Primary tooth emergence in young children is associated with a stress biomarker.

Early tooth emergence may reflect developmental stress exposures and compose part of a broader set of growth measures that may be accelerated in response to early stress exposure. We test the hypothesis that timing of primary tooth emergence is associated with stress exposure and stress biology in young children. Tooth emergence was tracked prospectively in a diverse sample of initially caries-free 1-3 year-olds; socio-economic and psychosocial determinants of oral health, oral microbiology, and salivary stress markers were assessed at baseline and at 6-monthly intervals for 2 years. The number of tooth surfaces observed at the initial assessment in caries-free children was associated with a stress-related pattern of salivary cortisol reactivity: diminished cortisol response to a laboratory stressor was strongly associated with the number of surfaces (estimate -6.51 [SE 1.90], 95% CI -10.23--2.79, p < 0.001), after adjusting for covariates. This effect was also found in longitudinal analyses across the two-year study period. The findings provide novel evidence that a marker of stress biology is positively associated with tooth emergence in young children and may reflect additional developmental and biological influences that underlie oral health in children.