A tooth is planned to be restored with an intracoronal restoration, but the decay or fracture is so extensive that a direct restoration, such as amalgam or composite, would compromise the structural integrity of the restored tooth or provide substandard opposition to occlusal (i.e., biting) forces. In such situations, an porcelain inlay/onlay/overlay restoration may be indicated.
Experts say that composite fillings can be expected to last about five to seven years; silver amalgram fillings last an estimated 12 years on average, however we do not use silver amalgam fillings due to its health risks; crowns last 10 to 15 years. Inlays, onlays and overlays generally do not need to be replaced for 20 to 30 years.
The materials we use to fabricate our inlay, olay and overlay continue to evolve and become more natural and tooth-like in terms of structure, how they are worn and longivity. Their use for our restorative purposes is not likely to be replaced by another treatment any time soon due to the combination of excellent functional longevity and esthetic naturalness associated with inlay,onlays and overlays. In fact, maintaining tooth color over the course of your lifetime may be further enhanced as the materials continue to improve, adding to esthetic value of the restoration.