Dental Implant in autooimmune teen patient

Patient is an 18 yo who had a root canal. Before crowning tooth, the dentist took a film which revealed an "abnormaity;inflamation (inflammation) & possible infection of only one of the roots". The dentist examined the tooth itself which appeared "fine-no fracture"  The dentist then proceeded too check the sensitivity of the tooth by using a blunted dental hammer. The dentist then re-examined the tooth and declared that it was indeed fractured. Since it already had a large  filled cavity, "it should be pulled and a dental titanium implant should be inserted & then capped"  This child has family hx of autoimmune disease ( lupus vs scleroderma) & has the begining signs of the same.  
Is a dental titanium implant in such a young person with this hx and the probability of repeated CT/MRI as well as possibe rejection & jaw bone deterioration reasonable?