Abstract: The addition of organo germanium compounds having the formulaR.sub.3 GeX or (R.sub.3 Ge).sub.2 Ywherein R is an aliphatic or cycloaliphatic hydrocarbon group and X is an anion, such as carboxylate, sulphonate, halogen or hydroxyl, and Y is oxygen, sulphur, or sulphate, to conventional agents used in oral hygiene will significantly reduce the formation of plaque on teeth and thus reduce the incidence of caries. The preferred germanium compounds are the tri-n-butyl and tri-n-pentyl. The fluoride ion is the preferred anion because of its known anti-caries properties.