5

Caring for Individuals with a TMD

Historically, the care of some individuals with temporomandibular disorders (TMDs), especially those with chronic and painful TMDs, has been fraught with challenges and complications. The committee identified several stumbling blocks in the evolution of effective care for individuals with a TMD, including the rise of multiple competing theories among different groups regarding what causes TMDs and how best to treat individuals with TMDs; minimal high-quality evidence about which treatments are appropriate for which patients; patient abandonment by clinicians who have exhausted their treatment capabilities; and a clouding of the role of surgery in care of patients with TMDs by harmful devices such as Proplast/Teflon- or silastic-based TMJ implants in the 1970s and 1980s.

This chapter discusses these challenges and describes the current state of prevention, detection, assessment, diagnosis, and treatment of TMDs. The final section of the chapter explores approaches for improving the evidence base for TMD treatments and patient care: conducting clinical trials, building a TMD patient registry, and developing clinical practice guidelines. Chapter 6 addresses other challenges to the caring for individuals with a TMD, including provider education, the medical–dental divide, the lack of access to specialty care, and payment and coverage issues.

FIRST, DO NO HARM

The multiple types of TMDs (see Chapter 2) and the extensive comorbidities often seen in patients with TMDs have posed a challenge to clinicians for decades. Correct diagnosis is the first barrier, and it is complicated further by confusing terminology and a lack of clarity about the causes and development of the disorders (see Chapter 2). As discussed in this chapter, management strategies are equally unclear, with limited or poor-quality data to support treatment decisions and siloed practices that limit the interactions of dental and medical health care professionals. Despite the best intentions of many of these professionals to improve the lives of individuals with a TMD and the positive treatment outcomes that many individuals with TMDs have achieved, significant challenges have led to inappropriate treatment and life-altering harm for some individuals.

Historically, patients suffering from a TMD have turned to dental and medical professionals for help, often to find little expertise available. Some are given non-evidence-based interventions, which can lead to a worsening of the disorder and unintended harm. One important historical example of a treatment approach that resulted in significant harm to patients involved the use of Proplast/Teflon-based implants in the temporomandibular joint (TMJ) in the 1970s and 1980s. These early TMJ implants reached the market through a streamlined regulatory pathway that required only demonstration of substantial equivalence to a device already on the market. Many patients who received Proplast/Teflon-based TMJ implants experienced serious adverse health events before the Food and Drug Administration (FDA) recalled these devices in 1990 (Ferreira et al., 2008). Because these ineffective and harmful implants have been removed from the marketplace, improved prosthetics have been developed. (See section below on implants.)

In addition to learning about this history of implants, the committee heard from many individuals with a TMD who have experienced a seemingly endless stream of interventions, continual frustration, and provider abandonment. Ineffective treatment often leads the patient to consult an increasingly diverse range of providers, and frustration and a sense of “not

being heard” can occur. This can be particularly true if a person’s original pain worsened or a new TMJ-related pain emerged as a result of treatment. Patients with chronic orofacial pain have said that it is important for health care professionals to be empathetic even when no effective treatments can be offered (Breckons et al., 2017). Some patients with a TMD grapple with resulting facial deformities, concerns about the long-term impact of implantable materials on physical health, and nutritional deficits. Persons with a TMD may face stigma for multiple reasons, including chronic pain, problems with chewing or speech, and alterations in their expressive facial features (see Chapter 7). Because pain is invisible, some stigma stems from a feeling of not being believed; some individuals describe being regarded as a malingerer by family, friends, or health care professionals. Given societal views regarding the importance of facial presentation, there is the additional potential toll of damaged self-concept, loss of self-esteem, and possibly shame due to changes in appearance.

Thanks to a combination of factors—patient advocacy groups such as The TMJ Association bringing concerns regarding harmful treatment to the forefront, the appearance of rigorous outcomes evaluation, honest results reporting by leaders in the TMD research community, and improvements in the basic science understanding of TMD—the field of TMD care has slowly become more evidence based; however, variations in care practices still exist. The recognition that some TMDs are systemic pain conditions with local manifestations around the TMJ, rather than a primarily orthopedic condition, has resulted in a shift away from surgery as a first-line treatment for most patients. As with the similar evolution of the management of low back pain (Deyo et al., 2014), surgery remains a critical component of TMD care for properly selected patients, but it is the primary treatment for few. Improvements in the understanding of joint physiology and in the diagnosis of TMD have supported these changes, bringing emphasis to holistic, patient-centered treatment and the avoidance of multiple and non-indicated invasive procedures.

When assessing the impact of disease management on the lives of patients, it is important to remember that harm can be caused either directly or indirectly. In the assessment of literature pertaining to treatments for individuals with TMDs, rarely can a small research study prove direct harm; rather, the outcome measure typically relates to treatment effectiveness. Proving direct harm from an intervention usually requires very large and well-designed studies—a rarity in the world of TMDs. Many treatment studies of TMDs have been generally poor with regard to adverse event collection methods and reporting (Gewandter et al., 2015). Moreover, indirect harm can also be caused by ineffective treatments. Most notably, the pursuit of ineffective treatment delays the receipt of optimal management. This delay can create disability, as preventing the exacerbation of symptoms and

dysfunction is lost. Furthermore, providing ineffective treatments can instill false hope in suffering individuals and their families as well as increase the costs of health care. It is through this lens that the committee examines management options for patients with TMDs in this chapter.

Chapter 6 discusses improvements needed in the health care management of individuals with TMDs including the proposal of centers of excellence for TMD care. The establishment of professional societies, such as the American Academy of Orofacial Pain, has helped to advance greater understanding and adoption of the role of scientific evidence in making clinical decisions by dentists and physical therapists who treat TMDs. Yet, many challenges remain in the optimization of TMD care. Among them is the minimal amount of high-quality data to guide clinical decision making, particularly regarding what treatment approaches are best for each specific type of TMD. This leaves well-meaning providers without reliable treatment strategies. When dentists and physicians feel handicapped by this lack of clarity, they must always fall back on their core principle of primum non nocere, “first, do no harm.” Cautious and collaborative management is the rule.

PREVENTION AND EARLY DETECTION

The cornerstone of the progressive management of disease is prevention. Some individuals with a TMD report a history of non-painful TMJ mechanical dysfunction and joint noise, often in their teenage years. While many patients who describe these findings will not progress to painful TMD, some individuals will experience a significant escalation of the pain and disability with no obvious external impetus or event. The committee received reports from individuals with a TMD who experienced a physical trauma to the TMJ area or face, a prolonged or unanticipated dental procedure that sparked their TMD pain, or no particular event that led to their TMD. Primary prevention strategies are handicapped by the lack of research aimed at more fully understanding the role of various physical traumas or prolonged dental experiences in leading to chronic, painful TMDs in some individuals.

With so little known about the causes and development of TMDs, primary prevention strategies have focused mainly on behaviors such as eating soft food and avoiding items like apples or large sandwiches that require excessive jaw opening. Although commonly suggested as a potential cause, no studies have implicated routine orthodontic treatment in the development of a TMD. Major head trauma may not be preventable, but it may be reduced by traffic safety and substance abuse laws. Minor jaw trauma has also been proposed as an etiologic mechanism of TMDs, and it may be avoidable via educational strategies. Examples of such minor trauma are

a traumatic intubation during an operation, excessively long restorative dental treatment requiring sustained wide mouth opening, poorly designed intraoral splint therapies, and similar interventions. While no data have confirmed that any symptoms from these minor traumatic events signify that these events have an etiological role in the development of TMDs, educating providers about these possible risks and about strategies to avoid such trauma when possible may be beneficial. For instance, dentists can offer a simple bite prop during longer dental treatments that require wide mouth opening.

Another prevention strategy is early recognition and management of the biological and psychosocial contributors to TMDs, including comorbid medical conditions such as juvenile idiopathic arthritis and other rheumatologic diseases. While juvenile idiopathic arthritis can affect any synovial joint, the TMJ can be disproportionally involved. Across all subtypes of juvenile idiopathic arthritis, the rate of TMJ involvement ranges from 39 to 75 percent (Resnick et al., 2016). In a study of adult patients with a history of childhood juvenile idiopathic arthritis, 62 percent reported TMJ pain, 43 percent had functional limitation of the jaw, and 76 percent had lower facial asymmetry (Resnick et al., 2017). Recent work on increased recognition and early diagnosis of TMJ involvement (Resnick et al., 2016) has led to more aggressive treatment with medications that target the inflammation caused by the condition, which may decrease the incidence of future TMDs in this population. A similar push toward the early diagnosis and management of other factors that cause or contribute to TMDs may decrease future morbidity.

The early treatment of malocclusion through orthodontic treatments was previously considered a viable preventive treatment for TMDs. However, the evidence was clear decades ago that orthodontic repositioning of teeth does not prevent the onset of a TMD (McNamara, 1997). Nevertheless, some dentists have the outdated belief that orthodontic treatment will prevent TMDs.

Prevention must not stop at the onset of a TMD. While data are starting to emerge from observational studies regarding the premorbid risk factors for TMDs (Ohrbach et al., 2020), there is little evidence concerning the early recognition and prevention of TMDs, so much of the prevention effort must take place after diagnosis. In a patient who has already developed the symptoms of a TMD, the prevention strategy becomes aimed at avoiding the progression of the disorder from a localized issue of the TMJ to a systemic pain condition that also affects regions of the body outside of the face. This secondary prevention approach requires close collaboration between the individual and his or her health care professional to avoid over-treatment, iatrogenic harm, or an aggravation of a TMD and to identify self-care or other interventions that may decrease the negative impact of the

disorder on that individual. Finally, in those patients who have developed TMDs along with widespread or multiple-site pain, a tertiary prevention strategy aims to minimize escalation to high-impact pain, which causes disability that limits work productivity and the ability to enjoy life.

ASSESSMENT AND DIAGNOSIS OF TMDs

Following the publication of the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) (see Chapter 2), a central concern was whether the DC/TMD in its present form is appropriate for clinical use. One question common to various critiques is: When is a diagnostic system “good enough” to rely on for clinical diagnosis? Part of the answer revolves around the further question: What is the alternative? Clinical dentists have reported, across many countries and health care systems, not using the DC/TMD because they deem it to be too complicated or incapable of diagnosing all TMDs. As noted in Chapter 2, there are more than 30 specific TMDs. Furthermore, some of these TMDs will occur simultaneously in the same patient. At present there is no empirical evidence indicating which treatments are most effective for a given DC/TMD classification.

A limitation common to all classification systems is that biology and pathology are continuously variable, while classification systems, in order to enhance their reliability and validity, construct disorders with fixed boundaries. Individuals will have disorders that fall outside the classification boundaries. For pain disorders, there may be notable variability around an identified phenotype, which may require particularly diffuse boundaries for a given diagnosis. Users of the diagnostic test need to have excellent decision-making skills as well as tools that can aid in those decisions. Challenges to using a diagnostic system such as the DC/TMD in clinical care include:

• The need for clinicians to have diagnostic tests that are simple and fast;
• Current reimbursement schedules for dentists that are focused on oral examination;
• Substantial clinical time required for a comprehensive history and adequate physical examination;
• Limitations in training on TMDs;
• The difficulties that clinicians face in having the time to consider the clinical implications of reliability and validity, the probabilistic basis underlying sensitivity and specificity, and the base rate influence on predictive values, with regard to whether a diagnostic test is useful; and
• The current lack of formal decision rules to assist clinicians.

No system can substitute for the provider’s critical decision-making skills, but decision making is greatly enhanced when reliable and valid procedures are used and when decision-making tools are built for practical use in clinical situations (Kassirer and Kopelman, 1991). Implementation research is needed, as discussed in Chapter 4, to assist clinicians in assessing complex disorders such as TMDs.

A clinical assessment for TMDs should include talking with the patient to hear the history of the symptoms and problems, an examination, special tests such as imaging when indicated, and psychosocial assessment (Schiffman et al., 2014). A pain history is recommended as a necessary part of the DC/TMD (Schiffman et al., 2014). This requires knowledge of differential diagnoses and of pain characteristics (Blau, 1982). An adequate pain history provides the necessary level of detail within each of the following attributes: timing (onset, duration, periodicity); location and radiation; quality and severity; relieving and aggravating factors (e.g., the effect of hot or sweet foods, prolonged chewing, eating, brushing of teeth, touching the face, weather, physical activity, posture, stress, and fatigue); associated factors (e.g., taste, salivary flow, clenching, bruxing habits, locking or clicking of jaw joint, altered sensation, and nasal, eye, or ear symptoms); other pain conditions (e.g., headaches, back pain, chronic widespread pain, and fibromyalgia); and other aspects of pain (e.g., sleep, mood, concentration, beliefs, and the quality of life). In diagnosing a pain disorder, the pain history is key because there are no confirmatory examination procedures or tests; to diagnose a specific type of TMD this history is also critical because only the history can provide the necessary information to guide prognosis and treatment selection.

While medical history taking is part of most practitioners’ training, taking a pain history may not be, and a psychosocial history is quite often outside a practitioner’s skills, or it may be set aside due to time constraints. Moreover, it may be difficult for a dentist to assess psychosocial status, as patients often regard it as unexpected if not inappropriate in a dental setting, while dentists often regard it as not part of dentistry. Actions for overcoming barriers to implementing the biopsychosocial model in clinical practice settings are being explored (Sharma et al., 2019).

The current standard for an examination pertinent to TMDs includes specific tests of the masticatory system and, when indicated, TMJ imaging. The examination should assess facial symmetry and extraoral soft tissues, jaw mobility and functional impact (e.g., limited mouth opening), possible disc disorders (TMJ noises, condylar deflection while opening during the acute stage), and the overall pattern of replication of pain from jaw mobility testing and extraoral muscle palpation. As described by Schiffman and colleagues (2014), an evaluation for overt changes in the stability of the occlusion as a consequence of degenerative joint changes is warranted as

part of an initial examination. The clinical tests and imaging protocols and interpretation standards are well described (Ahmad et al., 2009; Li et al., 2012).

To address the time limitations faced by the practicing dentist, a brief form of the DC/TMD examination procedures is currently being developed by an international group via the International Network for Orofacial Pain and Related Disorders Methodology. The brief procedures are expected to yield sufficient examiner reliability and diagnostic validity for the diagnosis of DC/TMD pain disorders. The reliability and validity of the clinical procedures for internal displacements and degenerative joint disease of the TMJ are expected to remain poor, and clinical decision-making skills will be required, as they are now, to decide when the history and clinical examination need to be accompanied by imaging of the TMJ. For the uncommon TMDs, other clinical tests are required (Peck et al., 2014), but these are not yet operationalized and hence not considered reliable. Nevertheless, these indicated tests represent the current best practice for the assessment of the uncommon TMDs.

TMD TREATMENTS

There are a wide variety of potential treatments for TMD, including self-management, physical therapy, medications, occlusal adjustments, intraoral appliances, and surgery. Evidence-based clinical practice guidelines for the treatment of TMDs do not currently exist, despite the fact that treatment is common. In one study of people who developed a TMD, 57 percent reported having received one or more treatments during a 6-month follow-up period (Slade et al., 2016). Evidence about the safety and efficacy of these treatments is sparse; many of the research studies that have been conducted are insufficiently powered to produce solid conclusions, lack appropriate comparison or control groups, are missing standardized outcome measures, or focus on individual interventions without the context of holistic patient care.

Many studies use pain intensity or similar measures as the outcome of interest, rather than measuring such outcomes as quality of life; physical, social, and psychological well-being; or restoration of function. While

reducing pain is an important goal for many patients, patients may also benefit from treatments that restore their ability to live, work, and play. Similar to the evolution in understanding of outcome measures for individuals suffering from low back pain, the goals of TMD care should focus on functional rehabilitation, that is, an individual’s ability to thrive despite the presence of the disease.

The following sections describe common TMD treatments and the evidence that is available about these treatments. This section is not intended to serve as a systematic literature review, but rather as a summary of published data. Recent systematic reviews are included where available as are Cochrane Collaboration reviews and meta-analyses; a frequent conclusion in the systematic reviews regarding clinical trials of treatments for TMDs is that methodological quality is generally low.

The treatments in this section are organized by type of intervention as follows: (1) psychological/behavioral/self-management, (2) physical, (3) complementary, (4) pharmacological, and (5) interventional. It is important to note that most current TMD treatments lack strong evidence to support or reject their use. The two exceptions to this rule are (1) self-management, for which there is strong evidence for improved outcomes in patients with chronic pain, although much of this evidence is not specific to individuals with TMDs, and (2) occlusal treatments, concerning which a large body of research exists, with the effectiveness of occlusal management in individuals with TMDs not having been consistently demonstrated.

In considering the appropriate role for evidence in making treatment decisions, strong evidence supporting the use of a particular type of treatment (e.g., self-management) and strong evidence against the use of a particular type of treatment (e.g., occlusal treatments) should be regarded as a starting point in choosing treatments in the spirit of the requirement to “do no harm.” Despite the evidence that is available, outdated beliefs about commonly recommended therapies can result in harm to individuals with a TMD. It is notable that the TMJ Patient-Led RoundTable reviewed information from 24 professional organizations claiming to diagnose and manage TMDs and found a wide variety of beliefs and guidance (Kusiak et al., 2018).

Historically, a lack of recognition and adoption of available evidence related to TMDs led many clinicians to avoid acceptance of new science which has led to poor treatment decisions and outcomes for many individuals with a TMD. When strong evidence becomes available about TMD treatments, interventions need to be implemented at the level of medical and dental school curriculum and residency. Waiting until clinicians are established in practice to try and motivate changes in their behavior may be too late. In addition, multiple system-level drivers impact the treatment approaches chosen for individuals with a TMD. The dental education and

care delivery has much room for improvement to (1) foster a culture of support for evidence-based treatments during training and once a dentist is in private practice, and (2) influence clinician behavior through system-level changes (e.g., paying for appropriate care and not paying for inappropriate care).

Psychological/Behavioral/Self-Management Treatments

Self-Management

Self-management, alone or in conjunction with other treatments, is a keystone of care for many chronic conditions, including TMDs (Dworkin et al., 2002; Türp et al., 2007; Greene, 2010; Kotiranta et al., 2014). Self-management refers to the tasks an individual engages in to live with a chronic condition (Adams, 2010). When one thinks of the self-management of TMDs, the tasks that typically come to mind are those related to medical management (e.g., taking one’s medications, doing jaw positioning exercises, and returning for follow-up visits). When TMD symptoms persist, however, individuals are often dealing with additional tasks such as managing their roles (e.g., as partners or workers) and managing emotions (e.g., dealing with emotional distress).

For some, the term “self-management” has negative connotations. First, some patients and health care professionals may believe that self-management means that patients should cope with their conditions primarily on their own. Instead, self-management is best understood and practiced as a way of expanding the patient’s agency over his or her condition and its treatment, in partnership with medical specialists and others in their network.

Second, individuals may believe that “self-management” means that they must triumph over or somehow conquer all aspects of their conditions. As a result, they may interpret their own inability to avoid certain negative consequences of a medical condition (e.g., flares in pain due to joint degeneration) as personal failures (i.e., that they are “poor self-managers”). Yet, a key element of self-management is educating individuals about their conditions so that they can better understand and prepare for outcomes that are part of the disease trajectory.

meditation or relaxation strategies, setting goals, staying involved in meaningful activities) are effective in managing a TMD. Alternatively, individuals might acquire strategies for managing a TMD from outside their own experiences, for example, by drawing on educational resources provided by a provider or on the Internet, reading self-help books on TMDs, or observing others who have coped with a TMD or other chronic medical conditions. Peer-guided self-management, on the other hand, is a more formal approach that uses a curriculum to educate patients about their conditions and teach self-management skills in group sessions. It features peer leaders who, because of their lived experience, have high credibility and can be powerful sources of support for helping individuals identify and cope with obstacles to self-management efforts. Peer training is often provided in a format that fits with participants’ language and cultural needs. Finally, therapist-guided self-management approaches combine a psychoeducational rationale with techniques drawn from cognitive-behavioral therapy (CBT) and biofeedback. These approaches are systematic (e.g., use standardized treatment protocols and manuals) and emphasize experiential learning (therapist modeling, guided practice, and supportive or corrective feedback) and the importance of home practice in mastering learned skills. Therapist-guided approaches have the advantage of being led by a trained health professional, often a psychologist. A professional is often in a better position to tailor training to the participants’ needs and past experiences, to provide knowledgeable feedback, and to recommend novel approaches that the participants might not have considered.

The most recent systematic review—by Aggarwal and colleagues (2019)—sought to examine whether formal training in self-management techniques (primarily CBT and biofeedback) is more effective than control conditions in improving long-term outcomes (>3 months) in terms of pain intensity and psychosocial well-being. The researchers’ search of the literature yielded a total of 14 randomized clinical trials that met their criteria for inclusion. All of these trials tested the effects of CBT, biofeedback, or both in patients with chronic orofacial pain or a TMD (12 of 14 studies focused on individuals with a TMD). Table 5-1 presents the CBT and biofeedback protocols used in several of these trials as well as a summary of the findings. The protocols shared several key features: (1) they were led by experienced and trained therapists (usually psychologists), (2) they provided participants

TABLE 5-1 Selected Randomized Clinical Trials of Cognitive-Behavioral Therapy (CBT) Interventions for TMD

NOTE: EMG = electromyography.

SOURCE: Adapted from Aggarwal et al., 2019.

with a psychoeducational rationale at the start of self-management training, and (3) they combined in-session experiential skills training with home-based practice assignments.

Several key findings emerged from that systematic review. First, at long-term follow-up, therapist-guided self-management was significantly more effective than control conditions in reducing pain intensity, depression, activity interference, and muscle palpation pain. Second, many of the studies included positive methodological features such as random assignment to one or more control conditions, well-described inclusion and exclusion criteria, a comprehensive set of well-validated outcome measures, and assessments of both short- and long-term outcomes. Third, as a group these studies were rated as having a low risk of bias, and the quality of evidence for the key outcomes was rated as high (Aggarwal et al., 2019). Taken together, these findings provided support for the efficacy of therapist-guided self-management (CBT and biofeedback) for TMDs.

The efficacy of peer-guided self-management has not been as widely studied in TMDs, though systematic reviews and meta-analyses conducted

on this approach in other chronically painful conditions (Jackson et al., 2014) and chronic diseases (Holden, 1991) have provided empirical support for its efficacy.

Much more needs to be done to advance the practice and science of self-management of TMDs. First, there is a need to involve patients, their families, health care professionals, and other key stakeholders in the review and evaluation of current TMD self-management materials and resources and peer-led and therapist-led self-management training protocols. Such a review could lead to the development of updated and tailored self-management materials. The availability of high-quality resources not only could heighten the impact of self-management approaches on patients and their families, but also could enhance health care providers’ awareness of self-management and knowledge about and skills in fostering self-management. Second, there is a need for programmatic research to develop and test novel self-management programs for individuals with a TMD. Novel psychosocial interventions (e.g., acceptance and commitment therapy, partner-assisted and couples-based training in self-management) and novel treatment delivery formats (e.g., eHealth approaches such as video over the Internet) could be more widely explored in TMD care. Third, although novel theoretical frameworks are available to guide the development of self-management interventions (e.g., the National Institutes of Health [NIH] stage model) that can be readily disseminated, these have not received much attention in the TMD area. These theoretical frameworks are important in guiding treatment development and in addressing the key limitations of the current TMD literature, including the need to involve patients and real-world providers in the development of training materials and methods, the need to link intervention components to theory, and the need to streamline treatments to make them easier to disseminate. Fourth, with the growing recognition that TMDs are a set of complex and multidimensional conditions has come heightened interest in the variance in how people respond to training in self-management. Finally, although there is evidence that formal training in self-management can be effective, much less is known about how it works. Research suggests that changes in measures of self-efficacy or in the perceived ability to control pain occurring

over the course of training are important in explaining improvements in pain and other outcomes (Lorig et al., 1989). Research is needed to identify other critical potential mediators of self-management training in TMD care. Among the potential key mediators are changes in biological responses (e.g., immune activity, changes in spinal cord responses to noxious stimuli, or activation of descending pain modulatory systems in the brain) and emotional responses (e.g., stress responding, emotional regulation). Box 5-1 lists a number of other important research priorities in this area.

Physical Treatments

Occlusal Treatments

As described in Chapter 2, discrepancies between an individual’s dental occlusion (how teeth fit together) and the ideal occlusion, as defined by a range of attributes, have been a target for TMD treatment for more than 50 years. Occlusal treatments modify the teeth and bite. Intraoral appliances fit over the teeth and do not modify the teeth or bite (see section below on intraoral appliances). A 2017 protocol for evaluating the effectiveness of occlusal interventions for managing TMDs has been approved by Cochrane, but the review is not yet complete (Singh et al., 2017). Occlusal approaches, and available evidence-based status, include:

• Occlusal adjustment: modifying the teeth through the addition of fixed crowns or removable devices in order to change the positioning of the lower jaw relative to the upper jaw. A 2003 Cochrane review found no difference between the group receiving occlusal adjustment and the control group (Koh and Robinson, 2003); the review was withdrawn in 2016 due to being out of date and not meeting Cochrane’s current methodological standards (Cochrane Library, 2016a).
• Occlusal equilibration: adjusting the occlusion by removing enamel from the chewing surface of the tooth in order to modify the manner in which the teeth achieve full closure or the manner in which the teeth move past each other as the lower jaw is moved to the side or to the front. This approach has also been called selective grinding—when a dentist grinds one or a few biting surfaces of an individual’s teeth to improve the interaction of those teeth with the teeth on the opposing jaw. A 2018 assessment of the literature found no evidence to support its use (Manfredini, 2018).
• Orthodontic treatments: the repositioning of some or all of the teeth with the goal of improving an individual’s bite. A Cochrane review (Luther et al., 2010) found that there were insufficient data available to inform clinical practice on the effectiveness of orthodontic treatments in reducing TMD symptoms. In 2016 the review was withdrawn due to being out of date and not meeting Cochrane’s current methodological standards (Cochrane Library, 2016b).

The time and cost for these different treatments vary. Full orthodontic treatment typically requires 2 to 3 years, and the cost depends on the geographic area. Adjusting the occlusion can require anywhere from a single treatment session to a series of recurring sessions over many years, which

are often stopped not because of therapeutic success but because of the tooth sensitivity that is inevitable with enough removal of enamel. Modifying the teeth through crowns or removable devices can require up to several years of treatment and cost thousands of dollars.

As discussed in Chapter 2, the current Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) considers the stability of the occlusion as a common symptom of degenerative joint disease but not as part of the diagnosis of a TMD. Over recent decades, research has not found sufficient evidence to support claims that dental occlusion is an important contributor toward TMDs (Clarke, 1982; Clark et al., 1999; Fricton, 2006; Klasser and Greene, 2009; Türp and Schindler, 2012). However, publications and position papers within the dental community often continue to promote the role of occlusion in diagnosing and treating individuals with TMDs (Dawson, 1996; Cooper, 2011; Racich, 2018).

Several studies have found that occlusion and a particular position of the TMJs (which includes freedom to move posteriorly relative to the fully closed occlusion) may actually be a protective factor for TMDs and an important adaptive response of the body (Levy, 1975; Pullinger et al., 1988). This research would suggest that treatment to correct the so-called “slide” in mandibular position (see Chapter 2) is misdirected as a treatment for TMD. The relationship between head posture and the closing position of the mandible and resultant stability of contact between lower and upper teeth reflects a complex interaction between cervical and masticatory systems (Mohl, 1984; Southard et al., 1990), highlighting the importance of understanding TMDs within broader frameworks (e.g., the role of the cervical system for both pain and mechanical jaw function). This contrasts with the common but unsupported belief that head or body posture problems are caused by TMDs (Manfredini et al., 2012), which is sometimes used to justify TMD treatments. Collectively, this type of information continues to not be typically incorporated into working clinical knowledge and research attention to these areas has waned over the years.

Intraoral Appliances (Splints)

Intraoral appliances, or laboratory-fabricated devices that fit over the teeth, are known by a wide variety of names such as splints, stabilization appliances, occlusal splints, occlusal appliances, interocclusal splints, fully balanced splints, repositioning splints, bruxism splints, nightguards, and several names denoting the commercial vendors of particular splint designs; the selected name usually relates to the perceived mechanism of action, for which evidence remains absent. Therefore, the theory-neutral term “intraoral appliance” is used. Intraoral appliance treatment is distinctly different than treatments that modify the occlusion (e.g., occlusal adjustment,

occlusal equilibration, and orthodontic treatments), which are described in the previous section.

The mechanism of action of intraoral appliances is unclear. When used during sleep, they were originally believed to stop sleep bruxism, but it became apparent that bruxism behavior decreased for some individuals, stayed the same for others, and increased for yet others, and this was independent of whether the symptoms improved (van der Zaag et al., 2005). Since then, the relationship between increased activity of the masticatory muscles during sleep and morning symptom reports has, if anything, become more uncertain, raising further questions regarding this treatment modality. As the real mechanism of action has still not been determined, the utility of one type of splint over another (e.g., a stabilization splint that separates the teeth but does not change the position of the jaw versus a repositioning splint that advances the mandible to a changed position) is similarly unclear. Data comparing several types of splint designs have not shown significant differences between them (Jokstad et al., 2005).

Data regarding the effectiveness of intraoral appliance therapy in the treatment of TMDs is generally of poor quality and yields mixed results (see Box 5-2). In one study of 51 participants with myofascial pain with or without limited jaw opening, those who received an intraoral appliance and received information about behavior changes reported earlier significant improvement in pain scores than those in a control group with no appliances (Conti et al., 2012). A study of 112 patients with painful TMDs who were randomly assigned to an anterior repositioning splint or biostimulation laser therapy found that the splint group had a greater decrease in pain intensity (Pihut et al., 2018). In a randomized trial of 81 patients with TMDs that were assigned to treatment groups including intraoral splint therapy, manual therapy, and counseling, all therapies were found to be effective in improving pain and quality of life, but no therapy was superior to another (de Resende et al., 2019). Many other studies have similarly shown intraoral appliance therapy to have minor or equivocal benefits for the improvement of pain in patients with TMDs.

While harms associated with TMJ surgery have been extensively investigated, the harms associated with intraoral appliances are less well understood. The committee was not aware of any specific literature that describes complications associated with intraoral appliances. Anecdotally, these harms include alteration in the occlusion or position of the teeth, aspiration of small appliances worn on the anterior teeth, dependence on a device and not acquiring self-management skills, and perpetuation of a belief that something is wrong with the masticatory system such that the appliance is necessary to “fix” it. Systematic research is needed to assess harms associated with occlusal appliances.

Several attempts have been made at meta-analyses and systematic reviews of the utility of intraoral splints in patients with TMDs. In 1999 a qualitative systematic review concluded that intraoral splints may be of some benefit in the treatment of TMDs but that the evidence to definitively support this conclusion was lacking (Forssell et al., 1999). In 2004 another qualitative systematic review indicated that most individuals with masticatory muscle pain are helped by intraoral appliances such as a stabilization splint but concluded that the evidence was uncertain as to whether the improvement in symptoms was caused by a specific effect of the appliance (Türp et al., 2004). A 2017 meta-analysis that included 30 randomized controlled trials found stabilization splints to have short-term benefits on pain reduction and pain intensity but no differences in long-term outcomes with other types of treatments (Kuzmanovic Pficer et al., 2017). In summary, intraoral splint therapy may confer a small benefit for the management of pain in individuals with TMDs, but the evidence for this is generally poor and mixed.

Physical Therapy

Physical therapists are fully integrated into the modern health system and work to meet the interdisciplinary and interprofessional management needs of individuals with chronic pain. Physical therapists are increasingly serving as primary care providers and may provide a gateway into the health care system for people with a TMD. Physical therapists use multiple approaches to the management of TMDs, including exercise, manual therapy, and education on self-management skills (see section on self-management above). Other therapies offered by physical therapists include electrotherapy and dry needling; these treatments need more evidence to support their use (see below).

exercise as one of the first-line treatments (Kia and Choy, 2017; Oliveira et al., 2018). There are several types of exercise that may be effective in the management of TMDs. These include jaw strengthening, jaw stretching, and postural exercises.

• Jaw strengthening exercises: Some studies support the effectiveness of exercises to build jaw strength and endurance, with or without stretching exercises, in improving pain, jaw opening, and TMJ sounds/clicking (Haggman-Henrikson et al., 2018; Wanman and Marklund, 2019). A study using supervised exercise training showed greater improvements than home exercises alone (Wanman and Marklund, 2019). Other publications, however, have not demonstrated as much benefit (Craane et al., 2012).
• Jaw stretching exercises: Some clinical trials show that home exercise aimed at stretching the soft tissue around the jaw muscles increases jaw opening and may decrease pain. However, other studies do not show an effect of stretching exercises, whether applied by a physical therapist or by the patient in a home program (Armijo-Olivo et al., 2016). Meta-analyses, however, indicate overall benefit of stretching to regain normal jaw opening for both myalgia and clicking problems (Armijo Olivo et al., 2016).
• Postural exercises: Individual studies and reviews have demonstrated some effectiveness of active and passive exercises that improve posture in reducing pain and improving the range of motion (McNeely et al., 2006; Medlicott and Harris, 2006). However, the methodological quality of the studies was found lacking (McNeely et al., 2006; Medlicott and Harris, 2006).

A recent systematic review and meta-analysis of exercise for TMDs (Armijo-Olivo et al., 2016) performed an extensive analysis of multiple types of exercise therapy. The review showed that jaw exercises were associated with a clinically significant increase in pain-free mouth opening and that postural exercises were associated with clinically significant increases in pain-free mouth opening as well as reductions in disturbances in daily living. It should be noted, however, that the researchers identified that no high-quality evidence was found and caution is warranted due to the low quality of the studies, large heterogeneity, and the small number of subjects per study.

One benefit of exercise in general (e.g., possibly more than jaw stretching or strengthening exercises) for patients with TMDs may be exercise-induced analgesia, the underlying mechanisms of which recent research has begun to uncover. In addition to improving function by increasing the range of motion, strength, and motor coordination of the joint and

muscles, exercise can also alter the immune system and the nervous systems in ways that promote healing and reduce pain (Brito et al., 2017; Lima et al., 2017a,b; Sluka et al., 2018). In addition, in chronic pain conditions, there are decreases in serotonin and increases in the serotonin transporter, both of which are normalized by regular exercise (Brito et al., 2017; Lima et al., 2017a,b; Sluka et al., 2018). In human subjects with chronic pain, researchers have found an interaction between the serotonin transporter gene and the mu-opioid gene that is associated with increased analgesia (Tour et al., 2017).

Understanding the underlying mechanisms by which exercise reduces pain and improves function may be important when designing exercise programs for individuals with TMDs. For example, if individuals with TMDs have a comorbid inflammatory condition or widespread pain with altered central nervous system processing, an aerobic conditioning program may be useful in both improving function and reducing pain. On the other hand, if there is significant weakness of the jaw muscles, more localized stretching and strengthening exercises are likely to improve function and may have a secondary effect of reducing pain.

Manual therapy and exercise are often combined; neither is frequently done as a stand-alone treatment. The review by Armijo-Olivo and colleagues (2016) examined data from seven studies and showed that manual therapy with exercise decreased symptoms of TMDs and increased the mouth opening and range of motion. These changes were of moderate effect sizes.

Other Physical Therapy Interventions

In addition to exercise and manual therapy, there are a number of other physical therapy treatments for TMDs that are used clinically but which lack clinical evidence or have varying degrees of evidence. These include the use of heat and cold therapy, low-level laser therapy, and dry needling. Heat and cold therapy are often recommended as part of a self-management program and are inexpensive with minimal risk. However, there is no research to support or refute their effectiveness for TMDs. Systematic reviews have shown that low-level laser therapy was somewhat better than placebo in reducing pain from TMDs, and improving related outcomes (Maia et al., 2012; de Pedro et al., 2019). Dry needling is becoming increasingly accepted and used as a treatment for myofascial pain and TMDs. A recent systematic review considered 18 studies examining the effectiveness of dry needling and injection with different substances (Machado et al., 2018). The review concluded that while dry needling and local anesthetic injections seem promising, there is a need to conduct randomized clinical trials with larger sample sizes and longer follow-up times to truly evaluate the effectiveness of these techniques. A 2019 study in five women with chronic masticatory myofascial pain found that deep dry needling increased the individual’s pressure pain threshold (Tesch et al., 2019). Among the limitations noted by the authors was that increasing pressure pain thresholds is an isolated outcome that is not directly comparable with more general outcomes such as the intensity and severity of the pain experienced or a patient’s perception of the treatment’s efficacy and impact on quality of life.

Complementary Treatments

Acupuncture

Acupuncture is another treatment approach that has been used for TMD but for which evidence is limited. A 2017 meta-analysis found a significant one-point difference (out of 10) on the visual analog scale of pain between acupuncture and sham acupuncture for TMDs (Wu et al., 2017). Interestingly, the effect was only found when the comparison was with non-penetrating sham acupuncture; the difference between acupuncture

and penetrating sham acupuncture was not significant. The meta-analysis also found that acupuncture was more effective for patients with TMDs that were related to masticatory muscle disorders versus related to the TMJ itself.

Dietary Intake and Nutrition

Changing one’s diet is a type of behavioral modification some individuals with a TMD might undertake to relieve or avoid pain. Pursuing a soft diet and seeking pain-free chewing has been related to important nutritional challenges faced by individuals with a TMD. Given that TMDs can affect an individual’s ability to chew and swallow, serious nutritional challenges and deficiencies can occur. The TMJ Association advises a soft diet for individuals who are able to adequately open their mouths and have minimal pain and a pureed diet for those who cannot tolerate a soft diet (The TMJ Association, 2017). Because evidence-based dietary guidelines for patients with chronic orofacial pain do not exist, clinicians may provide customized advice for individuals based on the challenges they report (Durham et al., 2015; Nasri-Heir et al., 2016). While dietary interventions are commonly recommended for patients with a TMD, more research is needed on whether and how dietary changes have an impact.

Electrotherapy

Transcutaneous electrical nerve stimulation (TENS) is a form of neuromodulation that applies electrical current through the skin for pain control. The mechanisms of TENS analgesia have been extensively studied and involve the activation of endogenous opioid, serotonin, and GABAergic pathways in a frequency-dependent manner which can reduce central excitability and central sensitization (Vance et al., 2014). High-frequency TENS has been shown to reduce pain and decrease electromyography (EMG) activity of the masticatory muscles in people with TMDs (Rodrigues et al., 2004). Low-frequency TENS reduces EMG activity (Kamyszek et al., 2001). A single treatment of either sensory-stimulation or motor-stimulation low-frequency TENS reduces the EMG activity of the masticatory muscles similarly and improves mouth opening (Monaco et al., 2013). Additionally, two 30-minute TENS treatments in combination with pharmaceutical treatment provide additional pain relief when compared with pharmaceutical treatment alone (Shanavas et al., 2014). However, it should be noted that these studies were small with short-duration TENS treatments.

Pharmacological Treatments

Oral Medication

A variety of pharmacological treatments have been suggested for the management of the pain and symptoms associated with TMDs. Most studies on pharmacological treatments have focused on evaluating the efficacy of various drugs in relieving pain, which is the primary reason for which individuals with a TMD seek medical care. However, there are no drugs specifically approved by FDA for this disorder, and the evidence for the efficacy of many of the recommended treatments is weak. Pharmacotherapies recommended for patients with a TMD have generally been based on drugs that have been shown to be efficacious for other musculoskeletal conditions or neuropathic pain states. Commonly recommended pharmacological agents for TMDs, based on expert opinion, include acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids, antidepressants, anticonvulsants, benzodiazepines, muscle relaxants, opioid analgesics, tricyclic antidepressants, and topical lidocaine patches.

To assess the effectiveness of pharmacological interventions in individuals with a TMD, a Cochrane Collaboration literature review was conducted and found that most trials had few participants and there was insufficient evidence to support or refute the effectiveness of the reported drugs (Mujakperuo et al., 2010). Large-scale efficacy and effectiveness trials of pharmacological agents in the treatment of TMDs are needed.

A brief summary of select pharmacological approaches to TMD pain relief and relevant studies is presented below.

Opioids

The inconsistent efficacy of NSAIDs in relieving chronic pain associated with severe TMDs has led to exploration of alternatives, including the use of opioid analgesics (Ouanounou et al., 2017). One randomized trial with 80 subjects provided moderate evidence that a combination analgesic product (NSAID and low-dose codeine) delivered relief from pain associated with TMDs (Shaheed et al., 2019). A recent review identified placebo-controlled studies that reported improved outcomes with morphine and fentanyl for TMJ arthrocentesis (Gopalakrishnan et al., 2018). Evidence supporting the use of opioids to manage chronic pain is lacking (NASEM, 2017). Given the high rates of opioid use disorder and opioid-related deaths, the use of opioid analgesics for TMDs should not be a first-line pharmaceutical treatment. The guidelines by the Centers for Disease Control and Prevention emphasize the improvements needed in prescribing opioids for chronic pain (CDC, 2019).

evidence for their efficacy in controlled trials. One randomized trial found diazepam to be efficacious in the short-term management of chronic orofacial muscle pain (Singer and Dionne, 1997). Other muscle relaxants (e.g., cyclobenzaprine) are also recommended for treating patients with orofacial muscle spasms, though the quality of the evidence for the efficacy of these drugs is weak. A 2009 Cochrane review cited two randomized controlled trials reporting the use of cyclobenzaprine for the treatment of myofascial pain. The two studies included in the review examined a total of 79 participants; however, there was insufficient evidence to support the use of cyclobenzaprine for the treatment of myofascial pain (Leite et al., 2009).

Topical Medication

Intramuscular Medication

into the muscles of mastication has been proposed to decrease muscle spasm and pain. Botulinum toxin is a neurotoxic protein that prevents the release of the neurotransmitter acetylcholine, thereby impairing muscle contraction. Some studies have reported improvement in facial pain in some patients with TMDs from botulinum toxin Type A injection into the muscles of mastication (Chaurand et al., 2017; Khawaja et al., 2017), but others have reported equivocal results (Chen et al., 2015; Keenan, 2015); the data are limited and often of poor quality. A Cochrane review (233 subjects in 4 trials) found inconclusive evidence concerning the effectiveness of botulinum toxin for myofascial pain in the neck and head muscles (Soares et al., 2014).

Navarrete and colleagues (2013) reported a study in which rabbits were injected with either botulinum toxin Type A or saline solution into the masseter muscle. The result was a dramatic loss of bite force, after 3 weeks, in the rabbits receiving botulinum toxin Type A injections. While this study, and others, indicated success in using botulinum toxin Type A to unload, or temporarily paralyze, the muscle and relieve the jaw joint, The TMJ Association issued caution to individuals with TMD pursuing treatment with botulinum toxin Type A due to the loss of bone strength resulting from the treatment in rabbits. There is concern for the health of the TMJ in humans using botulinum toxin Type A in the long term given the osteoporotic condition of the TMJ in rabbits (The TMJ Association, 2016).

Prolotherapy

Other intra-articular injection agents have been proposed for specific subdiagnoses of TMDs. In the case of chronic dislocation and hypermobility of the TMJ, for example, prolotherapy (injection of an irritant solution to promote a reparative immune response) has shown promise (Zhou et al., 2014; Cezairli et al., 2017; Refai, 2017). Two studies demonstrated a success rate of 80 percent in reducing or eliminating dislocations by 1 year after injection of autologous blood to the superior TMJ space and the joint capsule (Machon et al., 2009; Daif, 2010).

Interventional Treatments

Arthrocentesis and Arthroscopy

In patients who have not achieved relief from or who are not candidates for noninvasive treatment, minimally invasive surgical treatment may be indicated. The simplest of these minimally invasive operations is arthrocentesis. The indications for arthrocentesis include an identification of an intra-articular pathology such as disc dislocation in combination with

pain or joint dysfunction. Musculoskeletal pain may not be improved by arthrocentesis, and this treatment is typically used as only one component of a comprehensive management strategy.

Arthrocentesis involves the insertion of a needle into the superior TMJ space, followed by joint lavage. This can be accomplished with either a single needle for both the inflow and outflow of lavage fluid or by using two separate puncture sites to allow the inflow and outflow ports to be separated. The idea behind this intervention is to flush viscous synovium and inflammatory mediators from the joint and to release joint adhesions via hydraulic pressure. Arthrocentesis has been shown to be effective in relieving pain and improving mouth opening in patients with temporomandibular disc displacements (Dimitroulis et al., 1995; Nitzan and Price, 2001; Nitzan et al., 2017), though its benefits may decrease after 6 months (Bjørnland et al., 2007).

Arthroscopy, which involves the insertion of a small video endoscope into the superior TMJ space, is similar to arthrocentesis but with the added benefit of indirect visualization of the joint. The ability to visualize the joint space provides confirmation of joint access, enhances diagnosis, and allows additional therapy such as the laser resection of adhesions and disc repositioning (McCain and Hossameldin, 2011). The short-term outcomes of arthroscopy with regard to pain and function have been found to be similar to those for arthrocentesis (Fridrich et al., 1996), with both showing moderate effectiveness.

Both arthrocentesis and arthroscopy are often, but not always, combined with an injection of medication into the superior joint compartment. The most frequently injected medications are corticosteroid and hyaluronic acid. The reported results of these injections are mixed, with some studies demonstrating superior outcomes for pain relief with corticosteroid and hyaluronate (Liu et al., 2018), others purporting better outcomes with hyaluronic acid (Bjørnland et al., 2007), and several showing no significant difference among corticosteroid, hyaluronic acid, and saline alone (de Souza et al., 2012; Bouloux et al., 2017a,b; Davoudi et al., 2018).

Operations with Direct Access to the TMJ

“Open operations,” or surgical procedures that provide direct access to the joint, are reserved for individuals with severe and irreversible destruction of the TMJ and those who have persistent debilitating symptoms or dysfunction of the joint despite other treatment. Less than 3 percent of 2,104 individuals who completed treatment for a TMD received an open surgical procedure in a multi-site analysis (Brown and Gaudet, 2002).

The selection of an operation is based on the severity of the symptoms and the health of the joint components. Several classification systems exist

to guide treatment decisions (see Chapter 2), but there is no universally accepted protocol for operative management of a TMD. Imaging, particularly magnetic resonance imaging, plays a major role in the staging of the disease and the determination of the appropriate surgical treatment approach. Surgical treatment is sometimes graded, beginning with minimally invasive procedures and progressing to more aggressive operations as needed. Evidence has emerged, however, that shows that patients who have had fewer total TMJ operations have superior surgical outcomes than those who have had many smaller operations (Mercuri, 1999). This indicates the need to make an accurate diagnosis and choose the appropriate surgical intervention, when indicated, carefully.

Open operations are used when irreversible joint destruction has occurred and associated symptoms and dysfunction are present. Open operations require direct access to the TMJ via an incision adjacent to the ear. The diagnosis then dictates the procedure. When the TMJ disc is displaced from its normal position, it can be repositioned; when the disc is damaged, it can either be repaired or be removed (discectomy), with or without replacement. When the mandibular condyle or glenoid fossa has been eroded or free pieces of bone (osteophytes) are within the joint, a modification of the bony components of the joint, including the mandibular condyle, glenoid fossa, or articular eminence, may be indicated. Many other similar procedures can be performed within the joint once direct access has been obtained, depending on the objective of the operation.

When multiple components of the joint are severely damaged, reconstruction may be required. This can be accomplished with autologous tissues such as costochondral (rib) grafts or alloplastic materials (TMJ implants). TMJ implants will be discussed further in the next section.

Several subdiagnoses that may mimic TMDs but are not considered to be TMDs in this report require variations of the surgical considerations described above, each with corresponding evidence within the applicable subspecialty. In patients with a TMJ pathology such as a cyst or a tumor, an open operation may be required as the primary treatment. In patients with progressive condylar resorption disorders, including idiopathic condylar resorption and juvenile idiopathic arthritis affecting the TMJ, open operations for replacement of the degenerated joint components using autogenous or alloplastic implants may be required. Similarly, in patients with congenital anomalies of the TMJ, such as hemifacial microsomia, bilateral craniofacial microsomia, and Treacher Collins syndrome, construction of the joint with autogenous or alloplastic materials may be indicated as the first-line treatment. In patients with TMJ ankylosis, most commonly a result of trauma or infection, aggressive joint debridement and reconstruction is necessary. Patients with hypermobility syndromes such as Ehlers-Danlos and recurrent dislocation may require strategies to induce fibrosis of the

peri-articular tissues, such as autologous blood injection (Daif, 2010), and to eliminate anatomic factors that lead to dislocation, which may include resection of the articular eminence (eminectomy) (Tocaciu et al., 2019).

TMJ Implants

Patients with bony ankylosis, condylar injuries, developmental abnormalities, functional deformity, severe inflammatory conditions, and/or painful or dysfunctional internal derangements after failed conservative and surgical treatment, all of whom have not responded to less invasive treatments, may be candidates for a TMJ replacement with alloplastic implants (Sidebottom et al., 2008; NICE, 2014). Commensurate with improvements in biomaterials and long-term data demonstrating favorable outcomes in pain reduction, improved function (Wolford et al., 2015), and improved quality of life (Kunjur et al., 2016), the use of total alloplastic TMJ replacements has recently increased (Onoriobe et al., 2016). Several total alloplastic TMJ implants are currently available in the United States and are generally categorized as either stock implants (those that come in standard sizes and are then modified to fit the patient’s anatomy) or custom implants (those that are produced prior to implantation in a customized patient-specific shape and size based on preoperative imaging).

The TMJ implants that are currently on the market have been subjected to testing by manufacturers in compliance with FDA requirements for Class III devices. A follow-up study of 56 patients with implants found positive outcomes and stability at least 20 years after insertion, but only 50 percent of the initial cohort of 111 patients could be contacted and met study criteria (Wolford et al., 2015). However, earlier implants, which have since been removed from the market (discussed below), were associated with severe complications, which often went unrecognized until years after surgery. Unfortunately, this led to significant harm for some patients and clouded the field of TMJ surgery. The committee heard from individuals with TMDs and TMD patient representatives who reported significant challenges in the implant recall process. Not all patients who received the recalled device were properly notified by their oral surgeon. Even though the device was recalled by FDA in 1990, TMD patient representatives told the committee that some patients are just being notified now that they received the faulty device.

As introduced above, the use of Proplast/Teflon-based TMJ implants in the 1970s and 1980s resulted in severe adverse events and the need for corrective surgery in some patients (AAOMS, 1993; Lypka and Yamashita, 2007). In especially severe cases, implant recipients required multiple follow-up operations to fix the damage (Henry and Wolford, 1993). Many affected patients continue to suffer from irreversible iatrogenic damage and

require lifelong care. In 1991 an FDA bulletin recommended the removal of all previous Proplast/Teflon TMJ implants based on evidence of mechanical failures resulting in significant adverse health outcomes (Ferreira et al., 2008). Shortly thereafter, the American Association of Oral and Maxillofacial Surgeons issued a similar mandate recommending the discontinuation of Proplast/Teflon-based implants (AAOMS, 1993). In 1998 FDA issued regulations that required TMJ implant sponsors to submit premarket approval applications (GAO, 2007). Table 5-2 lists the TMJ implants that currently have premarket approval from FDA.

There is evidence that newer TMJ implants can improve function and quality of life in properly selected patients (Gruber et al., 2015). However, the National Institute of Dental and Craniofacial Research (NIDCR) still cautions patients about surgical approaches to treating TMDs, stating that the treatments are “controversial, often irreversible, and should be avoided where possible” (NIDCR, 2018). While there are outcome studies demonstrating some measurable benefits of TMJ reconstruction for select patients, there is a need for longer-term studies examining the safety and efficacy of TMJ implants (see section below on patient registries). The TMJ Patient-Led RoundTable—which involves patients, NIDCR, FDA, clinicians, and researchers—has a goal of defining the natural history and assessing biomarkers associated with outcomes in TMJ implant patients to better target therapies to patients most likely to benefit from them (Kusiak et al., 2018).

IMPROVING AND DISSEMINATING EVIDENCE

As discussed above, the evidence base for many TMD treatments is poor. Clinicians tend “to see what they treat and treat what they see,” based on the theory of TMDs in which they are educated and trained. To improve care and outcomes for people with TMDs, it is critical that researchers gather and disseminate high-quality evidence about these treatments. Three approaches for doing so are discussed here: conducting clinical trials, building a patient registry, and developing and implementing clinical practice guidelines.

Conducting Clinical Trials

Randomized controlled trials (RCTs) are considered the gold standard for assessing the effectiveness of a particular medication or treatment approach (Bothwell et al., 2016). RCTs in general can be challenging to carry out for several reasons, including difficulty with endpoint selection, inadequate randomization or blinding, and other logistical problems (Nichol et al., 2010). Although some RCTs for TMD treatments have demonstrated small to moderate reductions in pain intensity (as described earlier in this chapter), the quality of evidence is limited, and some of the studies have been plagued by methodological shortcomings (e.g., insufficient blinding, small sample sizes, a range of outcome measures and control treatments, and short follow-up times). Furthermore, many RCTs for TMD treatments are carried out in tertiary care centers (centers that focus on specialized care), and few, if any, take place in a primary dental care setting, which is often where patients go first if they begin experiencing orofacial pain (Velly et al., 2013). As of October 2019, 191 clinical trials were listed on clinicaltrials.gov for a variety of interventions for TMDs. Of those 191 trials, 29 were actively recruiting, and 4 were taking place in the United States. Given the currently inadequate research base for TMD treatments, more

well-designed clinical trials are needed in the future to inform evidence-based care for individuals with a TMD.

Ideal Characteristics of Clinical Trials for TMD Treatments

Ideally, clinical trials for TMD treatments would focus on outcomes that are meaningful to patients, such as improvements in health and quality of life, reduction in pain, restoration of function, and physical, social, and psychological well-being, and they would examine TMDs in the context of the real world in which patients live. The incorporation of patient preference data and real-world evidence and experiences is one of the key objectives of the TMJ Patient-Led RoundTable. Clinical trials for TMDs could be improved through the adoption of a universal TMD case classification system, such as DC/TMD, across all trials and could incorporate broad eligibility criteria as a way to reach a large, diverse patient population and increase the generalizability of the trial results. Detecting, measuring, and taking into account the comorbidities often seen in TMD patients is an important step toward improving the quality of clinical studies in this area.

Conducting pragmatic trials that incorporate real-world evidence may represent an opportunity to gather better information about the effectiveness of TMD treatments. Pragmatic clinical trials test an intervention in a real-world clinical setting (e.g., hospitals, clinics, primary care providers) and differ from traditional RCTs, which take place in a highly controlled setting (Weinfurt et al., 2017). One type of pragmatic trial that has been proposed for TMD clinical research involves cluster-randomized stepped-wedge blinded controlled trials. This type of trial attempts to alleviate flaws such as information, inferential, and selection bias and to improve reporting quality (Chiappelli et al., 2015).

Opportunity for a National TMD Clinical Trials Consortium

Bringing together researchers through a national TMD clinical trials consortium could provide opportunities to improve the quality of clinical studies of TMD treatments. The committee identified the following groups that could be beneficial to include in a national TMD clinical trial consortium:

• NIH Health Care Systems Research Collaboratory. It aims to improve the conduct of clinical trials through the development of a new infrastructure for clinical research with health care systems. The collaboratory supports the design and execution of pragmatic clinical trial demonstration projects.

• The Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT). The initiative develops consensus guidelines regarding how to improve the design, execution, and interpretation of clinical trials for the treatment of pain (IMMPACT, 2019). The IMMPACT recommendations for routine clinical measures (Dworkin et al., 2005) have been incorporated into Axis 2 of the DC/TMD (Schiffman et al., 2014). Ongoing IMMPACT developments will continue to provide guidance for the best approaches to measuring and assessing pain in clinical trials for TMD treatments.
• The Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION). A public–private partnership with FDA, ACTTION’s mission is to “identify, prioritize, sponsor, coordinate, and promote innovative activities—with a special interest in optimizing clinical trials—that will expedite the discovery and development of improved analgesic, anesthetic, addiction, and peripheral neuropathy treatments for the benefit of the public health” (ACTTION, 2020).
• Dental Practice-Based Research Networks (PBRNs). The major PBRN in the dental field is the National Dental Practice-Based Research Network with participation by more than 6,500 general dentists and practitioners who engage in clinical research (National Dental PBRN, 2019). Additionally, a number of other PBRNs are actively engaged in many areas of clinical research.
• National Patient-Centered Clinical Research Network (PCORnet). This network aims to use a patient-centered approach to increase the efficiency of clinical research. PCORnet consists of nine large clinical research networks, two health plan research networks, a coordinating center, and a central office (PCORnet, 2019). Clinical research carried out through PCORnet incorporates data from electronic health records, claims databases, and patient registries.

Building a Patient Registry

A patient registry offers a way to collect real-world data about clinical practices, patient outcomes, safety, and the effectiveness of treatments (Gliklich et al., 2014). Patient registries have been developed for a number of health conditions and take different forms depending on the specific condition and population. Patient registries can collect a wide variety of information, such as symptoms, pain levels, day-to-day functioning, treatments, and patient perceptions and goals. Developing common data elements is one way of improving the efficiency of the registries as is being done through the Core Outcome Measures in Effectiveness Trials (COMET) Initiative (COMET Initiative, 2020). There are platforms that are designed

to facilitate the creation and connection of condition-specific registries. One example is PEER, which is operated by Genetic Alliance (see Box 5-3).

One common use for a patient registry is the monitoring of medical devices that are on the market. After devices receive clearance from FDA, companies may be required to collect information about patient outcomes and how the device performs over time. There have been several patient registries in the TMD space—existing and planned—all of which are designed to collect information about implants.

National TMJ Implant Registry and Repository at the University of Minnesota

Alloplastic TMJ implants are Class III devices, the most complex and highest risk devices regulated by the Center for Devices and Radiological Health (CDRH) at FDA. FDA ordered device manufacturers to conduct Section 522 postmarket surveillance studies on TMJ implants as a way to gather additional data on the natural life cycle of the devices (FDA, 2011). A brief description of the 522 studies of Class III TMJ prostheses is provided

in Table 5-3. However, these studies do not provide enough evidence about the performance and clinical outcomes associated with TMJ implants, and there is a need to redesign and strengthen studies of FDA-approved TMJ implants. In 2002, NIDCR recognized the need for further examination of TMJ implants and the reasons for their failures and awarded funding to the University of Minnesota School of Dentistry to develop a national TMJ implant registry and repository (Myers et al., 2006). This registry allowed researchers to access and study explanted TMJ prostheses and other biological specimens in conjunction with clinical outcomes. The effort involved two parallel tracks: a registry that recruited clinicians, surgeons, and patients to collect patient data over time and a repository that housed biological specimens and explanted prostheses. A potentially important

distinction is that this registry did not include samples from patients who received total joint implants, but rather only samples from those patients who had disc replacements. Funding for the registry ended in 2010, but the biospecimens remain available at the University of Minnesota and represent a potentially valuable research tool.

FDA is also working toward increasing the quality of data on the safety and effectiveness of TMJ implants through the Medical Device Epidemiology Network (MDEpiNet), a global public–private partnership initiated in 2010 (MDEpiNet, 2019a). MDEpiNet aims to advance the collection and use of real-world data from routine patient care in order to improve outcomes. In 2014, MDEpiNet convened a Medical Device Registries Task Force with the goal of strengthening the medical device postmarket surveillance system as a way to support better regulatory decisions and patient care (Krucoff et al., 2015). The Medical Device Registries Task Force proposed strategically coordinated registry networks (CRNs) as a way to link existing complementary registries and provide interoperability solutions to data-related challenges including disparate and potentially incomplete data sources. In 2017 the Department of Health and Human Services’ Office of the Assistant Secretary for Planning and Evaluation awarded FDA/CDRH funds to develop a CRN community of practice, which is comprised of 14 CRNs operating or in development, one of which is focused on TMDs (MDEpiNet, 2019b). One key stakeholder involved in developing the TMD CRN is the TMJ Patient-Led RoundTable. The TMD CRN aims to do the following:

• Create a standardized data infrastructure,
• Develop new and more effective ways to incorporate patient and real-world evidence data in clinical trials,
• Support the design of predictive analytics algorithms,
• Foster evidence-based protocols and best practices for inclusion into health care, and
• Promote collaborative multidisciplinary research (MDEpiNet, 2019c).

Efforts to build the TMD CRN also include coordinating with other registries and databases that collect information on the comorbidities present in TMD patients. Care is being taken to align the minimum core datasets to the greatest extent possible. The TMD CRN is also enlisting help from patients via The TMJ Association, which has amassed a great deal of information directly from individuals who are affected by a TMD (The TMJ Association, 2019a). The involvement of public and private payers will be key to the success of the TMD CRN because they can provide valuable input on TMD claims data and how best to standardize the collection of that information.

Need for a Patient Registry

Despite these important existing efforts, the committee believes that it would be beneficial to explore the development of a comprehensive national registry that would collect a wide variety of data from all types of TMD patients and would incorporate a core set of data elements. Ideally, this registry would be easily accessible for individuals with a TMD and their care providers in order to facilitate data collection. An important first step would be to gather information about best practices and lessons learned from other and ongoing patient registry efforts, including, but not limited to, the University of Minnesota implant registry, the TMD CRN, and the PEER platform. (See recommendations in Chapter 8.)

Developing and Implementing Clinical Practice Guidelines

There are currently no formal clinical practice guidelines that provide evidence about effective TMD treatments, for whom or for what specific types of TMDs particular treatments may be effective, and criteria for when to escalate treatment beyond the initial conservative approaches. Given the historical misunderstanding of TMDs and misguided treatment approaches that have led to iatrogenic harm for some, and as current diagnosis and treatment remains disparate and heterogeneous, TMD clinical practice guidelines are greatly needed.

Some professional associations, federal research agencies, and patient advocacy organizations have developed general guidance for treating TMDs. However, this guidance is largely focused on self-care, is not firmly grounded in evidence, and is in some cases inaccurate or contradictory (see Table 5-4). The American Dental Association (ADA), as part of the Choosing Wisely campaign, released guidance in 2016 on TMDs. The Choosing Wisely campaign is aimed at improving communication between providers and patients and encouraging patients to choose treatments that are evidence based, free from harm, and truly necessary. ADA’s guidance on TMDs encourages patients to avoid irreversible procedures as a first-line treatment and notes that many TMDs resolve spontaneously without treatment (see Table 5-4).

The American Academy of Orofacial Pain has published six editions of guidelines for assessing, diagnosing, and managing orofacial pain (de Leeuw and Klasser, 2018). The guidelines are geared toward a professional audience and have increasingly focused on rigorous incorporation of sound evidence.

The publication of these types of guidelines for diagnosing and treating individuals with a TMD has elicited controversy. For example, in 2010 the American Association for Dental Research (AADR) approved a new guideline for the care of patients with TMDs (Greene, 2010). The

TABLE 5-4 TMD General Guidance from Various Associations and Federal Agencies

guideline encouraged clinicians to (1) diagnose TMDs using information on the patient’s history, clinical examination, and, when indicated, TMJ radiology and other imaging modalities, as opposed to adjunctive diagnostic tools, and (2) initially treat patients with conservative, reversible, and evidence-based modalities unless specific indications suggest a different initial treatment. In response to AADR’s new guideline, the Journal of the American Dental Association received an unprecedented 228 letters, the vast majority in opposition to the guideline (JADA, 2010). The published letters opposing the guideline mostly came from dentists following the neuromuscular approach to TMDs, who cited a number of issues including disagreement that a biopsychosocial model is best for treating individuals with TMD, disagreement about the effect of dental appliances for treating TMDs, and disagreement that most cases of TMD resolve on their own (JADA, 2010). The published letters in support of the guideline were from orofacial pain dental providers and indicated that the clinical data point to the majority of patients with TMDs benefiting from “reversible, nonsurgical, non-orthodontic treatment, for a fraction of the cost” (JADA, 2010, p. 1415).

This debate highlights the deep divide between different approaches to TMDs, and how the lack of clear evidence creates confusion about how to

treat TMDs. At present, even the principle regarding what constitutes strong evidence remains disputed. Absence of training in research methods and statistics or in the skills needed to critically evaluate published literature pervade much of the dental field. Without such critical skills to evaluate evidence and incorporate it into the behavioral repertoire of the clinician, the deep divide between those who adhere to belief-based models versus those who work flexibly and adaptively according to current evidence will continue.

Related Clinical Practice Guidelines

Clinical practice guidelines in related areas may serve as guides to the formal development of clinical practice guidelines for TMDs. The ADA Center for Evidence-Based Dentistry publishes clinical practice guidelines for a number of conditions, for example, although it has not done so for TMDs (ADA Center for Evidence-Based Dentistry, 2019). Clinical practice guidelines are available for pain conditions similar to TMDs, such as low back pain and fibromyalgia. For example, the American College of Physicians released clinical practice guidelines in 2017 for the treatment of low back pain (Qaseem et al., 2017). The recommendations encourage patients and providers to first select non-pharmacological treatment (such as massage, acupuncture, exercise, yoga, mindfulness therapies, and CBT). For chronic back pain that does not respond to these therapies, clinicians and patients can consider pharmacological treatment with NSAIDs, tramadol, or duloxetine. Similarly, the American Physical Therapy Association’s clinical practice guidelines for low back pain emphasize the importance of physical activity and active pain coping strategies (see Box 5-4).

While the development of clinical practice guidelines is often led by associations of health professionals, patient-focused organizations may be able to fill this role as well. For example, the Alzheimer’s Association convened a group of experts to develop consensus clinical practice guidelines (see Box 5-5).

Need for TMD Clinical Practice Guidelines

There is a clear need for formal clinical practice guidelines to reduce confusion among providers and patients about TMD management. In contrast to the general guidelines discussed above, clinical practice guidelines are “statements that include recommendations intended to optimize patient care that are informed by a systematic review of evidence and an assessment of the benefits and harms of alternative care options” (IOM, 2011, p. 4). Trustworthy clinical practice guidelines:

• Are based on a systematic review of existing evidence;

• Are developed by a knowledgeable, multidisciplinary panel of experts that includes representatives from key affected groups;
• Acknowledge important patient subgroups and patient preferences, as appropriate;
• Are developed using an explicit and transparent process that minimizes distortions, biases, and conflicts of interest;
• Provide a clear explanation of the logical relationships between alternative care options and health outcomes and provide ratings of both the quality of evidence and the strength of the recommendations; and
• Are reconsidered and revised as appropriate when important new evidence warrants modifications of recommendations (IOM, 2011).

Currently, there is minimal robust, high-quality evidence on which to draw in developing clinical practice guidelines. However, conducting basic and translational research (see Chapter 4), conducting clinical trials (this chapter), and creating a patient registry (this chapter) would greatly improve the evidence base and facilitate the creation of clinical practice

guidelines. Clinical practice guidelines for TMDs need to be developed with a strict eye toward balancing biases and avoiding conflicts of interest.

CONCLUSIONS

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