Vertical Shoulder Laminate (VSL) Veneer

 Myths are often attached to new practices (using new techniques and materials) that replace those that have become unfounded when cycles change and new technology and new materials become available that totally, not gradually, alter the landscape and, therefore, the best practice of the day. Often, new practices scare professionals and others who don’t want to make changes. So, old ideas are held in place by professional schools, professional practices, laboratory technicians, and journal articles that often continue to discuss "traditional preps" for veneers done by habit, experience, and convention. 

Language about the new practice, often captured in slogans or stock phrases, is generated and then repeated. The use and power of such slogans are well-known in the arena of political campaigns: "no prep, no good." (Notice how this idea is "suspended" in language, and is therefore "held" in place.)

Some Background on Replacement Technology
First, let’s clear up a misconception: Many articles in journals and speakers on aesthetic dentistry, refer to "traditional veneers" as those that involve preparations; that is, prepping to the degree that tooth structure is removed as "traditionally/conventionally" done today. Historically, one must remember that original porcelain veneers were meant to be "prepless" (without preparation). It is a myth that the original version of the traditional veneer included the amount of preparation as we observe as the norm today, and that no-prep veneers are a "new" trend. 
When "cosmetic bonding" was introduced, the more conservative-minded dentists used the material to aesthetically improve a smile. I remember laboratory-fabricated composite veneers that were en vogue for a very short time, as they were quickly replaced by porcelain veneers. Cerinate porcelain veneers released in the 1980s by Dr. Robert Ibsen, were meant to be done with no preparation, and I did many of these in the 1980s. However, when we wanted to improve the aesthetics on larger or misaligned teeth, we developed "veneer preps" that would enhance the aesthetics of these formerly "prepless" porcelain veneers. 
With time, veneer prep design "matured," and as dentists and dental technicians demanded better aesthetic results, the preps grew more and more aggressive, often removing all the enamel, shortening the teeth, sometimes wrapping over the incisal edges and even opening the interproximal contacts. We can look at many veneer articles in journals and find, in some cases, aggressive veneer preparations are practically impossible to distinguish from nearly full-crown preparations

TO PREP OR NOT TO PREP
My philosophy from day one has been and is: It is always desirable to preserve natural tooth structure for our patients, whenever it is possible.
—Such a benign-sounding word, but its meaning is anything but benign. Prep in this context means drilling or shaving, grinding down to a depth that leaves little behind, making the result irreversible. 
The term "no-prep veneers" generally refers to very thin shells of porcelain that are designed to cover or replace enamel.

Top Reasons We Believe We Still Have to Prep
First, dental schools, in general, and most aesthetic teachers/gurus in particular, teach prepped veneers. They advocate reducing the labial of the tooth, rounding it off, removing the proximal line angles, shortening the incisal edge, and bonding to enamel and/or dentin. This is what many dental students are taught. Fortunately, in the author’s opinion and that of others, this trend is gradually changing. At a recent meeting, a speaker recently noted that he no longer "tells [attendees/students] to drill as much as I used to." It’s how we were taught, but the cycle of new technology and materials is responsible for a sea of change in our procedures. We now have materials and techniques available to us that eliminate the need to prep.
Second, dental laboratory technicians want more "room" to create their restorations. Instructions from the laboratory may dictate to the professional the amount of room necessary to create aesthetically pleasing porcelain veneers. Again, this is usually determined without the dental technician being able to personally and visually evaluate the patient with the doctor.
Third, habit and experience keep this idea for prepping (more often than not) perpetuated. Many dentists still believe in "remove and replace" dentistry. Some say there are times you have to prep, such as in a case of severe misalignment. This may be the case, but, with the new materials, you no longer have to prepare the tooth to the previous depth, and a shoulder or chamfer is no longer needed at the gumline unless the presence of caries or a previous fracture dictates it. Also, I have found that a supragingival margin with a feather edge (similar to a feather edge design that is used with gold) will not cause a periodontal reaction. Of course, orthodontics as an adjunct to veneers is always a good option for severe misalignment.