Used wax dental floss with cheek cells (yellow) and bacteria (green) on dental floss fibres (pink), coloured scanning electron micrograph (SEM). Cheek cells often get scraped from the inside of your mouth when flossing your teeth. Numerous bacteria are present as part of the normal mouth flora. Bacterial plaque consists of a film of bacteria embedded in a glycoprotein matrix. The matrix is formed from bacterial secretions and saliva. The microorganisms that form the plaque biofilm are almost entirely bacteria (mainly Streptococcus mutans and other anaerobes) with the composition varying by location in the mouth. Plaque is the main cause of tooth decay. The bacteria feed on sugars in food, producing acid as a waste product. This acid corrodes the teeth's enamel coating, resulting in dental cavities. A build-up of dental plaque can also lead to inflamed and infected gums. Severe gum disease can lead to teeth falling out. Magnification: x500 when