The potential importance in caries prevention of solubility reducing and antibacterial factors in unrefined plant products

Abstract

Aqueous extracts of plant materials which have been considered to contain anti-caries factors (wheat bran, wheat germ, oat hulls, pecan hulls, peanut hulls and cocoa) and alcoholic extracts of wheat bran, oat hulls and wheat germ were prepared. The alcoholic extracts were evaporated to dryness and the residue dissolved in water. Comparisons were made of the effects of these extracts on the solubility rate in acid buffer of calcium phosphate and on inhibitions of acid production by salivary bacteria or Streptococcus lactis. It was found that all the aqueous extracts reduced solubility but the only aqueous extract to inhibit bacteria was that from pecan hulls. Alcoholic, but not aqueous, extracts of oat hulls and wheat bran inhibited the bacteria. Procedures were adopted which differentiated between true antibacterial effects and buffering actions which might be confused with it. It is concluded that any anti-caries effect exerted by these materials is more likely to be brought about by the diffusion into saliva of the water extractable substances which affect the solubility of teeth than by the inhibition of bacteria which appears to require alcoholic extracts.