Developmental ecology of the infant oral ecosystem: a framework for early childhood caries

Early childhood caries (ECC) has traditionally been regarded as a biofilm-mediated disease driven by sugar exposure and acidogenic microorganisms. However, this perspective primarily captures the final stage of a much longer biological process. We propose the Developmental Ecology of the Infant Oral Ecosystem as a conceptual framework in which ECC represents the clinical manifestation of a disrupted developmental ecology of the infant oral ecosystem, resulting from altered host-microbe-environment interactions that operate from the prenatal period through the first 1,000 days of life with maternal, nutritional, inflammatory, immune, metabolic, microbial, and environmental influences shaping early developmental trajectories.

This narrative review synthesizes current evidence into an integrated developmental ecological framework encompassing maternal microbial transmission, infant oral microbiome assembly, breastfeeding, complementary feeding, dietary ecology, tooth eruption, biofilm maturation, and the oral-gut axis. These processes are interpreted within the One Health and Developmental Origins of Health and Disease (DOHaD) paradigms to provide a comprehensive ecological perspective on ECC development.

The reviewed evidence supports a developmental-ecological interpretation in which interconnected early-life ecological processes shape microbial succession, oral ecosystem resilience, and susceptibility to dysbiosis. Rather than acting as the primary cause of disease, the cariogenic biofilm is interpreted within the proposed framework as the ecological endpoint of disrupted developmental trajectories that impair the establishment and maintenance of oral homeostasis.

Reframing ECC as a developmental ecological disorder complements established preventive approaches, including fluoride use, dietary sugar control, oral hygiene, and regular dental care, while highlighting the importance of maternal health, early-life nutritional ecology, and microbiome-informed preventive strategies aimed at preserving oral ecosystem resilience from the earliest stages of life. The proposed framework is intended to generate testable hypotheses for future longitudinal and interventional research.