Bone erosion is a function of friction and has been mostly associated with silicone chin implants, especially to the chin where the movements over it result in friction and hence the erosion. Usually they are sewn into a 'pocket' and if the pocket is a tad too big there can be micro movements which over time can result in erosion. Although they can be screwed in, soft silicone usually used is not really a good material to screw. Their advantage as implants is that they can mimic a combo of both soft tissue and bone and can be squeezed into place. However silicone implants can also be HARD.
Porous implants (like porex) take a screw very well, accommodate tissue ingrowth and lend themselves to SCULPTING by hand. They can be hard to remove though if they need to be. Both Silicone and porous implants can be custom designed.
There are other porous implant materials such as coral. As for bone whether it's your own, cadaver bone or even bone made from an OX, (xENO-GRAFTS) those are not used as ONLAY materials but rather bone BUTTRESS between CUT SURFACE of your bone where your bone grows into the pores.
Titanium is good for things like rods through bones and is more associated with implants for cranio-facial DEFORMITIES or jaw reconstruction than it is for aesthetic cases. It is non yielding meaning that if the fit were not 'exact' there would be no option to press it in there for totally exact fit.
There are other bio-compatible material used for implants such a PEEK used for implantable medical devices that are promising.
Which ones to use, often depend on the surgeon's preference or what ever options they offer as to selection. There is really no 'final verdict' I know of.
