Ask the Doctors: Jaw trouble needs doctor’s attention whether it’s from TMJ or trismus

Dear Doctors: I had trouble opening my mouth wide when getting my teeth cleaned, and the hygienist said it could be TMJ. My sister, a chiropractor, thinks it’s a muscle spasm. What is TMJ anyway?

Answer: TMJ refers to the temporomandibular joint, which connects the jaw to the skull. We have two, one on each side of the jaw. These allow us to open and close our jaw and move it side to side and back to front.

The temporomandibular joint is a complex and delicate mechanism. It gets almost nonstop use as we speak, chew, yawn, smile and swallow. For some, the joint continues to get a workout throughout the night as they clench their jaws or grind their teeth.

When the joint stops working properly, it’s known as a temporomandibular disorder or TMD, though this disorder has widely come to be referred to as TMJ.

Symptoms can range from mild, occasional clicking to severe issues that interfere with eating or speaking.

Sufferers might experience tenderness or pain in the joint, in or around the ears or in other areas of the face. The joint can make crackling or popping sounds, and it can lock, making it difficult, even impossible, to fully open or close the mouth.

Malfunction in the joint also can cause tinnitus, a ringing in the ears.

Your sister’s suggestion that your problem is related to the jaw muscles refers to a condition called trismus, sometimes called lockjaw, which brings to mind the contractions associated with tetanus. These days, trismus refers to any muscle spasm in the temporomandibular joint that limits range of motion.

If you can’t open your mouth wider than 1.3 inches, that’s considered trismus.

It can be caused by injury and as a result of TMD. Symptoms include reduced range of motion, pain or cramping and difficulty when exerting pressure, as when eating.

Whatever the cause, we urge you to see your doctor or a TMD specialist.

Treatment of TMD and trismus can include resting the jaw with a soft food diet, medications for pain, muscle-relaxers, exercises to gently stretch the jaw, behavioral therapy, devices to prevent nighttime clenching and, in rare cases, surgery.

Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, is an internist and assistant professor of medicine at UCLA Health.