To become a specialist requires training in a residency or advanced graduate training program. Once a residency is completed, the doctor is granted a certificate of specialty training. Many specialty programs have optional or required advanced degrees such as a master's degree, such as the Master of Science (MS or MSc), Master of Dental Surgery/Science (MDS/MDSc), Master of Dentistry (MDent), Master of Clinical Dentistry (MClinDent), Master of Philosophy (MPhil), Master of Medical Science (MMS or (MMSc); doctorate such as Doctor of Clinical Dentistry (DClinDent), Doctor of Medical Science/Sciences (DMSc), or PhD;or medical degree: Doctor of Medicine/Bachelor of Medicine, Bachelor of Surgery (MD/MBBS) specific to maxillofacial surgery and sometimes oral medicine).