Head or neck pain, problems with chewing or a clicking sound in the jaw joint may be due to a functional disorder in the chewing system known as Craniomandibular Dysfunction (CMD).
CMD is not a single disease but a collective term for disorders in the interaction of jaw joints, masticatory muscles and teeth.
The causes are varied, but stress often plays a decisive role.
If you clench your teeth during the day or grind them at night, a condition known as bruxism, can overload the chewing system. That can lead to tension, inflammation or displacements in the joint, which may also radiate to the head, shoulders or neck.
Symptoms such as pain in the jaw itself, clicking or problems opening the mouth may occur, as well as complaints in the shoulder and neck and sometimes in the ears, often accompanied by headaches.
"Most people don't know that the cause of headaches can also be the jaw," dentist Jean-Marc Pho Duc from LMU Munich told Germany's consumer advisory unit Stiftung Warentest.
Many people affected see numerous doctors before they find the connection.
Stiftung Warentest says those who notice typical symptoms should consult a dentist.
Specialists mainly recommend self-help measures such as relaxation exercises or massages for treatment. Individually fitted bite splints are also used but they are not always covered by health insurance so check your local regulations.
Permanent interventions like orthodontic corrections are rarely considered sensible. "Studies show that targeted exercises can be just as effective in the long term as wearing a splint," CMD specialist Olaf Bernhardt from the University Medicine Greifswald told Stiftung Warentest.
What counts is to consider your behaviour in daily life and consciously relax your jaw if you are feeling tense.
Observe yourself, says Jean-Marc Pho Duc. "Brief moments during the day are enough to pause and become aware of how you are holding your jaw. Is it tense, are the teeth clenched? Then just relax again!"
Often, those with headaches resort to painkillers like aspirin, ibuprofen or paracetamol.
But try not to make this a habit. Headache medication should be taken on no more than 10 days a month, says the German Brain Foundation. Otherwise, they can themselves trigger headaches, creating a pain spiral that is not easy to escape.