Porcelain Veneers - Overview / Applications / Advantages & Disadvantages.
What are they?
Porcelain veneers (also referred to as dental laminates), are wafer-thin shells of porcelain that are bonded onto the front side of teeth.
They're generally about .5 to .6 mm thick. That's about 1/2 the thickness of a dime or twice the thickness of an eggshell.
(Some, like Lumineers®, can be even thinner. We discuss ultra-thin veneers here.)
What are they used for?
The primary purpose of placing veneers is to improve the appearance of teeth.
They're routinely use as a way of making changes for those that are discolored, worn, chipped, or slightly misaligned.
In most cases, placing them is an elective procedure.
How do they work?
The way porcelain veneers are attached to teeth is really just an extension of the science of tooth bonding.
With that, a series of steps are used to create a strong bond between dental composite (white filling material) and tooth enamel.
With this, similar materials are used to create a bond with both enamel and porcelain.
The net result is a situation where the bonding acts as cement sandwiched between the veneer and tooth, holding everything together.
Why do they work?
You may wonder how a wafer-thin shell of porcelain can successfully withstand all of the wear and tear that it's ultimately exposed too.
The answer lies in the fact that although porcelain is inherently brittle, when it's firmly bonded to and supported by a sturdy substructure (a tooth), it creates a very strong and durable surface.
How do veneers differ from dental crowns?
While both give the same cosmetic end result, a crown covers over more of the tooth and involves far more tooth trimming. (This page explains in greater detail.)
What advantage do porcelain veneers offer?
A) They create a very natural-looking appearance.
Due to their ability to closely mimic the way natural teeth reflect light, well-crafted porcelain veneers can look astoundingly lifelike. Here's how this works.
a) How teeth handle light.
Tooth enamel is translucent. And because of this ...
1) When light strikes it, it penetrates into it ...
2) ... then, once the light has passed through the full thickness of the enamel, it reflects off the opaque (non-translucent) tooth dentin that lies underneath ...
3) ... and then back out of the tooth.
This penetration in and reflection back out is what gives teeth their characteristic glass-like lustrous appearance.
b) How porcelain veneers handle light.
When light strikes the surface of a porcelain veneer ...
1) ... it penetrates into it (just like with enamel) ...
2) ... and after traversing the full thickness of the veneer, it's reflected off the opaque cement layer that lies underneath (just like light reflects off dentin in natural teeth) ...
3) ... and then, back on out of the tooth.
This similarity in the way light is handled is why (well designed and well crafted) porcelain veneers give a natural, life-like appearance.
c) In comparison ...
Dental bonding, which can also be used to make veneers for teeth, is only semi-translucent.
That means when light strikes it, it's mostly reflected off the veneer's front surface (there's much less light penetration). We compare this and other aspects of porcelain vs. bonding on this page.
B) Porcelain veneers resist staining.
Applications and uses.
Porcelain veneers can be used to overhaul the appearance of teeth that are chipped, worn, discolored, or even crooked. But they do have their limitations (see below).
They can make a good choice for cases where the extent of change that's needed, and the circumstances under which the veneers will function, are fairly routine and normal. Beyond that, other types of restorations (usually dental crowns) make the wiser choice.
a) Repairing minor tooth imperfections and defects.
Teeth that have small chips or whose surface is worn or misshapen (dimpled, pitted) are often good candidates for porcelain veneers.
In situations where the affected area is very small, dental bonding usually makes the better choice (it's a simpler, less invasive procedure).
But if a substantial portion of the front side of the tooth could benefit from resurfacing, the durability, stain resistance and life-like appearance that porcelain veneers can offer can make them an excellent solution.
b) Concealing stained fillings.
The process that's used to bond a veneer to a tooth will create a bond with existing white filling material (dental composite) too.
Since restorations made with it tend to discolor over time, the ceramic surface of a porcelain veneer offers a more durable, long-lasting result.
c) Making color changes for teeth.
Porcelain veneers can be used to lighten the color of teeth. This includes those that have tetracycline or fluorosis staining, or have darkened in response to trauma or having had root canal treatment.
The situation needs to be one where the teeth are structurally sound; they just need a simple color change.
Veneers don't make a good choice for treating teeth that are exceptionally dark. Using this technique with them can result in over trimming, bulky/poorly contoured veneers or needing to use very opaque porcelain (which sacrifices the translucency effect described above).
(As a solution for this type of situation, bleaching treatments are performed first, so to lighten the teeth somewhat. Then veneers are placed.)
d) Instant orthodontics.
1) Porcelain veneers can be used to close spaces between a person's teeth. In fact, they are ideally suited for this purpose. (Although, with very small gaps dental bonding usually makes the better choice.)
2) If a person's misalignment isn't too severe, veneers can be used to give their smile a more even appearance.
When porcelain veneers shouldn't be used.
There can be situations where certain teeth, or even certain people, are not good candidates for this procedure. Some areas of concern are:
A) Teeth that need strengthening.
Teeth that have lost a significant amount of structure due to wear, decay or fracture, and those that have large fillings don't make good candidates. That's because porcelain veneers do not strengthen teeth, they only improve their appearance.
In this type of situation, dental crown placement makes the more appropriate choice.
B) Teeth with little enamel.
A porcelain veneer won't stay in place well unless it's primarily bonded to tooth enamel. Here's why.
1) When it's bonded onto enamel, the enamel is the more rigid of the two and it tends to absorb most of the forces applied to the tooth.
2) When bonded directly to dentin (the layer underneath enamel), the porcelain veneer is the stiffer object and any forces directed to the tooth tend to become focused in it. This can lead to veneer fracture or debonding.
Some teeth may have little or no enamel remaining on their front surface due to wear, erosion, trauma, or previously placed dental restorations. If so, they don't make good candidates. A dental crown would make the more appropriate choice for these teeth.
C) Excessive forces.
People who clench and grind their teeth (referred to as bruxism by dentists), or have a bite where their front teeth come together edge-to-edge, don't make good candidates.
The level of forces generated by these conditions can be substantial and can cause veneers to chip, break or debond. One study (Beier 2012) found that a habit of bruxism increased the failure rate of a subject's porcelain veneers by a factor of 8.