Portion of crown fell off when eating. Korean dentists tell me there is 50/50 chance that I would need extraction once they remove my old crown. They told me if there is damage to the post they would have to replace that, but don't understand why my American dentist made the post so deep and big. They tell me there may be grafting, extraction, implant after they open it up and see how my tooth is. Wait it out till my crown breaks and I definitely need extraction? Or risk 50/50 now?