In vivo studies with a dicalcium phosphate dihydrate/MFP system for caries prevention

Recent basic studies have shown that increasing supersaturation with respect to dicalcium phosphate dihydrate (DCPD), above and beyond the amount present in saliva, enhanced the efficacy of fluoride in vitro. Since the combination of monofluorophosphate (MFP) with DCPD abrasive is unique for fluoride stability, dentifrices containing the combination were evaluated in a variety of in vivo tests. MFP with silicon dioxide (silica) abrasive at an equivalent fluoride concentration was used for comparison. The influence of slurries of DCPD or silicon dioxide on the intraoral plaque pH was measured following sucrose challenge in humans. The data indicated that DCPD slurries were more effective than silica in preventing plaque pH drop when compared to silica. A toothpaste containing MFP and DCPD was significantly more effective than an MFP/silica toothpaste. A toothpaste containing radiolabeled DCPD was applied topically in rats' teeth during a cariogenic challenge. The results showed that calcium45 was incorporated into the enamel with a concomitant reduction in enamel solubility. In a rat caries study using MFP/DCPD, matching placebo and MFP/silica, MFP/DCPD dentifrice showed a significantly greater reduction in smooth surface caries. Two dentifrices were also tested in an in situ human model for fluoride uptake in artificial root caries lesions where MFP/DCPD provided a significantly higher fluoride uptake than MFP/silica. A second in situ study in humans evaluated the same dentifrices. MFP/DCPD increased salivary plaque calcium and fluoride. These results of laboratory, animal and in situ studies taken together indicate that the MFP/DCPD combination is unique in providing extra supersaturation in saliva and plaque with concomitant enhanced anticaries efficacy.