Why does chin implant cause bone erosion but HA fillers do not?

The filler is placed at the same place and feels just as hard as an implant. How come? And will botox in the muscle over the implant/filler prevent erosion of the bone? And also, is it a higher risk to inject HA fillers over the muscle in the chin? Like just below the skinsurface? I feel that it gives more volume than injecting under the muscle where it often migrates in my case. I have been treated by different certified injectors.