Porcelain veneers: to prep or not to prep

When I graduated from the University of the Pacific School of Dentistry in 1988, no-prep veneers were a hot product.

When I graduated from the University of the Pacific School of Dentistry in 1988, no-prep veneers were a hot product. In February of 1988, I became the first student in the history of my school to do a porcelain veneer case. The patient was a model and told me that her moderate tetracycline staining was preventing her from getting jobs as a model. Initially, the head of the fixed prosthodontics department refused to let me do the veneers on the basis that it was a non-teaching case. Considering the fact that no faculty member had done a veneer case yet, I had to admit that he had a point. The patient, however, would not take no for an answer and began to leave voice mails for the instructor, first weekly, then daily.

We ended up doing six veneers on her, Nos. 6 through 11, a treatment plan decision I would never make today based on the buccal corridor problems it creates. Today, we would extend and go from first bicuspid to first bicuspid, or second bicuspid to second bicuspid. If the patient has a broad smile and shows a lot of teeth, we may do veneers from first molar to first molar. In conservative cases with minor corrective needs, we will often just do veneers on 7 through 10.

As I got ready to prep the case, I asked my instructor whether or not we would be prepping the teeth. Remember, back in these dark ages before bis-acryl temporary materials, we did not temporize our veneer patients, and they all left the office with a coarse diamond finish on their enamel! For this reason, the no-prep option was attractive because at least the patients got to leave without their enamel looking like they had just finished a make-out session with a model trimmer.

Since I barely knew how to prep a crown, let alone a veneer, I was hoping to do this as a no-prep veneer case, but it wasn't meant to be. My instructor pointed out that there is really no such thing as a no-prep restoration in dentistry. His biggest issue was with the margins, particularly the gingival margins. Without any reduction done for the gingival margin, it was inevitable that there would be poor contour in that area of the restoration, and due to its bulbous nature, it would become a plaque trap that would ultimately lead to gingival inflammation and discoloration. He pointed out that even when proper reduction was done, if the emergence profile was incorrect and too bulky, the same negative effects would occur to the gingiva. The goal in restorative dentistry is to mimic Mother Nature with proper dimensions and contours. If a tooth is left a little bulky in the middle or incisal third it may or may not be problematic from an aesthetic standpoint, but not from a health standpoint. However, if a tooth is left bulky in the gingival third, the ramifications are much more serious, since they are occurring at the perio-prosthetic interface.

As you flip through dental journals these days, you may notice more advertisements about no-prep veneers. I agree that it is extremely patient friendly to talk about no-prep veneers; no one wants to get their teeth drilled on. The idea of having a dental version of Lee Press-On Nails-where we have some veneers made and simply glue them on-would undoubtedly appeal to a patient, but only if they were uneducated about restorative dentistry. Many of the no-prep cases I did in the early days looked very bulky, and I ended up having to replace some of these cases. That's when I learned the procedure was not nearly as reversible as I had been led to believe. Since the veneers had been bonded to enamel, the strongest bond we have in dentistry, they did not simply pop off as advertised and I ended up inadvertently removing tooth structure while removing the veneers. I was planning on redoing the cases with reduction anyway, but if the patient had wanted to return to square one, I would have had a lot of explaining to do.

If it sounds too good to be true, perhaps it is. During 15 years of doing veneers, I have come to some conclusions. No-prep works every once in a while on individual teeth with an arch that is lingually positioned. If you do no-prep veneers, you must accept the fact that the margin will be less than ideal. Many CEJs don't contribute to the health of the gingiva, let alone when a no-prep margin is placed.

I truly believe the best approach is minimal prep veneers. Recontour the teeth before placing depth cuts to ideal arch form. Add composite where necessary to bring teeth back into ideal arch form, then place depth cuts of .3 mm. Stay in enamel whenever possible to increase bond strength, reduce microleakage, and reduce postoperative sensitivity. And prepare the gingiva margin right at the free margin of the gingival to give your lab enough room to build a veneer that will blend with the emergence profile of a tooth and promote gingival health.

Dr. Michael DiTolla is director of clinical research and education at Glidewell Labs in Newport Beach, Calif., where he also teaches over-the-shoulder courses on topics such as aesthetic restorative dentistry. Dr. DiTolla also teaches a two-day, live-patient, hands-on laser-training course that emphasizes diode and erbium lasers. In addition, he teaches a two-day, hands-on digital photography course emphasizing intraoral and portrait photography, and image manipulation. More information on these and other courses can be found by email at mcditolla@mac.com or by calling (888) 535-1289.

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