Investigation of the most common perinatal and postnatal risk factors in children with MIH compared to healthy (non-MIH) children aged 6-12 years in Arak City.

Background: Molar-Incisor Hypomineralization (MIH) is a widespread developmental enamel defect impacting children globally, with a multifactorial etiology that remains incompletely understood. Its rising prevalence presents significant challenges to oral health and quality of life. This study examines both perinatal and postnatal risk factors associated with MIH in a pediatric population.

Methods: This case-control study involved 426 children aged 6-12 years, with 213 diagnosed with MIH and 213 healthy controls, recruited from a university dental clinic and local schools in Arak City, Iran. Parents completed a validated 48-item checklist covering perinatal factors (e.g., delivery mode, preterm birth) and postnatal factors (birth to 3 years, e.g., feeding practices, illnesses, medication use). MIH was diagnosed using the European Academy of Paediatric Dentistry criteria. Data were analyzed using chi-square tests and multivariate logistic regression to identify risk factors, with a significance level of 5%. Ethical approval and informed consent were obtained.

Results: Vaginal delivery (42.9% vs. 62.9%, p = 0.004) was protective against MIH (OR = 0.54, p = 0.037), reducing odds by 46%, while preterm birth (18.1% vs. 8.6%, p = 0.048) showed a modest association. Frequent analgesic use (65.7% vs. 57.4%, p = 0.034) and recurrent diarrhea (37.0% vs. 32.4%, p = 0.033) were more prevalent in the MIH group, though effects were weak. Although a history of chickenpox was more frequent in the MIH group (31.5% vs. 17.6%, p = 0.058 in univariate analysis), multivariate logistic regression, adjusting for confounders, showed that children with a chickenpox history had lower MIH risk (OR = 2.12 for absence of chickenpox, p = 0.040). Vitamin D deficiency (6.5% vs. 8.3%, p = 0.829) and breastfeeding < 6 months (4.6% vs. 8.3%, p = 0.700) showed no clear link. Hypoxia at birth (6.7% vs. 3.8%, p = 0.353) and high fever (9.3% vs. 7.4%, p = 0.953) were not associated with MIH.

Conclusion: Vaginal delivery and chickenpox history emerged as protective factors against MIH, while preterm birth, analgesic use, and diarrhea showed modest associations. These findings underscore MIH's complex etiology, with regional variations suggesting diverse influences. Further longitudinal research is needed to validate these relationships and guide targeted prevention strategies.