Japan's Four-Decade Natural Experiment in Early Childhood Caries: A Perspective on Prevention Pathways Beyond Fluoride.

Japan's marked decline in early childhood caries (ECC) has been documented through uniquely comprehensive national dental examinations, with standardized population surveys conducted continuously for more than four decades. This perspective discusses how Japan achieved sustained reduction in ECC despite the absence of community water fluoridation and historically limited use of toothpaste with effective fluoride concentration in infancy. Drawing on national surveillance and epidemiological evidence, I consider how changes in dietary patterns, caregiver practices, oral health behaviours, and broader social conditions may have contributed to a less cariogenic environment for young children. Importantly, this experience does not diminish the established effectiveness of fluoride-based interventions; rather, it highlights complementary, system-level factors operating over long time horizons. Japan's experience may inform context-sensitive ECC prevention strategies, particularly in settings where fluoride use is limited, unevenly implemented, or difficult to sustain.