Diagnosis and management of arthrogenous temporomandibular joint disorders: a literature review

Introduction

Temporomandibular joints (TMJs) are among the human body’s most unique, complex, and intricate joints. They play a vital role in executing critical biological processes such as mastication, communication, and, to an extent, breathing (1). Temporomandibular joint disorders (TMJDs) have been reported to be the most common cause of chronic pain of non-odontogenic origin in the orofacial region (2). TMJDs comprise more than 30 conditions that can affect TMJ and the muscles of the jaw and primarily include disorders associated with pain, such as myalgia, myofascial pain, or arthralgia, as well as disorders causing functional or structural changes in the TMJ, such as disc displacement disorders and degenerative joint disease (3). Diagnosis and management of TMJDs can be challenging for clinicians because of their complex and multifactorial etiology, and patients often seek consultation from multiple healthcare professionals from different disciplines and medical specialists, resulting in inappropriate treatment without any improvement in the pain symptoms (3,4). Though various treatment strategies that include conservative management by self-care, occlusal appliances, physiotherapy, jaw manipulation, arthrocentesis, and surgical management are available to manage TMJDs, there is a lack of evidence to support the preferred treatment for specific TMJD (5). However, effective management of TMJDs requires a centered, multidisciplinary approach to address the chronicity of TMJDs and for better patient care (4,5).

Anatomy

TMJ is a synovial, ginglymoarthrodial joint formed by the bilateral articulation between the glenoid fossa of the temporal bone and mandibular condyle (6-8). TMJ is a synovial, ginglymoarthrodial joint formed by bilateral articulation between the glenoid fossa of the temporal bone and mandibular condyle. The articular surfaces of the glenoid fossa and mandibular condyle are distinct from other articulations as they are covered by fibrocartilage, a fibrous tissue containing chondrocytes. The synovial joint comprises a fibrous capsule, disc, adjacent ligaments (sphenomandibular, stylomandibular, and lateral ligaments), synovial membrane, and fluid. The biconcave articular disc is interposed between the two bony components, thereby dividing the joint space into two compartments containing synovial fluid: (I) superior compartment that allows translational movement (sliding or gliding) of the joint and (II) inferior compartment associated with rotational movements. The disc’s thickness varies throughout; as the disc is biconcave in shape, its peripheral zones (anterior and posterior bands) are thicker and thinner in the central portion (intermediate band). The articular disc prevents joint damage by providing lubrication to the joint, and it facilitates the sliding of the mandibular condyle about the glenoid fossa during the opening and closing of the mouth. The disc is stabilized posteriorly by the bilaminar zone (methodical tissue), which is inserted into the posterior portion of the posterior band of the disc (6-8).

Epidemiology

There are wide variations in the incidence and prevalence of temporomandibular joint disorders (TMJDs). Variations in study methodology, including sampling strategies, lack of clinical confirmation through validated diagnostic criteria, and incidence-prevalence bias, have contributed to these variations (9). TMJDs have been reported to affect approximately 5% to 12% of the population worldwide, with a higher prevalence among young adults aged between 20 and 40 years (2). Valesan et al. investigated the prevalence of TMJDs among the general adult population using worldwide recognized research diagnostic criteria for temporomandibular disorders (RDC/TMDs) and diagnostic criteria for temporomandibular disorders (DC/TMDs); 31.1% of individuals were found to have TMD-related joint disorders; among them, 25.9% had disc displacement with reduction (DDwR), which was the most prevalent TMJD (2). A meta-analysis by Minervini et al. on the prevalence of TMJDs in children and adolescents estimated it to be 16% in that age group, with jaw locking and clicking being the most common symptoms (10). The Orofacial Pain Prospective Evaluation and Risk Assessment (OPPERA) study reported an annual incidence of 3.9% in adults, and this condition was found to occur as a recurrent episode in 65% of the symptomatic population (11). Bueno et al. demonstrated two times greater risk in women (12.7%) to develop TMJDs when compared to men (6.7%). Also, they identified bruxism, impaired masticatory efficiency, and gender as significant risk factors for the development of TMJDs (12). Beaumont et al. reported that women have overall greater pain sensitivity than men, up to four times as many women seek treatment for chronic TMJD pain, and negative experiences or events during childhood may be a cause for the development or persistence of chronic pain conditions, including TMJD pain in adulthood (13).

Etiological causes of TMJDs are diverse, and the condition is multifactorial, with numerous local and systemic factors. In recent years, etiological concepts have transitioned from predominantly gnathological theories focussed on occlusion to the biopsychosocial model. The biopsychosocial model emphasizes the dynamic interrelationship between biological, psychological, and social factors (9,14). These interactions can result, amplify, and maintain pain and disability. The most vital factors associated with the onset of TMJDs were found to be smoking, self-reported jaw parafunction, major and minor trauma, comorbid health conditions, non-painful orofacial symptoms, frequency of somatic symptoms, and sleep quality (15). Literature has revealed a strong association between extrinsic or intrinsic trauma and incident TMJD (1,16). Among the parameters, the strongest association for incident TMJD was trauma from repeated yawning with prolonged mouth opening, any extrinsic trauma, with the impact of a single injury possibly more significant than multiple injuries (17). OPPERA prospective cohort study by Sharma et al. determined risk factors that influence chronic TMD pain in a cluster of individuals (adaptive, pain-sensitive, and global symptoms cluster) identified by supervised cluster analysis. It was observed that individuals in the pain-sensitive cluster had increased pain sensitivity, and those in the global symptom cluster had both increased pain sensitivity and experienced more significant psychological distress. It was also seen that compared to the adaptive cluster, individuals in pain-sensitive and global symptom clusters had greater pain intensity, jaw functional limitation, and more co-morbid conditions. They concluded that individuals in the worldwide cluster experienced more severe acute pain, were less responsive to treatment, and had a higher probability of undergoing transition into chronic pain after an injury or a surgical procedure. However, further research is needed to validate the findings (17). The association of malocclusion as an etiological factor for the development of TMJD symptoms has been documented in the literature. However, the role of occlusion in the initiation and progression of TMJD symptoms is debatable among researchers (18,19). Most investigators report that occlusal discrepancies, particularly posterior crossbite, overjet/overbite more than 5 mm, edge-to-edge bite, anterior open bite, sagittal relation class III, and five or more missing teeth, can lead to the onset and perpetuation of TMD symptoms. Contrary to this, malocclusion or unstable occlusal relationships can occur secondary to TMJDs because of joint effusion and degenerative joint disease (14). Therefore, it is essential to recognize the occlusal discrepancies before planning orthodontic treatment, prosthetic rehabilitation, or orthognathic surgery to prevent aggravation of TMD symptoms (18). Bruxism has been identified as a risk factor for TMJD pain. As a result, several clinical signs, such as tooth wear, chipping of incisal edges, cracked teeth, fractured restorations, occlusal wear facets, mobile teeth, and scalloping of the lateral borders of the tongue, should be paid attention to during clinical examination (13). Furthermore, various studies have found a close association between psychological factors (anxiety, stress, and depression) and the persistence of TMJD symptoms. These psychological comorbidities can alter the pain perception and influence the treatment outcome in patients. Therefore, due to multifactorial etiology, multidisciplinary treatment approaches comprising conservative management, biofeedback, and cognitive behavioral therapy (CBT) are needed to reduce the symptoms and improve the psychological well-being of an individual (13,20).

Clinical features

TMJDs may have essential physical, functional, biological, and psychological consequences on the well-being of individuals, which can be either transient or longer-lasting (21). TMJDs refer to disorders associated with alterations in the physiology, structure, or function of the TMJ and the associated structures, including disorders of the masticatory muscles. They may be related to medical comorbidities or systemic conditions. The presentation of TMJDs is often diverse, and the symptoms may vary from mild, transient, and self-limiting to severe and disabling, affecting the individual’s quality of life (QoL). Characteristic TMJD symptoms include joint and masticatory muscle pain, opening limitation, jaw deviation or deflection during mouth opening, and joint sounds (clicking or crepitation) (21). In addition, many patients present with the dysfunction of the TMJ but are asymptomatic. Patients with TMJD usually experience clicking when the condylar head moves over the rear edge of the displaced articular disc during the opening and closing of the mouth or both (22). An opening click indicates the recapture of the disc between the articulating surfaces. In contrast, a closing click occurs immediately before the tooth contact, although not as loud as the closing click. In disc displacement without reduction (DDwoR), there is no disc recapture while opening the mouth. As a result, the clicking disappears or diminishes in intensity (23). Asymptomatic joint clicking usually does not require treatment. However, the patient can become symptomatic if the patient continues to have parafunctional habits of clenching or grinding the teeth (22,24).

Diagnosis of TMJDs

A correct diagnosis is the first step to successful management. A good history and comprehensive clinical examination form the basis for diagnosing TMJDs. The assessment of these patients should begin with a detailed history followed by extensive clinical examination. History should include details such as the onset of malocclusion (sudden/chronic), trauma (microtrauma/microtrauma, whiplash), previous treatments, associated symptoms such as pain, limitation of opening, detailed medical history (systemic conditions having manifestations in TMJD or primarily responsible for the TMJD), presence of systemic symptoms (undiagnosed which needs further evaluation), medications, habit history, family history. Detailed clinical evaluation should focus on extraoral evaluation, looking for evident facial asymmetries, cranial nerve screening, comprehensive assessment of TMJD and masticatory musculature, range of movements, occlusion, and detailed intra-oral evaluation (25).

Classification systems and diagnostic criteria

Over the years, several classification systems and diagnostic criteria for TMJDs have been proposed. One of the earliest validated classifications was the dual-axis system of RDC/TMD criteria with a focus on clinical history, physical examination findings (Axis I) and mandibular jaw function, pain parameters, level of psychosocial function, and psychological status (Axis II) (26). However, the diagnostic validity had to be evaluated. Hence, DC/TMD criteria were subsequently published, which expanded and improved the basic principles of RDC/TMD (25). Schiffman et al. reported that newly developed DC/TMD criteria are more comprehensive and suitable for clinical and research settings to identify patients with simple and complex TMJDs. DC/TMD criteria Axis 1 protocol has adequate validity to detect any pain-related TMD and for differentiating the most common pain-related TMDs (sensitivity >0.86 and specificity >0.98), and for detecting one intra-articular disorder (sensitivity 0.80 and specificity 0.97). The Axis II protocol comprises original RDC/TMD screening instruments, new instruments to assess jaw function, and behavioral and psychosocial factors (25). Extensions of the DC/TMD have been proposed and include classification by the American Academy of Orofacial Pain (AAOP) and the International Classification of Orofacial Pain (ICOP) (27). AAOP broadly divides TMDs into two categories: (I) muscle-related TMDs (myelogenous) and (II) joint-related TMDs (autogenous) (28). Both types can be present simultaneously in a patient, making diagnosis more challenging. Myogenous form is more common, affecting masticatory muscles and jaw movement. In contrast, TMD symptoms of arthrogenous origin result from inflammation or degenerative changes in the joint’s hard or soft tissues, including TMJ capsulitis and synovitis, disc displacement disorders, arthralgia, osteoarthritis, and osteoarthrosis (29,30).

On further exploring orofacial pain conditions, a more comprehensive ICOP classification modeled on the International Classification of Headache Disorders (ICHD-3) to identify the different TMJDs has been introduced (25,31). ICOP is essential in identifying different pain conditions involving the orofacial region. It enables the dentist to determine the pain conditions that require primarily dental intervention rather than medical and surgical intervention (31). ICOP divides TMJD pain into primary and secondary subtypes (Figure 1). Primary TMJD pain conditions are idiopathic, in which the specific cause or etiology cannot be determined. Primary TMJD pain is localized to the joint and is present during rest, jaw movement, or palpation, with no known cause. This can occur during jaw function or para-functional movements. At the same time, secondary TMJD pain could occur due to a particular cause or an underlying medical condition (31). In the secondary type, the cause is known to be conditions such as inflammation, structural changes, or due to injury or sensitization of the tissue. Secondary TMJD pain has similar characteristics as primary TMJD pain but is due to a secondary cause, with the symptoms leading to the discovery of the cause of pain. The pain worsens with the progression of the cause and improves with the resolution of the same (31). Pigg et al. highlighted the contribution of endodontic research to the validation and improvement of ICOP classification. They reported that although the proposed diagnostic criteria include clinical observation of signs such as pain on biting, lingering pain after stimulation, and thermal hypersensitivity, suggestive of pulpal inflammation, however a high level of evidence about the extent of pulpal inflammation is lacking, and further scientific validation is needed. ICOP is a newly developed classification, but for specific case scenarios, this diagnostic criterion needs to be refined and improved through research (32,33). A review of masticatory muscle disorders is presented separately, so this article will focus on the disorders of the joint itself. It is essential to remember that TMDs do not occur in isolation. Indeed, potential co-morbidities such as fibromyalgia, migraine, chronic fatigue syndrome, and pelvic pain point toward a dysregulation in the modulatory pathways, which are classified as central sensitization syndromes (34). This further complicates the diagnosis and management of TMJDs (35).

Figure 1 Key diagnostic features and management for primary and secondary TMJD pain conditions based on ICOP classification. DDwR, disc displacement with reduction; DDwoR, disc displacement without reduction; DMARD, disease modifying anti-rheumatic drugs; ICOP, International Classification of Orofacial Pain; LLLT, low-level laser therapy; NSAIDs, non-steroidal anti-inflammatory drugs; TMD, temporomandibular disorder; TMJ, temporomandibular joint; TMJDs, temporomandibular joint disorders.

Rationale and knowledge gap

TMJDs are complex and heterogeneous groups of disorders affecting the orofacial region, leading to pain, dysfunction, and reduced QoL in patients. The prevalence of TMJDs is increasing in both primary and secondary healthcare settings. As a result, accurate diagnosis and successful treatment of TMJDs have become a challenge for clinicians (36). As mentioned, various diagnostic criteria and clinical protocols have been proposed in the literature in identifying and categorizing the patients reporting TMJD associated pain, the new classification system, ICOP was published in January 2020. As a new specialty, all research in the growing field of orofacial pain should be based on this classification, as the language for research and clinical practice will be the same worldwide (31). In addition, the etiology of TMJDs has been described as multidimensional, with a combination of physical, psychological, and social factors. Therefore, proper management necessitates an integrated multidisciplinary team approach for improved patient care (37). Existing guidelines recommend patient education, self-care management, and other conservative, non-invasive interventions as an initial approach to managing TMJD. However, there is weak evidence to support the efficacy of occlusal splint therapy, prosthodontic treatment, and occlusal correction as a therapeutic option for TMJDs (38). This implies the necessity of in depth understanding of the pathomechanisms and causal factors contributing to TMJDs, to address the evidence gap, to optimize the implementation of research into clinical practice, and to advance the research by developing standard guidelines and effective treatments. In 2020, the comprehensive classification system ICOP for orofacial pain was published, which could improve the accuracy of TMJD diagnosis and provide the scientific basis for developing new treatment strategies for different TMJDs.

Objective

This review aims to summarize the literature on diagnosing and managing different TMJDs. It provides an overview of the ICOP classification system as a diagnostic tool for clinicians and researchers to characterize patients with pain associated with TMJDs. We present this article in accordance with the Narrative Review reporting checklist (available at https://fomm.amegroups.com/article/view/10.21037/fomm-24-47/rc).

Methods

Search strategy and data extraction

Two authors (R.N. and J.K.) independently searched for relevant literature up to December 2024 by using PubMed, Scopus, Web of Science, Cochrane Library, Embase, and Ovid MEDLINE electronic databases and a combination of keywords based on Medical Subject Headings (MeSH) as “Temporomandibular Joint Disorders”, “Temporomandibular disorders”, “Diagnosis”, “TMJ and Management”. Screening of the titles and selecting relevant literature for inclusion in this review was carried out by two authors (J.K. and M.K.) and was cross-checked by other authors (S.S.K. and R.N.). Any disagreement was resolved by mutual discussion between the authors until a consensus was reached (Tables 1,2).

Eligibility criteria

Inclusion criteria included case reports, case series, original research, short communication, and reviews focussed on diagnosing and managing different TMJDs such as TMJ pain due to arthritis, disc displacement with and without reduction, degenerative joint disease, and subluxation and published only in the English language to avoid bias. Original research articles detailing the results of clinical studies, descriptive surveys, cross-sectional studies, randomized controlled trials (RCTs), retrospective or prospective cohort studies, and case-control studies were considered. In contrast, animal studies, in vitro studies, letters to the editor, and commentaries were excluded (Table 2).

Discussion

Figure 1 describes the key diagnostic pain features and management for primary and secondary TMJD pain conditions based on ICOP classification.

• TMJ pain attributed to arthritis: in this situation, persistent inflammation of the articular tissues causes pain, which worsens with arthritis and improves with treatment. Arthritis can be non-systemic or systemic (8,39).
• TMJ pain attributed to DDwR: TMJD pain is caused by disc displacement due to mechanical derangements. This results in clicking, popping, and snapping noises during jaw opening and/or closing, as well as lateral and/or protrusive movements. The pain occurs with the noise.
• TMJ pain attributed to DDwR, with intermittent locking: the criteria are the same: intermittent jaw locking with limited mouth opening followed by unlocking within the last 30 days.
• TMJ pain is attributed to a DDwoR: the jaw gets locked close, so the opening is prevented, and TMJD pain develops in close temporal relation to the disc displacement, interfering with jaw function.
• TMJ pain attributed to degenerative joint disease: TMJD pain is caused by a degenerative joint disorder in the absence of TMJ arthritis. Crepitus is detected during palpation and jaw movements. Pain develops in close temporal relation to the degenerative joint disease, with symptoms improving with treatment.
• TMJ pain is attributed to subluxation: this is usually acute and occurs due to overstretching of the TMJ tissues without the presence of TMJ arthritis. The subluxation has been diagnosed by the jaw locking open, preventing closure from the wide-open position. Unless the individual or the healthcare professional performs a specific manipulative procedure, the mouth cannot be returned to the wide-open position.

The presence of red flags in the history and cases not responding to classic treatment should alert the treating doctor for detailed evaluation/workups and appropriate referrals (40). Therefore, along with clinical examination of TMJDs, several investigations, including radiographs, laboratory studies like blood/serum studies (to rule out underlying systemic disorders), and urine analysis, are generally ordered to refute or confirm the provisional diagnosis. Additional chairside tests, such as loading tests, tests of provocation, and diagnostic blocks, can be used as necessary. Imaging plays a pivotal role in diagnosing TMJDs as it reduces uncertainty, which may occur due to complex TMJ anatomy and pathologies affecting TMJDs (41,42). Additionally, radiographs provide information on functional associations between condyle, articular tubercle, and glenoid fossa. Plain radiographs serve as basic screening aids to rule out gross morphological changes in the bony structures of TMJ and accurately determine the location and extent of bony alterations secondary to cysts, tumors, fractures, and developmental and degenerative joint disease (41). Advanced imaging modalities such as cone beam computed tomography are indicated for conditions affecting the hard tissues of the TMJ, such as arthritis, and developmental disorders, such as hyperplasia. Magnetic resonance imaging (MRI) is used for soft tissue imaging, such as instances of internal derangements (IDs) of the TMJ, and a positron emission tomography scan may be necessary in cases where there is suspicion of malignancy or growth disorders (43). Imaging is helpful in patients presenting with TMJD issues such as clicking, jaw deviation, or limited mouth opening without any TMJD pain (41,43). Larheim et al. found that disc displacement was seen in MRI images in 78% of patients with TMJ dysfunction and pain and 35% of asymptomatic individuals (44). Another MRI study by Jerele et al., conducted on 219 patients with unilateral TMJD symptoms, reported that imaging abnormality other than DDwR was related to osteoarthritis and disc deformity on the symptomatic side. In contrast, imaging abnormality, including DDwR, was related only to osteoarthritis on the symptomatic side. This finding suggests the interrelationship between the onset and progression of TMJDs in symptomatic and contralateral asymptomatic joints (45). Laboratory studies that include serological testing for various systemic conditions such as arthritis and may consist of a rheumatoid panel, complete blood count with differential, erythrocyte sedimentation rate, C reactive protein, anti-nuclear antibody, complete metabolic panel with electrolytes should be advised in TMJD patients only when necessary, taking into consideration radiation exposure and financial implications (42).

Management

Treatment is generally indicated when the condition is painful and affects function significantly (46-48). TMJ has tremendous healing and adaptation capabilities (49). Thus, conservative therapy comprising medications and non-surgical treatment modalities is usually the first line for management of most cases of TMJ pain. Acute and chronic TMJ pain need different management approaches. Chronic pain is pain that lasts for longer than three months. Patients with chronic painful TMJDs may not respond quickly to conservative approaches (50). Greene et al. stated that among TMJD patients with initial acute symptoms, 75% to 80% of patients may respond to conservative therapy. Still, patients with a long-standing history of untreated TMJDs are challenging to diagnose and treat (51). Moreover, a combination of vulnerability factors and iatrogenic damage could contribute to the transition of acute TMJ pain to chronic painful TMJD. Unfortunately, most studies do not differentiate between acute and chronic TMJ pain when comparing treatment modalities. The co-existence of different TMJD diagnoses is also a concern when assessing the efficacy of treatment modalities for individual conditions (49,52). Depending on the etiology, there may be a necessity for a well-co-ordinated multidisciplinary team consisting of an orofacial pain specialist, an oral and maxillofacial surgeon, a rheumatologist, a physical therapist, psychotherapist, a psychologist to provide comprehensive care to these patients, especially in chronic and refractory cases, presenting with significant co-morbidities. Hence, no single treatment works in all patients. Thus, individualizing therapy based on patient requirements may improve the outcome (1,53).

Conservative management strategies

Conservative therapy includes non-surgical treatment strategies [self-care, occlusal splints, physiotherapy, transcutaneous electrical nerve stimulation (TENS), low-level laser therapy (LLLT), and acupuncture] and pharmacotherapy [non-steroidal anti-inflammatory drugs (NSAIDs), opioid analgesics, tricyclic antidepressants (TCAs), and topical medications] (1,54,55).

Non-surgical conservative treatment

Self-care

This entails patient education regarding their condition, with recommendations for avoiding a hard, chewy diet, using hot and cold packs, reducing parafunctional habits, improving sleep quality and posture, and undertaking relaxation techniques (56). Self-care is the only treatment approach with strong evidence for improved outcomes in chronic pain (1). Aggarwal et al. suggested that self-management strategies using a biopsychosocial approach comprising education, physical (jaw posture regulation), and psychological (cognitive and behavioral) components should be used as an initial intervention for chronic TMJD pain. This approach should be prioritized over invasive and surgical interventions (57). Carlson et al., in their study, compared the effectiveness of physical self-regulation (PSR) training involving breathing, postural relaxation, and proprioceptive re-education with standard dental care. Preliminary findings showed that pain severity and life interference from pain were decreased in both the groups (P<0.001), and there was an increase in perception of control (P<0.001) as well as incisal opening without pain (P<0.05). However, after 26 weeks of follow-up, the PSR group showed a more significant reduction in pain (P<0.04) and an increase in incisal opening with pain (P<0.04) and without pain (P<0.001). They suggested the use of PSR as an initial treatment option for short and long-term (6-month period) in the management of TMD pain (58). Yamaguchi et al. found an increase in the range of motion of TMJ after a range of self-motion exercises in a 25-year-old female with acute limitation of mouth opening [painless maximum mouth opening (MMO) was 30 mm, and painful MMO was 34 mm], and clinically diagnosed as DDwoR. The range of motion of TMJ was maintained and managed by self-traction therapy, and MRI confirmed improvement in TMJ function. Therefore, this indicated the effectiveness of the exercise program in symptomatic improvement of patients with DDwoR (59).

Recently, Busse et al. provided recommendations for the management of patients with chronic pain for ≥3 months associated with TMJD in comparison to placebo or sham procedures. The guideline panel issued strong recommendations for CBT with or without relaxation training, manual trigger point injections, therapist-assisted mobilization, supervised posture, and jaw exercise, stretching with or without manual trigger point therapy, and usual home care for chronic pain secondary to TMJD (60). It is more important that the patient is taught to understand their condition and its natural progression or regression, as well as strategies to manage if there is an exacerbation of pain, which will assist in the overall management of TMJD pain.

Occlusal splints

These are a prevalent therapy modality for TMJD pain; however, the exact mechanism of action is unknown. Multiple designs are fabricated with various materials. They can be hard or soft, providing full or partial coverage (61,62). There is no consensus on the protocol regarding the hours of usage and whether nighttime or daytime use is better. Some adverse effects secondary to the use of occlusal splints, such as occlusal changes with partial coverage splints, have been reported (63). Al-Moraissi, through a network meta-analysis of RCTs, found that for arthrogenous TMJDs, there is low-quality evidence in the literature that suggests that anterior repositioning splint (ARS) and counseling therapy in combination with a rigid stabilization splint are more effective in reducing TMJD pain and sounds.

Another very low-quality evidence suggests that rigid stabilization splints provide little or no benefit than soft stabilization splints; in contrast, moderate-quality evidence reports that a combination of hard acrylic stabilization appliance with counseling therapy is an effective type of occlusal splint in reducing TMJD pain. Similarly, this combination is effective in reducing pain secondary to myogenous TMJDs when compared to counselling therapy and rigid stabilization splints as a single therapy (64). Zhang et al. analyzed six studies which included 498 TMJD patients (251 occlusal splint therapy and 247 therapeutic exercises) and observed comparable results with no mean significant difference between occlusal splints and exercise in the improvement of MMO (P=0.51), right laterotrusion (P=0.99), left laterotrusion (P=0.32), and protrusion (P=0.77). Therefore, they reported that these equivalent results could be due to a few included studies and the lack of high-quality evidence to prove the effectiveness of occlusal splints and jaw exercises in reducing TMJD symptoms (65). Limited evidence is available to elucidate the advantage of occlusal splint in treating TMJD disorders over other therapeutic interventions; this necessitates further research on a large-scale population. Moreover, it is essential to point out a significant heterogenicity of studies, with varying follow-up periods and a combination of different types of TMDs, which muddies the waters in coming to a clear consensus.

Physiotherapy

Various physiotherapy modalities have been used to manage TMJDs, including manual therapy, active and passive exercises, postural interventions, ultrasound, electrotherapy such as laser, and TENS (66). Armijo-Olivo et al. reported that 72% of respondents considered physical therapy as a treatment option for TMJD, and it has become one of the most common treatments for TMJDs to decrease pain and to re-establish muscle and joint function (67). Manual therapy may include joint and soft tissue manipulation. The evidence for manual therapy and exercise, particularly TMJD alone, is low. However, studies have shown positive effects of manual therapy and training in improving symptoms and function in TMD patients (68). Calixtre et al. reported that manual therapy has greater efficacy in improving MMO and pressure pain threshold than usual care in TMJD patients, and more studies should strengthen the clinical relevance of manual therapy protocols (68).

TENS

TENS is a non-invasive, commonly used physical therapy modality for pain management in medicine, and Shane and Klesser first described its use in odontology in 1967 (69,70). TENS helps in relieving TMJD pain by use of an electronic device that emits biphasic electrical waves of variable frequency, intensity, and pulse width (1–100 Hz, 0–50 mA, and 20–500 µs, respectively) through the electrodes when placed onto the skin surface. TENS has been reported to reduce pain intensity by gate control principle or activating the brainstem periaqueductal gray-rostral ventromedial medulla (PAG-RVM) circuit, thereby releasing endogenous opioids (69). In a systematic review by Fertout et al., immediately after a TENS session, there was a 19.2% to 77.2% reduction in pain intensity, patients mouth opening increased from 3.3 to 5.53 mm, and a significant increase in interocclusal space from 1.23±0.72 mm (before the session) to 3.03±1.17 mm (after the session), P<0.05. Lower electromyographic (EMG) activity in the masseter and anterior temporalis muscles was also observed after the TENS session (69).

Zhang et al. conducted a study on 20 patients with TMJD pain with DDwoR; TENS attenuated movement-evoked pain and improved jaw motor function during repeated jaw movements (P<0.001). The results are based on the pain adaptation model of temporal summation of nociceptive inputs, which plays a vital role in shaping and adapting jaw motor behavior. As a result, repetition of jaw movements could lead to an increased perception of perceived pain and a decrease in jaw movement distances. TENS was found to be a promising therapy in reducing movement-evoked pain (20 repeated jaw movements, 4×5 sessions) within 45 minutes in TMJ patients with DDwoR. The analgesic effect of TENS has been explained by various theories, such as repetitive muscle contraction caused by TENS stimulation to motor nerves, increasing blood flow, and decreased accumulated toxins with a subsequent reduction in pain. Another theory relates to inhibiting nociceptive activity at the dorsal horn and brainstem level by TENS therapy. As motor-generated pain may be associated with central hyperalgesia and persistent chronic pain, the analgesic effect of TENS on movement-evoked pain demonstrates its therapeutic potential in chronic TMJD pain with DDwoR (70). In a clinical study by Shanavas et al., TENS given as two sessions of 30 minutes each, separated 5 days apart, was found to be more effective in reducing pain in TMD patients (P=0.019) when compared to a control group who were treated by a combination of analgesics and muscle relaxants (71).

LLLT

LLLT is a promising modality for reducing TMJD symptoms due to its anti-inflammatory and analgesic effects and ability to promote vascular endothelial cell proliferation and regeneration (72-74). There is considerable controversy about the efficacy as there is heterogenicity in reporting protocols, dose, power, usage time, and a lack of protocols for usage (75). Although studies have reported the higher effectiveness of LLLT compared to placebo in treating TMJDs, few studies have demonstrated the comparable efficacy of LLLT with placebo (76). Melis et al. found LLLT more efficacious in reducing TMJD pain than myofascial pain (77). In a meta-analysis, Chang et al. found the analgesic effect of LLLT on TMJ pain, which could be explained by the ability of the low-level laser to penetrate the tendon or joint capsule to decrease the release of prostaglandins [(prostaglandin E2 (PGE2)] with subsequent reduction in inflammation (78). Other mechanisms proposed include an increase in beta-endorphin in the central nervous system, stimulation of microcirculation of peripheral nerve tissue, and few researchers believe that LLLT increases the production of adenosine triphosphate in the mitochondria, which results in inhibition of the release of endogenous pain-producing substances, such as histamine acetylcholine and bradykinin (78).

Studies reported that a laser with a wavelength of 830 nm was more effective in reducing TMJ pain as it could penetrate soft tissue to a depth of 1 to 5 cm. In contrast, few studies reported better efficacy of a 780 nm wavelength laser as it was not easily absorbed and provided better penetration. Additionally, few studies found that the therapeutic effect of LLLT on TMJ pain depends upon laser wavelength and radiation dosage (74,78). LLLT is an advantageous, non-invasive, safe, and promising modality in reducing TMD pain and may also improve the psychological well-being of an individual (78). More RCTs are needed to evaluate the therapeutic effect of LLLT on TMJD pain, considering the disparity in the treatment parameters: dose, power, wavelength, number, and frequency of laser application.

Acupuncture and laser acupuncture

Acupuncture origin was in China over 3,000 years ago as a part of traditional Chinese medicine and is widely used as adjunctive therapy for treating TMJDs. It reduces TMJD symptoms by inserting needles at specific acupuncture points (79). Studies have demonstrated the effectiveness of acupuncture in the reduction of pain intensity in TMJD patients; Liu et al. found reduced pain intensity with acupuncture when compared to the sham group at week 4 (P<0.001) and week 8 (P=0.001). They observed a 30% to 50% improvement in response rate and jaw function after acupuncture, and it was more beneficial in improving the psychological status of TMJD patients than the sham group (79). In a recent systematic review, Di Francesco et al. evaluated the evidence from the literature about the effectiveness of acupuncture and laser acupuncture in relieving TMJD pain. Laser acupuncture employs low-intensity laser irradiation to stimulate the traditional acupuncture points and is considered a non-invasive, safe alternative therapy for pain management when compared to needle acupuncture. The RCTs showed reduced pain intensity, improved interincisal opening, and masticatory function in TMJD pain with muscle origin. After 3 months of treatment, laser acupuncture effectively reduced the TMJD symptoms and accelerated the healing process compared to placebo (80). It was suggested to be a suitable alternative therapy for short-term management of TMJDs. However, more studies with high methodological quality addressing the long-term effectiveness of both therapies, acupuncture, and laser acupuncture, are required (80).

Pharmacotherapy

This consists of medications effective in other painful joint conditions, such as NSAIDs, corticosteroids, and acetaminophen. The patient’s underlying medical history should be considered before prescribing these medications, and the dosage should be limited to the lowest, most effective dose prescribed for the least amount of time (50,81).

NSAIDs

NSAIDs have been proven to be beneficial in reducing pain in TMJDs due to their anti-inflammatory effects. Among NSAIDs, sodium diclofenac is most frequently used to relieve joint pain at a dose of 50 mg three times a day (82). Ekberg et al. compared the efficacy of 50 mg diclofenac sodium two or three times a day to a placebo in 32 patients with pain localized to TMJ. Patients in both groups were assessed before treatment (visit 1), immediately after treatment (visit 2), and after another 2 weeks (visit 3). Findings showed a significant reduction in TMJD pain with diclofenac at visit three compared to placebo (P<0.05), and there was a more substantial reduction in tenderness on palpation of masticatory muscles with diclofenac. Diclofenac was effective in treating short-duration pain (<6 months). Still, they reported that there is no evidence available to prove the efficacy of diclofenac as a primary treatment for TMJD pain, and it could be used as a complementary therapy to other interventions for TMJD pain (83). In a systematic review by Kulkarni et al., nonspecific diagnosis, variable control groups, and heterogeneity across studies affected the outcome. As a result, a definitive conclusion could not be made. Hence, further research with consistent diagnostic criteria and treatment strategies is needed to support the efficacy of NSAIDs in relieving TMJ pain (82).

Opioid analgesics

The use of opioids in cancer pain management and chronic noncancer pain has been well documented. Still, limited data reports have focussed on the efficacy of opioids in chronic TMJD pain (84). There is a controversy between short and long-acting opioids for reducing TMJ pain, taking into consideration adverse effects. Short-acting opioids have a rapid onset and are easy to titrate. Still, an increase in adverse drug-related behavior limits their use in chronic TMJD pain management. In contrast, long-acting opioids have been reported to provide a more significant reduction in pain intensity, better patient compliance, and less potential for adverse drug-related behavior (85). Moreover, investigators have suggested that adjunct medications such as TCAs and selective serotonin reuptake inhibitors should be used before opioid use. This reduces the dose of opioids required and the incidence of side effects that may occur with prolonged opioid use in chronic pain patients (85). The use of opioids to reduce TMJD pain needs to be determined by clinical trials as current evidence is inadequate and uncertain about the efficacy and safety of opioids for the management of TMJDs.

TCAs

The association between psychological factors as a contributing factor in the development of TMJD symptoms has been reported in several studies (86). Chronic TMJD pain could also cause anxiety to the patient, with subsequent contraction of facial muscles and clenching or grinding of the teeth (bruxism). As a result, there is worsening or aggravation of TMJD symptoms in the patient; the condition is termed an “anxiety-pain-tension cycle” (87). Therefore, TCAs, due to their analgesic properties, are suitable alternatives for TMJ patients with comorbid depression and sleep disturbances. The use of TCAs that include amitriptyline, nortriptyline, desipramine, and imipramine as a treatment for chronic TMJD pain is being explored (88). In a recent RCT, de Sousa et al. stated that a low dose of amitriptyline (25 mg/day) is a useful therapeutic option for patients reporting chronic TMJD pain (89).

Alajbeg et al., in a pilot study, found that at 12 weeks of therapy from baseline visit, visual analogue scale (VAS) scores improved significantly in the amitriptyline group (P=0.002) and the stabilization splint group (P=0.005) compared to placebo. Maximum comfortable mouth opening improved with stabilization splint relative to amitriptyline and placebo groups. Thus, the stabilization splint had more significant effects and was superior in increasing the maximum comfortable mouth opening in TMJD patients. TMJDs negatively influence patients’ QoL, which was evaluated using oral health impact profile-14 (OHIP-14) in their study. TMJD patients have been found to have decreased OHIP-14 scores, and amitriptyline was more beneficial in improving OHIP-14 scores in chronic TMJ pain patients when compared to stabilization splints and placebo (90). Cascos-Romero et al. suggested that antidepressants should not be considered as a first-line treatment option for TMJDs. A multidisciplinary team consisting of consultation with the psychologist and psychiatrist along with other disciplines is required before making a definitive treatment plan for persistent TMJD pain patients (88). Rajan et al. mentioned that dosing of amitriptyline for TMJD patients with depression requires careful consideration, as amitriptyline shows a dose-response relationship when used as an analgesic. The analgesic window for amitriptyline as an antidepressant is narrow and ranges from 75 to 150 mg, as higher doses could result in side effects, dry mouth, and drowsiness in a patient (87). As limited quality or inconsistent patient-oriented evidence is available in the literature on the use of TCAs for treating TMJDs (91), more RCTs on a more extensive group of patients are needed in this domain.

Topical medications

Topical medications include diclofenac sodium, indomethacin, methyl salicylate, capsaicin, and cannabinoids. The significant advantage of using topical medications is the avoidance of systemic adverse effects on long-term use or drug interactions that need to be taken into consideration before prescribing a systemic medication (92). Mena et al. in their meta-analysis of nine RCTs, found significant improvement in pain intensity with cannabidiols when compared to a placebo in one study (P<0.001). In one RCT, there was a substantial reduction in pain after 10 days of treatment with Theraflex-TMJ (P=0.003) and 5 days after the last application (P=0.027) of Theraflex-TMJ. In contrast, no significant reduction in pain was observed with NSAIDs (P=0.288) and capsaicin (P=0.465) compared to placebo (92). A common adverse effect reported was local allergic reaction (92). There are insufficient data reports about the effectiveness of topical medications for TMJD pain, and further studies with larger sample sizes are needed to confirm the results.

Invasive and surgical management strategies

The next step in management, after conservative therapy has been tried, and if results are mixed or the patient is non-responsive, may include intra-articular injections, either alone or in combination with arthrocentesis (54,93). However, there is increasing evidence that minimally invasive procedures should be considered earlier in the treatment timeline than waiting to exhaust conservative therapy (64).

Prolotherapy

Prolotherapy is injected with a hypertonic dextrose solution, which may promote tissue proliferation and nutrition to the cartilage function. This procedure can be accompanied by adverse effects, such as painful and burning sensations, mild bleeding and swelling, and temporary paralysis of a facial nerve branch (94,95). Studies show improvement in dysfunction and maximal inter-incisal opening, with repeated injections, without report of side effects, so further studies are necessary to assess the long-term benefits of prolotherapy (95,96). Dasukil et al. found a significant reduction in TMJD masticatory muscle tenderness and improved mouth opening and clicking. TMJ deviation after prolotherapy procedure with 50% (0.75 mL) dextrose, two parts lidocaine (1.5 mL), and one part warm saline (0.75 mL), and concluded it to be a promising alternative treatment for patients with unremitting TMJD pain and dysfunction (97). Medications such as corticosteroids, sodium hyaluronate, and platelet-rich plasma are also used for intra-articular injections with mixed results (1,98).

Intra-articular injection

Intra-articular drugs that include steroids, hyaluronic acid (HA), and analgesics after TMJ arthrocentesis are used in clinical settings for improved treatment outcomes. Gopalakrishnan et al. reported inconclusive evidence on intra-articular use of NSAIDs and opioid analgesics. It has been stated that not all NSAIDs are suitable for intra-articular use because of formulation, and they inhibit chondrocyte biosynthesis, resulting in cartilage destruction (99). Among NSAIDs, intra-articular injection with tenoxicam has shown encouraging results in relieving pain in TMJD patients attributed to its ability to concentrate in the synovium. It also has an aqueous base without an organic stabilizer, thus making it ideal for intra-articular administration (99).

Another group of analgesics, opioids that include morphine, fentanyl, tramadol, and buprenorphine, are used as an intra-articular injection for the reduction of TMJ pain. Opioids produce an analgesic effect by inhibiting specific cellular and peripheral receptors in the peripheral and central nervous system, and these receptors are also present in the synovial tissue of the joint (100). Sipahi et al. injected morphine and tramadol intra-articular after arthrocentesis of painful TMJs and compared the analgesic effect with a placebo. It was observed that VAS decreased from 7.30 to 1.20 in the morphine group (P=0.005), from 7.10 to 1.50 in the tramadol group (P=0.005) in comparison to the placebo group in which VAS decreased from 6.90 to 2.6. Although morphine is more potent than tramadol, the analgesic effects of both opioids were similar, and morphine has a long-lasting impact (6 months) on nociceptive pain in contrast to the short-term effect of tramadol (101). In a placebo-controlled trial, Ziegler et al. compared the analgesic effect and safety of repeated intra-articular infiltration with 5 to 10 mg of morphine with bupivacaine (carbostesin) 0.5% and isotonic saline solution as placebo in TMJD pain patients (102). Results revealed that one week after the last and third injection with 10 mg morphine, 16.7% of TMJD patients reported no pain, 41.7% had distinct pain relief, 33.3% showed a poor response, and 8.3% had no improvement. In contrast, with 5 mg morphine, 25 % of patients reported a decrease in pain, and 50% had no pain relief. In the bupivacaine group, 8.3% of patients showed noticeable improvement, 41.7% had a poor response, and 50% had no improvement, and in the saline group, 16.7% showed an inadequate response, and 83.3% had no improvement. Hence, intra-articular injections of 10 mg morphine could be considered as an option for pain management in TMJDs and have a long-lasting analgesic effect (102).

Recently, HA has been gaining attention as an intra-articular drug for TMJDs, which is a chondroprotective drug with the ability to reduce mechanical wear, lubricate the tissues, promote the repair process in the cartilage, and reduce the endogenous synthesis of acid by synovial cells (103). HA is a non-sulfated glycosamine present in the synovial fluid, where it plays a role in cartilage repair and normalization of viscoelasticity of the synovial fluid (54,104). Studies with HA or sodium hyaluronate injections have shown improved pain, function, and degenerative changes due to their anti-inflammatory, nutritional, and lubrication properties (96,105). MRI studies have shown increased thickness of articular surfaces and the articular disc after a series of arthrocentesis and HA intra-articular injections (96). Agostini et al., in an umbrella review comprising 18 articles with 13 RCTs, found intra-articular injections of HA as a safe and effective treatment option for reducing pain intensity and improving the function of patients with TMJ pain. However, no statistically significant differences in the reduction of TMJD pain were observed between HA and corticosteroid intra-articular injections; this indicates the need for future RCTs to confirm the efficacy of HA (103). Studies have reported that corticosteroids, due to their anti-inflammatory action, have long-term effects in reducing TMJD signs and symptoms. Intra-articular injection of corticosteroids can reduce joint effusion, decrease pain, and increase the range of motion in TMJ arthritis (106). Singh et al. used the combination of 40 mg triamcinolone acetonide (kenacort) and 20 mg HA as an intra-articular injection, one injection every week for 4 weeks, to treat TMJ arthritis as it takes benefits of the anti-inflammatory action of corticosteroids, and viscoelastic properties of HA in improving patient symptoms; 90% of patients showed reduced pain intensity, and 92% in clicking sounds (P<0.05). There was also improvement in other symptoms, such as restricted mouth opening and discomfort in medial and lateral movements; however, there was no statistically significant difference. They concluded that intra-articular administration of steroids and HA is a safe, simple, and cost-effective procedure and is recommended for the treatment of TMJ osteoarthritis (106).

Arthrocentesis

Arthrocentesis is a minimally invasive intervention where the superior joint compartment of the TMJD is irrigated with physiological or Ringer’s solution. This promotes the removal of debris from cartilage degradation and inflammatory mediators (47). It seems to be an effective intervention for arthrogenous type TMJD pain (54,64,96). This procedure may be performed by using either one or two needle techniques. In the latter, the solution used for the lavage is introduced through one needle, while the joint fluid exits through the second needle. In the single-needle technique, the inflow and outflow occur through the same needle. Systematic reviews and a meta-analysis comparing both methods suggest that there is not much difference in the outcomes between both techniques (107,108). One possible complication of arthrocentesis is temporary facial paresis due to inadvertent anesthesia of the facial nerve branches when anesthetizing the masseteric and deep temporal nerves (96).

Arthroscopy

Arthroscopy is a moderately invasive surgical procedure that allows direct visualization of the intra-articular space with an endoscope (1). This provides lysis, lavage, osteophyte removal, cyst removal, or TMJ biopsy. It is usually performed under general anesthesia and may have complications such as injection, bleeding, injury of vessels or nerves, damage to the ear or parotid gland, and perforation of the middle cranial fossa (109). Therefore, arthrocentesis is a more attractive option, as it is more conservative, has fewer adverse effects, and is still effective. Tang et al. conducted a meta-analysis to determine the efficacy of arthroscopic surgery (AS) and arthroscopic lysis and lavage (ALL) at short-term (<6 months), intermediate-term (6 months to 5 years) and long-term (>6 years) follow-up periods for patients diagnosed with TMDs based on DC/TMD criteria (110). Comparison was made with arthrocentesis for TMJ, and no significant differences in pain reduction were found between AS or ALL and arthrocentesis. These procedures enable the removal of inflammatory mediators (pro-inflammatory cytokines and degradation products) from the joint space, thereby reducing the pain intensity experienced due to TMJ synovitis. For MMO, AS at intermediate-term follow-up and ALL at short-term follow-up showed equivalent efficacy to arthrocentesis. Contrary to this, at an intermediate-term follow-up, ALL was found to be superior to arthrocentesis as in TMJDs, limitation of mouth opening occurs due to the formation of intra-articular adhesions, and arthroscopy allows direct visualization of joint with more targeted lysis of adhesions. They concluded that further studies should address the effectiveness of arthroscopy in managing TMJDs due to low quality and insufficient evidence available to draw any conclusions about the reliability of AS or ALL in TMJD symptom reduction (110).

Studies have shown TMJ arthroscopy as a long-term effective therapy for relieving TMJD pain; however, for patients with relapse or with recurrent arthralgia or TMJD pain, the selection of procedure is still questionable (109). Ângelo et al., in a 3-year prospective study, evaluated the efficacy of bilateral TMJ arthroscopy in 80 patients with different categories of TMJ symptoms severity based on Dimitroulis classification (categories 2 to 4). After an average follow-up of 523.7 days, a statistically significant reduction in TMJ pain from 4.63±3.14 preoperatively to 0.38±1.12 postoperatively was observed (P<0.0001), and 86.25% of patients showed improvement in TMJ pain symptoms. MMO improved from 33.50±8.79 preoperatively to 40.06±5.02 postoperatively (P<0.0001), and myalgia significantly improved from a mean of 2.29±1.02 preoperatively compared with 0.37±0.75 postoperatively (P<0.0001) (111). The overall success rate of one bilateral TMJ arthroscopy in their study was around 69% with no adverse effects, and they suggested it to be a safe and effective first-line treatment for moderate to severe TMJDs, thereby reducing the need for TMJ open surgeries. Arthrocentesis was suggested as a preferable reintervention in patients with recurrent TMJ arthralgia and cases with primary failure of the arthroscopy procedure (111).

Management strategies in specific TMJDs

The majority of patients with primary TMJD pain improve with conservative treatment modalities, which thereby become their first line of treatment. A meta-analysis of RCTs showed a moderate level of evidence for short-term management of TMJD pain with no history of trauma and systemic disease using low-level lasers (112). Figure 1 shows management strategies for different categories of TMJDs.

Disc displacement with and without reduction

In patients with TMJD pain attributed to disc displacement with and without reduction, conservative therapy is preferred, as many patients adapt or cope with pain over time, making the painful TMJD condition self-limiting. When acute disc displacement is accompanied by limited mouth opening and pain, reduction of the disc by jaw manipulation may improve mouth opening, and when accompanied by self-performed exercises, CBT, and education, it also helps in pain reduction (66). There is moderate evidence that an anterior repositioning appliance can improve TMJ clicking and pain, though a hard, acrylic stabilization appliance may be similarly effective (113). In a small, randomized study comparing treatment modalities for disc displacement with and without reduction, arthrocentesis alone was the only treatment modality demonstrating significant improvement of maximal mouth opening between pre and 6-month post-treatment (46). In another study, Lei et al. used the combination approach comprising arthrocentesis, mandibular manipulation (MM), and ARS for the management of DDwR. A high success rate of 95.2% was achieved in reducing TMJ closed lock using MM along with arthrocentesis. ARS was effective in maintaining the normal condyle-disc relationship by positioning the condyle forward and also minimized the relapse of closed lock (114). Literature revealed conflicting thoughts about the results of MM; it was considered to recapture the displaced disc by repositioning the condyle on the anteriorly displaced disc by pulling the affected condyle antero-inferiorly, whereas other investigators refer to this as reduction of the disc, successful disc reduction, or non-reducible to reducible disc. Few studies have documented the carrying out of arthrocentesis before MM, as it facilitates disc reduction by decreasing the frictional and adhesive joint forces. Moreover, arthrocentesis and intra-articular anesthesia helped decrease the TMJ pain and enhance patient cooperation during MM. They suggested ≤3 months’ time point for acute DDwR may be crucial for successful treatment outcomes (114). Dawoud et al. (115) in a systematic review found that arthrocentesis resulted in slight improvement in pain although this was statistically non-significant (P=0.07), and a significant improvement in MMO (P=0.005) when compared to occlusal coverage splints in 343 participants with DDwoR. Hence arthrocentesis was reported as a superior and useful management strategy for the management of DDwoR.

TMJ pain attributed to osteoarthritis

In patients with TMJ pain attributed to osteoarthritis, the main objectives of management are pain reduction, disease progression control, and jaw function improvement (63). Among the NSAIDs, naproxen seems to provide better pain relief than celecoxib and placebo within 3 weeks in TMJ osteoarthritis (81,116). Arthrocentesis has been recommended for TMJ osteoarthritis since it effectively reduces pain and improves jaw function.

TMJ pain attributed to systemic arthritis

With TMJ pain attributed to systemic arthritis, disease-modifying anti-rheumatic drugs and biologics are used, in addition to soothing treatment with NSAIDs and corticosteroids for pain relief (47). In more severe cases, changes in occlusion, such as an anterior open bite, and accompanying dysfunction may affect the QoL. The anterior open bite has been reported to be frequently associated with TMJDs, and studies have been conducted to evaluate the relationship between malocclusion and TMJDs. Treatment of anterior open bite, particularly in patients reporting TMJD pain, is challenging for orthodontists, and treatment options range from observation, control of childhood parafunctional habits, orthodontic appliances (braces), temporary anchorage devices and surgical procedures may be considered if skeletal discrepancies are present. Alloplastic TMJ total joint replacement has been reported as the most reliable surgical procedure to correct the malocclusion caused by severe degenerative changes in the TMJ (47).

TMJ pain is attributed to subluxation

For TMJD pain attributed to subluxation, a minimally invasive, acute therapy aiming to reduce pain, including exercises to improve jaw coordination, stability, and muscle strength, is often prescribed and considered the first-line treatment in this condition (1,117). TMJ subluxation is usually self-managed; patients’ self-care to avoid the occurrence of subluxation by limiting the wide opening of the mouth plays an integral role in the success of any therapeutic modality. Contrary to subluxation, luxation or TMJ dislocation usually requires a clinician to reposition the disc condyle complex manually. This may require local anesthesia of the TMJ to provide comfort, followed by self-care and a few days of analgesic medications (1). However, jaw exercises should be considered a non-surgical treatment option for TMJ subluxation and luxation as they aim to improve muscle strength and coordination in TMJD patients. Exercise can prevent further aggravation to the irritated tissues and repeated TMJ luxation. Still, sufficient scientific evidence is lacking to support its efficacy, and more studies with longer follow-ups are needed (65).

Among the minimally invasive management modalities for recurrent TMJ luxation, intra-articular and pericapsular injection with autologous blood showed a high success rate at 16 months. In contrast, the modified dextrose intra-articular injection (lignocaine and 50% dextrose) showed promising results, but further studies are necessary. Intra-articular injection therapies are believed to induce fibrosis, therefore limiting the condyle movement and, consequently, mouth opening. When the recurrent luxation is secondary to lateral pterygoid muscle dystonia, botulinum toxin (BTX) A injections might be the treatment of choice (118).

Most of the early studies and anecdotal clinical observations were fraught with flaws in their study design and subject to systematic bias. Deeply rooted personal beliefs, professional training, and clinical experience have also contributed to the stigma of TMJDs. Stigma attributed to chronic TMJD pain has been documented in literature, and it refers to patient’s attitudes and beliefs that they perceive as being different (119). The psychological status of an individual has been reported to be a contributing factor in the initiation of TMJD symptoms; as a result, because of uncertain diagnosis and stigmatization of being abandoned or socially rejected, TMJD patients continue to suffer with no cure for their painful condition (119). For decades, elective irreversible occlusal adjustments and non-scientific treatments were often attempted to prevent and manage TMJDs. The treatment suggestions were usually from the perspective of the healthcare professional with whom the patient sought treatment. These procedures sometimes resulted in an exacerbation and worsening of the patients’ symptoms, and they were often passed from one speciality to another (120).

Outcome of studies on management strategies for TMJDs

Recent studies (121-130) conducted on the effectiveness of therapeutic modalities for TMJDs has been summarized in Table 3. The characteristics of each study recorded included (I) study year and type, (II) objective, (III) TMJD and diagnostic criteria, (IV) sample size, (V) gender and mean age of participants, (VI) study groups including experimental and control groups, (VII) treatment sessions, (VIII) outcome measures and outcome measurement, (IX) assessment sessions, and (X) outcome.

Ozmen et al. (121) found dry needling and face yoga as effective treatment options for pain relief and improved jaw movements in TMJD patients. Patients experienced decrease in pain levels (P=0.001), and increase in jaw movements (P<0.05) 6 weeks after treatment with both dry needling and face yoga therapies, leading to considerable improvement in their QoL and sleep quality however further studies are needed to explore the long-term effects of these interventions for management of TMD symptoms. Saleh et al. (122) in a clinical trial found significant increase in craniovertebral angle (P<0.05), pain pressure threshold of the masseter and temporalis muscles (P<0.001), TMJ range of motion (P<0.001), and a significant decrease in numerical pain rating (P<0.001), and TMJ function (P<0.001). Therefore, in clinical practice, the addition of proprioceptive neuromuscular facilitation (PNF) exercises of masticatory muscles to routine physical therapy programs in managing TMD patients with forward head posture should be recommended than physical therapy alone. Recently, health care providers have integrated digital therapeutics (DTx) into TMD care and observed potential benefits of DTx in patient education, behavioral modification, and in improving adherence to treatment (123). Park et al. (123) observed decrease in pain scores (P=0.016) and improvement in maximal mouth opening (P=0.0079) in TMD patients by combining DTx software application with usual TMD treatment however further research should be conducted to explore the therapeutic effect of DTx on the behavioral and psychological factors. Shah et al. (124) in a study reported that combination of physical therapy and manual therapy plus patient education is a useful therapeutic method in alleviating pain and improving pain free MMO for TMJDs. Both treatment groups (physical therapy plus manual therapy versus physical therapy alone) showed significant reduction in VAS scores for pain at rest and increased median MMO after the intervention (P<0.001).

Heo et al. (125) suggested combination protocol of arthrocentesis and subsequent stabilisation splint therapy as a reliable treatment modality for ID of TMJ. Arthrocentesis was conducted first for rapid improvement in patients’ discomforts, at 6-month follow-up, VAS pain scores showed significant decrease in patients with unilateral anterior disc displacement (P<0.01), and pre operative MMO and maximum protrusive movements significantly increased after treatment in anterior disc displacement without reduction (ADDwoR), and anterior disc displacement with reduction (ADDwR) groups, as well as in cases with erosive and non-erosive changes associated with unilateral ADDwoR (P<0.01). Similarly, in another clinical trial, Li et al. (126) observed significant decrease in pain intensity at 6 weeks post intervention (P<0.01), and at subsequent time points of 3 months (P=0.001), 6 months (P=0.10) and at one year (P=0.02) in TMJ arthralgia patients treated by early arthrocentesis supported by an occlusal splint compared use of an occlusal splint alone. The study findings suggested that arthrocentesis with occlusal splint may be considered as first line treatment for patients with TMJ arthralgia.

Two studies by Mishra et al. (127) and Al-Quisi et al. (129) investigated the effectiveness of LLLT in the management of TMDs. In a Mishra et al. (127) study both TENS and LLLT showed significant improvement in mouth opening, pain intensity, and muscular soreness (P<0.001) in TMJDs after 4 weeks post intervention, however LLLT was found to be more effective than TENS therapy for TMD treatment. Al-Quisi et al. (129) evaluated and compared the effects of red light emitting diode (LED) light (660 nm wavelength and power =1.6 Watt) and low-level diode laser (wavelength =810 nm, 2.5 Hz, and power =1 Watt) with the placebo as LED light device applied near the tender points without switching the device on. There was improvement in pain scores and reduction in number of trigger points at 3^rd visit and 4^th follow-up visit in both treatment groups when compared with placebo. In addition, patients reported no limitation in mouth opening during the treatment sessions or presence of any side effects with the application of LLLT and red LED light device. Al-Quisi et al. (129) suggested that both LLLT and red LED light could effectively relieve the symptoms associated with TMD. Red LED light should be considered as the preferable choice for TMD treatment due to biosafety and lower cost compared with LLLT.

In a multicentric RCT, Reeve et al. (128) found comparable effects of 100-units of onabotulinumtoxinA (OnabotA) and 0.9% normal saline injections in decreasing pain and in improving jaw function at all time points from baseline of 1, 2, and 3 months for patients with myofascial pain disorder, and additional studies with higher OnabotA dose should be conducted to explore the short- and long-term effects of OnabotA on pain reduction and improvement in QoL of patients. Anwar et al. (130) in a cross-sectional observational study explored the use of BTX among the clinicians for TMD management by evaluation of BTX type and regimen used, the muscle group(s) injected, and patient follow-up after BTX treatment. It was observed that most common brand of BTX used was Botox (Allergan), and masseter followed by temporalis, procerus and lateral pterygoid muscles were injected by the clinicians. Botox doses varied between 30 and 100 units and follow-up varied with most patients seen every 3 to 9 months. The survey demonstrated wide variation in BTX administration among the clinicians however further evidence-based research is needed for BTX dose optimization and standardization for TMD treatment.

Clinical implications and future recommendations

TMJ is one of the most adaptable joints in the body. Combining symptom-based and mechanism-based approaches is essential for successfully managing these cases. Since TMJDs are generally self-limiting, symptom alleviation to carry through acute phases is critical. Targeting the pathological process through mechanism-based approaches is necessary for long-term success, especially when TMDs are secondary to systemic diseases, benign or malignant lesions, and growth disorders. Systematic reviews have now concluded that irreversible treatments such as orthodontic and prosthodontic modalities would not be preventive or a treatment option for most TMJDs. Tran et al. (38) in a systematic review on management of TMJDs reported that contrary to existing guidelines, there is insufficient evidence to support the efficacy of occlusal splint therapy, occlusal adjustment or prosthodontic treatment for TMJDs. Though their review reported the continued recommendation of NSAIDs, acetaminophen and ibuprofen, for the initial management of arthrogenous and myogeneous TMDs, however high-quality evidence is needed to validate the efficacy of oral pharmacotherapeutics such as TCAs, benzodiazepines and muscle relaxants for the management of chronic TMDs. Management of TMJDs should follow the general guidelines published by the AAOP. The management strategies should begin with the least invasive, reversible procedures, and etiological factors should be considered while planning the treatment for TMJDs. When the conservative strategies fail, or patients have mixed results, intra-articular injections, either alone or in combination with arthrocentesis, could be an option. Busse et al. (60) reported that when considering management options for patients with chronic TMJD pain, clinician should apply at first strongly recommended interventions (usual standard care, CBT, jaw mobilisation, trigger point therapy, jaw exercises combined with jaw stretching and/or trigger point therapy and posture correction) followed by conditional recommendations against interventions (manipulation, acupuncture, jaw exercise combined with jaw mobilisation, manipulation combined with postural exercise, and CBT delivered in conjunction with NSAID), then conditionally against (acetaminophen, benzodiazepine, beta blocker, BTX injection, capsaicin cream, cartilage supplements, HA injection, NSAIDs, low level laser therapy, removable occlusal splint, biofeedback, relaxation therapy, trigger point therapy, TENS, arthrocentesis and ultrasound guided arthrocentesis) should be considered for chronic TMD if other options are not suitable as benefits of pain reduction and improvement in function are uncertain with conditional recommendations against therapies. Strong recommendations against interventions such as discectomy, irreversible oral splint, and NSAID combined with opioid analgesic were made for chronic TMDs as these may be associated with significant harms or adverse effects. Furthermore, Busse et al. (60) suggested that while formulating the recommendations, guidelines should focus on patient perspectives, availability and cost of interventions for chronic pain associated with TMJDs should be considered in decision making. Limited studies have highlighted about the influence of the interventions targeting the chronic TMD pain on oral health related QoL, therefore effects of the interventions on patient important outcomes such as physical functioning, role functioning, social and mental functioning, sleep quality and adverse effects should be explored in future clinical trials.

Strength and limitations

The strength of this review is that we compiled evidence from the literature on the diagnosis and management of TMJDs. The limitation was in the extraction of high-quality evidence, particularly about the treatment of different TMJDs, and there was heterogeneity in outcome measures (pain intensity, jaw function, MMO, and psychologic distress) and treatment response in diagnostic categories across the studies in the literature. In addition, data on the effectiveness of different types of occlusal splints, physical therapy, acupuncture, and standardization of laser parameters for the treatment of TMDs was inadequate, and this points to the need for more studies and systematic reviews to validate the findings of previously reported studies.

Conclusions

TMDs include both autogenous and myogenic disorders. In this review on TMJD, primary and secondary TMJ pains are discussed, along with an update on various management modalities. The literature revealed improvements in understanding the pathophysiology of TMJD, which is of complex multifactorial etiology. The newly proposed ICOP classification has addressed treating and managing different TMJDs. It provides new insight to the clinics for better prevention and treatment of causal factors contributing to TMJDs. However, due to insufficient high-quality evidence, further long-term follow-up studies should be conducted on different treatment modalities in diagnostic categories based on ICOP classification.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, Frontiers of Oral and Maxillofacial Medicine for the series “Orofacial Pain”. The article has undergone external peer review.

Reporting Checklist: The authors have completed the Narrative Review reporting checklist. Available at https://fomm.amegroups.com/article/view/10.21037/fomm-24-47/rc

Peer Review File: Available at https://fomm.amegroups.com/article/view/10.21037/fomm-24-47/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://fomm.amegroups.com/article/view/10.21037/fomm-24-47/coif). The series “Orofacial Pain” was commissioned by the editorial office without any funding or sponsorship. J.K. served as an unpaid editorial board member of Frontiers of Oral and Maxillofacial Medicine from June 2024 to May 2026 and served as the unpaid Guest Editor of the series. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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