In vivo Measurements of Sulcal Plaque pH After Topical Applications of Sorbitol and Sucrose in Rats Fed Sorbitol or Sucrose

Abstract

To test whether adaptation to sorbitol could be observed in rat plaque, we made pH measurements of rat sulcal plaque in vivo, following topical application of 10% sorbitol solution. Rat pups were inoculated orally with S. mutans 6715 and fed diet MIT 305 (5% sucrose) for 16 days. Baseline sulcal plaque pH response of these rats to topical application of 10% sorbitol solution was measured. One group of 16 rats was then fed 20% sucrose in the diet, and a second group 20% sorbitol. After 13 days' feeding of the experimental diets (four days were used for accommodation to dose, and nine days at the 20% level for sorbitol), there was a significantly greater (p less than 0.01) drop in pH following topical application of 10% sorbitol in this group than in the sucrose-fed group. There was no difference in the pH response of the two groups to topical application of a 10% sucrose solution when tested six days later. The sulcal enamel caries score was significantly higher (p less than 0.001) in the sucrose group, but buccal enamel scores were similar in both groups. Adaptation in rat plaque took place, and could be measured in vivo as an increased drop in sulcal plaque pH following topical application of sorbitol. It is not clear whether this adaptation was primarily due to selection of sorbitol-fermenting micro-organisms, or, more likely, by induction of sorbitol-specific enzymes. Relative to the sucrose-containing diet, the sorbitol diet was hypocariogenic, even under experimental conditions.

The use of sorbitol- and xylitol-sweetened chewing gum in caries control

“…14 Cariogenic microorganisms can "learn" to metabolize sorbitol when their sugar supply is restricted; this form of adaptation to sorbitol has been demonstrated in animals. 15 Firestone and Navia 15 suggested that this adaptation could have occurred owing to selection by sorbitol-fermenting bacteria or induction by sorbitol-specific metabolizing enzymes. Chewing sorbitol-sweetened gum for about five minutes after receiving a sucrose rinse has been shown to substantially reduce demineralization.…”

Effect of dentifrices containing sorbitol, combination of xylitol and sorbitol on salivary Streptococcus mutans and Lactobacillus counts in 14-15 year old children: a randomized trial

“…Firestone and Navia suggested that this adaptation could have occurred owing to selection by sorbitol-fermenting bacteria or induction by sorbitol-specific metabolizing enzymes. 18 Combination of xylitol and sorbitol are used in various products. Study carried out by the Hujoell, Makinen on acid production in the oral cavity from sorbitol in the presence of xylitol in chewing gum containing sorbitol reduces acid production from sorbitol.…”

Sulcal Plaque pH and Remineralization of Sulcal Caries in Rats Exposed to Dietary and Water Fluoride

“…The method used to measure in vivo plaque pH in rats has been reported elsewhere [Firestone and Navia, 1986b], Briefly, the ani mals are restrained, placed in a holder, and their mouths gently held open. A 200-pl volume of distilled water is used to rinse saliva from the maxillary left first molar.…”