Fluoride Concentration in Enamel Surfaces Among 12- to-14-year Old Children

Objectives: Water fluoridation has been implemented in HoChiMinh city Vietnam since 1990 with 0.7 ppm F in the city public water system but the fluoride concentration has adjusted in 0.5 ppm since 2000. The objective of this study was to compare fluoride concentration in enamel surfaces of premolars among 12 to 14 year-old children living in fluoridated area (F+) and non-fluoridated area (F-) in HoChiMinh city, Vietnam in year 2014.

Methods: A total of thirty extracted premolars (by orthothodontic treatment plans) were collected from 12 to 14 year-old children living continuously since birth in F+ (15 premolars) and F- (15 ones) in Ho Chi Minh city. All the premolars were sent to Oral Biological Laboratory of Mahidol University to analyse F in enamel surfaces by using etched microsampling technique. Each sample was covered by the nail varnish to expose the window of enamel, 2x2 mm² . Then, 3 ml 1M HClO₄ was placed on the window to dissolve the enamel layer. Four ml 1M acetate buffer and deionized water were added, the procedures were repeated in three times. Solution was divided into two parts to determine the fluoride and phosphorus concentration. Repeat the procedure to dissolve 6 successive layers.

Results: There were statistically significant differences in fluoride concentration of premolar enamel surfaces among 12-14-year-old children living between fluoridated area and non- fluoridated area in HoChiMinh city at depths of 5 μm, 10 μm and 20 μm (p<0.001). Fluoride concentrations (ppm F) in the surfaces were 2196±886, 1672±637, 1149±482 and 1397±624, 1027±465, 657±356 in F+ and F- at depths of 5μm, 10μm and 20μm, respectively.
Conclusions: The effect of water fluoridation with 0.5 ppm F on enamel surfaces among 12 to 14 year-old children living in fluoridated area of the city could be demonstrated by in vitro study.