Since we originally wrote about this topic in 2011,¹ there have been some advancements in the literature on temporomandibular joint and muscle disorders, or temporomandibular disorders (TMDs). One advancement has been the first evidence-based diagnostic criteria developed to help health professionals better diagnose TMD, which affects an estimated 10% to 15% percent of Americans.² In any given year, approximately 20 million adults (10% of women and 6% of men) have TMD pain.³ About 5.3 million people seek treatment for TMD within 6 to 12 months after onset of symptoms.³ Although adequate data are lacking on indirect costs, research indicates that 28% of TMD patients report disability and limitations, as well as unemployment.⁴ Assuming that indirect costs would most likely exceed direct costs, projections from research put the total cost of TMD in excess of $4 billion per year.⁵ Thus, TMD is clearly a fiscal burden to both patients and society.
Although TMD is commonly considered a jaw problem, researchers have determined that most people with chronic temporomandibular problems also contend with other ailments. For many, symptoms of TMD resolve on their own without significant medical intervention. However, 5% to 10% of adults suffering from TMD symptoms require professional treatment.⁶ If pain persists beyond 3 to 6 months, the condition is considered chronic.
The goal of this article is to review clinical studies that identify patients at high risk for chronic TMD and suggest early interventions that may be used successfully during the acute phase of TMD.
The Problem of Pain
Temporomandibular joint pain is part of a broad category of disorders involving the muscles of mastication and the hard and soft tissues of the temporomandibular joint. A complex disorder, TMD may involve disc displacement, muscle disorders, internal derangement and/or degenerative changes in the joint, or combined muscle-joint disorders. The primary symptoms of TMD that were defined in 2003 by Glaros and Lausten remain the same today: pain in the muscles of mastication in the preauricular area or in the temporomandibular joint; clicking, popping, or grating sounds in the joint; difficulty opening the mouth wide; a patient’s perception that their occlusion or bite is “off”; and jaw locking in the open or closed position.⁷
Different measures of pain also can serve as risk factors for TMD. In 2006, the National Institute of Dental and Craniofacial Research (NIDCR) introduced the very first large-scale, 7-year prospective study called Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA).⁸˒⁹ The study has followed 2,737 healthy men and women (ages 18 to 44) to see who develops TMD and why. The latest published data are based on a median 2.8 years of follow up, during which 260 participants developed their first case of painful TMD, which translates to an incidence rate of 4% per year in the study cohort.
A notable finding of the OPPERA study was that high levels of pain sensitivity, as well as an increased heart rate, were associated with an increased likelihood for developing TMD.⁸ It is suspected that an increased heart rate is indicative of hyperactivity in the sympathetic nervous system, which may result from dysfunction in central processes that control baroreceptors.⁷ The OPPERA study also found that having a pain disorder (eg, low back pain, migraines, irritable bowel syndrome, etc.) increased one’s chances of developing TMD.⁹
Patients often cite pain as the main reason for seeking medical or dental care.¹⁰˒¹¹ Managed care treatment costs per year for orofacial pain range from $12,000 to $20,000 per person.¹² Studying 372 TMD patients over a 3-year period, Von Korff et al, concluded that this pain population visited more health care providers than controls.¹³ As health care costs continue to escalate, research indicates that some cognitive-behavioral treatments offer a significant medical cost offset.¹⁴ Thus, not only are there physical and psychosocial benefits associated with preventing the progression from acute to chronic TMD, there are financial benefits, as well.
Clearly, more effective and economic treatment modalities are needed. It has been more than a decade since Stohler and Zarb urged the scientific community to adopt a “low-tech, high prudence therapeutic approach” to assessing and treating TMD.¹⁵ Since then, attention has shifted toward a behavioral medicine approach to treatment.
As the duration of pain increases, patients become less responsive to intervention.¹⁶ Conventional treatments of TMD include, surgery, occlusal adjustments, and pharmocotherapeutic techniques. Intra-oral appliances, nocturnal alarms, and physical therapy also have been used. However, conventional treatments fail to address the psychosocial factors of this painful, complex disorder. A comprehensive biopsychosocial model and guidelines for applying the model to diagnosis and treatment are needed.
Chronic Pain Links
Dworkin first identified the similarities between TMD and low back pain (LBP).¹⁷ Both disorders generally are recurrent, and they often are chronic. Furthermore, the severity of pain and related unhealthy behaviors are highly inconsistent between patients as well as over time. As noted by Von Korff, TMD, like LBP, can be described as “an illness in search of a disease.”¹⁸ LBP and TMD often are idiopathic in nature. Invasive treatments have not been shown to be as beneficial or cost-effective as had been hoped. Because of the similarities between the disorders, several TMD studies have paralleled Gatchel et al’s LBP clinical research program.¹⁹
Mishra et al compared the effectiveness of biofeedback (BFB), cognitive-behavioral therapy (CBT), combined BFB and CBT, and no intervention on patients with TMD.²⁰ The 3 treatment groups had significantly reduced pain scores (from pre- to post-treatment) and significantly better mood scores relative to the group with no intervention. BFB was shown to be the most effective modality for reducing pain.
The same researchers followed the original study with a 1-year outcome evaluation.²¹ All of the treatment groups sustained therapeutic gains from pre-treatment through 1-year of follow-up, relative to the group without any intervention. At 1 year, the BFB/CBT group had greater improvement than the group that received BFB alone. The researchers concluded that treatment received in the BFB group was directly associated with the patients’ primary physical pain complaint and likely contributed to greater significant gains immediately post-treatment. This association may have influenced patient motivation to complete in-session treatment and comply with home practice. In contrast, CBT requires more time for the patient to fully understand, accept, and put changes into practice, thus positive changes related to CBT took longer to manifest. Immediate positive outcomes provided by BFB intervention, combined with longer-term gains of the CBT treatment achieved via beneficial lifestyle modification, explained the increased improvement in both physical and emotional functioning in the 1-year BFB/CBT group.
Early Intervention vs. No Intervention
The aforementioned studies initiated the trend toward a biopsychosocial treatment approach. This low cost and noninvasive therapeutic method stimulated a series of studies in patients with acute TMD that were supported by the NIDCR. The first issue addressed in this series of studies was whether the progression from acute to chronic TMD pain could be prevented by early intervention in patients considered “at risk” for developing chronic pain.
Epker et al created a statistical algorithm²² (based on a logistic regression model) using certain components of the Research Diagnostic Criteria/Temporomandibular Disorders (RDC/TMD).²³ (It should be noted that the original RDC/TMD has been replaced by the newer Diagnostic Criteria for Temporomandibular Disorder [DC/TMD]).²⁴ Epker et al found that this algorithm could successfully categorize the risk status of 91% of these patients for developing chronic TMD at 1-year follow-up.
In subsequent studies, it was hypothesized that high-risk patients given early intervention would have lower levels of pain at 1-year follow-up compared with patients not receiving early intervention. It was further theorized that the early intervention patients should have increased levels of coping and decreased emotional distress at 1-year follow-up.
A study by Gatchel et al clearly supported these hypotheses.⁵ Among patients at high-risk for chronic TMD, those receiving early intervention had a significantly lower prevalence of chronic pain and emotional distress compared with patients who did not receive early intervention. The outcome data, reviewed in Table 1, showed significant differences between the early intervention and the no intervention groups at 1-year follow-up. Patients classified as high-risk for chronic TMD who received early intervention exhibited significantly fewer signs of chronicity on measures of pain, health care utilization related to jaw pain, and emotional distress (as measured by symptoms of maladaptive coping styles and psychopathology, including depression), in contrast to patients categorized as high-risk for chronic TMD who did not receive early intervention.
To evaluate the cost-effectiveness of early intervention, Stowell et al launched a comprehensive study.²⁵ Health care costs related to jaw pain were collected from all patients for the duration of the study (ie, initial complaints of pain to the 1-year milestone of the study). Expenses included costs for health care visits, treatments requiring appliances/splints, travel distance and time to visits, medication, etc. When compared with the intervention group, there were significantly greater costs for those in the no intervention group. The group receiving no intervention spent an average of $422.91 per person, whereas the early intervention spent an average of $131.84. These costs did not include averages at the initial intake because there were no differences between the 2 groups at that time (Figure 1).
Long-term Results
To determine if early biopsychosocial intervention and the benefits achieved at 1 year in patients with acute TMD pain were maintainable, Robinson studied long-term (2 to 6 years) post-treatment results.²⁶Her findings supported sustainability, with the early intervention group exhibiting reduced pain and fewer indicators of depression at long-term follow-up, compared with the group not receiving early intervention. Moreover, patients who received early intervention reported a continuation in use of coping/management skills long-term. Patients rated early intervention as helpful, with 96% very likely or likely to recommend intervention to others. Also, as demonstrated in the Figure, patients who received early intervention had fewer visits to health care professionals for jaw-related pain compared with patients who did not receive intervention.²⁶ These results are promising and underscore the efficacy and sustainability of early biopsychosocial intervention.
Gatchel et al is currently evaluating a population of TMD patients from community dental clinics over a 2-year study period.²⁷ High-risk acute TMD patients were randomized to 1 of 2 intervention groups: biobehavioral or self-care. The biobehavioral group receives a combination of CBT and BFB, whereas the self-care group receives patient education. Low-risk acute TMD patients also are included and serve as a control group. Preliminary findings from the study reveal that the high-risk groups exhibit more pain than the low-risk group, but 2 years after the intervention, the pain experienced by the high-risk patients in the biobehavioral group is comparable to that of the low-risk patients.²⁸ Thus, clinical research is continuing to demonstrate the efficacy of biopsychosocial interventions. Therefore, CBT in combination with BFB is effective in the treatment of TMD pain. As initially demonstrated in a meta-analysis by Morley et al, both of these treatment modalities have been found to be effective in the treatment of pain.²⁹ Other research demonstrates that biopsychosocial intervention is effective, regardless of medical diagnoses.³⁰˒³¹ The efficacy of CBT for TMD patients has been shown in a number of studies, further validating the clinical value of this treatment.³²⁻³⁵
Barriers in Clinical Practice
Several factors can prevent efficacious, cost-effective interventions from becoming the standard of care in clinical practice, including secondary gain, tertiary gain, and inaccurate diagnosis.
Secondary gain needs to be considered when treating patients who are disabled as a result of chronic pain. Long considered a factor that can perpetuate chronic pain and disability, secondary gain has been widely explored in the literature.³⁶˒³⁷
A less-studied concept that may explain continued illness and disability in chronic pain patients is the concept of tertiary gain. First defined by Dansak in 1973, tertiary gain is defined as those gains sought or received by someone other than the patient as a direct result of the patient’s illness.³⁸ To illustrate this concept, Dersh described gains that a patient’s spouse may receive (eg, greater freedom in day-to-day activities and increased control or power within the spousal relationship).³⁹ Unfortunately, spouses and family members are not the only potential beneficiaries of a patient’s illness. Health care professionals, health care systems, pharmaceutical companies, and even the government also can obtain tertiary gain from chronic illness.⁴⁰
Furthermore, there have been some discrepancies in the diagnostic procedures used for TMD in research and clinical settings, which is suspected to have led to inaccuracies in diagnoses and treatments.⁴¹ With the development of the DC/TMD, it is anticipated that these issues will be resolved.²³
Summary
The decade began with a call to find cost-effective treatments and early interventions that could prevent musculoskeletal disorders from moving beyond the acute phase into an intractable chronic phase. Linton posited that we must find ways to identify patients at high risk for chronicity and deliver treatment early.⁴² A great deal of progress has been made with the development of interventions for acute LBP and acute TMD. However, we must remain focused on bridging the gap between research and implementation into clinical practice.
Our next challenge is to persuade patients to embrace cost-effective, evidence-based approaches for early intervention in TMD. Collaboration between primary care providers and pain management specialists must be encouraged. Standards for interdisciplinary pain management teams need to be developed to ensure an integrated, consistent treatment approach and accurate tracking of outcomes. According to Frohm and Beehler, bringing health care stakeholders to the table to form a consensus is an important step in making systemic change.⁴³ Even as consensus is found, change to a health care system as large as that of the United States is likely to occur slowly. As daunting as the task may be, it must be done if we are to provide the best outcomes for patients suffering from such complex disorders as TMD and other chronic pain conditions.