medpor is about 10 percent at the jaw angles during the integration phase. its much lower after, howerver, if you get a tooth infection a decade later, it can get infected again.
silicone can get randomly infected decades later. also the forces from the massater supposedly cause it to change shape at the jaw angles.
im not familliar enough with other implant materials. supposedly bio-oss is like the god material. idk though.
they all can cause bone resorption, but then again so can osteotomies.