Respiratory problems in early childhood and molar-incisor hypomineralization: systematic review and meta-analysis

PURPOSE: To evaluate the association between early childhood respiratory problems and Molar-Incisor Hypomineralization (MIH). METHODS: . This systematic review followed PRISMA guidelines and was registered in the PROSPERO database (CRD42022320707). Risk of bias was assessed using the Joanna Briggs Institute (JBI) checklist for cross-sectional studies and the Newcastle-Ottawa Scale for case-control and cohort studies. The certainty of the evidence was rated using the GRADE framework. Meta-analyses were performed to explore associations between respiratory conditions and MIH (significance level p < 0.05). RESULTS: From 1228 identified articles, 27 met the inclusion criteria, and 12 were included in four meta-analyses. Most cross-sectional and cohort studies showed low risk of bias, while case-control studies showed moderate risk. Quantitative synthesis was feasible only for asthma and pneumonia. In adjusted analyses, asthma was not significantly associated with MIH (OR 1.93; 95% CI 0.60-6.20), with substantial heterogeneity across studies. Pneumonia showed a positive overall association with MIH (OR 3.33; 95% CI 1.05-10.51). However, the certainty of evidence for all associations was considered very low. CONCLUSION: Early childhood respiratory conditions may be associated with molar-incisor hypomineralization, but the available evidence is inconsistent and of very low certainty, precluding causal inference.