Water fluoridation (WF) in HoChiMinh City (HCMC), Vietnam, started in January 1990 at 0.7±0.1 ppmF and adjusted to 0.5±0.1 ppmF in June, 2000 but it doesn't cover the entire metropolitan area, determining three geographical areas: Fluoridated (S2), non-fluoridated (S0) and mixed (S1).