Bacteria colonize biological and inert surfaces in the form of matrix-encapsulated communities referred to as biofilms. These microbial biofilms are a highly distinct form of microbial life compared with the planktonic, or freely floating, form of microbial life that has been exhaustively studied for the last century. Bacterial biofilms account for the majority of chronic diseases, including gingivitis, endocarditis and nosocomial infections. Microbial biofilms are involved in approximately 65 % of human bacterial infections and up to 60 % of hospital acquired infections are caused by biofilms that contaminate implants and catheters. Oral diseases, such as dental caries and periodontal disease, should be considered as consequences of ecologically driven imbalances of oral microbial biofilms. Control of oral biofilms is fundamental to the maintenance of oral health and to the prevention of dental caries, gingivitis, and periodontitis.