Plaque is a biofilm that contributes to two oral diseases: dental caries and periodontal disease. It is a complex community of microorganisms that have a negative surface charge that attaches to the host surface enamel or gingiva. Biofilm can also contribute to peri-implantitis. The initial layer or formation of plaque is called the acquired pellicle. This layer will reform within two hours after removal and will also form on artificial prosthesis, such as dentures. With over 700 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. Plaque requires the following to metabolize: streptococci mutans and a processed carbohydrate. The end product, lactic acid consists of intracellular polysaccharides and extracellular polysaccharides. When plaque is not removed from the oral cavity it may mineralize and become calculus. This mineralized formation is formed by calcium and phosphates in the saliva and it has been found that tobacco use accelerates the formation of calculus. However, recent research studies link plaque as the contributing factor to periodontal disease rather than calculus. Daily removal of biofilm is critical to reduce oral diseases.