Thyroid Function during Early Life and Dental Development

Abstract

Children with low levels of thyroid hormones (hypothyroidism) have delayed tooth eruption, enamel hypoplasia, micrognathia, and anterior open bite, whereas children with hyperthyroidism may suffer from accelerated tooth eruption, maxillary, and mandibular osteoporosis. However, it is still unknown whether thyroid function variations within the normal or subclinical range also have an impact on hard dental tissues in healthy children. The objective of this study was, therefore, to investigate the association between thyroid function from the fetal period until early childhood and dental development at school age. This study is embedded in the Generation R Study, a population-based cohort study established in Rotterdam, the Netherlands. Maternal thyroid function (thyroid-stimulating hormone [TSH], free thyroxine [FT4], and thyroid peroxidase antibody [TPOAb] concentrations) was measured during early pregnancy, and thyroid function of the offspring (TSH and FT4) was measured in cord blood at birth and in early childhood (6 y). Dental development was assessed from panoramic radiographs of children of school-going age (9 y). In total, 2,387 to 2,706 subjects were available for the multivariable linear regression analysis, depending on the point in time of thyroid function measurement. There was an inverse association between cord blood and early childhood TSH concentrations with dental development, with a –0.06 lower standard deviation (SD) per 1 mU/L of TSH (95% confidence interval [CI], –0.11 to –0.01) and a –0.06 lower SD per 1 mU/L of TSH (95% CI, –0.11 to 0.00), respectively. There was no association between the maternal thyroid function during pregnancy and the dental development score of the child. However, TPOAb-positive mothers had children with a –0.20 SD (adjusted 95% CI, –0.35 to –0.04) lower dental development score compared with TPOAb-negative mothers. The findings of this study suggest that the thyroid hormone is involved in the maturation of teeth from the early stages of life onward.