Hypomineralized primary teeth and their association with Molar Incisor Hypomineralization: a cross-sectional study

Environmental and systemic factors play a role in the development of hypomineralization characterized by demarcated opacities. This study aimed to investigate the prevalence, distribution, severity, and etiologic factors associated with hypomineralization in all primary teeth, hypomineralized second primary molars (HSPM) and evaluate its association with Molar Incisor Hypomineralization (MIH). A sample of 2,102 male and female Brazilian children aged 3 to 10 years exhibiting good general health was examined by 30 calibrated dentists using WHO probes and clinical mirrors, using the index proposed by Ghanim et al. Data were collected through clinical examinations and a questionnaire answered by mothers, addressing sociodemographic and prenatal, perinatal, and postnatal factors. Prevalence was assessed by calculating frequency, whereas etiologic factors were evaluated using univariate and multivariate Poisson logistic regression with robust adjustment. In addition, multivariate analysis was conducted using nonparametric resampling with Jacknife adjustment. The overall prevalence of hypomineralization in primary teeth was 18.5%, with second molars affected in 17% and canines in 6.7% of the cases, while other teeth were affected at lower rates. Exclusive breastfeeding for six months showed a protective effect against hypomineralization (p = 0.40). Children with HSPM were five times more likely to develop MIH, regardless of sex (OR: 4.92). Furthermore, lower family income increased the likelihood of MIH. In conclusion, hypomineralization in primary teeth is prevalent, exclusive breastfeeding for six months is associated with a lower prevalence of enamel defects, and children with primary dentition defects are at greater risk for similar conditions in their permanent teeth.