Masseter muscle reattachment after jaw implant?

I am not clear as to what type of jaw implants were placed, but having performed corrective jaw surgery for over 25 years where we electively release the masseter muscle during these procedures. the muscle will spontaneously reattach itself during the recovery. The same occurs when the "sling" is released to repair a mandibular angle fracture. As far as the asymmetry, it is possible that your implant has migrated; this can be evaluated with a CT scan. Good luck