Ultra-thin porcelain veneers
The placement of Lumineers® (or similar products) using a no-drilling/no-shots technique has its critics. Two major problem issues that are typically brought up are:
- Ultra-thin porcelain veneers have a reputation for being comparatively opaque, as opposed to translucent and life-like.
- No-drill technique can easily result in the creation of bulky, over-contoured teeth. That can make new veneers hard to get use to. It can also make the teeth harder to clean.
Proper case selection is the key.
In response to these criticisms, dentists who favor the use Lumineers® and equivalents are quick to point out that these issues can be kept in check by way of proper case selection.
Potential problems and concerns -
1) Difficulty in achieving a natural-looking result.
Ultra-thin veneers are often very opaque.
The very thin veneers used with no-drill technique are often criticized because they must be made using comparatively opaque porcelain and/or placed using relatively opaque cement. This can be especially true in cases where they are used to make a large color improvement for teeth.
(It's the opaqueness of the porcelain/cement combination that helps to keep the darkness of the underlying tooth structure from showing through.)
How tooth enamel handles light. (Use the in-text links for an explanation.)
Why is this a problem?
Tooth enamel, the part of a tooth that a veneer tries to mimic, is translucent. And a great deal of what gives a tooth its lustrous look has to do with the way light enters into its enamel layer and is then reflected back out. (See diagram.)
If a veneer (or veneer/cement combination) doesn't simulate this same light-handling effect, it won't look natural.
Take the case where an ultra-thin product like a Lumineer® is used to lighten the color of a relatively dark tooth.
- Since it's so thin, to mask the stained tooth structure that lies underneath it must be made using relatively opaque porcelain.
- But due to this opaqueness, light will tend to reflect off the veneer's front surface and not penetrate into it like it does when it strikes enamel (the link below illustrates this point).
- Because of this difference in light handling, the veneer won't look truly life-like.
(This is the exact same problem that occurs with dental bonding. This page explains and illustrates this issue in detail, just substitute the words "dental bonding" with "opaque veneer.")
How traditional veneers differ.
Because they are thicker, conventional porcelain veneers can be made out of comparatively less opaque porcelain, yet they are 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 the lustrous look of a natural tooth. (This page explains and illustrates this issue in detail.)
A thicker veneer also offers the dental technician more opportunity to incorporate characterization and shading qualities into the veneer itself by way of using different shades of porcelain when it is made. (See images below.)
Many people don't appreciate this difference.
We do have to admit that when it comes to the issue of a life-like appearance, many people just don't seem to care. The comfort advantage that no-drilling/no-shots technique offers simply outweighs a less than perfectly natural-looking outcome.
Times have changed.
That's probably because people's attitudes about tooth appearance have changed over the last 25 years, likely due to the explosion of tooth-whitening options that have become available over this same time frame.
The whitening process tends to rob tooth enamel of translucency and results in a set of uniform, bleached-white "Chiclets" teeth.
Nowadays, it seems that that is the look a lot of people are seeking. And if that's the one you want, it's easy enough to get with a set of Lumineers®.
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 a perfect match with the 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."
- A - This tooth displays pronounced color uniformity and lack of characterization. It would be relatively easy for a dentist to make an ultra-thin veneer that would match this tooth.
- B - This tooth demonstrates a fairly high degree of translucency at its biting edge (the grayness you see). And its color is not perfectly uniform. It would be relatively difficult to mimic this look with an ultra-thin no-prep veneer.
2) Bulky, over-contoured teeth.
It's easy enough to see how placing no-tooth preparation, ultra-thin veneers 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?
It's likely that the look of the finished teeth will be fuller and larger. In extreme cases, the terms bulbous or even horse-teeth might apply.
That's just a fact of life associated with this technique. And for some, when compared to the convenience and comfort of being able to take advantage of no-drilling/no-shots technique, it's an easy trade-off to choose.
Another area of concern is how the increased size of the new teeth will affect the person's daily activities.
Larger teeth can 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.
C) Dental health issues.
If you bond a porcelain veneer directly onto the untrimmed surface of a tooth, it will change the tooth's contours, and create a ledge (a "speed bump") right at the veneer's edge (see our graphic).
This over-contoured configuration can make it more difficult to remove dental plaque (especially right at the gum line). It also tends to 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. (And just a minor amount of gum recession can easily spoil the appearance of a set of veneers.)
Research into the matter.
Several studies have evaluated how an over-contoured dental restoration tends to affect the health of the surrounding gum tissue.
As an example, one study (Deng 2001) [reference sources] determined that:
- Increasing the contours of a tooth as little as .5mm can cause adverse affects.
- A .2mm increase resulted in no statistically significant problems.
Since Lumineers® 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 person'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.
This seems to justify (rationalize) the placement of no-prep veneers, even in situations where the resulting contours of the teeth will be less than ideal. However, one must realize that doing so commits them to performing satisfactory home care, every day, for the rest of their life. (How many of us do that?)
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.
a) 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.
b) The conventional approach.
Our second graphic illustrates the use of conventional veneering technique.
With it, the most prominent portions of the teeth are trimmed back first and then the veneers are made and placed.
Advantages of no-preparation placement.
Besides the obvious (no drilling, no shots), there are some additional advantages to the use of a no-tooth-preparation technique when placing veneers.
a) No temporaries are needed.
Unlike with conventional technique where temporary veneers are sometimes needed to cover the patient's trimmed teeth (they may be rough or sensitive), with no-drilling protocol they are never required.
b) Minimal tooth sensitivity.
Since your teeth still remain fully intact, it's unlikely that they'll experience any post-placement sensitivity. This isn't always the case with conventional veneers.
c) A very secure bond is created.
No-preparation veneers are bonded directly to tooth enamel and this is the strongest type of bond created in dentistry.
In comparison, with conventional veneering technique it's possible that some of the tooth's dentin (an inner tooth layer) will be exposed during the trimming process. The bond created in these areas (at least in theory) will be less secure.
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