Tuesday, February 08, 2005

Cerec and Andrew Tobias

Andrew Tobias previously opined on his new Cerec Crown made by his Miami Beach based dentist.

Another dentist wrote to him and offered another opinion:


Mark the Tooth God (or so I gather from his screen name): “The restoration you received is certain to be great so please don’t read on expecting to have buyers remorse. But the CEREC process your dentist used is not exactly a panacea. I know it sounds great when you have a metal temporary and it takes four visits to get your crown, but here's just a little bit more info:

1) It’s nice to be able to temporarily cement the crown to be sure the nerve is happy and healthy. With CEREC you can’t do this. The porcelain is too weak to be supported by temporary cement. This can lead to the new crown having to be destroyed if a root canal proves necessary.

2) The fit has improved with this new CEREC 3 model, but the margins (the gap where the restoration meets the tooth) are still only fair.

3) If any of the margins of the crown are below the gum line, the ability to ‘bond’ the CEREC on is greatly hampered: It is difficult to keep that area properly dry under the tissue while you bond it in.

4) While your crown is on Herbie, a tooth pretty far back in the mouth (out of what we call the esthetic zone), the esthetics of CEREC crowns are only fair compared to what a live lab tech can do. The CEREC mills from a monobloc of porcelain. This gives a single homogenous color. Most teeth have multiple shades. If it were a crown on a bicuspid, the CEREC crown is not terribly attractive for most applications. Unfortunately due to the investment made by the dentist, most will use it for nearly all crowns. [Mine said he generally uses it only for the teeth you don’t see. – A.T.]

5) The CAD CAM technology continues to improve. There is a system out there, I believe it is being completed in Israel, that will be on the market in a couple of years which has marginal integrity more like what a lab would make. The CEREC was churning out margins with gaps ranging from 80-100 microns. A really good lab gets it down to 25 microns. The Israeli machine I believe has it down to 10. Bacteria are 8 microns tall, so floss.

All that said, most of the CEREC crowns I see in my practice, even the ones made with the earliest unit, seem to be doing OK. So no buyer’s remorse.”

Well, Andrew, you have not seen the many failures of Cerec that I have. There is NO WAY I would ever have a Cerec CAD-CAM crown placed in my mouth!

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