The effect of a topical fluoride regimen consisting of a four-minute pre-treatment with a saturated dicalcium phosphate dihydrate (DCPD) solution followed by a four-minute application of APF was compared with that of a four-minute application of APF alone with respect to the deposition of fluoride in enamel in an apatitic form in vitro. Following the topical applications, specimens were washed in either (1) an inorganic wash solution for 24 hrs or (2) an inorganic wash solution with 1 ppm F added for 28 days; specimens were then subjected to KOH extraction for 24 hrs. Fluoride-by-depth profiles revealed that the DCPD/APF treatment resulted in a significant increase in the apatitic F concentration of enamel to a depth of 20 microns, while APF application alone did not. All groups exposed to the 1 ppm F wash acquired significant amounts of apatitic F, with the differences between groups remaining relatively constant.

The ability of a topical fluoride regimen consisting of a 4‐min application of a saturated dicalcium phosphate dihydrate (DCPD) solution followed by a 4‐min application of 1.23% acidulated phosphate fluoride (APF) to inhibit caries‐like lesion formation in sound enamel was compared to that of a 4‐min application of APF. Following the applications, specimens were washed for 24 h in an in organic wash solution or for 28 days in a wash solution containing 1 ppm fluoride. The mean overall lesion depth for specimens treated with APF and washed for 28 days was significantly greater than that for the group treated with DCPD/APF and washed for 28 days, and for the group treated with APF and washed for 24 h (p<0.05). For those specimens washed for 24 h, the mean width of the surface zone was greater (p<0.05) for the DCPD/APF group compared to the APF group.