Crystal Zirconia Full Contour Crowns

September 3, 2009

Just a quick update regarding a post from last week regarding full contour crowns milled from shaded zirconia -

We have an account who started asking for this type of restoration, and although I was little skeptical, I agreed to fabricate a few.  I wasn’t crazy about our first attempt – designed using 3Shape CAD software and milled out of Crystal Zirconia on a Digital Dental milling machine – was a little disappointing.  I wasn’t crazy about the morphology or the margins, so we decided to print the same file on our wax printer and then refine the margins and anatomy by hand.  Once we were happy with the design of the pattern, we simply set it up as a copymill, and sent it to the same milling machine.

Much better result, and – in my humble opinion – something definitely worth considering as an alternative to full cast crowns or maybe even e.Max.  I would love to get some feedback from some manufacturer’s regarding 1) the apparent increase in flexural strength of the Crystal zirconia (950 mPa) over that of e.Max Press (400 mPa), and 2) the potential for detrimental effect to opposing natural dentition of highly-polished zirconia.

Here’s a pic of the final restoration (simply polished with Yeti Diamond Polishing Paste – no stain or glaze )  Eat your heart out, Willi …

BTW – We have the same crown being milled with Lava zirconia, just to see if there is any demonstrable difference in the milling.  Also, just had the Vident rep in – this could be an interesting application for their Invizion zirconia designed and milled on the Cerec InLab (I have to think of something to do with that giant-sized paper weight…)

Follow-up:  The Lava Crown came in, and there was no difference in the quality of the mill – either the morphology or the marginal integrity – that I could discern.  However, I can say that the HT Crystal zirconia is definitely more translucent than Lava, but you need to keep in mind you’re giving up about 20% in terms of fracture resistance.  I will assume that the LT Crystal zirconia is probably comparable to Lava in terms of both translucency and strength.  The question becomes, “How strong is strong enough?”

© 2009, Jeff Saylors. All rights reserved.