First of all, partial jaw deformity refers to a complex deformity with uncoordinated lateral relationship between upper and lower jaws, inconsistent tooth midline and chin deviation as its main clinical features, and it is a very common jaw deformity. The formation of partial jaw often leads to bilateral facial asymmetry and disorder of jaw relationship, which will seriously affect the patient's appearance, chewing and pronunciation functions and cause great pressure on the patient's physiology and psychology. Moreover, many diseases can cause the occurrence of partial jaw deformity, and its manifestations are also very diverse. The classification is complex, and each type has different secondary changes. According to the etiology and pathology, it can be roughly divided into three types, namely, hypoplasia, overgrowth and maxillofacial deformities caused by trauma. But it can be divided into two categories: congenital and acquired.

Among congenital factors, due to embryonic development disorder, one side of craniomaxillofacial skeleton is three-dimensional hypoplasia, bilateral development is unbalanced, and the jaw grows eccentrically, which leads to mandibular deviation and subsequent changes in adjacent structure and morphology. Acquired factors may be caused by trauma, infection and benign hyperplasia. Among these factors, mandibular deviation caused by trauma is more common. Childhood chin trauma may lead to developing condyle and neck fractures, and may also affect the development of condyle and cause jaw deviation. Blood-borne systemic infections in infants, such as septicemia, osteomyelitis of maxilla and mandible, and unilateral joint ankylosis, may also lead to partial jaw. There are other reasons for mandibular deviation, such as benign hyperplasia and hypertrophy of condyle, chondroma of condyle and compression of surrounding soft tissue. In addition, some bad habits in life can also lead to mandibular deviation, such as the pelvis leaning forward, chewing food on one side, sleeping on one side for a long time, and often holding the chin with one hand.

Some jaw deformities are hereditary. At present, we have no way to estimate its probability and avoid it completely. But it is also important to keep good habits the day after tomorrow.