Botox for TMJ Disorders May Not Lead to Bone Loss in the Short Term, But More Research is Needed on Higher Dose, Long-Term Use

Full story originally posted on NYU.edu

Botox injections to manage jaw and facial pain do not result in clinically significant changes in jaw bone when used short term and in low doses, according to researchers at NYU College of Dentistry and UConn School of Dental Medicine. However, they found evidence of bone loss when higher doses were used.

The researchers, whose findings are published in the Journal of Oral Rehabilitation, call for further clinical studies to track bone- and muscle-related changes with long-term use of Botox for TMJD, or temporomandibular muscle and joint disorders.

“This was a true multi-disciplinary and multi- institutional collaborative study with significant impact on our understanding of treatment strategies for TMJD patients. We developed and standardized a novel method to evaluate bone density using Cone Beam CT scans for this study,” said Dr. Aditya Tadinada, co-researcher and Associate Dean for Graduate Research, Education and Training at the UConn School of Dental Medicine.

Tadinada was joined by Dr. Alan Lurie, professor and chair of Oral and Maxillofacial Diagnostic Sciences at UConn. “The findings emphasize the importance of thoughtful treatment planning and moderation in the treatment of temporomandibular and myofascial pain disorders.  Loss of mineral in the TMJ could have long-lasting, adverse effects on the comfort and function that patients experience in the months and years following such treatments,” said Lurie.

TMJDs are a group of common pain conditions that occur in the jaw joint and surrounding muscles, with the most common type involving the muscles responsible for chewing. While many individuals manage their TMJD symptoms with conservative treatments such as jaw exercises, oral appliances, dietary changes, and pain medication, some do not respond to these treatments.

Botox (or botulinum toxin), an FDA-approved injectable drug known for its wrinkle-reducing capabilities, is approved to treat certain muscle and pain disorders, including migraines. It works in part by temporarily paralyzing or weakening muscles. In the U.S., a Phase 3 clinical trial is currently underway to study the use of Botox to treat TMJD, but in the meantime, it is increasingly being used off-label.

Thus far, small studies using Botox to treat TMJD in humans have had mixed results. In animal studies, Botox injections in jaw muscles have led to major bone loss in the jaw. This is thought to be due to the muscles not being used to exert force needed for bone remodeling, but Botox may also have a direct effect on bone resorption, the process of breaking down bone tissue.

“Given these concerning findings from animal studies, and the limited findings from clinical studies, more research on the safety of Botox for jaw muscles and bones is critically important,” said Karen Raphael, professor in the Department of Oral and Maxillofacial Pathology, Radiology and Medicine at NYU College of Dentistry and the study’s lead author.

The NYU study included 79 women with TMJD affecting their facial muscles: 35 of whom received Botox injections (between two and five rounds in the past year) and 44 who were not treated with Botox but may have used other TMJD treatments. Using specialized CT scans, the researchers measured participants’ jaw bone density and volume.

The researchers found that jaw bone density and volume were similar between women who had Botox injections to treat their TMJD and those who did not. While most study participants were given relatively low doses of Botox—smaller than in most clinical trials for TMJD—individuals who received higher doses of Botox were more likely to have lower bone density.

Raphael and her colleagues recommend that more human studies be conducted to better understand the impact of the long-term use of Botox on jaw muscles and bones—and whether it just reduces muscle force on bone or also plays a direct role in altering bone resorption.

“Should Botox receive regulatory approval for the treatment of TMJD, we would recommend that a phase IV study be done using low-radiation CT and MRI to track bone- and muscle-related changes with Botox use, examining both dose and long-term use,” said Raphael. “Unless specialized imaging of muscle and bone are conducted among patients who receive Botox treatment over long periods, true cumulative effects will remain unknown.”

In addition to Raphael, Tadinada, and Lurie, study authors include Malvin Janal, Vivian Santiago, and David Sirois of NYU College of Dentistry.

This research was supported in part by the National Institutes of Health’s National Institute of Dental and Craniofacial Research (R01DE024522).