Evidence on the association of overall dietary factors, selected environmental, medical, demographic, and biological factors and developmental defects of enamel, including MIH and enamel fluorosis.

Introduction: Developmental defects of enamel (DDE) encompass a spectrum of conditions that occur during tooth formation, including enamel fluorosis, molar-incisor hypomineralization (MIH), and other forms of enamel hypoplasia. It has been proposed that DDE are associated with nutritional deficiencies as well as environmental exposures during tooth development. Objective: This scoping review summarized and analyzed the evidence on the association between dietary habits, environmental exposures, medical/health-related factors, demographic factors and biological factors and DDE aiming to provide a comprehensive overview of the available evidence in this area. Methodology: Following the Joanna Briggs Institute (JBI) framework using Population, Concept, and Context (PCC) to guide the development of the research question and eligibility. The population of interest were individuals from any age group or gender diagnosed with DDE. The eligibility concepts were factors that may contribute to DDE such as dietary and environmental exposures. The study selection followed the PRISMA guidelines. Studies published from January 1993 to December 2024 were identified through searches in Web of Science and PubMed. Results: Our review included 125 studies from 1993 to 2024, mainly on fluorosis (105 studies), mostly cross-sectional, and conducted in Asia and North America. Fewer studies addressed MIH (5) and other non-fluorosis DDE (15), primarily in Europe, South America, and Asia, with most participants being children aged 6-12 years, and small sample sizes. The review evaluated DDE and its main subtypes, molar-incisor hypomineralization (MIH) and enamel fluorosis across conditions, overlapping risk factors were identified, such as excessive fluoride intake, vitamin D deficiency, early childhood illnesses, and exposure to environmental contaminants. Condition-specific patterns were also noted, fluorosis being primarily associated with high fluoride exposure and early weaning, whereas MIH was more frequently linked to vitamin D deficiency and early systemic. Conclusion: The findings highlight that enamel fluorosis, MIH, and other enamel hypoplasias are part of a shared continuum of DDE influenced by interrelated dietary, environmental, and biological factors. These findings suggest common developmental pathways leading to enamel disruption and emphasize the need for longitudinal and mechanistic studies to clarify causal relationships and inform preventive strategies.