- The doctor of philosophy degree in Oral Health Sciences is a program of the Rackham Graduate School, offered at the School of Dentistry. The primary objective of this program is to train outstanding students to become leaders in academic research in oral health science. Major areas of study include developmental craniofacial biology; mineralized tissue biology and musculoskeletal disorders; oral and pharyngeal cancer; oral health disparities; oral infectious and immunologic diseases; oral sensory systems and central circuits; and tissue engineering and regeneration.