Prevalence and association of Molar Incisor Hypomineralization (MIH) in patients presenting dental fluorosis: a systematic review and meta-analysis

Molar Incisor Hypomineralization (MIH) and Dental Fluorosis (DF) are two developmental enamel defects with overlapping clinical features. From an epidemiological perspective, studying the co-occurrence of MIH and DF provides a more comprehensive view of enamel health, helping to avoid underestimation of their true prevalence and to identify shared environmental risk patterns. Despite their frequent co-occurrence, evidence regarding a potential relationship between MIH and DF remains unclear. This systematic review and meta-analysis aimed to assess the prevalence of MIH among children with DF and to investigate the possible association between these two conditions. Following PRISMA guidelines, a systematic search was conducted in PubMed, Scopus, Web of Science, and the Cochrane Library. Cross-sectional studies reporting the prevalence of MIH in populations with DF were included. Two reviewers performed study selection, data extraction, and quality assessment independently. A meta-analysis with a random-effects model was conducted in RevMan. Five cross-sectional studies, including 3,071 children aged 8–16 years, met the inclusion criteria. Across the included studies, the prevalence of MIH and DF was 21% and 51%, respectively. The prevalence of co-occurrence ranged from 3.7% to 26%. A statistically significant association between MIH and DF was observed (χ² = 10.1, p = 0.002; OR = 1.36, 95% CI: 1.12–1.65). However, the meta-analysis based on four studies (n = 1,503) did not confirm this association (OR = 1.11, 95% CI: 0.86–1.42, p = 0.43), with moderate heterogeneity (I² = 56%). Most MIH cases were of mild severity (55.1%). While descriptive analyses suggested a potential relationship between MIH and DF, meta-analytic results did not support a significant association. These findings highlight the need for further standardized diagnostic criteria and well-calibrated epidemiological studies to clarify whether environmental fluoride exposure influences MIH occurrence. This systematic review was registered in the PROSPERO database (ID: CRD42024628754).