Clinical effectiveness of fluoride-releasing elastomers. II. Enamel microhardness levels

The purpose of this study was to examine the effect of fluoride-releasing elastomers on enamel microhardness levels. Sixteen teeth from four patients scheduled to have premolars extracted as part of their orthodontic treatment were examined in this study. Orthodontic brackets were bonded to the buccal surface of the test teeth with a nonfluoridated adhesive. Two of the patients had fluoride-releasing elastomers placed on the right upper and lower brackets and conventional elastomers placed on the left side. This sequence was reversed for the remaining two patients. After 1 calendar month, the experimental teeth were extracted, sectioned, and embedded in acrylic. Microhardness tests were performed 50 to 75 microns cervical to the bracket. Indentations were taken at the surface and continued in 20 microns increments to a depth of 200 microns. Results showed the enamel was significantly harder (p < 0.05) in the fluoride group at the 20 microns depth compared with the control group. No other microhardness readings showed a statistically significant difference.