Fluoride retention following topical fluoride foam and gel application

The purpose of this study was to compare the oral fluoride (F) retention following acidulated phosphate fluoride (APF) foam and gel applications in children. Fifty-nine children were divided into two groups, 6-9 years old and 10-13 years old. They each received a randomly assigned sequence of topical F foam and gel applications in two consecutive visits, using either sponge-lined or unlined trays. Approximately 0.6-0.8 g of APF foam, or 3-4 g of APF gel was used in each of the 4-min F applications. The amounts of F applied, recovered from the mouth, and retained were calculated for each treatment. The retention of an average of 1.26 mg F after an APF foam application was significantly less than 2.53 mg F for the APF gel. The sponge-lined trays also reduced significantly the F retention, compared with unlined trays. However, there was no significant difference in the amount of F retained between the two different age groups. The amount of F retained was reduced significantly from 3.65 mg F in the first appointment, to 1.24 mg F in the second appointment when unlined trays were used.