Could that nagging headache and painful jaw be tied to your oral health? Many headache sufferers might want to consult their dentist as well as their doctor since headaches and dental pain have a lot in common, says Director of the Orofacial Pain and Oral Medicine Graduate Program at the USC School of Dentistry Glenn Clark.

Pain centered in the nerves and muscles running throughout the face and neck, as well as poor habits the discomfort may cause, can trap sufferers in a painful feedback loop, with head pain triggering jaw and neck pain and vice versa.

"Headaches and toothaches all transmit through the trigeminal nerve, the largest sensory nerve in the head that supplies the external face, scalp, jaw, teeth and much of the intra-oral structures," Clark says. "Pain in one branch of the nerve has the potential to activate other branches of the nerve, and when that pain is chronic and sustained, it is more likely to trigger a sequence of events that might lead to a headache. In people who have headaches, a continuous, sustained toothache can easily trigger one of the episodic headaches such as migraines."

Besides the close anatomical links between head, face and jaw pain, reflexive behaviors caused by pain and tension such as jaw clenching and muscle tightening can exacerbate and transfer pain.

"There is a good deal of interconnectivity between the orofacial and craniocervical systems; for example, when you clench your teeth you contract your neck muscles inadvertently," Clark says. "When patients have an acute neck injury they often start holding tension in their teeth, and jaw muscle pain will occur. When you have a chronic toothache or bad temporomandibular joint, this may also cause bracing and guarding in the muscles on the same side of the jaw and in the neck."

When head and face pain spring from tooth or jaw joint injury, such as when a patient unknowingly clenches or grinds their teeth for long periods of time and damages tissue inside and below the teeth, it can be difficult for a physician to decipher the cause of the pain, he says. That's where a dentist with a trained eye for the medical and behavioral causes of orofacial pain comes in.

"In general, headaches don't have physical signs, and diagnosis is all related to the history and pattern of the pain," Clark says. "If the patient is being treated for the migraines, tension headaches or sinus pains and the medications or other methods of treatment given by the physician are not effective, they are often referred to a dentist for evaluation. At the Orofacial Pain and Oral Medicine Center, we actually receive a number of patients from physicians who want us to check the teeth and the jaw joints for problems."