Porcelain inlays and onlays are very aesthetic alternatives to composite fillings. They have a high degree of strength, and as such, are excellent for restoring weakened back teeth. Inlays and onlays protect and restore large portions of decayed, heavily restored teeth under very heavy load (i.e. back teeth). Unlike crowns, they only cover a portion of the tooth, and are therefore more conservative on the amount of tooth preparation required.
They are made with porcelain, customized to your natural tooth shade, and look like your natural tooth. Porcelain inlays and onlays are made from the same strong, tooth colored material that is used for crowns and bridgework. A customized shade makes them virtually undetectable. The main differences between tooth-colored composite restoration and inlay/onlays is that the latter are fabricated using a laboratory process and differing materials, thereby making them stronger and more durable.