Oral and maxillofacial system is the general name of various oral and maxillofacial structures, including teeth, temporomandibular joint, masticatory muscles, nerves and so on, and it is a functional whole that restricts and coordinates each other. Under the unified command of the central nervous system, teeth, temporomandibular joint and masticatory muscles perform their respective functions and jointly complete complex functional movements. Oral and maxillofacial system is responsible for pronunciation, speech, expression, chewing, swallowing and other important functions.