Of course Eppley is going to say 'it makes no difference'. He hasn't been allowed to use materials like peek until recently. Eppley is the typical business scammer. s**tty results for low price. He loves silicone: easy to take out when something goes wrong. And oh boy, does it go wrong alot of times in his cases.
The shape of the implant plays a role as well. But solicone usually looks a bit more unnatural due to the smoothness of the surface. It also has a tendency to make the screws loose long term due to its softness.
Yes, that is what I was thinking, his insistence on silicone seems to be ease of access and his monopolization of the custom implant business in the US which probably allows for some rapport with silicone manufacturers.
However, I think Eppley has some aesthetic eye for producing dramatic, angular results with silicone, but a lot of the time he goes overboard. I have seen some PEEK results with Joel DeFrancq but I didn't notice much of an aesthetic improvement over silicone, or any aesthetic improvement at all. For example, here's a DeFrancq result that didn't produce any angularity and still lends itself to that bloated silicone look:
So far, the best jaw implant results I've seen have come from Dr. Terino (who I believe is retired or extremely old), Dr. Yaremchuk and Dr. Eppley, with the later 2 also having some terrible results and bad reviews as well, but all use silicone.