
JohnWilson
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Bernard thanks.
HI John,
I agree with many of your pros and cons, would love to discuss a little more.
1. Weight, we stopped providing conventional hybrid restoration in 1990 due to breakage of teeth and or acrylic. At that time we moved all these cases to porcelain to gold. Some patient with severe bone loss would require 22-23 mm of restorative material. I remember cases that had close to 3 ounces of gold in the casting. That said, we never ever had a patient comment on weight.
4. You're right about the best verification jigs having a possible discrepancy. That said, Isn't it more about tension on the implant-bone interface than the tension on the CAD base?
I hear you Bob, so glad the days of 65sf casted bars and substructures are a thing of the past. I always think of the one bar I did when we calculated the wax weight we needed to throw 3.6oz just for the pattern and then double that for the runner bar/sprue and button. I watched the casting tech do this one and I am sure having me watching made it even worse. Thank god for no splash and the thing worked but I always hoped for a better way.
As to the verification I mentioned, I noticed that when a verification jig gives a false reading its because the analog is often too LOW in the model and this allows the jig to seat in the mouth and unless the client is taking perfect radiographs at exactly a right angle to the fixture the film will look like everything is correct.
This leads to the screw constantly pulling and essentially extracting the cad base from the zirconia as its constantly under tension and is not bottomed out in the morse taper of the implant. This is when I see things start to go sour down the line.