Inlays and onlays are used when large, defective fillings or tooth fractures need to be fixed. Inlays and onlays are made of porcelain and cover the grooves of the teeth. The difference between an inlay and onlay is that an onlay covers one of more cusp or corner of the tooth as opposed to the smaller inlay. Also used to replace large silver fillings, they can strengthen the tooth by acting as a core or backbone to the tooth, hence maintaining tooth integrity. The onlays and inlays differ from composites since they are harder and more durable than a composite filling and do not stain over time. They are cemented to the tooth’s surface, creating a watertight seal. As opposed to crowns, onlays and inlays are a conservative option, saving more of your natural tooth structure.