Conclusion: "Caries experience in permanent teeth", "poor salivary buffering capability" and "parents' low income" were factors associated significantly with the increment of at least 1 - 2 DMFS after 1 year; and "caries experience in permanent teeth" had a very strong correlation with the caries increment among 9 - 10-year-old school children in Binh Chanh, Hochiminh city, Viet Nam (p<0.001).