FWIW, only externally connected implants should be cast in all plastic. There is no way to lap an internal connection. I wouldn't do it. Use a gold plastic combo, or mill one and pass on the cost.
I always use gold-resin cast to abutments.
If you have an engaging type with ext hex, there is no way you can make a lapping tool for the internal feature to meet that external hex either.
Most lapping tools are not designed to refine the screw seat - only the hole itself for screw to pass through. And if you do, then comes the question how
much of the metal remains after 'refining' the seat - since I know of none that
has 'stop' to the vertical component.
I agree - pass the cost and preferably, use the original implant manufacturer's parts for warranty reason - although some, like Atlantis, would
cover those of the implant itself from what I understand.
LCM