Sorbitol adaptation of dental plaque in people with low and normal salivary-secretion rates.

Caries-related bacteriological and biochemical factors were studied in 12 persons with low and 11 persons with normal salivary-secretion rates before and after a four-week period of frequent mouthrinses with 10% sorbitol solution (adaptation period). After the adaptation period, an increase in total numbers of sorbitol-fermenting bacteria and mutans streptococci was found in plaque samples from both groups. The pH drop in dental plaque in situ after a mouthrinse with sorbitol was more pronounced after the adaptation period, especially in the group with the low salivary-secretion rate. Increased acid production in plaque from sorbitol was also observed in the two groups in vitro. The composition of the fermentation end-products was affected by the sorbitol exposure. It is suggested that in subjects with diminished natural protection against caries development, such as patients with low salivary-secretion rate, a cariogenic potential of sorbitol should be considered when this polyol is included in products that might be used frequently.