Lumineers® - Disadvantages / Potential problems.
"No-drilling" placement isn't always the best choice.
Two of the most common problems associated with placing Lumineers® using a no-prep (no-drilling) veneering technique are:
Proper case selection helps a dentist to avoid these problems.
Potential problem -
A) Difficulty in achieving a truly life-like result.
Ultra-thin Lumineers® are often very opaque.
Lumineers®, notably the ultra-thin ones used with no-prep technique, are often criticized because they must be comparatively opaque. This can be especially true in cases where they are used to lighten dark teeth.
(Opaque objects block light. Metals are opaque. In comparison, objects that let light pass through are said to be translucent. Frosted glass is translucent.)
What's the problem with opaque veneers?
Tooth enamel, the part of a tooth that a veneer tries to mimic, is translucent. A great deal of what gives a tooth its natural look has to do with the way light enters into it and then is reflected back out.
If a veneer can't simulate this same light-handling effect, it won't look life-like. (We discuss the problem of restoration opaqueness here.)
The problem with ultra-thin Lumineers®.
Now, take the case where an ultra-thin veneer is used to lighten the color of a tooth. Since it is so thin, the only way it can mask the darker tooth structure that lies underneath is if it is comparatively opaque.
But due to its opaqueness, light will tend to reflect off its surface and not penetrate within like with enamel. Additionally, any light that does enter the veneer will only find the shallowest thickness into which to penetrate.
Sum total, the light handling characteristics of a thin, opaque veneer are unlike a natural tooth, and therefore it will not look truly life-like.
How traditional veneers differ.
Because they are thicker, conventional porcelain veneers can be made so they are comparatively less opaque, yet still able to mask dark tooth structure that lies underneath them.
That means light will be able to enter into and reflect back out of them in a fashion that truly mimics a natural tooth. A thicker veneer also offers the dental technician more opportunity to incorporate characterization and shading qualities into the veneer itself when it is made. (See the images below.)
Many people don't appreciate this difference.
We do have to admit that when it comes to placing a set of veneers, the difference we've described doesn't seem to matter to a lot of people.
It seems that attitudes about tooth appearance have changed over the last 20 years. Much of this is probably due to the explosion of tooth-whitening options that have become available over this same time frame.
This process tends to rob tooth enamel of some of its natural translucency. Loss of translucency and characterization in favor of the brightest "Chiclets" smile possible seems to be the trend.
This difference may be important with some cases.
In the case where only one or a few veneers are being placed, the characterization that's possible with a thicker veneer may be an important asset in creating the perfect match with your tooth's neighboring teeth.
The two teeth shown in our graphic illustrate this point. Both teeth have a nice appearance. One does, however, look more life-like and the other more "plastic."
- This tooth displays pronounced color uniformity and lack of characterization. It would be relatively easy for a dentist to make a veneer that would match this tooth, even a thin, opaque one.
- This tooth demonstrates a fairly high degree of translucency at its biting edge (the grayness you see). And its color is not perfectly uniform. In many cases, it would be relatively difficult to mimic this look with an ultra-thin no-prep veneer.
Potential problem -
B) Bulky, over-contoured teeth.
It's easy enough to see how placing no-preparation Lumineers® could result in the creation of bulky, over-sized teeth. After all, if you bond veneers directly to the surface of teeth without trimming them back first, their overall dimensions will be larger. It's only a question of how much and if it's enough to cause problems.
What are some of the concerns with over-sized teeth?
A) Appearance and function.
It's possible that the appearance of the teeth may simply seem too big or too full. The term "horse teeth" might apply. More likely, the problem will lie with the way the new teeth affect the person's daily activities.
The new, larger teeth may be cumbersome. They may also affect the person's speech, the way they bite into things or change the way their lip wants to position itself. Fortunately, with time people often adapt to these types of difficulties.
B) Dental health issues.
An over-contoured veneer can result in a gum-line configuration that interferes with plaque removal (see our graphic). It can also inhibit the natural cleansing action created by a person's lips and cheeks as they rub against a tooth's surface.
Of course, when dental plaque is not removed, problems such as tooth decay and gum disease can occur. Even minor gum inflammation can cause gum recession, which can easily spoil the appearance of a set of veneers.
Several studies have evaluated how an over-contoured dental restoration can affect the health of its tooth's surrounding gum tissue.
One study (Deng, 2001) found that increasing the contours of a dental restoration as little as .5mm can cause adverse affects whereas a .2mm increase shows no statistically significant change.
Since Lumineers® veneers can be fabricated as thin as .2mm in thickness, the above findings seem to confirm that placing them using a "no drilling" technique can produce acceptable results. The potential for problems comes into play when this technique is used when ideal pre-treatment conditions do not exist (see our example below).
A patient's oral home-care habits may be the most important factor.
Some studies (Ehrlich, 1980 and Kohal, 2003) have found that the most significant issue associated with over-contoured restorations is the effectiveness of the person's oral hygiene. Those people who put in the effort and do an effective job do not develop problems.
And while this seems to justify the placement of no-prep Lumineers®, even in situations where the resulting contours of the teeth will be less than ideal, one must realize that doing so commits them to performing satisfactory home care, every day, for the rest of their life.
Here's an example of the type of case where the placement of no-drill Lumineers® could easily result in teeth that are too over-sized.
It involves the situation where veneers are placed to improve the apparent alignment of crooked teeth.
The no-prep approach.
Our first graphic illustrates how the veneers, while ultra-thin in some areas, will need to be relatively thick in others.
That's the crux of the problem. With a no-prep approach the veneers alone make up the needed thickness variations. And this is the type of situation that can easily result in bulky or over-contoured teeth.
The conventional approach.
Our second graphic illustrates a conventional porcelain veneers approach.
In this case, the most prominent portions of the teeth are trimmed back first and then the veneers are made and placed.
This method gives the dentist much more control over the final contours of the tooth. And allows them to design them so they remain within proper limits.