Second Opinion: To Prep or Not to Prep? By David S. Hornbrook, DDS, FAACD

One of the hottest topics in dentistry today is the concept of “minimal prep” and/or “no-prep” veneers. One of the primary reasons for this controversy is that patients are now asking about this treatment due to direct consumer marketing. When I ask attendees in my lectures about whether their patients are asking about “no-prep” veneers, the majority of the audience states that they are. Many clinicians, however, are divided as to whether acceptable aesthetics can be achieved without preparing the teeth prior to veneer placement. In fact, I have witnessed statements made on several dental forums that it is impossible to achieve good aesthetics without first removing enamel, yet I personally have had multiple patients accept treatment only if I did not have to remove any healthy tooth structure prior to veneer placement. Is there a right or wrong in the need to remove tooth structure? Are no-prep veneers an option for patients who want a beautiful new smile? Are paradigms or lack of knowledge keeping clinicians from providing their patients the treatment they desire? Having placed thousands of veneers since graduating from UCLA in 1986, my personal opinion is based on the same principles that we make all clinical decisions, proper diagnosis and treatment planning! Unlike many of the clinicians I have met who state that, “you must prep;” I think there is a tremendous opportunity to meet the needs of patients without prepping. I also think that, unlike many of the advertisements I have read regarding prepless veneers, there are limited opportunities to provide this service and understanding the limitations and compromises is mandatory.

The use of porcelain veneers has become an important and popular adjunct to most progressive restorative practices. The opportunity to significantly enhance a patient’s smile without the need for aggressive tooth reduction is a major benefit to traditional dentistry. Many clinicians began their journey with the use of prefabricated resin laminates in the 1970s. These resin “facings” provided the clinician an opportunity to improve the aesthetics of a patient’s smile by etching the enamel, filling the prefabricated resin laminate with a direct composite resin and then applying it to the unprepared tooth surface. Although shading was generally improved upon, the limitations of this technique were obvious. The definitive results were usually bulky, misshaped, and the marginal integrity was unacceptable. The use of ceramic became increasingly popular in the early 1980s because of the improved aesthetics of custom-fabricated ceramic and the improved marginal integrity because of impressing of the preparation and fabrication onto a master die. To avoid the bulky and over-contoured result seen with the pre-fabricated resin laminates, the recommendation was to remove enamel from the front of the tooth and then replace it with the ceramic veneer.

The dentinal materials at the time also influenced preparation design. True dentinal adhesion had not been developed and the prudent clinician limited facial tooth reduction solely within enamel. The other limitation was the inherent strength of the powder-liquid ceramics used to fabricate the veneers. In the absence of pressed ceramics and accurate refractory die materials, the ability to fabricate feldspathic veneers that varied significantly in thickness or extended interproximally was laborious and difficult for the ceramist. These limitations established an ideal preparation design that was very conservative, and most educators at the time recommended 0.3 - 0.5mm facial tooth reduction. With the introduction of hydrophilic primers coupled with acid etching of the dentin (fourth generation dentinal adhesives) and the development of pressed ceramics, traditional veneer preparation recommendations were challenged. With the opportunity to adhere to dentin, facial reduction could now be increased to compensate for darker, more discolored and malpositioned teeth. The increased strength of the pressed ceramic also added to the flexibility of preparation design because it could be fabricated easily, even if the thickness of a single veneer varied significantly. The pressed ceramic technique also enhanced the ability for the ceramist to achieve accurate margination, even if the preparation design included the removal of Class III lesions or pre-existing restorations resulting in an interproximal box form.