Certain antidepressants can help alleviate chronic jaw pain caused by temporomandibular disorders (TMDs), according to a research review by a team of researchers with expertise in dentistry and pharmacy.
"TMDs are a group of conditions that affect the jaw joint and the surrounding muscles that control your jaw," explains oral medicine specialist Reid Friesen, senior author of the paper and assistant professor in the Mike Petryk School of Dentistry. "They can cause pain in the jaw itself, which may also radiate to the face, neck, and other areas of the head."
Chronic TMD pain can be debilitating, with sufferers experiencing persistent jaw pain, headaches, sleep disturbances, and even difficulty chewing or speaking, says Friesen, who is also a member of the Women and Children's Health Research Institute. The current standard of care often includes options such as dental appliances to reduce muscle overactivity and alleviate pain, physiotherapy and targeted exercises to improve jaw function, medications to manage symptoms, and strategies for self-care and behavioural modification.
Because many people with chronic TMD pain also experience anxiety and depression, and previous studies have shown certain antidepressants can help manage other pain conditions, the researchers sought to examine how effective these medications might be in relieving TMD-related pain specifically.
For their review, the researchers looked at past studies involving adults who had TMD pain for at least three months and who were being treated with antidepressant medication. All the included studies — seven randomized controlled trials — included outcome measures where the participants described how their pain intensity was affected by the treatment.
They found that several tricyclic antidepressants (such as amitriptyline) and SNRIs (serotonin-norepinephrine reuptake inhibitors, like duloxetine) were effective at reducing pain in people with TMDs. However, SSRIs (selective serotonin reuptake inhibitors), a common type of antidepressants, performed no better than the current standard of care for chronic TMD pain, suggesting that norepinephrine may be a key piece of the puzzle.
"Despite the pain pathways being very serotonergic, it seems that drugs which only work on serotonin and don't touch on norepinephrine are not as effective when used for pain," says Nathan Beahm, co-author of the review and clinical associate professor in the Faculty of Pharmacy & Pharmaceutical Sciences.
The researchers also found that antidepressants were most effective when combined with other treatments such as dental appliances, physiotherapy, other medications, and strategies for personal self-regulation and self-care, creating a comprehensive approach to reducing chronic TMD pain.
"That's something we see with other pain conditions — when you use what we call multimodal therapy, you're more likely to have a beneficial effect," says Beahm. "You're coming at the pain from a couple of different avenues."
"Chronic pain, in particular TMD pain, rarely has a single cause. There are a lot of physical factors, but also psychological and neurologic factors," says Friesen, noting that this complexity is why a combination approach is ideal.
Some specialist clinics, like the one where Friesen and Beahm work, have already incorporated antidepressants into treatment plans for patients with TMD. However, they emphasize that most general dentists should co-ordinate with dental specialists or family physicians, rather than prescribing these medications themselves, to develop the most appropriate care plan. Because these medications can cause side-effects such as dry mouth and sedation (with tricyclics) or hypertension and nausea (with SNRIs), and are used off-label for TMD pain, their prescription should involve shared decision-making and careful monitoring.
Patient education is another important factor, they say, adding that some patients may be reluctant or even offended when antidepressants are proposed as a potential solution, worrying their pain is perceived as "being all in their head."
"It's well documented that patients with chronic pain often have aberrant pain processing," notes Friesen. "The nervous system may amplify or misinterpret pain signals, so even without the presence of depression, many of these medications can help modulate how pain is processed."
