"If you just took the skin and transplanted it to the other patient, the bony structure is different, " Papay said.

CNN: How gunshot survivor became first to receive face transplant

"One of the ways you can tell that is how your upper teeth fit to the lower teeth, " Papay said.

CNN: How gunshot survivor became first to receive face transplant

"We thought we were going to wait a long time because we had to find a Caucasian female in her mid 40s to match Connie, so we expected a year before we were able to find a donor, " said Papay, who is also head of craniofacial surgery.

CNN: How gunshot survivor became first to receive face transplant