). Functional constipation during childhood was associated with decreased daily toothbrushing frequency. Although the underlying mechanism of daily toothbrushing behavior in prompting bowel movements remains unclear, it is a major basis of self-health management in children that plays an important role in managing functional constipation.