Dr. Jimmy C. Wu is a San Diego native, completing his bachelor’s degree in biology at UC San Diego and going on to get his DDS from the University of Southern California. He runs Sutra Dental Spa in La Mesa, California, and talks here about gold versus porcelain inlays and onlays, explaining why he prefers porcelain-bonded ones.
Nowadays, there is not much of a difference between porcelain and gold inlays and onlays. Inlays are fillings cemented into place to fix a cavity. Onlays are much the same but extend to the whole cusp, which is why a crown is a type of onlay.
It used to be that gold was the gold standard. But with gold inlays, you are gluing the onlay in place. The problem with that is you can get what is called cement washout. In the lab, they have to make a space for the glue so that the glue can sit between the thin layer of the onlay and your tooth. What can happen is that glue can actually wash out over time, so there will be a gap. If the glue washes out, you are allowing bacteria inside the tooth, and cavities will appear.
The difference also depends on the gradience of the gold, so how much gold you use on the inlay and onlay is also a factor. The less gold you use, the harder and the less malleable it is. The material will last longer with less gold. But the problem with less gold is that you will be unable to seal the margins of the inlay or onlay. So you are much more likely to get cement washout in that area.
Porcelain Inlays and Onlays
Porcelain inlays and onlays are generally bonded in place. Different types of porcelain can be more brittle or not as strong as your own enamel. But there are also types of porcelain that are just as strong as your own enamel, if not a little stronger. Also, different dentists will use different porcelain based on their education and skill set.
The porcelain route is much more technique-sensitive than the gold route. The best type of porcelain is one that is as similar as possible to your own enamel. It is bonded in place, a process that is a lot stronger than the glue or cementing process. That’s because instead of creating a space for cement, you are opening the pores of the tooth and the crystalline structure of the porcelain, and allowing a mechanical bond. So in essence there is minimal or no gap between the inlay or onlay and your own tooth.
I prefer using porcelain-bonded inlays or onlays because this way you won’t have cement washout and you won’t have recurring cavities. The bonding process also will bring the cracks of the tooth together, which may occur during the preparation process, from wear and tear, from chewing, or if a tooth is broken. The bonding will make the tooth stronger and is a more effective process.
