People tend to be a little confused when we talk about porcelain veneers and porcelain crowns. They think that these restorations are going to be fragile. That’s because the experience most of us have is with porcelain plates –we’ve all dropped at least one and seen it shatter before our eyes. And then there is grandma’s collection of porcelain figurines and china dolls that were too fragile to even be touched or handled.
But dental porcelain isn’t like that, at all. Instead, porcelain veneers and other cosmetic dentistry restorations are made of strong, advanced ceramics that are much more durable.
Traditional materials described as porcelain is a ceramic material that is formed using kaolin clay, then fired in a kiln to a temperature over 1200 degrees. Porcelain was developed in China sometime before 200 BC. The first porcelain dishes to reach the West undoubtedly came via the Islamic world, and were named porcellana, which was a name for cowrie shells, which the ceramic resembled in appearance. Porcelain may also include feldspar, glass, bone ash, and other elements.
Although relatively strong for ceramic, traditional porcelain is not strong by modern standards. Instead, it was porcelain’s other properties that made it appealing as a dental restoration material, appearing first in dentures in the 18th century, then in veneers in early 20th century Hollywood. These properties are the color–white–and the translucency of the material, which made it very similar to tooth enamel. The standard strength test for porcelain dinnerware should yield an impact strength of about 0.36 foot-pounds of force. The flexural strength for these materials is about 60-70 megapascals (MPa), about 8700-10,200 pounds per square inch (psi), at best, with earlier examples being significantly weaker.
This type of material was used at least through the 1980s for dental restorations, including porcelain veneers. Since then, we have developed much more advanced ceramics.
Since the 1980s, dental restorations have gotten stronger. First, new stronger feldspathic porcelains were developed. Similar in composition and appearance to previous porcelains, but about 50% stronger.
But the next development came in the form of leucite glass ceramics. These press manufactured ceramics initially had a strength of about 120 MPa, about 17,400 psi. Many dentists complained that the appearance of these ceramics wasn’t as good as the feldspathic ceramics, which by this time had increased in strength to nearly 15,000 psi. For the marginal gains in strength, many dentists kept working with feldspathic ceramics.
Lithium disilicate was introduced in the early 2000s as a new alternative. This glass ceramic has more translucency than leucite glass restorations, and it’s much stronger. Lithium disilicate is nearly four times as strong as the strongest feldspathic porcelains, about 400 MPa or 58,000 psi. For many dentists, lithium disilicate restorations are at least as beautiful as feldspathic porcelain, and at four times the strength, who can complain?
In addition, we have developed some even stronger materials. Zirconia ceramics (the same materials used in our metal-free dental implants) are over twice as strong as lithium disilicate, up to 1100 MPa or 160,000 psi! The drawback is that these restorations aren’t quite as natural in appearance. In fact, they’re a little less natural in appearance than leucite glass ceramics.
Why We Still Call Them “Porcelain” Veneers
Technically, only the feldspathic porcelain veneers are actually made of porcelain. So why do we keep using the name?
Partly, it’s just what they’re called. Objects are given a name, and it can be hard to change the name. It’s similar for temporomandibular joint disorders, which many people still call “TMJ” despite the fact that there’s been an agreement among professionals that they should be called “TMD” from now on. We sometimes call them “dental veneers,” but it’s a name that isn’t very descriptive and feels kind of bland. With “porcelain,” you get something of the feel of what they’re supposed to be like: white, translucent, and beautiful.
Durable Materials That Last
So when you are considering cosmetic dentistry, don’t be thrown off by the use of the word “porcelain.” They’re not really made of porcelain at all. You won’t have to worry about them chipping and fracturing the way all the plates in your cabinet might be.
Instead, modern ceramic restorations have a 97% survival rate or higher over ten years. That means that you can count on your cosmetic dentistry to keep giving you great results for a long, long time.