The abdomen area is one of the toughest places to master in anatomy. A typical med school start from thorax (chest) and either go up (to head and neck) or down (abdomen and pelvic vicera) in subsequent semesters. NYU starts w/ the head and neck, which is the toughest place to master. There is a separate master course called "organ system" which overs pretty much every other essential parts of the body. Since the boards weigh heavily on the head, neck, and nervous systems, it'd be an ego decision for a dental school to cover all parts of the body. I heard some of the institutions where dental and med students attend classes together, the curriculum tends to follow the med school version (e.g. harvard, columbia, etc).