A filling is a way to restore a tooth damaged by decay back to its normal function and shape. The first step is to remove the decayed material from the tooth; the affected area is then cleaned, shaped and filled with a filling material.

By closing off spaces where bacteria can enter, a filling helps protect the tooth by preventing further decay. Materials used for fillings include composite resin (white fillings), and an amalgam (an alloy made of silver and other metals). No one type of filling is best for everyone. What is right for you will be determined by the extent of the decay and where in your mouth the filling is needed.

What is Tooth Decay?

Tooth decay, also known as dental caries, is an infectious disease that damages tooth structures, resulting in cavities, which are holes in the teeth. It is one of the most common diseases throughout the world; it is estimated that 95 % of the population has had at least one cavity.

A cavity occurs on a tooth surface where enough of its mineral content has been lost that a hole has formed. The process by which this occurs is called demineralization and it takes place because of the presence of acids on a tooth's surface. When acids build up on an unprotected tooth surface, they dissolve the minerals in the enamel, creating holes and weak spots (cavities). As the decay spreads inward into the middle layer (the dentin), the tooth may become more sensitive to temperature, touch, food and sweets. When the decay reaches the centre of the tooth (the pulp), the resulting inflammation leads to a bad toothache.

The acids that cause tooth decay are produced by specific types of bacteria that live in a complex colony called a biofilm. A biofilm is a well-organized colony of bacteria that adheres to surfaces and is embedded in a slime layer. A biolfim in your mouth is called dental plaque.

The bacteria in dental plaque consume sugars that start to produce the acids that cause tooth demineralization (tooth decay). Dental plaque not only provides a home for oral bacteria but it also acts as a medium that holds the acid they produce directly against a tooth's surface.

Everyone's mouth is inhabited by bacteria, but you can minimize your potential for having tooth decay by regular brushing and flossing, thereby not allowing the bacteria that are present to form organized colonies. Remember, there must be both dental plaque and dietary sugars present for tooth decay to occur. It is important to brush and floss often and effectively to completely remove dental plaque from all tooth surfaces. Also, limit the amount, frequency, and duration of sugars in your mouth.