Fillings are needed when decay begins to eat away at the tooth’s surface. Most often cavities cannot be seen or felt. In fact, they often occur underneath the tooth or inside it, and cannot be detected without the doctor or an x-ray. Even though you often don’t feel tooth decay occur in its early stages, regular checkups help diagnose it early, before a larger restoration (crown or onlay) may be required. Modern fillings use composite resin, which when placed properly are superior in both esthetics and durability to silver (amalgam fillings).