Prevalence of molar-incisor hypomineralization in Mexican population: A systematic review and meta-analysis

Background: Molar-incisor hypomineralization (MIH) is a qualitative defect in enamel formation with a multi- factorial etiology. Studies indicate a high prevalence of MIH across the Americas, yet the prevalence in Mexico remains uncertain. Aim: This study aimed to review the literature on the prevalence of MIH in the Mexican population and its associated factors. Methods: Six electronic databases were searched for relevant studies: PubMed, Scopus, Dentistry & Oral Science, Science Direct, Web of Science, and Google Scholar, covering the period from March 10th, 2024. Cross-sectional studies were assessed for risk of bias using the Joanna Briggs Institute (JBI) tool. Results: Nine studies met the inclusion criteria, encompassing 5039 children aged 6-12 years, with a mean age of 9.02 +/- 1.19 years; 50.1% were boys, and 49.9% were girls. The overall prevalence of MIH was 23%, with a higher prevalence in boys (34.1%) than in girls (30.4%). MIH was more common in molars (30.7%) than in incisors (10.8%), with no cases reported in permanent second molars. Five studies (55.5%) noted dental caries in MIH-affected individuals, with 78.7% showing caries and 21.3% caries-free. The JBI analysis found 33.3% of studies with moderate risk and 66.7% with low risk of bias. Conclusion: The prevalence of MIH in Mexico aligns with rates reported in Brazil and Venezuela. The evidence indicates no significant gender differences in MIH distribution, with molars being more frequently affected than incisors. A substantial proportion of Mexican children with MIH also present with dental caries.