Lactobacilli and human dental caries: more than mechanical retention

Abstract

Lactobacilli have been considered as major contributors to human dental caries for over a century. Recent in vitro model studies have shown that when compared to Streptococcus mutans, a keystone pathogen of human dental caries, the ability of lactobacilli to form biofilms is poor, although differences exist between the different major species. Further studies using molecular and bioinformatics approaches provide evidence that multiple mechanisms, including adhesin-receptor mediated physical contact with S. mutans , facilitate the adherence and establishment of lactobacilli on the tooth surface. There is also evidence that under conditions like continuous sugar consumption, weak acids and other antimicrobials such as bacteriocins from lactobacilli can become detrimental to the microbial community, especially those in the proximity. Details on the underlying mechanisms of how different Lactobacillus sp. establish and persist in the highly complex microbiota on the tooth surface await further investigation.

Epigallocatechin gallate (EGCG) alleviates the inflammatory response and recovers oral microbiota in acetic acid-induced oral inflammation mice

“…It has also been considered to be related to dental caries for over a century. 67 In a clinical trial involving children with a high prevalence and risk of caries, EGCG reduced the abundance of Lactobacillus in their oral cavities. 68 This observation further suggests that EGCG may regulate Lactobacillus levels to a range that promotes oral health.…”

Antimicrobial activity of Limosilactobacillus fermentum strains isolated from the human oral cavity against Streptococcus mutans

“…Interestingly, the three non-functional isolates survived at pH 2.5 while the nine functional isolates only survived at pH 3.0 than the three non-functional isolates (Supplementary Fig. S1 ), suggesting differences in proton pumping, proton consumption, or alkali production pathways between the two groups 30 .

Figure 2 L. fermentum -mediated S. mutans growth inhibition is mediated by H 2 O 2 .

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The submandibular and sublingual glands maintain oral microbial homeostasis through multiple antimicrobial proteins

“…Here, we manipulated constituents of saliva by removing the SMG or SLG. Lactobacillus , a major contributor to dental caries ( Wen et al., 2022 ), was significantly more abundant in both removal groups and showed strong acid tolerance. Lactobacillus has been shown to survive strong acidity.…”