We would always like to be able to repair crown margins that have developed recurrent decay for our patients; however, while this is possible in some cases, in others it can be risky. So when is it a good idea to repair crown margins and when is it in the best interest of our patient to replace the crown? At the end of the day it really comes down to being able to access the area of concern and confirm that all the decay has been removed.
In my opinion, the best areas to consider repairing are the buccal and lingual margins because they allow access to physically remove the decay and the opportunity to visually confirm success. However, just because you can’t see any more decay doesn’t mean that there isn’t additional decay under the crown. Often when I remove a crown - or any restoration for that matter - with recurrent decay, I often find decay beyond and separate to the area I saw clinically or radiographically. In my opinion, bonded restorations are by far the best restorations to attempt margin repairs because they allow me to test the restoration for seal once the area of decay is removed.
The reason this is important is that if I prepared back to an area that is not sealed, there is a reasonable chance that there has been leakage beyond this point and subsequent decay at a secondary site.
Testing the seal of bonded restorations is really simple. After preparing the area I want to repair I simply place Sable Seek from Ultradent in the preparation as pictured above. After letting the Sable Seek sit for at least 10 seconds I simply wash it away. If you have a good seal it will all rinse out, but if you don’t you'll see a line of residual Sable Seek.
If confirmation of a good seal can be achieved, there will not be additional decay from this source at a secondary location and I’m comfortable placing my materials to repair the margin.
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John R. Carson, D.D.S., PC, Spear Visiting Faculty. www.johnrcarsondds.com