Presence of molar-incisor hypomineralization is associated with dental caries in Brazilian schoolchildren.

This study aimed to identify the prevalence of molar-incisor hypomineralization (MIH) in schoolchildren and its association with dental caries experience. This was a cross-sectional study with a sample of 471 children aged 8 to 10 years. Data were collected via a sociodemographic questionnaire. Intra-oral clinical examination was done to identify and diagnose MIH (EAPD Criteria) as well as dental caries (ICDAS Index). Statistical analyses were performed with Person's Chi-square, Fisher's exact, and Mann-Whitney tests, and Poisson regression models were built. Statistical significance was set at an alpha-level of 0.05. The prevalence of MIH in our participants was 9.8%, with lesions being mostly of the mild form (65.2%) and affecting the first permanent molars but not the incisors in 54.2% of the children. Dental caries was observed in 88.1% of subjects. We observed a significant association between dental caries and the following variables: presence of MIH (p < 0.01; PR = 1.13), dental visit (p < 0.02; PR=0.92), and parents or legal guardians' education level (p < 0.05; PR = 1.07). A MIH diagnosis was also significantly associated with family income (p < 0.05; PR = 4.09). Children with MIH had more caries lesions on molar surfaces (p < 0.01; PR = 4.05). The prevalence of MIH was found to be moderate, based on previous studies, and the presence of enamel defect was associated with dental caries. The teeth most affected by MIH lesions were the first permanent molars.