In recent years we have seen an exponential growth in scientific research aimed at characterising the structure and composition of the microbiota, which colonises various organs and systems. These investigations were supported by the development of very recent microbiological analysis techniques, most of which include molecular methods. In more recent times, however, scientific research has focused more on the study and characterization of relationships between the microbiota and systemic diseases. The purpose of this review is to present the scientific evidence, published from April 2019 to March 2020, on the relationships between oral microbiota and systemic pathologies.