Summary by Karen Raphael, Ph.D., Professor, New York University College of Dentistry
This review was also summarized most recently by James Keenan at NYU College of Dentistry in the publication Evidence Based Dentistry, (2015) again concluding that benefits and risks of Botox® for treatment of TMJ-related muscle pain remain unclear.
Increasingly, clinicians, research scientists like myself, and advocates at The TMJ Association are asked, "What about Botox® therapy for treatment of my painful muscles? Does it help?" As TMJ News Bites has noted in the past, use of Botox® for treatment of TMJ disorders is not approved by the FDA, yet a growing group of dentists and some physicians--especially those who also offer Botox for cosmetic reasons--offer it to TMJ patients "off label," injecting the chewing muscles approximately once every three months.
In the past decade, several published clinical position papers have advocated its use for patients suffering from facial pain. In contrast to these general review papers, a recent systematic review focusing on studies presenting only the highest quality of evidence was conducted by Chen and colleagues and published in the International Journal of Oral and Maxillofacial Surgery (2015). Although well over 100 published articles addressed some aspect of the use of Botox® in TMJ disorders, surprisingly, only 5 studies published through 2014 met the highest scientific standards for research with human subjects. These were randomized, controlled clinical trials, involving a total of 123 patients treated with Botox®. All participants had chronic, muscle-based TMJ pain.
These five studies reached different conclusions, with two reporting that Botox® reduced pain, one reporting that its improvement was similar to improvement among patients treated with a muscle manipulation technique, and two reporting that it did not reduce pain at a level that was statistically different than a "placebo" injection consisting of salt water. Thus, given the increasingly broad use of Botox® for multiple clinical problems, it is frustrating that studies are still unable to answer the question, "What about Botox® therapy for treatment of my painful muscles? Does it help?" Unfortunately, in 2016, we still have no answer. We do not even know enough about potential side effects of Botox® when used to treat muscle-based TMJ pain, particularly when used over long periods, with repeated injection cycles. None of the five studies examined long-term beneficial effects or side effects over multiple treatment sessions.
Source: Chen YW, Chiu YW, Chen CY, Chuang SK. Botulinum toxin therapy for temporomandibular joint disorders: a systematic review of randomized controlled trials. Int J Oral Maxillofac Surg 2015; 44: 1018-1026.
Editor's note: TMJ News Bites has reported on Botox treatments for TMD a number of times over the decade, always recommending caution. As Dr. Raphael points out, human studies have been inconclusive with regard to risks or benefits, and provide no long-term follow-up. In contrast, animal studies (rabbits, rats) show loss of bone density over time and some muscle atrophy from disuse. So there is every reason to continue to urge caution in trying Botox treatments, especially if injections are to be repeated multiple times. As TMJA President Terrie Cowley notes, "The history of treatments for TMD is noteworthy for sensational claims of the efficacy, even cures, with this or that treatment, which all too often has resulted in more harm than good."