Probiotic treatment increases salivary counts of lactobacilli: a double-blind, randomized, controlled study

Lactobacilli are used in the prevention and treatment of several diseases, but they are also known to play a role in the pathogenesis of dental caries. The aim of our study was to evaluate whether the oral administration of lactobacilli could change the salivary counts of these bacteria compared with placebo. Moreover, lactobacilli were administered in liquid and in capsule form to determine the role of direct contact with the oral cavity.

Thirty-five healthy volunteers were randomized into three groups to receive lactobacilli and/or placebo for 45 days: group A (n = 14) received probiotics in capsules and placebo in liquid form; group B (n = 16) took liquid probiotics and placebo in capsules, and group C (n = 5) used placebo in both liquid and capsule form. Streptococcus mutans populations served as control. The salivary counts of lactobacilli and S. mutans were measured semi-quantitatively using the CRT bacteria kit.

Compared with placebo, the oral administration of probiotics, both in capsules and in liquid form, significantly increases salivary counts of lactobacilli (p = 0.005 and p = 0.02, respectively). S. mutans populations were not significantly modified.

The increased salivary counts of lactobacilli may indicate the need to closely monitor the dental health of patients undergoing long-term probiotics treatment, even when this treatment is administrated in a form that avoids direct contact with the oral cavity.