Plaque is a biofilm that contributes to two oral diseases: dental caries and periodontal disease. It is a complex community of microorganisms. Biofilm can not only cause decay or periodontal disease it also contributes to peri-mucositis and peri-implantitis around dental implants. The initial layer or formation of plaque is called the acquired pellicle. This layer will reform immediately after removal and will also form on artificial prosthesis, such as dentures. With over 800 species of aerobic and anaerobic bacteria in the human oral cavity, microbes grow as complex colonies in biofilm. In fact, it takes only two days for plaque to double in mass. Although calculus is an irritant, plaque is the contributing factor to periodontal disease rather than calculus. Daily removal of biofilm is critical to reduce oral diseases.