Clearance and metabolism of starch foods in the oral cavity.

The presence of carbohydrates and organic acids was monitored in the oral cavity over a 3-hour period following the ingestion of six foods containing cooked starch (popcorn, potato chips, corn flakes, bread stick, hard pretzel and wheat cracker) and compared to a food containing sugar (chocolate-covered candy bar). Oral fluid samples were collected at 30-min intervals from five different tooth sites from 7 volunteers using absorbent paper points. Samples were analyzed for carbohydrates and organic acids using high-performance liquid chromatography. Analytical data for each food were pooled and compared to the results of the sugar food. The amount of lactic acid produced 30 min after ingestion was highest with the potato chips and lowest with the corn flakes. Potato starch contributed more readily to oral lactic acid production than wheat or corn starch. A direct linear relationship existed between lactic acid production and the presence of oral glucose produced from starch, which occurred via the metabolites maltotriose and maltose. Oral clearance of foods containing cooked starch proceeded significantly slower than that of the sugar food, thus contributing to a prolonged period of lactic acid production.

Enhanced retention of glass-ionomer sealant by enamel etching: a microleakage and scanning electron microscopic study.

OBJECTIVE: A microleakage study and a scanning electron microscopic investigation were conducted to test whether etching of enamel would improve adhesion of glass-ionomer cement sealants to fissure enamel. METHOD AND MATERIALS: Forty-eight extracted human molars and premolars were divided into 2 equal groups, and their crowns were cleaned with pumice. In group 1 enamel was etched for 45 seconds with 37% phosphoric acid. In group 2, enamel was not etched. Glass-ionomer sealant was applied to all 48 teeth. Twenty teeth from each group were thermocycled in water (120 cycles between 0 degree C and 56 degrees C) and stained with 0.5% methylene blue solution. The remaining 4 teeth from each group served as a control for the scanning electron microscopic evaluation. Twelve teeth from each group were cut into 5 sections, and 12 were cleaved into 3 sections in a buccolingual direction. RESULTS: Statistically significant differences in amounts of microleakage were found between group 1 and group 2. Minimal microleakage was detected in 90% of the etched teeth, whereas extensive microleakage was observed in 85% of nonetched teeth. The scanning electron microscopic evaluation correlated positively with the microleakage observations. The etched teeth revealed a cohesive failure within the sealant material, while the nonetched teeth demonstrated an adhesive failure at the sealant-enamel interface. Observation of the nonthermocycled teeth confirmed those findings. CONCLUSION: Results suggested that etching prior to application enhances the bonding of glass-ionomer sealant to fissure enamel.