Dental plaque. Coloured scanning electron micrograph (SEM) of a fracture through a tooth showing dental plaque (top) and dentin (bottom). Plaque consists of a film of bacteria embedded in a glycoprotein matrix. The matrix is formed from bacterial secretions and saliva. 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 caries. A build-up of dental plaque can also lead to inflamed and infected gums. Severe gum disease can lead to teeth falling out. Dentin is mineralised connective tissue, that makes up the majority of the tooth. Magnification: x350 when printed at 10 centimetres wide.