Abstract
Dental caries are caused when acid, produced by bacteria found in plaque, demineralizes the teeth. However, caries can be prevented by a low concentration of fluoride in dental plaque. One way in which fluoride acts to prevent dental caries is through its anti-enzyme activity that inhibits the glucose metabolism of plaque bacteria, thereby reducing their production of organic acids, such as lactic acid. To clarify the actual effects of fluoride, we investigated the effects of fluoride on dental plaque bacteria by rinsing the mouth with either a 250 ppmF sodium fluoride (NaF) solution (experimental group,n＝10) or distilled water (control group, n＝10), followed 10 min later by a 10% glucose solution rinse and measurement of the lactic acid produced during bacterial metabolism. Dental plaque was collected 5 min after the glucose rinsing, and the fluoride, lactate, and glucose concentrations in the collected plaque were measured. The following results were obtained :・The fluoride concentration was significantly increased in the experimental group compared to the control group.・The experimental group showed a significantly decreased concentration of lactate production after glucose rinsing compared to the control group.・The experimental group tended to have a large concentration of residual glucose.The results of this study indicate that fluoride ions are incorporated into the plaque during NaF mouth rinsing, thereby inhibiting the production of lactic acid by plaque bacteria. However, because rinsing with NaF only temporarily increased fluoride concentration in dental plaque, in the future, it will be necessary to consider how to maintain a high concentration of fluoride in dental plaque over the long term.
