Objective: To determine the prevalence of and factors associated with molar incisor hypomineralization (MIH) in schoolchildren aged 6-12 years.
Study design: This study included 1156 schoolchildren aged 6-12 years, living in Mexico City. A previously standardised examiner (k = 0.79) applied the diagnostic criteria for MIH from the European Academy of Paediatric Dentistry. Children's parents completed a questionnaire about medical conditions in the perinatal period and the first 3 years of their children's lives. Descriptive measures were examined, multivariate logistic regression analysis was performed, and odds ratios (ORs) were calculated.
Results: The subjects were 582 (50.4%) females and 574 (49.6%) males, with an average age of 8.4 ± 1.6 years. The prevalence of MIH was 15.8%, and this condition was more prevalent in children aged 9-12 years than in those aged 6-8 years (18% vs. 13.7%, p < 0.05). Risk factors for MIH were low birth weight (OR = 1.905, 95% confidence interval [CI] 1.130-3.211, p = 0.014), urinary tract infection (OR = 4.841, 95% CI 2.863-8.186, p = 0.001), chickenpox (OR = 1.826, 95% CI 1.196-2.786, p = 0.005), and history of allergies (OR = 4.370, 95% CI 2.538-7.523, p < 0.001).
Conclusions: The prevalence of MIH in a group of Mexican schoolchildren was 15.8%. Medical conditions in the first years of life were more prevalent in children affected by MIH.
Keywords: Mexican; Molar incisor hypomineralization; children; etiological factors.