species as oral residents and infectious agents with potential impact on systemic conditions.

Oral are known as anaerobic commensals on oral mucosae and in dental plaques from early life onwards, including pigmented and and non-pigmented species. Many species contribute to oral inflammatory processes, being frequent findings in dysbiotic biofilms of periodontal diseases (), cariotic lesions ( (formerly ) ), endodontic infections (), and other clinically relevant oral conditions. Over the years, several novel species have been recovered from the oral cavity without knowledge of their clinical relevance. Within this wide genus, virulence properties and other characteristics like biofilm formation seemingly vary in a species- and strain-dependent manner, as shown for the group organisms (, and ). Oral species are identified in various non-oral infections and chronic pathological conditions. Here, we have updated the knowledge of the genus and the role of species as residents and infectious agents of the oral cavity, as well as their detection in non-oral infections, but also gathered information on their potential link to cancers of the head and neck, and other systemic disorders.