• Pichian Angchanpen
• Supathra Amatyakul
• Chalida Nakalekha
• Supachai Kiatsakuntong
• Nuingrutai Tuksinmanee

Objective The preliminary in vitro study was performed to determine the fluoride retention on enamel surface after topical application with 1.23 % acidulated phosphate fluoride (APF) gel.

Materials and methods Thirty caries-free human third molars were used in this study. The teeth were cross sectioned at 2 millimeters below cervical line. Five specimens were randomly chosen as a control group. The fluoride content of the enamel surface was measured by using scanning electron microscope and energy dispersive spectroscopy. Other 25 specimens were topically applied with APF gel for 4 minutes and suspended in artificial saliva. Each five randomized specimens were evaluated for fluoride content at 30 minutes, 2, 4, 6, and 8 weeks after APF gel application. The data were analyzed statistically by using Mann Whitney U test and Kruskal Wallis test.

Results Fluoride content on enamel surface of the control group was 0.60 ± 0.51 %, those of the test groups suspended in artificial saliva for 30 minutes, 2, 4, 6, and 8 weeks were 21.50 ± 11.06, 2.30 ± 0.72, 0.88 ± 0.24, 0.09 ± 0.14, and 0.89 ± 0.67 % respectively. The statistical analysis showed that fluoride contents of the 30-minute and 2-week test groups were significantly different from the control group (p > 0.05).

Conclusion Under the conditions of this preliminary in vitro study, fluoride retention after topical application of APF gel on enamel surface may sustain for more than 2 weeks but no longer than 4 weeks.

(CU Dent J. 2006;29:111-118)