Fillings are made to fill holes in a tooth. When a tooth is broken down or a filling starts to make up most of the tooth, it is time for a crown. A crown is more effective because it is stronger and it encloses the tooth ensuring that the force of biting is equally distributed to the root. Crowns are made of gold, gold and porcelain, zirconia and porcelain, or straight porcelain. We tend to stay away from metal but in certain circumstances, it is the best choice. Crowns are lifelike and strong and generally last much longer than fillings.