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New Report on Temporomandibular Disorders: Priorities for Research and Care

Over a year and half ago, the National Academy of Medicine (NAM) began the most comprehensive study ever undertaken on Temporomandibular Disorders (TMD). The study assessed the current state of TMD research, education and training, the safety and efficacy of clinical treatments, and associated burden and costs.

Statement by NIDCR Acting Director on the National Academies of Sciences, Engineering, and Medicine Report on Temporomandibular Joint Disorders

I am pleased to announce the release of the National Academies of Sciences, Engineering, and Medicine (NASEM) report, Temporomandibular Disorders: Priorities for Research and Care. As underscored by the comprehensive report, temporomandibular joint disorders (TMJDs) are a diverse and still poorly understood set of complex, painful conditions affecting the jaw muscles and tissues, temporomandibular joints, and associated nerves. Clearly, there is much more to be understood, and these conditions continue to confound medical and dental health care providers and researchers.

Have you seen the film Dark Waters?

The Film. Dark Waters is about attorney Robert Billott's real-life 20 year legal battle against DuPont chemical for releasing toxic waste - perfluorooctanoic acid, or PFOA - into Parkersburg, West Virginia's water supply, with devastating health effects on the townspeople and livestock. PFOA, also known as C8, is a man-made chemical. It is used in the process of making Teflon and similar chemicals known as fluorotelomers.

Online TMD Diet Diary Research Project

Online TMD Diet Diary Research Project The TMJ Association received the following request from Professor Justin Durham and his research team at Newcastle University. We encourage TMJ patients to participate in this project as it is an under researched

Drug Induced Bruxism

The authors of this article state that orofacial movement disorders (bruxism) are treated typically by dental professionals and not by those specialists (neurologists) researching and treating the other movement disorders (Parkinson's disease, Huntington's disease, tremors, etc.). Again, this is more evidence of the complexity of TMD and the need for multidisciplinary research and treatment in TMD.

Dentists in Distress

  • Nov 16, 2018

by Sophia Stone, TMJA contributing author  

Fear of the dentist is practically a rite of passage in youth. Growing up, I wasn't exactly afraid of the dentist; rather, any excuse to leave school early was a powerful incentive. These days, I have a more complicated relationship with dentistry: I go to get answers and try to feel better, but I always pop a prophylactic ibuprofen or two in case my jaw protests from the oral gymnastics.
But we the patients rarely get a glimpse into the psyche of the dental provider. The paper, Dentist's distress in the management of chronic pain control: The example of TMD pain in a dental practice-based research network by Yokoyama et al. (2018) gives us a rare glimpse into the minds of dentists who treat TMD. The study examines which aspects of TMD management are most distressing to dentists. Spoiler alert: patients aren't the only ones losing sleep over TMD.
Despite the prevalence of TMD in the general population [1], prior studies have shown that about half the dentists in practice are not confident in their ability to diagnose and treat TMD [2]. Frankly, this statistic is alarming. Imagine if half of primary care physicians weren't comfortable treating diabetes, which is similarly prevalent among about 10% of the population [3] [4]. Then imagine that these providers recommended dubious, expensive, irreversible, or potentially harmful therapies that haven't been proven effective. In the case of dentistry, even though clinical practice guidelines* advise against occlusal adjustment as a treatment for TMD (because it's irreversible and probably doesn't work), a whopping 64% of US dentists do it anyway [5].
A major motivation for this study was to understand barriers and misperceptions that hinder TMD care and result in variable treatment recommendations and outcomes from practice to practice. It was the authors' hope that addressing dentists' distress around providing TMD care would bridge the gap between what is known about TMD and what dentists actually do.

In this study, 113 Japanese dentists were surveyed about their experience treating TMD. The majority (84%) of dentists surveyed were male, which is not all that unusual, but a striking contrast from the predominately female TMD patient population. Just over half (57%) were aware that TMD practice guidelines existed, and even fewer (42%) had actually read them. It’s not clear from this study why so few dentists were familiar with these guidelines, nor is it clear why a fraction hadn’t read them when they know they exist, but this seems like a pretty important oversight if you’re going to be treating TMD patients. Given that education on TMD orofacial pain is not required of US dental schools, and postgraduate programs on orofacial pain are few and far between, it is not all that surprising that this knowledge gap might exist among dental providers in other nations.

To better understand dentists’ feelings of distress regarding TMD treatment, the researchers classified this self-reported distress according to six major themes.

  1. Prognosis – The form of distress most frequently reported by dentists was the difficulty in predicting prognosis and therapeutic outcomes for TMD patients. Dentists reported not knowing whether TMD can be cured, let alone how “cured” is defined. Uncertainty in the face of treatment failure was also reported.
  2. Diagnosis – The second most frequently reported form of distress was the difficulty in diagnosing TMD. This difficulty was primarily rooted in patient encounters in which the chief complaint was “ambiguous” or in which the subjective complaint did not align with the objective examination.
  3. Treatment – Many dentists reported difficulty in deciding whether to use occlusal adjustment in treatment, being uncertain if it would help at all or if they should instead resort to a more conservative approach.
  4. Etiology – A number of dentists found it difficult to identify the underlying cause for TMD-related pain, particularly in cases where multiple causes might be to blame or the cause was unclear.
  5. Communication – Some dentists were challenged in their ability to communicate with TMD patients. This included discomfort treating patients with psychosomatic symptoms, those deemed difficult or “not cooperative,” and those unable to understand the dentist’s explanations.
  6. Social Health – One dentist reported health insurance barriers to TMD treatment coverage and reimbursement.

Now for the interesting part. Researchers then investigated the relationships between sources of dentist distress and the characteristics of their TMD patients. Specifically, they found that dentists distressing over whether to use occlusal adjustments in treatment and those challenged with patient communication were more likely to have patients with shoulder stiffness and headache. Only four TMD symptoms (inability to eat, fear of locked jaw, shoulder stiffness, and headache) were surveyed in this study, but shoulder stiffness and headache were previously reported to be the most frequent TMD-related symptoms in Japanese patients [6]. An explanation for these associations might be that dentists with more symptomatic patients may have been more willing to consider occlusal therapy to be able to offer something to their patients. They may also have perceived their patient encounters as more difficult due to the pain their patients were experiencing.

The study also revealed that awareness of TMD guidelines was associated with lower prognostic distress. Due to the self-reported nature of this study, it’s hard to say whether knowledge of these guidelines leads to the enhanced ability to predict therapeutic responses, or simply the belief in one’s ability to do so. Furthermore, this study does not weigh in on whether such knowledge actually leads to better patient outcomes, although one would certainly hope so.

One of the challenges with interpreting this study is the difficulty in extracting causative relationships from associative data. Do dentists perceive more symptomatic patients as more “difficult” to communicate with? Or are symptomatic patients more likely to seek out certain providers, or to work or live in more in stressful environments? Does knowledge of TMD guidelines lead to prognostic confidence, or are successful dentists generally more well-read on current practices? Nonetheless, despite the possibility of confounding factors, significant relationships were still found between sources of dentist distress and characteristics of their patients. Thus, such disparities in provider distress and knowledge could have profound consequences for patients, particularly given the lack of educational standards for orofacial pain. 

TMD pain is distressing to the patient, and it’s not exactly comforting to think that the prospects of treating TMD brings distress to dental providers. The results of this study suggest that dental education, particularly focused on TMD care directives and whether occlusal adjustments hold therapeutic merit, is one possible remedy.

This study also indicates that some dentists have a hard time talking to and educating their patients. It’s natural that communication difficulties may be more pronounced when faced with more complicated and severe cases. However, patient care may be compromised when patients are labeled as “difficult” or “uncooperative,” their condition is overly contributed to psychological factors, or they are wrongly perceived as noncompliant or exaggerating their pain. Given the historical dismissal of women with unexplained medical conditions as “hysterical,” these concerns are heightened for female TMD patients by the fact that TMD is more than twice as prevalent in women than in men, yet more than 80% of dentists in this study were men. This is consistent with the gender gap among US dentists, nearly 70% of whom are men [7]. Thus, educational tools that help dentists understand not only the pathology, prognosis, and treatment options for TMD pain, but also the experience of the TMD patient, may alleviate such difficulties, thereby reducing distress among dental providers.


* There are scientific statements and parameters of care, but no formal guidelines for TMD treatment formulated by professional groups for the management of TMD. This was gleaned from reviewing 24 professional organizations that profess to diagnose and manage TMD, by researching their websites to obtain information about their organizations’ theories and practices.


1 Yokoyama, Y., Kakudate, N., Sumida, F., Matsumoto, Y., Gordan, V. V., and Gilbert, G. H. (2018). Dentist’s distress in the management of chronic pain control: The example of TMD pain in a dental practice-based research network. Medicine 97(1), e9553.

2 Lindfors, E., Tegelberg, Å., Magnusson, T., and Ernberg, M. (2016). Treatment of temporomandibular disorders—knowledge, attitudes and clinical experience among general practising dentists in Sweden. Acta Odontologica Scandinavica 74(6), 460-5.

3 Statistics About Diabetes. (n.d.). Retrieved from
4 Prevalence of TMJD and its Signs and Symptoms. (n.d.). Retrieved from

5 Velly, A. M., Schiffman, E. L., Rindal, D. B., Cunha-Cruz, J., Gilbert, G. H., Lehmann, M., Horowitz, A., and Fricton, J. (2013). The feasibility of a clinical trial of pain related to temporomandibular muscle and joint disorders: The results of a survey from the Collaboration on Networked Dental and Oral Research dental practice-based research networks. Journal of the American Dental Association 144(1), e1–0.

6 Watanabe EK, YataniH,Kuboki T, et al. (1998). The relationship between signs and symptoms of temporomandibular disorders and bilateral occlusal contact patterns during lateral excursions. Journal of Oral Rehabilitation 25(6), 409-15.

7 Professionally Active Dentists by Gender. (2018, May 31). Retrieved from

TMJ Disorders


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