Dental fillings are placed to restore teeth when there is a cavity, or when they have fractured or chipped. Fillings are subject to the same stresses that your teeth are such as chewing, grinding and clenching, so fillings may fracture, chip or wear just as your teeth do. The tooth structure surrounding the filling provides support and can be damaged by grinding or clenching as well as plaque and acidic food or drink in your diet.
If the supporting tooth structure weakens the filling may need to be replaced. When a filling is placed the margin between the filling and tooth is tight and sealed, if this margin breaks down bacteria can leak into this area and there is a risk of a cavity adjacent to the existing filling, if this happens it is best to replace the filling before the cavity can grow.
Keeping your teeth free of plaque and avoiding sugars and acidic foods will keep tooth structure strong so it can better support your fillings and they may last longer. Your dental exam will include an evaluation of your fillings, the dentist will be checking for fractures and wear, as well as any leakage at the margin between filling and tooth structure.