TMD, or temporomandibular joint disorder, is caused by the erosion of the small disc that separates your jaw bones. This can occur with overuse (often from teeth grinding) or shifting resulting from conditions like arthritis or injury. Symptoms of TMD can be quite painful and may include: clicking/popping sound or grating sensation when opening and closing your mouth or chewing; headaches and neck pain; and tenderness and pain around the jaw joint, ears, face, and temples. Your dentist can help diagnose and treat TMD, and may recommend a night guard to prevent teeth grinding, relaxation techniques, or a physiotherapist referral.