Tag: Crown Repair

 

A quality crown repair is important for successful patient centered outcomes. What’s desired is a quality core and an esthetic closure. There are options in achieving these goals, and presented here is just one process. I’ll outline the steps, materials, and rationale. This case was a retreatment from a restorative failure; the core was poorly adapted and the tooth was symptomatic. The patient was highly motivated to prevent this mode of failure on the retreatment. Amalgam as a core has a long track record and because of it’s handling characteristics works will in very conservative accesses where pulp horns have been intentionally preserved.

1. Chamber Cleanup: After obturation, I like to clean up the obturation interface with a peezo with that little bump cut off. Just zip it off with a football bur.  A #2 works well if your final file is around a Protaper F1 (22.07). If more conservative instrumentation is used, I find the #1 works well. Then alcohol to clean up any remaining sealer, followed by etch. That’s my chamber cleanup protocol.
2. Bonded Amalgam: At this point you gotta decide if your going to bond your amalgam. The available evidence suggests there are likely benefits, so I do it. Clearfill primer, air dry, then Clearfill bonding agent which is light cured. A second unset bonding agent is placed and the amalgam is condensed into this second top layer of uncured bonding agent. The dual cure nature of this bonding agent creates the bonded amalgam.
3. Carving the Amalgam: I like a spoon for this. If you want you can get some mechanical retention by undercutting the casting a little. Hard to say if it makes a difference. But I do it on Zirconium crowns.
4. HF Etch: At this point make sure you have a good bevel using a course football bur. Then hydrofluoric acid is used to etch the porcelaine, this minute feels like forever. Then my assistant suctions the acid and she rinses while I scrub the precipitate off. If you don’t scrub it, the bond won’t be as good. I just use a piece of sponge. Then dry the water off.
5. Silane: You can use an additive to the Clearfill Primer or just the silane. The silane has a long track record. Newer isn’t always better. The silane needs to be air thinned.
6. Bonding: Then I place the Clearfill bonding agent over the porcelaine and amalgam.
7. Opaquer: I like the permaflow flowable composite. It has an opaquer shade that hides the silver really well.
8. Composite: We use Filtek body- it works well with Clearfill products. My assistant expresses part of a carpule on a mixing pad, then scoops up the composite on the back of a spoon. We use the orange filter so the composite doesn’t set, and apply the first bank of composite. After it’s manipulated in place and cured, we add a couple more increments using an endo explorer or a spoon to shape the composite.
9. Finish and polish: Usually we don’t need much adjustment. But it’s important to get the occlusion right. A fine football and a zirc polishing point helps on any adjusted parts of the crown.

That’s it! Pretty and predictable.