Porcelain veneers, alternatively termed dental veneers or dental porcelain laminates, are wafer-thin shells of porcelain that are bonded onto the front side of teeth so to create a cosmetic improvement for a tooth.
Porcelain veneers are routinely used by dentists as a way to make cosmetic changes for teeth that are discolored, worn, chipped, or misaligned.
Porcelain veneer technique is an offshoot of the basic science of cosmetic dental bonding. Dentists have had materials available to them for decades that are capable of creating a tenacious bond with tooth enamel.
Porcelain veneer technique utilizes the bonding capability of these materials to securely attach a thin shell of porcelain (the porcelain veneer) to a tooth. Although porcelain is inherently brittle, when it is firmly bonded to a sturdy substructure (a tooth) it becomes very strong and durable.
You might be surprised to learn that while a large portion of every tooth is composed of dental enamel, teeth are not solid enamel. The enamel component of a tooth is actually just an outer encasement. The hard tooth tissue that lies underneath a tooth's enamel layer is termed "dentin."
One property of tooth enamel is that it's translucent. This means that when light strikes a tooth's surface it is not immediately reflected off, but instead penetrates into its enamel layer. Once the light has passed through the full thickness of the enamel it reflects off of the opaque (non-translucent) tooth dentin that lies underneath, and then on back out of the tooth. This manner of handling light, the translucency effect of a tooth's enamel, is an important aspect of what give teeth their characteristic lustrous appearance.
In the past the only cosmetic dental bonding materials that dentists had available to them were just semi-translucent. This meant that most of the light that struck a repaired tooth would not penetrate into the bonding but instead be reflected off its outer surface. The net result was that while the bonding did give the tooth an improved appearance, there was no sense of translucency (luster).
Since porcelain veneers are glass-like in nature (ceramic) they have a great advantage over other cosmetic bonding techniques by way of the fact that they are translucent. When a porcelain veneer is bonded onto a tooth's surface it will closely mimic the light handling characteristics of dental enamel.
When light strikes the surface of a veneered tooth it can penetrate on into the veneer's porcelain, just like it does with dental enamel. Once it has traversed the full thickness of the porcelain the light will reflect off the opaque cement and tooth dentin that lies underneath the veneer, and then on back out of the tooth. This translucency effect of the porcelain creates a lustrous appearance for the tooth that very closely resembles the appearance of enamel.
As a group, cosmetic dental bonding materials have the shortcoming of being susceptible to staining and discoloring. This is especially true when they are used in conjunction with individuals whose consumption habits include the use of tea, coffee, red wine, and tobacco products.
A significant advantage of placing porcelain veneers as opposed to cosmetic dental bonding is that a porcelain veneer's surface is just that, porcelain. Since porcelain is a ceramic, and therefore glass-like, a veneer's porcelain surface will be extremely stain resistant.
Below shows before and afters of a case done by Dr. Doug Weber in July 2011 combining bleaching with porcelain veneers on the upper 4 front teeth.