Ear pain when opening mouth can be caused by temporomandibular joint disorder syndrome, acute inflammation of the ear, facial soft tissue injury and other factors. 1. Temporomandibular joint disorder syndrome: when temporomandibular joint disorder syndrome occurs, it can cause pain and distension at the joints, dyskinesia, popping and ringing and other symptoms, which can cause pain at the root of the ear when opening the mouth. 2. Ear inflammation: when acute inflammation occurs in the external auditory canal, such as acute otitis media, acute otitis externa, etc., because opening the mouth involves the external auditory canal, it can lead to pain in the root of the ear when opening the mouth. 3. Facial soft tissue injury: acute trauma to the facial muscles (facial muscles, chewing muscles, etc.) bruises, ecchymosis, swelling, restricted movement, etc., can lead to the symptoms of pain in the root of the ear when opening the mouth. If you have pain in the root of your ear when you open your mouth, you should consult a doctor in time, and under the guidance of a specialized doctor, you should actively carry out the appropriate treatment, which will help to alleviate the uncomfortable symptoms as soon as possible.