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.

John R. Carson, DDS, PC, Spear Visiting Faculty. [ www.johnrcarsondds.com ]


Tony Molina
March 17th, 2014
What is your protocol for restoring this type of case? How do you get an adequate seal against the restoration?
Kevin Huff DFS
March 17th, 2014
I agree with Dr. Carson. If I might add my two cents.... I air-abrade the prep and then apply Scotchbond Universal bonding agent and then restore with composite, or sometimes RMGI like Fuji II LC, depending on the case. Isolation and tissue retraction is, of course, critical. If the patient does not object and crevicular fluid is an issue, I am not afraid nor ashamed to use amalgam in these cases.
John Carson
March 17th, 2014
Tony, I will often use a material such as Fuji II LC or even Fuji IX and in rare cases I use composite. If using composite you can use a material such as Interface from Apex to bond to the porcelain. While repairing a margin with any material is not going to give you as ideal a seal as the original restoration in the right cases it can give you an acceptable seal to buy some more time before the restoration has to be replaced. Additionally when using tooth colored materials to repair the margins it does help facilitate further monitoring of the area for leakage (if you see discoloration you have leakage). Kevin, thanks for the comments. Lastly just to be clear the times that I feel comfortable repairing a margin are few and far between (at most a handful of times a year) as I don't feel good about it unless all the above criteria are me, it is however a option to consider in the right situations.
December 31st, 2014
Has anybody used the new bioactive material Pulpdent's Activa? Seems ideal for this type of situation.
John Carson
January 2nd, 2015
Goloskov, I have not used this material, it looks interesting from what I read on their site but as I said I have zero experience with it. I would suggest making a post on Spear Talk and see if anyone there is familiar with it.