In cases with larger cavities or broken down areas, an inlay or onlay to cover more of the tooth's surface may be indicated. These restorations are indirect because they require two visits and fabrication by a dental laboratory. The ceramic restorations are considerably more expensive and therefore simple, one-visit composite fillings are typically used instead for small fillings. Ceramic restorations are much more durable and will not stain. Naturally speaking, the final result with ceramics is spectacular. White inlays or onlays are actually glued into the tooth and there is now a body of research that claims that because of this the tooth ends up stronger after such a procedure, less prone to problems down the road.

Picking the right ceramic for the job, proper tooth preparation, quality laboratory work, and meticulous cementation technique are all needed for a successful tooth restoration. It costs about the same as an indirect composite inlays and onlays and takes two visits. Most ceramic and resin-based materials contain metals in the form of oxides (such as aluminum) or even heavy metals (such as cobalt, barium or cadmium). These are usually added to give the materials strength and improve their appearance. Sometimes they are added to make the restoration show up on x-rays. The number of materials that do not contain any of these products is very limited. However, the advantage of being oxide-free is lost when these are bonded to the tooth using an oxide-containing luting agent.

Gold Inlay/Onlay Because of gold’s long history, it is the standard against which other materials are judged. This type of restoration is used when maximum strength is desired and appearance is not a factor. Gold is almost never used in its pure form; rather gold is used as an alloy with other metal elements. It costs approximately three to four times more than an amalgam and takes 2 visits. There are many formulations of gold, varying from 1% to 99%. The other metals are added in order to give the gold strength and the ability to bond to porcelain (in the case of porcelain veneer fused to cover a gold crown). The most commonly added metals are palladium, silver, copper, and platinum.

The composition and amount of each metal in the alloy determines whether it is classified as a “high noble,” “noble,” or “base” metal. “Noble” metals are defined as gold, platinum and palladium. The most expensive gold alloys are “high noble” and they are defined as hving at least 60% noble metals and at least 40% gold. An alloy can still be called “noble” if it has at least 25% noble metal content. The cheapest materials fail even that test and are called “base” alloys–they have less than 25% noble metals. It is especially important for patients with metal sensitivities to avoid the base alloys since these usually contain toxic metals such as nickel and chromium;. But even the high noble materials can be incompatible for patients and even toxic; palladium, for example, is toxic.