Developmental defects of enamel in preschool twins - Coincidences, heritability, and multilevel analysis

To compare the coincidences of developmental defects of enamel (DDE) between monozygotic and dizygotic twins, determine heritability in primary dentition, and identify associated factors.

A cross-sectional study was conducted among preschool twins aged 3-5 years in Teresina, Brazil. Non-cooperative children were excluded. Data were collected through questionnaires and clinical examinations. Clinical assessment was conducted in a school setting using the modified DDE Index for diagnostic purposes. Coincidences were analyzed using tetrachoric correlations and multinomial logistic regression, deriving Odds Ratios (OR) and 95 % confidence intervals (95 %CI). Heritability was estimated using Holzinger's formula. Multilevel Poisson regression identified associated factors with developmental defects of enamel occurrence (p < 0.05).

In total, 239 twin pairs were included (Monozygotic = 96, Dizygotic = 143). Correlations for developmental defects of enamel were strong/very strong in monozygotic (overall DDE, 0.829; demarcated opacities, 0.645; diffuse opacities, 0.812; hypoplasia, 0.786) and weak/moderate in dizygotic (overall DDE, 0.322; demarcated opacities, 0.076; diffuse opacities, 0.562; hypoplasia, 0.156). Monozygotic twins had more positive (OR; 95 %CI = 2.04; 1.01-4.08) and negative coincidences (OR; 95 %CI = 3.91; 1.47-10.36) than dizygotic twins did. Heritability was 74.8 %. Pre-eclampsia/eclampsia and high fever during the first year of life were associated with a higher prevalence of DDE in primary dentition.

Higher coincidences in monozygotic twins and high heritability suggest a genetic influence on the development of developmental defects of enamel in primary dentition. Pre-eclampsia/eclampsia and high fever in the first year of life were associated factors.