Fillings are required when there is a cavity or hole in your tooth due to decay or trauma. When a filling is required there is a variety of filling materials that can be used, all of which have unique properties and advantages.
A tooth filling is generally made from composite and is used to prevent further damage to a tooth. Most commonly, a filling will be used to seal a tooth off from bacteria to prevent further decay. Fillings are designed to be virtually invisible.
Constant wear and tear can cause fillings to, chip or crack, creating the seal between the filling and tooth to break allowing food particles and decay-causing bacteria. However if you see your dentist regularly, this can be avoided.