Complex sentence: Unfortunately after six months 90% of the implanted donor bone was reabsorbed or removed surgically because of infection and at present the patient is in need of a structural prosthesis to replace the missing lower mandible to provide her with normal breathing, sleeping, eating and speaking.
Split into simpler sentences: Unfortunately after six months 90% of the implanted donor bone was reabsorbed. Some of it was removed surgically because of infection and today the patient is again in desperate need of a structural prosthesis to replace the missing lower mandible and provide her with normal breathing, sleeping, eating and speaking.