Composition of subgingival microbiotas has long been seen as being of primary importance in the etiology of periodontal diseases. Development of advanced molecular methods has improved our knowledge about the role of traditional periodontal pathogens as well as resulted in the recovery of novel pathogen candidates. Detection rates of these microorganisms vary considerably between geographical regions but also between ethnic groups within a country. We have gathered information of various types of microorganisms inhabiting subgingival sites of individuals living in different parts of the world for the present review, the purpose of which is to highlight the potential impact of geography and ethnicity on subgingival findings, especially in chronic periodontitis.
