Abstract: The compounds of the present invention are linear and branched dextrans having a plurality of their glucose units modified at the 3-position ring carbon with groups selected from the class consisting of keto, amino, halo, benzyl, alkyl, sulfonyl, carboxyl and hydrogen. The modified dextrans reduce and/or modify activity of glucosyltransferase enzymes (GTF) which are produced by oral strains of Streptococcus mutans bacteria. GTF enzymes mediate oral biosynthesis of plaque-forming glucose polymers (glucans) from ingested sucrose. Therefore, the dextrans of the present invention, which reduce and/or modify activity of GTF enzymes, are useful in reducing the formation of dental plaque. The present invention is further directed to a dental health method comprising the step of contacting the oral cavity with linear or branched dextran compounds having a plurality of their glucose units modified at the 3-position carbon with a group such as keto, amino, halo, benzyl, alkyl, sulfonyl, carboxyl or hydrogen.