Yeah this is all somewhat uncharted territory as it's hardly mainstream practice to graft bones from other parts of one's body or from cadaver bone etc. to your face.
Sinn told me that where cadaver bone for example was used to fill-in parts that had been broken and augmented, that cadaver bone would gradually turn into one's own bone. I'm not sure if it's because the cadaver bone keeps the gap open as your own bone grows to fill in and take over that osteotomized gap OR whether it's cause your own blood vessels etc. fill in to the bone as they would to a medpor implant OR whether your own bone recognizes it as bone and begins to take over it and turn it to your own bone (the last seemed to be what Sinn was suggesting).
But everyone says that overlay grafts whether your own bone or cadaver (how Sailer uses it) will eventually resorb.
But really, we have so few actual case studies for even anecdotal evidence it's hard to say.
Regardless, you have great results and I'm sure if you haven't noticed anything over 3-5 years you're probably totally in the clear!
Interesting stuff.