The effects of medium chain fatty acids and fluoride on fissure caries in Wistar rats

This work was to compare the degree of caries protection provided by fatty acids with chain lengths of 9-12 carbons and to assess the anti-caries potential of a fluoride-fatty acid mixture. Male Wistar rats were weaned at 21 days, maintained on a standard laboratory diet for 7 days and then provided with a cariogenic, 45% sucrose diet for 34 days. This regimen produced a very reproducible degree of fissure caries and the inclusion of 1% powdered potassium nonanoate or decanoate in the diet gave large and significant reductions in total and advanced lesions. Decanoate was significantly more inhibitory towards advanced lesions than was nonanoate. In contrast, 1% potassium laurate was considerably less effective under these conditions. Caries protection with a mixture of 0.25% decanoate and 76 parts/10(6) fluoride was found to be cumulative rather than synergistic. It is suggested that the optimal effect obtained with decanoate was due to a favourable combination of the surfactant and wetting properties of this molecule at the low pH values found in fissure dental plaque. It is also suggested that fluoride and decanoate acted in an independent manner to enhance remineralization of early lesions and to inhibit the acidogenic flora, respectively.