What are Dental Inlays and Onlays?
 Inlays and onlays are indirect dental restorations, which means they are made outside of your mouth in a laboratory. An inlay or onlay is typically used when a cavity is too large for a simple filling. Inlays and onlays can increase a tooth’s strength by up to 75 percent.

What is the difference between an inlay and an onlay?
Therefore, rather than re-shaping a sound tooth to fit under a crown, your dentist can simply use an inlay or onlay. An inlay fills the gap in the tooth while the onlay is applied to the top of the tooth – but apart from positioning they essentially play the same function.

What is an onlay filling?
An inlay is a small filling that fits into the biting surface of a tooth. An onlay covers a larger area of the tooth and is better suited to bigger cavities. Gold was traditionally used for these types of restorations. However, in recent times hard-wearing tooth-coloured porcelain has become a more popular choice of material.