Inlays and onlays (also known as indirect fillings) can be used to restore areas of decay or damage that are too extensive to be treated with a normal filling and can provide a less invasive, more affordable alternative to a crown. They are usually placed in teeth at the back of the mouth or can be used to repair large areas on the front teeth. An inlay fits within the confines of the teeth. An onlay covers the entire chewing surface of the tooth. These can be made of either plastic resin, porcelain or gold.