Fluoride profiles in premolars after different durations of water fluoridation in Ho Chi Minh City, Vietnam

In order to evaluate the uptake of fluoride (F) into tooth structures following water fluoridation in Ho Chi Minh City, F concentrations were measured from the enamel surface through the enamel–dentine junction (EDJ) to dentine close to the pulp in premolars. Calcification had been completed in all the teeth before fluoridation. Samples were obtained from fluoridated areas of the City ([F]: 0.7 parts/106) after 3 years (eight samples), 6 years (eight samples) and 8 years (nine samples). Samples were also taken from regions outside the fluoridated water supply of the City in 1998 after 8 years of water fluoridation. An abrasive microsampling method was used to determine the profiles of fluoride and phosphorus concentrations. In enamel surfaces, F concentrations tended to increase with increasing periods of fluoridation. In dentine close to the pulp, F concentrations also increased statistically significantly with the increasing duration of fluoridation of water (between 6 and 3 years: P=0.006; between 8 and 3 years: P=0.001; between 8 years and 8 years without F: P=0.0001). It was concluded that F concentrations in enamel and dentine had tended to increase gradually with the duration of water fluoridation in Ho Chi Minh City. The increase was most obvious in dentine near the junction with the pulp.