Sameer Puri D.D.S. We all know CEREC does a great job with a patient's restorative needs with an onlay or a crown in a single visit. The procedure works very well and those that use CEREC in their practices know that the results can be extraordinary. The one question that arises from new and potential users however is what do you do when you have to deal with a subgingival margin?
Lets look at it like this- first, a sub gingival preparation is not a contraindication for CEREC. You simply need to isolate the sub gingival area for imaging and bonding. The best way to describe this is what would you do if you have a clinical situation where you can't stop the bleeding and you are going to take a regular impression with PVS? You see, CEREC is no different. In order to get a good impression, you have to have a dry clean field.
Without a dry clean field, essentially what happens is that you have a poor impression (whether its digital or physical) and you end up with a poor fitting restoration. The goal is to have healthy tissue so that you can have an operating field that you can work in properly.
If I have a situation with unhealthy tissue, what I typically end up doing in situations such as this is I will still scan in an imperfect field and design a restoration milled out of a temporary block (Enamic, LAVA, VITA, Empress - all work well with for this) and then cement the temporary crown with temp cement and then wait a few weeks for the tissue to heal and finalize my impression.
The case below shows an example of a restoration that needs to be replaced due to poor esthetics and an open margin that is clearly visible on the buccal.
Upon removal of the existing restoration, you can see the irritated tissue. Despite the best efforts to try to get the tissue health under control, we were unsuccessful.
So rather than try to fight the tissue and end up with a suboptimal result, we milled out a temporary crown and cemented it to allow the tissue to heal. The patient was asked to clean the area thoroughly each night as well as participate in proper brushing and flossing. This will help to heal the tissue and in about 2-3 weeks, I can remove the temp crown and take my final impression.
Couple of points- the shade is obviously off because the patient is going to bleach her teeth. In addition, using the articulation function on the software allowed me to dial in the occlusion in both excursive and static movements. In hindsight, on the final restoration, I probably need to use the Incisal Variation tool a bit and shorten the buccal cusp ever so slightly.
The summary is that just because you have a CEREC doesn't mean that every single restoration has to be completed in a single visit. There is a time and a place for two visit dentistry if the tissue, occlusion or anything else does not cooperate.
