The state of hexose sugar in human dental plaque and its metabolism by the plaque bacteria

Abstract

Twenty-four hour accumulations of human dental plaque have been examined for total and extractable hexose. Total hexose was found to comprise almost 20 per cent of the dry wt. of the plaque. Approximately half of this hexose was extractable with water and alkali. After incubation at 37 °C for 24 hr only 10 per cent dry wt. of the plaque estimated as hexose and again approximately half of this value represented extractable hexose. This loss of hexose on incubation was accompanied by the production of acid which, if not neutralized, partially inhibited the loss of hexose. These results indicate that dietary sugar can be retained by human plaque as intra- and extracellular polysaccharides and that half of this polysaccharide is metabolized to acid in 24 hr. This breakdown is a self-controlling process which combined with the remaining extracellular polysaccharide bears a close resemblance to systems shown to produce artificial lesions in vitro.