[Comparative studies of dental plawue in students with and without dental caries. I. Enzymatic determination of the capacity to synthesize lactic acid in an aerobic medium].

In cultures of dental plaque taken from healthy dental surfaces of children susceptible to caries and children free from caries, the lactic acid content was determined. The cultures had an initial germ count of between 10(3) and 10(4) organisms per ml. After the cultures had been kept in artifical saliva for 7 hours under aerobic conditions, the samples of caries-susceptible children showed a considerably higher acid content than those of caries-free children. In comparative tests carried out in plaque samples simultaneously taken from the same dentitions, the micro-organisms of the samples taken from carious dental surfaces produced more lactic acid under the above mentioned conditions than those of the plaque samples taken from healthy dental surfaces.