Periodontal diseases are infections caused by micro-organisms that colonize the tooth surface at or below the gingival margin and results from the formation of biofilms on tooth surfaces and are of immediate concern. Dental biofilms are defined as a diverse community of microorganisms living as a structural unit,with complex communication pathways between species. The presence of a oral biofilm alone is often not sufficient to cause disease because most oral biofilm-associated diseases are complex with a multifactorial etiology. Advances in molecular techniques have given rise to a much greater understanding of the diversity and complexity of human micro-biota communities,including dental plaque. Plaque development may no longer be thought of in generic terms,but rather,as a highly individualized process. With that come new avenues for the understanding of plaque development in relation to its host,and therefore the potential for the development of more effective treatments.