A filling is a way to restore a tooth damaged by decay back to its normal function and shape when it effects less than 50% of the tooth structure. If you have a tooth that requires a filling, the dentist will first remove the decayed tooth material, clean the affected area, and then fill the cleaned out cavity with a filling material. A filling helps prevent further decay by closing off any cracks or spaces where bacteria can enter. Fillings only protect the tooth when the width is less than 50% of the tooth. When the decayed area is greater than 50% a filling does not adequately strengthen the tooth. This leaves the tooth subject to fracture which can result in root canal or tooth loss.
Amalgam (silver) has stood the test of time for over a hundred years. That being said they have not advanced significantly in that time period. With advancement of composite resins their indication is more and more limited. They still have a limited application clinically when composite resin cannot be used. Limitations of silver fillings are esthetics, more tooth structure needs to be removed for bulk of material, expansion/contraction issues.
Composite resins are custom made to the color of your natural teeth, creating a more natural appearance. These restorations allow the dentist to remove only infected tooth structure because they are bonded to the tooth. Silver fillings in smaller cavities require the removal of healthy tooth structure for material bulk to resist fracture. Another benefit of composite resin is that it expands and contracts more similiar to tooth structure. Silver fillings expand and contract with hot and cold foods very differently than tooth structure leading to gaps between the tooth and the filling over time. These gaps are impossible to keep clean as the tooth brush bristles cannot get into the gaps and a cavity will develop.
Porcelain fillings are called inlays or onlays and are custom created in a lab and then bonded to the tooth. They are just like composite resin with some added benefits of resisting stain and lasting longer.
If decay or a fracture has damaged more than 50% of the tooth, a crown (or “cap”) may be required to prevent tooth fracture which could lead to root canal or tooth loss.