It is a common dental and maxillofacial deformity, usually due to congenital hypoplasia of the mandible or trauma, infection and other factors affecting the growth and development of the mandible, resulting in the shortening of the mandibular branch and mandibular body, mandibular recession, serious cases can be bird’s beak-like deformity, resulting in facial disproportion, patients open lips and teeth, smile and gums, bite function abnormalities, serious conditions and even affect the patient’s psychological The condition may even affect the patient’s psychological status. To determine whether a receding jaw is present, a direct visual examination of the face can be performed. I. Physical signs: The most direct way to diagnose mandibular recession is to observe the patient’s physical signs through the naked eye. 1, mandibular recession, the upper jaw position is basically normal, the anterior teeth are deeply covered, the upper anterior teeth are obviously tilted, the lower anterior teeth are biting high on the lingual bulge of the upper anterior teeth or palatal mucosa, and the lower lip is attached to the lingual surface of the upper anterior teeth. 2.The lower jaw is receding, the lower dental arch is smaller than the upper dental arch, the height of the lower 1/3 of the face becomes shorter, and the lower jaw is obviously receding when observed laterally. 3.In the case of deep coverage of upper front teeth, the upper front teeth are exposed outside the mouth, the lower jaw and chin are receding in lateral observation, and the upper and lower jaws are extremely disproportionate. Second, auxiliary examination: through jaw and face X-ray, CT and other imaging examinations, the scope of jaw recession and its severity can be roughly estimated.