This can be determined by looking at the patient’s mouth to see if it can be closed, by looking at the shape of the face and touching the front of the ear, and also through X-rays. 1. Whether the mouth can be closed: When the patient’s mouth can not be closed, can not eat, and can not swallow, and has been drooling, the patient may have a dislocated mandible. 2. The shape of the face: when the patient’s mandible extends forward and the lower one-third of its length becomes flattened, it may also be a dislocated mandible. 3. Touch the position in front of the ear: the front of the ear is fuller in patients who do not have dislocation of the mandible. If the patient has dislocation of the mandible, the front of the ear on both sides will be seen to be concave and the position of the joint cannot be felt. 4. X-ray: In general, as long as the mouth is closed, the condyle will immediately retreat to the articular nodes. If the patient has a dislocated mandible, the condyle will be found to be in front of the mandibular nodes and cannot be retracted. The above ways can be used to determine whether the mandible is dislocated or not, if the patient has a dislocated mandible, he should go to the hospital in time, and actively cooperate with the doctor for treatment.