• Pichian Anchanpen B.Sc., D.D.S., Dr.med.dent.
• Supathra Amatyakul B.Sc., M.Sc., Ph.D.
• Siriporn Chotipaibulpan D.D.S. (Hons)
• Pratchya Habkongleg
• Vorawat Pukjaroon

Objective To determine the enamel fluoride retention after application with fluoride gel.

Materials and methods Fourteen subjects, aged between 20-22 years old, were included. The
buccal enamel biopsies were conducted on the middle buccal surfaces of the upper premolar before
and at 30 minutes, 2, 4 and 8 weeks after 1.23% acidulated phosphate fluoride application. Fluoride
concentration of the etching solution was determined using a fluoride electrode. Calcium concentration
was evaluated by an atomic absorption spectrophotometer. The data were analyzed by Wilcoxon
Signed Rank test and Friedman test at significant level .05.

Results The baseline value of enamel fluoride content was 2,107±498 ppm. After the application with
fluoride gel at 30 minutes, 2, 4 and 8 weeks the fluoride content were 6,525±699, 4,751±966, 2,906±663
and 1,792±466 ppm, respectively. Statistical analysis revealed a significant increase in the enamel
fluoride content at 30 minutes, 2 and 4 weeks when compared to the baseline value (p < .01).
No significant difference between the 8 weeks value and the baseline was observed.

Conclusion The enamel fluoride retention after topical application with acidulated phosphate fluoride
gel lasts for more than 4 weeks but no longer than 8 weeks.

(CU Dent J. 2005;28:229-36)