Implant specialist Alex Rugh discusses Nobel Biocare's Angled Screw Channel (ASC) abutment which makes it possible to fabricate screw-retained restorations, even when the angle of the implant normally wouldn't allow it. Alex explains how they work, what they're used for, and some of their advantages.
These abutments make it possible to fabricate screw retained restorations even when the angle of the implant normally wouldn't allow it.
The way they work is through a special screw called the Omnigrip that is designed to be torqued at an angle. This screw does require a special omnigrip driver instead of the usual unigrip driver, but it still gets torqued to 35 Ncm.
The access hole can be adjusted up to 25 degrees which is sufficient for most cases. However, there are some limitations in regards to the thickness of the abutment which are affected by the implant placement and the amount of space available.
The abutments are made of zirconia and are mechanically retained to a titanium base. The abutments can be designed as full contour zirconia crowns or with cutback for stacking porcelain directly to the abutment.
They can also be designed as a base for a screwmentable crown such as e.max
One really nice aspect of these is that they are also available with non-engaging titanium bases so that you can utilize them for bridges.
When you are handling these abutments, take care not to lose the titanium base. The base fits semi-loosely in to the bottom of the abutment and can easily fall out or detach when removing the abutment from a model or implant. When the abutment is torqued in to place, the screw holds the two pieces together.
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