Abstract
Six subjects wore intra-oral devices carrying eight bovine enamel blocks which were covered with a layer of S. mutans. They rinsed their mouths for five sec, one min, or multiples of one min with a 5 or 10% glucose (G) solution. Demineralization was measured after 45 min by determining the change in iodide permeability (ΔIp) of the enamel. In addition, saliva samples, taken at intervals during the test, were analyzed for G, and the time of clearance (t c ) was calculated. Demineralization scores (ΔIp) were consistently greater from the 10% than from the 5% G solution. Both solutions produced an increase in ΔIp with an increase in the rinsing time (t r ). The G remaining in saliva after the rinse did not significantly affect ΔIp. The ΔIp scores showed good correlation with the final pH of the S. mutans cell mass, r= -0.77. For each rinse solution, the scores also showed good correlations with t r (r=0.87 and 0.79) and much weaker correlations with t r + t c (r=0.44 and 0.53). Continuous in vitro exposure to 1, 5, or 10% solutions of sucrose (S) in saliva for 30 min or more caused a linear increase in ΔIp with time with no concentration effects. A linear increase was also observed in vivo when a one-minute mouth-rinse with 10% solution of S was administered every 30 min. The findings indicate that significant demineralization may occur while carbohydrate foods are consumed, and that brushing the teeth or rinsing the mouth after meals may not be as effective against caries as is generally believed.
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