Subgingival Biofilm Communities in Health and Disease

Oral biofilm-related diseases such as periodontal disease are infection processes that arise from the resident (indigenous) flora. Prior to the development of a periodontal lesion, a change in the proportion of certain species with greater pathogenic potential occurs within the biofilm. This change from a “commensal” flora to one considered pathogenic is accompanied by a disruption of the immune homeostasis and development of an inflammatory response. Chronic inflammation of the supporting periodontal structures eventually progresses to tooth loss. Although periodontal diseases have a multifactorial etiology in which environmental and host factors play an important role, polymicrobial biofilm communities with pathogenic properties are the primary etiological factor of periodontal lesions. Therefore, a thorough understanding of the events that lead to the maturation of subgingival biofilm communities is necessary in order to develop better diagnostic and treatment strategies. This review article will summerize our current understanding of the ecology of subgingival biofilms and the role of these multi-species communities as etiological agents of periodontal disease. An overview of the process of subgingival biofilm formation will be presented followed by a description of the ecological determinants of biofilm development in the subgingival environment. Finally, the concept of subgingival polymicrobial biofilm communities as the etiological agents that initiate a host-mediated inflamamtory response will be discussed.