Salivary mutans streptococci and lactobacilli levels after ingestion of the probiotic bacterium Lactobacillus reuteri ATCC 55730 by straws or tablets

Objective. Previous studies have suggested that lactobacilli-derived probiotics in dairy products may affect oral ecology, but the impact of different vehicles of ingestion has received little attention. The aim of the present study was to investigate the effect of the probiotic bacterium Lactobacillus reuteri ATCC 55730 on the levels of salivary mutans streptococci and lactobacilli in young adults when ingested by two different delivery systems. Material and Methods. The material comprised 120 healthy young adults ( 21 - 24 years) and a placebo-controlled study design with parallel arms was utilized. The subjects were randomly assigned to four equally sized groups: group A drank 200 ml of water through a prepared straw containing L. reuteri ATCC 55730 once daily for 3 weeks, while group B took 200 ml water through a placebo straw during the same period. Group C was given one tablet containing L. reuteri ATCC 55730 once daily for 3 weeks, while group D received placebo tablets without bacteria. Salivary mutans streptococci and lactobacilli were enumerated with chair-side kits at baseline and 1 day after the final ingestion. Results. A statistically significant reduction of the mutans streptococci levels was recorded after ingestion of the probiotic bacteria via the straw ( p < 0.05) and the tablets ( p < 0.01), which was in contrast to the placebo controls. A similar but non-significant trend was seen for lactobacilli. Conclusions. A short-term daily ingestion of lactobacilli-derived probiotics delivered by prepared straws or lozenges reduced the levels of salivary mutans streptococci in young adults.