Prepless Prerequisites - How and Why to Incorporate Prepless Veneers

Recently there has been an effort to reintroduce the "prepless" or "minimal preparation" veneer. The primary driving force has been a marketing effort suggesting that patients' smiles can be drastically improved without using the "dental drill, shots or removal of healthy tooth structure." Consequently, dentists often have been forced to utilize a prepless veneer at the request of their patients, despite the fact that the treatment might be contraindicated. Another important compromise is that many clinicians are unaware of (or unfamiliar with) indications in which eliminating teeth preparation may be an option. Because of this, the dental industry has seen a rebirth of over-contoured and bulky smile designs using ceramic veneers. This has lead many to believe that the prep-less veneer option should not be considered because of the inability to achieve acceptable esthetics.

This is unfortunate, because with a complete understanding of when and how to use the prepless veneer, definitive results can be very appealing. The new materials available in the marketplace provide more vitality than those previously used for restorations; and more patients have the opportunity to achieve the smile of their dreams, which they wouldn't have considered in the past due to the requirement to remove tooth structure.

Prepless prerequisites

When treatment-planning veneers, adding 0.2 to 0.3 mm to the facial surface of the maxillary anterior teeth can yield results that are not overly bulky, providing certain criteria exist. Having placed thousands of veneers during the past 19 years, and personally experiencing the successes and failures with modified preparations, I have devised prerequisites that must exist if prepless (or even minimally prepared) veneers are to be placed. These are as follows:

• The shade of the natural tooth must be close to the desired shade. Although some block-out and addition of increased value can be achieved with very thin veneers, the increased opacity needed to cover dark teeth will yield unesthetic results. Typically, it is suggested that when using the correct ceramic, teeth can be lightened up to two shades whiter with prepless veneers.
• The profile of teeth must be as close to ideal as possible, or lingually inclined. Although these veneers can be fabricated as thin as 0.2 mm, if the teeth are already buccally inclined, addition of facial porcelain will only exaggerate this situation. Prepless veneers are ideal when teeth are naturally inclined lingually, because adding facial porcelain actually enhances the esthetics by increasing the reflective surface of the teeth.
• The teeth must be in ideal arch form (or close to it). Prepless veneers have become an excellent post-orthodontic treatment, especially in the case of microdontia where there is a tooth-width, arch width discrepancy. If the teeth are misaligned, the final result will yield teeth that have significant different incisal-edge thicknesses. Also, misalignment that includes overlapping teeth makes it impossible to avoid concave surfaces and provide interproximal contours that appear natural.

Most ceramists and clinicians feel that prepless restorations, because of their minimal thickness, should be fabricated using a powder-liquid ceramic. I have found that pressed ceramic (IPS Empress) can be fabricated in restorations as thin as 0.3 mm.

These pressed ceramic restorations are waxed and pressed at approximately 0.5 mm, and then thinned after the pressing process. The difficulty lies in the ceramist's ability to thin these pressed ceramic restorations; few ceramists will accommodate clinicians by fabricating these thin restorations. Because there is not a margin for the ceramist to finish to, there will be a ceramic "ledge" at the gingival margin. Following cementation and complete polymerization, it is imperative to polish down the gingival margins using a flame tip diamond. A 15-micron finishing diamond is used, and then the margins are polished using porcelain polishing points.

The prepless option can certainly yield esthetics that rival traditionally prepped veneers. And, some people in dentistry believe that you cannot achieve a satisfying esthetic outcome using prepless veneers. But I have found that if you have a thorough knowledge of prepless veneers—when and how to use them—and follow several prerequisites, which I detail here, you can achieve a very attractive result.

For more information on these and other esthetic procedures, visit the Hornbrook Group online.