In general when preparing teeth for veneers, my goal is to be as conservative as possible and leave everything in enamel. This would mean leaving the interproximal intact and not preparing through the contact. Unfortunately, depending on the clinical situation this may not always be possible or recommended.

This article will address the clinical situations that are encountered in practice that I feel necessitate breaking the interproximal contact.  

Existing interproximal restorations

In a majority of clinical situations, if a Class III restoration is present, I will prepare through the contact in order to get beyond the composite and place the margin on sound tooth structure. (Figures 1a, b and c) 

existing interproximal restorations figure 1a
Figure 1a
existing interproximal restorations figure 1b
Figure 1b
existing interproximal restorations figure 1c
Figure 1c

In these situations, I will also typically replace the existing composite during tooth preparation so I know it is sound. The risk of placing the margin on the existing interproximal restoration is micro-leakage, which may lead to discoloration/caries.1  

It must be noted that there are times in which I will leave my veneer preparation on composite with the idea of being more “conservative” with the preparation. Generally, the existing interproximal restorations in these situations extend much farther onto the palate – so much so that if you wanted to get beyond the restoration, you would end up preparing the tooth for a partial crown. In these circumstances, it is critical to replace the existing composite and place the veneer margin through the contact on the palatal surface so that it is accessible if/when future leakage occurs.

Diastemas/triangular-shaped teeth/open gingival embrasures

It is imperative to prepare teeth with diastemas or black triangles through the interproximal embrasure and place the margin at the interproximal-palatal line angle. (Figures 2a, b and c) 

Diastemas figure 2a
Figure 2a
triangular-shaped teeth figure 2b
Figure 2b
open gingival embrasures figure 2c
Figure 2c

This allows the technician the ability to close the diastema while maintaining a smooth emergence off of the preparation. In addition, the tooth preparation in these situations needs to be dropped subgingival for the same reason of creating a natural subgingival emergence profile that is easily cleansable.

Significant color change is desired

The more dramatic the color difference between the natural tooth and the desired veneer restoration, the more apt I am to prepare through the interproximal. (Figures 3a, b and c) 

Significant color change 3a
Figure 3a
Significant color change 3b
Figure 3b
Significant color change 3c
Figure 3c

The main goal here is esthetics Moving the margin more palatally removes the risk of seeing the junction or show-through from the tooth.

It is interesting to note that when you combine the above clinical scenarios with the many other reasons why veneers would typically be placed, you will find that it is not uncommon for the preparation to break the interproximal contact.

Resources

1. Peumans M, De Munck J, Lambrechts P, Vanherle G, Van Meerbeek B. A prospective ten-year clinical trial of porcelain veneers. Journal of Adhesive Dentistry. 2004;6(1):65-76.

(Click this link for more dentistry articles by Dr. Gregg Kinzer.)

Gregg Kinzer, D.D.S., M.S., Spear Faculty and Contributing Author


Comments

Erin D.
March 9th, 2017
Just talking to my ceramist about this very issue. This will help. Thanks Greg.