Tooth decay is the gradual erosion of enamel (the protective covering of the tooth) and dentine (the substance below the enamel). Plaque formation is the main cause of tooth decay. The most common sites of initial decay are areas where plaque easily becomes trapped,�such as the grinding surfaces of the back teeth (which have minute grooves in them), the lateral (side) edges of adjacent teeth, and near the gum line. Plaque consists of food remains, salivary mucus by-products, and the bacteria that live in the mouth.
The bacteria feed mainly on the fermentable carbohydrates (simple sugars and starches) in food, and in breaking them down, create an acid that gradually destroys enamel, forming a cavity. If the process is not checked, the dentine gets eroded. The cavity gets enlarged enabling the bacteria to invade the pulp at the centre of the tooth and causes infection.
Early decay does not usually cause any symptoms. The chief symptom of advanced decay is tooth ache, which may be aggravated by eating very sweet, hot or cold food. Decay may also cause bad breath.
Treatment consists of the drilling away the area of decay and filling the cavity with either dental amalgam (a mercury alloy) or cement (a composite resin that matches the colour of the tooth). In cases of advanced decay, it may be necessary to remove the infected pulp (the central, living part of a tooth) and replace it with a filling or to extract the tooth.
It is a modern dental procedure to save a tooth in which the pulp (the living tissue within a tooth) has died or become untreatably diseased, usually as a result of extensive dental caries.
(1) A hole is drilled into the crown to remove all material from the pulp chamber. The root canals are then cleaned with fine-tipped instruments. The procedure is usually monitored by X-rays.
(2) The cavity is washed out, and antibiotic paste and a temporary filling are packed into it. Some days later, the filling is removed and the canals are checked for sterlity.
(3) When no infection can be detected, the cavity is filled with a sealing paste and/or tapering solid ' point' made of gutta - percha resin mixed with zinc and bismuth oxides. The mouth of cavity is then sealed with cement.