Gold onlay with porcelain facing?

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Posts: 5
Joined: Tue Nov 14, 2017 12:16 pm

Gold onlay with porcelain facing?

Post by jgold1981 » Tue Nov 14, 2017 12:26 pm

I recently had RCT on my upper first molar, which turned necrotic about 2 years after a large MO amalgam was put in. I've been advised that there appears to be enough sound tooth structure left that it can be restored with an onlay covering all the cusps and parts of the walls.

I tend to favor function and tooth health over aesthetics when making decisions about my teeth, and would ordinarily want a gold onlay because I understand that it is strong, can be thinner than porcelain, and puts less wear on the opposing tooth. However, I'm not happy about the idea that the portion covering the buccal cusps (and any portion extending beyond them on the cheek side) would show at the corner of the tooth, which is visible when I smile.

If I were getting a crown, I would ask for gold crown that has a porcelain facing on the cheek side to deal with this problem, i.e. PFM. I've seen only a few passing references to "PFM onlays" in a google search and notice there is no insurance code for such a thing. I don't care about perfect aesthetics (i.e. I don't mind if a porcelain facing is too thin to perfectly replicate the look of tooth enamel), but I really don't like the idea of flashing gold to the side when I smile. I was wondering if a gold onlay can be fabricated with a porcelain facing on one side?

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Re: Gold onlay with porcelain facing?

Post by sbornfeld » Tue Nov 14, 2017 2:39 pm

I've never seen it done. Porcelain needs adequate support--it has poor edge and torsional stress, and I doubt it would survive in this application. I don't do a lot of onlays (especially on endodontically-treated molars) because I find the difference in the amount of tooth structure preserved doesn't usually compensate for other factors. Most important of these is that most patients who need root canal have a significant history of decay, and an inlay or onlay exposes loads of restoration margin to the oral environment.
But I will occasionally get a middle-aged or older patient who has lots of old fillings and little recent decay. Some of these teeth with large old fillings will break, and need restoration. These are the type of patients I will consider onlays.
If you are looking for esthetics in onlays, I'd consider e.max (lithium disilicate) or zirconia. Zirconia has the edge in strength; e.max in esthetics. My reading implies that zirconia is harder, and could be expected to cause more wear than e.max; but I have not seen it, and have not read any reports. I would certainly not use zirconia against gold. But unless you grind and clench, they both should work.
Steven Bornfeld, DDS
Brooklyn, NY

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