Dislocation of the jaw is clinically known as temporomandibular joint dislocation, which refers to the slipping of the condyle out of the joint fossa beyond the normal limits of joint movement and cannot be restored to its original position on its own, and is divided into three types: acute, recurrent and old dislocation. To determine whether temporomandibular joint dislocation has occurred, a clear diagnosis can be made based on the cause of the dislocation, physical examination and clinical symptoms. After TMJ dislocation, the dislocated condyle is mostly stuck in the front and bottom of the articular tuberosity, which is difficult to reset by itself, and it is difficult for the upper and lower jaw teeth to bite together normally. With the prolongation of dislocation, the masticatory muscles attached to the mandible will have different degrees of spasm, the soft tissues around the joint will swell, and the pain will gradually increase. II. Judgment based on physical examination and medical history There are certain causative factors leading to TMJ dislocation, mainly including sudden over-opening or over-opening of the mouth, such as dislocation occurring during oropharyngeal examination or undergoing surgery or dental treatment; loosening of the joint capsule and joint ligaments, habitual excessive jaw movement, etc. By taking a medical history and performing a detailed dental examination, it is usually possible to determine whether the dislocation is a unilateral or bilateral dislocation without the need for x-ray examination and to treat it accordingly.