[Dental plaque pH in patients with hereditary fructose intolerance]

There is little doubt that the initial cariogenic attack upon dental enamel is caused by acids stemming from metabolic activity of dental plaque microorganisms fermenting carbohydrates. However, a direct correlation between caries activity and pH changes of plaque has not yet been established. In-vio and in-vitro plaque pH was recorded in 4 caries-free HFI children by the method of Graf, R., and Graf, H. Application of 10% glucose were followed regularly by pH drops from the fasting range pH 6.2-7.2) reaching values of 4.7 to 6.5 after 20 minutes. These were comparable to values found in normal subjects. 10% sucrose treatment resulted in a slower and less pronounced pH lowering, reaching a pH between 4.8 and 6.5 compared to normal control subjects, which showed the classical drop down to pH 4.0 to 4.3 The results indicate that human dental plaque grown under sucrose- free conditions cannot metabolize sucrose (or its initial breakdown produce fructose) to produce an in-vivo pH drop below the critical range of enamel demineralization. The zero caries activity of the children may be explained by the lack of a demonstrable classical pH drop or acid attack.