Treatment of Temporomandibular Pain With the Selective Serotonin Reuptake Inhibitor Paroxetine

Sir: In clinical dentistry, patients frequently have orofacial pain caused by temporomandibular disorder (TMD). TMD is characterized by a combination of symptoms affecting the temporomandibular joint and/or chewing muscles. Patients with TMD usually develop chronic or recurrent pain, contracture/ tenderness of chewing muscles, clicking condylar noise, limitation of jaw function, and limited mouth opening.

In the treatment of TMD, various types of dental therapy, such as occlusal splints and physical therapy, are used. Chronic TMD pain is usually treated with analgesics and muscle relaxants. However, these drugs do not always contribute to the success of treatment. Recently, the use of tricyclic antidepressants (TCAs) has been proposed, and the agents have demonstrated efficacy in controlling chronic pain.¹ Furthermore, a possible role of the new selective serotonin reuptake inhibitor antidepressants (SSRIs) has been proposed for chronic pain management with better tolerability by reducing the incidence of side effects, leading to higher patient compliance when compared with TCAs.²

We report 2 patients with chronic pain due to long-term TMD in whom chronic pain was markedly reduced following administration of the SSRI paroxetine hydrochloride. We obtained informed consent from these patients for this report.

Case 1. Ms. A, a 64-year-old woman, developed tinnitus, ear pain, shoulder stiffness, and insomnia, for which a psychiatry clinic prescribed a minor tranquilizer and hypnotics at the age of 52 years. At the age of 61 years, she developed limitation of mouth opening, pain in the temporomandibular region, and tongue pain. She consulted a dental clinic. Pain was extended to both sides in her mouth, and splint therapy and mouth opening training were administered. The pain gradually worsened and fluctuated due to mental stress. She was referred to our psychiatric department.

As to her odontological diagnosis, masticatory muscle disturbance was doubted because of persistent bruxism. She complained of pain on both sides of the temporomandibular articulation as well as the tongue. Anxieties regarding her husband's health and uneasiness about the future were considered background mental factors. She scored 44 points on a self-rating depression scale (SDS).³ She was diagnosed with DSM-IV pain disorder. Administration of paroxetine 10–20 mg/day reduced muscle tension and pain in the lower jaw in about 3 weeks. The intensity of pain and discomfort was evaluated using a visual analog scale (VAS) and distance of opening mouth. The mouth-opening movements were registered by the distance between incisal edges. At rest, her mouth opening improved from 27 mm to 38 mm, and her VAS score decreased from 100 mm to 30 mm.

Case 2. Ms. B, a 24-year-old woman, developed a sense of discomfort that was disabling and pain in the temporomandibular region on yawning around the age of 20 years. She was able to open her mouth less each day. At the age of 22 years, she consulted a dental clinic (different from the clinic in case 1). Ms. B's mouth opening was improved by splint treatment from 8 mm to 25 mm, and her pain almost disappeared. At the age of 24 years, the pain began again. She was referred to our psychiatric department with comorbid mental uneasiness.

She complained of anxiety over worsening of TMD and her future. Her SDS score was 48 points. She was diagnosed with DSM-IV pain disorder. Administration of paroxetine 10–20 mg/day reduced tension and pain of the jaw in about 2 weeks. The distance of her mouth opening improved from 19 mm to 26 mm, and her VAS score decreased from 100 mm to 30 mm.

TMD patients may have symptoms that are acute and resolve without therapy or with only limited, conservative therapy. For chronic TMD, drug therapy with analgesics is usually indicated. However, in some cases, analgesics are ineffective. Antidepressants have an antinociceptive (analgesic) effect on chronic pain independent of the antidepressant effect.⁴ In the past, TCAs were considered the gold standard in the treatment of different kinds of neuropathic pain, as studies showed their superiority compared to placebo or other available drugs.² There have been case studies^1,5 demonstrating that TCAs were sufficient to significantly reduce pain and discomfort due to chronic TMD. However, with TCA treatment, a large number of side effects are observed, which, although not life-threatening, significantly affect the patient's quality of life, causing a limitation of tolerability. Common side effects include dry mouth, sedation, memory impairment, constipation, and ortho-static hypotension. Patients who are intolerant or resistant to TCAs may be treated with SSRIs.⁶ Although a complex mechanism underlies the antinociceptive effects of antidepressants, it is suggested that SSRI-induced antinociception involves both central opioid and serotonergic pathways.⁷

Until now, there have been no case reports describing the beneficial effects of SSRIs for TMD patients. We report 2 patients with chronic or recurrent pain due to long-term TMD who were treated with an SSRI. These patients were diagnosed with TMD and received standard dental therapy along with analgesics without significant efficacy. Administration of the SSRI paroxetine remarkably reduced the persistent and unpleasant pain of TMD within a short period without side effects.

SSRIs can be beneficial in reducing TMD pain complaints as one method of dental therapy. Dentists and physicians, including psychiatrists, should have an understanding of the increasing utilization of SSRIs for managing chronic TMD pain.

TMD develops from multiple factors, causing long-term pain and interfering with the patient's daily life. The bio-psychosocial conceptualization of the pain experience illustrates the close connection between pain and psychosocial factors. Common emotional problems include anxiety, depression, and anger. It is important to recognize and treat psychiatric or emotional concerns as well as physical symptoms.⁸ Although dental treatment should be a priority in cases of TMD when psychiatric factors dominate, a psychosocial approach is also needed.