Chin implant placed Intra orally, and taken out submental approach - explanation?

I've heard that if you have a chin implant placed Intra orally , it should be taken out the same way. The surgeon who placed my implant says he can take mine out submental, even though he placed it Intra orally. Can someone here explain to me why most surgeons say that it won't do this? Why should it be removed the same way it was placed? Will I have more complications if it's done this way? Please explain?