THE ACIDITY OF SALIVA AFTER INGESTION OF CARBOHYDRATE- AND ACID-CONTAINING SUBSTANCES

stated that there is little doubt that the direct cause of tooth decay is the breakdown of carbohydrate foodstuffs on the surface of the teeth, forming acids,' and that it is now widely believed that decay of the enamel is caused by acids produced in fermentation of sugars.2 In studying a factor which might have a bearing on this process, we have investigated and previously reported data on the magnitude and duration of concentrations of carbohydrate in the saliva after ingestion of a variety of common carbohydrate-containing substances.3 It is now generally accepted by dental research workers that this decalcify-ing action of acid resulting from carbohydrate in the mouth is not related to acidity of the saliva but is due to isolated areas of high acidity on the surfaces of the teeth which are protected from the diluting and neutralizing action of the saliva. However, a number of studies have been recently reported in which teeth were immersed in acidulated liquids in vitro,4 or in which acidulated liquids were fed to animals5-"1 with resulting erosion of the teeth. Although several of these reports have warned that the animal experiments do not justif