One of the most challenging clinical situations often encountered in practice is trying to mask a “dark prep” (Fig. 1). It must be noted that bleaching the tooth internally can significantly help change the prep color and make the restoration more typical. However, oftentimes this is not an option and we must restore the tooth as is.
Traditionally, this was accomplished by using either a metal ceramic restoration to mask the dark prep or a high strength opaque all-ceramic restoration (Figs. 2A, 2B). The difficulty with both options is that if at try-in the restoration doesn’t match, you only have one option to improve it – and that is to “stain” the restoration.
However, if the restoration is already too low in value (too dark), staining is not an option, since it will only drop the value further. So, in these situations, if the restoration doesn’t match, the restoration must be remade. I’m not a big fan of having to remake restorations due to potential for increased lab costs and lost revenue from the additional appointments.
This article will describe the technique we have employed in practice that has been quite successful in masking dark preps. In fact, since I have started doing this, I haven’t had to send a single restoration back to the lab for a remake.
When masking dark preps, what is needed are additional options other than external staining or complete remake when the restoration does not match. The method I use to increase the predictably of the outcome is having the full coverage restoration made in two separate pieces: a coping to mask the dark prep and a veneer that sits on top of the coping (Fig. 3).
My technician and I feel most comfortable using lithium disilicate (IPS e.max) in these situations due to the multiple options available for value and opacity, as well as the ability to achieve a predictable bond to the intaglio surface.
Additional options that can be utilized to improve the esthetics when making the restoration in two pieces include:
- Change the color or opacity of the try-in paste/resin cement
- Stain the external of the coping
- Stain the external of the veneer restoration
At the seating appointment, the opaque copings are tried in first to verify the fit and masking ability (Fig. 4). The veneer restorations are tried in next with water (or a translucent try-in paste) to evaluate color and value (Fig. 5).
If the restorations do not match, I try altering the try-in past first, since that is the easiest. If that option doesn’t solve the issue, then I either stain the coping or stain the veneer. Once the desired esthetic results have been achieved, the two pieces of the restoration (coping and veneer) can be bonded together outside the mouth by etching with HFL acid, silane, adhesive and resin cement (Fig. 6).
The definitive restorations can then be taken to the mouth and bonded in place, blending nicely with the adjacent natural teeth, despite the dark substrate (Figs. 7A, 7B).
As with any new technique, please consult with your lab technician prior to initiating clinical treatment with these types of situations.
Dr. Greggory Kinzer, D.D.S., M.S.D., is a member of Spear Resident Faculty.