Variation in human oral lactobacilli following a change in sugar intake

For 19 wk oral lactobacilli was registered continuously in 10 dental hygienist students. During the study period these subjects were submitted to a change in between-meals consumption, rinsing with chlorhexidine and determination of sugar clearance, flow rate and buffer effect of saliva. An increase in the frequency of sugar consumption increased the number of lactobacilli in saliva, and in particular of Lactobacillus casei. However, in spite of an hourly intake of sugar between 7 a.m. and 9 p.m. every day for 4 wk, this increase of lactobacilli was small. The probable reason for this was the very high dental health consciousness of the test subjects, with a perfect oral hygiene and a strong wish to have a clean taste in the mouth. The sugars were too rapidly eliminated to create such an acid oral environment as favors the aciduric lactobacilli. A week of twice daily rinsing with chlorhexidine had no obvious effect on the number of lactobacilli in saliva.