The gut microbiome in oral health and disease: evidence toward bidirectional oral-gut axis communication

The oral-gut microbiome axis has largely been seen as a unidirectional framework, in which dysbiotic oral flora is considered to contribute to gastrointestinal and systemic disease. However, recent evidence now challenges this view, indicating that gut microbial imbalance can act upstream to modulate oral immune homeostasis and disease susceptibility. Therefore, in the current perspective paper, we present a structured narrative review that synthesizes recent evidence from human microbiome, immu