Written by Louis Malcmacher, DDS, FAGD Monday, 31 March 2003 19:00
Porcelain veneers are a wonderful conservative modality for creating and restoring aesthetics in the human dentition. The beauty of porcelain is unsurpassed because of the natural light transmission that occurs through the porcelain and ultimately through the tooth. It is color stable, strong once bonded to the tooth, and has the capacity to last for years.
Porcelain veneers originally were adopted as a very conservative treatment. It took the place of crowns in many instances because you did not have to remove a lot, if any, tooth structure to restore the teeth and change the aesthetics. It was because of the fact that porcelain veneers were conservative restorations as well as beautiful that they gained in popularity. We all realize how aggressive a crown preparation is to the tooth, and when a tooth needs a crown, in most circumstances there really is no choice but to be aggressive in the preparation. Porcelain veneers allowed us to change the color and shapes of teeth without eliminating solid tooth structure.
In recent years, techniques have been taught regarding porcelain veneers that include equally aggressive preparations. In fact, some of these preparations are really three-fourths or seven-eighths crown preparations as opposed to porcelain veneers. Many times, this is because of the properties of the porcelain being used, which may require significant reduction of the tooth in order for that particular porcelain to be successful. My philosophy regarding dental materials, including porcelain or any other material, is that they should never determine the tooth preparation, but rather the functional and aesthetic needs of the patient should determine preparation design. For example, if I am going to use porcelain veneers on a case, it is going to be a case where there will be a minimal preparation, if any preparation at all. If three-fourths of the tooth needs to be prepared in order to provide the best treatment for that situation, then I am going to go ahead and finish that last quarter of the tooth and make it a complete crown preparation, be it ceramic or PFM.
The advantages of a no-preparation or minimal-preparation porcelain veneer are obvious. With only a slight reduction in the tooth, there will be no harm to the pulp, and thereby no postoperative sensitivity. Many practitioners to whom I have lectured over the years have reported numerous cases of postoperative sensitivity after an aggressively prepared porcelain veneer case was cemented. We shouldn’t be surprised at all. When you remove most if not all of the enamel and some of the dentin from a healthy tooth, chances are you will get sensitivity unless you work very hard to seal the dentinal tubules properly. It is disheartening to both the dentist and the patient when you have completed a beautiful aesthetic case and the patient can’t take a drink of hot coffee or cold soda. No preparation means there is still plenty of enamel left on the tooth to protect it. You will have no postoperative sensitivity, which goes a long way in building a practice.
Another major advantage of a minimal- or no-preparation porcelain veneer is that you will have plenty of enamel for bonding. While bond strengths to dentin are certainly improving, they are still nowhere near the tremendous bond strengths of enamel to resin. The more enamel you have, the better bond you will have, and the longer any bonded restoration will last. An aggressively prepared tooth for a porcelain veneer that removes most of the enamel on the facial and the interproximal surfaces is probably doomed to failure over the long term. I have personally seen cases where these types of veneers have popped off one by one within a year of being placed. Porcelain veneers are a tremendous practice builder, but not when they constantly fall off and cause an aesthetic emergency for the patient.
Another advantage of this kind of porcelain veneer preparation is ease of impression, because you do not have to manage the gingival tissues. Supragingival placement of the porcelain veneers also makes them easy for the patient to clean and maintain, and the ease of placement for these kinds of veneers is unparalleled. Another major advantage is that no temporization is needed. The phone calls about chipped, loose, broken, or rough temporaries are eliminated because there are no temporaries to deal with.
Many dental professionals make the mistake of thinking that no preparation veneers mean that you just place them and you are done. That is not true. No-preparation porcelain veneers does not mean that these veneers, when inserted, are finished and you don’t need to do anything else. The margins of the veneers are finished up against the natural tooth just like any other bonded restoration that we place.
In order to accomplish a minimal- or no-preparation veneer case, you do need a porcelain veneer material that can be made very thin, is able to build colors internally, and is very strong. Many times, a dental laboratory that does not specialize in veneers will use the same porcelain that they use for PFM crowns. For the most part, the particle sizes of these porcelains are large, and the veneers must be made close to a millimeter thick in order to permit the technician to do a good job with the porcelain materials.
This article presents case reports in which minimal-or no-preparation porcelain veneers were provided, using a porcelain that I find to be well suited for these types of restorations.
The cases presented used Cerinate porcelain (Den-Mat Corporation). This porcelain is specifically designed for porcelain veneers. It is a beautifully translucent leucite-based porcelain with a very small particle size. Cerinate porcelain can be made into a porcelain veneer as thin as 0.3 mm thick that is able to maintain its strength and beauty. A study done by Strassler and Weiner at the University of Maryland Dental School has shown that over a 16-year period, there were no debondings of veneers done with Cerinate porcelain.1 The veneers remained color stable and demonstrated minimal if any shade change. Cerinate is available in either stackable porcelain or pressable porcelain and has very high strength.
Figure 1 shows a patient who wants to improve the appearance of her anterior teeth. The central incisors are linguoverted and have had composite resin incisal restorations that have discolored over time. She could not afford to do all 6 anterior teeth at one time so she decided to do the central incisors first and will save money for the remaining teeth. She only had one condition—she did not want to sacrifice any tooth structure. She had been seen by another dentist for a cosmetic consultation who wanted to prepare these teeth for veneers, and she decided against it. She was thrilled to be able to have these veneers placed without any tooth reduction (Figure 2).
|Figure 1. Pre-op patient to receive central incisor porcelain veneers with no preparation.||Figure 2. Post-op patient pleased that no tooth reduction was necessary.|
|Figure 3. Patient interested in veneers only if there is no “grinding” involved.||Figure 4. These 0.4-mm Cerinate veneers still need finishing like any other restoration.|
|Figure 5. A very pleased patient with her no-prep veneers.||Figure 6. Bruxed lower teeth of an elderly patient.|
|Figure 7. Pressed Cerinate porcelain veneers restore beauty and strength with no preparation.|
In the second case, the patient is a 21-year-old woman who has had some orthodontic relapse and also some discolored composite resins on her anterior teeth (Figure 3). She desired “instant orthodontics” with porcelain veneers and wanted to make the teeth slightly longer and whiter. No preparation was done, and a polyvinylsiloxane impression (1st Impression, Den-Mat Corporation) was taken. No temporaries were needed while the laboratory completed the case. These veneers were measured to be 0.4 mm thick at cementation. Finishing of the margins is imperative to ensure proper contours and a smooth transition from the tooth to the veneer (Figure 4). The cemented case is shown in Figure 5. Notice the excellent gingival response to the porcelain, which has been properly finished at the margins. There was obviously no postoperative sensitivity because no enamel had been removed.
In the third case, Figure 6 shows a 75-year-old woman who showed only her lower teeth when she smiled. This woman’s grandchild was getting married and she desired an aesthetic improvement so she would look nice in the wedding pictures. These teeth had never been prepared for any kind of dental restoration. She had “prepared” them herself with years of a bruxism habit. None of these teeth were sensitive to her because the pulp tissue had receded deep into the teeth. No preparation was needed in this case. Because of her bruxism habit, pressable Cerinate porcelain was used for this case because of its strength. Figure 7 shows the final postoperative result after 4 years.
Many dentists have complained over the years that porcelain veneers are too difficult to do, but this is certainly not true when the proper porcelains are used for this nonpreparation porcelain veneer procedure. Porcelain veneers work best as a conservative treatment, where little or no preparation of the teeth is needed. This makes the aesthetic treatment much less complicated and eliminates steps such as making temporaries and managing subgingival tissues. It also eliminates any postoperative sensitivity issues because the enamel is left intact, ensuring the best bond possible.
Porcelain veneers have a high rate of patient acceptance and satisfaction, especially when little or no tooth structure has to be removed.
1. Strassler HE, Weiner S. Long Term Clinical Evaluation of Etched Porcelain Veneers. J Dent Res. 2001;80 (Special Issue, abstract no.194):60.
Disclosure: Den-Mat is a sponsor of certain lectures presented by Dr. Malcmacher.
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