Recent studies have revealed that oral bacteria themselves may enter the bloodstream, form into clumps, and trigger systemic inflammation and disease.
Additionally, "it has been recognized that oral infection, especially periodontitis, may affect the course and pathogenesis of a number of systemic diseases, such as cardiovascular disease, bacterial pneumonia, diabetes mellitus, and low birth weight." *
Reference: Li, X., Kolltveit, K. M., Tronstad, L., & Olsen, I. (2000). Systemic diseases caused by oral infection. Clinical microbiology reviews, 13(4), 547–558. https://doi.org/10.1128/CMR.13.4.547