The oral microbiome, comprising bacteria, fungi, viruses, and protozoa, is essential
for maintaining both oral and systemic health. This complex ecosystem includes over
700 bacterial species, such as Streptococcus mutans, which contributes to dental caries
through acid production that demineralizes tooth enamel. Fungi like Candida and pathogens
such as Porphyromonas gingivalis are also significant, as they can lead to periodontal
diseases through inflammation and destruction of tooth-supporting structures. Dysbiosis,
or microbial imbalance, is a key factor in the development of these oral diseases.
Understanding the composition and functions of the oral microbiome is vital for creating
targeted therapies for these conditions. Additionally, the kynurenine pathway, which
processes the amino acid tryptophan, plays a crucial role in immune regulation, neuroprotection,
and inflammation. Oral bacteria can metabolize tryptophan, influencing the production
of kynurenine, kynurenic acid, and quinolinic acid, thereby affecting the kynurenine
system. The balance of microbial species in the oral cavity can impact tryptophan
levels and its metabolites. This narrative review aims to explore the relationship
between the oral microbiome, oral diseases, and the kynurenine system in relation
to certain systemic diseases.
