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tyjthomas
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Hey guys - I'm pretty new to in-house production of zirconia crowns. I am trying to do a zirconia crown on a straumann RN variobase abutment. It is scanned using the scan body, designed in exocad, milled using millbox and Roland DWX-52D mill out of Argen HT+ and sintered according to their program specifications. The fit is good but there is a little rotational movement. I have milled it now probably 7 times and they all have a little rotational play in them:
1. Milled out according to regular screw retained implant protocol in exocad.
2. Tightened the crown +.01 in millbox
3. Tightened the crown +.02 in millbox
Since you can't adjust the fit/crown bottom of an implant from the library, I scanned in the variobase abutment itself as a crown prep and designed on top of that.
5. Milled out according to regular workflow
6. Set cement space to 0
7. Dropped Anticipate milling from 1.2 to 1.0
With each one, the milling preview looks clean. Each fully seats on the titanium base. It looks like Straumann's variobase abutments don't have tons of anti-rotational features so I'm wondering if that may not be the culprit? Anyone else have experience with this? The play probably allows it to rotate 10 degrees. I don't want to just rely on the cement but is that normal?
(The mill is calibrated and the milling seems clean/not chipping so I don't think burs are the issue)
1. Milled out according to regular screw retained implant protocol in exocad.
2. Tightened the crown +.01 in millbox
3. Tightened the crown +.02 in millbox
Since you can't adjust the fit/crown bottom of an implant from the library, I scanned in the variobase abutment itself as a crown prep and designed on top of that.
5. Milled out according to regular workflow
6. Set cement space to 0
7. Dropped Anticipate milling from 1.2 to 1.0
With each one, the milling preview looks clean. Each fully seats on the titanium base. It looks like Straumann's variobase abutments don't have tons of anti-rotational features so I'm wondering if that may not be the culprit? Anyone else have experience with this? The play probably allows it to rotate 10 degrees. I don't want to just rely on the cement but is that normal?
(The mill is calibrated and the milling seems clean/not chipping so I don't think burs are the issue)