Comparative fermentability of sorbitol, glucose and glycerol by common oral microorganisms

Effect of polyol gums on dental plaque in orthodontic patients

Sixty 11- to 15-year-old children wearing fixed orthodontic appliances were given chewing gums containing polyol for daily use after meals and snacks, to study whether the chewing of gums that contained slowly fermentable polyols (xylitol and sorbitol) affects the amount of dental plaque and the number of mutans streptococci present in plaque and saliva. The 60 subjects were randomly divided into four groups, each of which was provided with a supply of 1.35 gm pellet-shaped gums for a period of 1 month, as follows: (1) xylitol; (2) sorbitol; (3) xylitol-sorbitol mixture I (3:2); and (4) xylitol-sorbitol mixture II (4:1). In each group, two pellets with a total initial gum mass of 2.7 gm (maximum polyol dose per day: 10.5 gm), were used six times a day. The fresh and dry weight of dental plaque, collected at baseline and 28 days later from incisors, canines, and premolars from the area between gingival margin and the bracket, reduced in all groups, but most significantly (by 43% to 47%) in children receiving xylitol gum. The plaque and saliva levels of mutans streptococci did not change in the sorbitol group, but was significantly (in most cases) reduced by 13% to 33% in groups that received gum containing xylitol. Provided that the quantity of dental plaque and the plaque and salivary levels of mutans streptococci can be regarded as risk factors in dental caries, these results suggest that regular use of polyol gum--and especially gum that contains xylitol as the predominant sweetener--can reduce the caries risk in young patients wearing fixed orthodontic appliances.

Effect of culture medium on acid production from sorbitol by oral bacteria

The fermentation of sorbitol or glucose and the acid production by strains belonging to the genera Actinomyces, Lactobacillus, and Streptococcus isolated from the predominant sorbitol-fermenting human dental plaque flora were studied in cultures in complex or defined bacteriologic broths and in saliva-based broth. The growth yields of Lactobacillus and Streptococcus in the saliva-based media and of Actinomyces in the defined broth were poor. Addition of fermentable carbohydrate to the saliva-based broth favored the growth of Streptococcus and Lactobacillus but not that of Actinomyces. The results showed obvious differences in the capacity of oral bacteria to ferment sorbitol between cultures in saliva-based and bacteriologic broths. Lactobacillus failed to utilize sorbitol when saliva was the only source of nutrients. Lower proportions of lactic and formic acids were formed from sorbitol by Actinomyces and Lactobacillus in the saliva-based than in the bacteriologic media. The findings illustrate some mechanisms possibly involved in the interactions between sorbitol and dental plaque flora.

In vivo measurements of sulcal plaque pH after topical applications of sorbitol and sucrose in rats fed sorbitol or sucrose

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.

Effects of 3 months frequent consumption of hydrogenated starch hydrolysate (Lycasin), maltitol, sorbitol and xylitol on human dental plaque

Lozenges containing hydrogenated starch hydrolysate (Lycasin), maltitol, sorbitol or xylitol were consumed 4 times daily during 3 months by 4 groups of persons (in all 85 subjects). In the maltitol-, sorbitol- and xylitol-group the plque wet weights were of the same magnitude before and after the test period. In the Lycasin-group, a higher value was found after than before the 3-month period (p less than 0.01). The acid production in suspensions of dental plaque material from Lycasin, maltitol and sorbitol expressed as per cent of that from glucose was approximately the same before and after the test period. From xylitol no acid production could be demonstrated either before or after the 3-month period. There were no statistically significant differences between the plaque pH-changes induced by rinsing with 50% solutions of Lycasin, maltitol, sorbitol or xylitol before and after the test period. However, there was a tendency (p less than 0.05) towards lower pH-values induced by the maltitrol and sorbitol rinse after the 3-month period compared with before. No difference in the relative numbers of facultative anaerobic streptococci. Streptococcus mutans or facultative anaerobic lactobacilli before and after the test period was found.

Acid production from Lycasin, maltitol, sorbitol and xylitol by oral streptococci and lactobacilli

The acid production from maltitol was compared with the acid production from hydrogenated starch hydrolysate (Lycasin), sorbitol and xylitol by a number of oral strains and reference strains of Streptococcus mutans, S. sanguis, S. salivarius, S. mitior, S. milleri, S. faecalis, S. faecium, S. avium, Lactobacillus casei and L. salivarius. The polyols were added to a final concentration of 1.0% to two different basal media. Incubation was performed at 37 degrees C for 7 days after which the pH was recorded. Maltitol was fermented only by the lactobacilli (about two thirds of the strains). Lycasin was fermented by all strains of S. faecalis, more than 90% of the lactobacilli, about half of the S. sanguis strains, about one third of the S. mutans strains, and by a few other streptococcal strains. Acid production from sorbitol was observed among more than 80% of the S. mutans strains and the S. faecalis strains and most of the lactobacilli strains. Sorbitol-fermenting strains of S. sanguis and of S. mitior, all isolated from sorbitol-consumers, were observed. No other sorbitol-fermenting streptococci were found. Only the reference strains L. salivarius subsp. salivarius ATCC 11741 and S. avium ATCC 14025 fermented xylitol.