When the bone next to the ear hurts after opening the mouth wide, it is the occurrence of temporomandibular joint dysfunction syndrome, which manifests as painful mouth opening and reduced mouth opening, etc. The causative factors include long-term tooth loss, tonicity or spasm of the masticatory muscle group, wear and tear of the joint disc, and adhesions in the joint area, etc., as follows: 1. Long-term tooth loss: when teeth are missing for a long time and a lateral chewing habit is formed, uneven wear and tear occurs in the temporomandibular joint on both sides, causing 2. Tonicity or spasm of masticatory muscles: When suffering from diseases such as night grinding, clenching of teeth, or mental tension and lack of rest, the masticatory muscles around both sides of the joint are in a state of tonicity or spasm, resulting in pain. 3. Articular disc wear: When the teeth are crowded and the occlusal relationship is misaligned, the wear of the articular disc can be caused, resulting in obvious pain. 4. Adhesions in the joint area: After trauma, inflammatory substances are continuously generated in the joint area, resulting in adhesions. After trauma, inflammatory substances are continuously produced in the joint area and adhesions occur, resulting in pain when opening the mouth.