Your doctor or dentist will take x-rays, a CT scan, or an MRI of your jaw to determine whether you have TMJ. You then have to show that you suffer from TMJ because of your service. You will have to obtain your medical records from when you were in the service to show that you sustained injuries to your head, neck and/or face.
If you suffer from TMJ caused by post-traumatic stress disorder, your doctor will have to show that the TMJ is caused by the stress pressure you put on the bones and muscles in your face and neck.