Diagnostic Classification of Temporomandibular Disorders (TMDs): A Guide for Dental Professionals and Patients
- Dr. Chizobam Idahosa
- Dec 27, 2025
- 9 min read
Welcome to my fifth post in an ongoing series on temporomandibular disorders (TMDs). To read the previous posts, click the titles below.
Today’s focus is on the Diagnostic Classification of Temporomandibular Disorders (TMDs).
Diagnostic Classification of Temporomandibular Disorders (TMDs)
Jaw pain, limited opening, headaches, and difficulty chewing are among the reasons patients seek care for temporomandibular disorders (TMDs). Despite their common occurrence, these symptoms are often misunderstood. TMDs are not a single disorder but rather a broad group of conditions involving the temporomandibular joints (TMJs), the masticatory muscles, and the surrounding structures that enable speech, chewing, swallowing, and yawning.
What makes TMDs particularly challenging is that many of their symptoms overlap with those of dental pain, ear disorders, sinus disease, and even neurologic conditions. This overlap can delay diagnosis, lead to unnecessary dental treatment, or result in persistent symptoms. For this reason, a diagnostic classification system is essential for both patients and dental professionals.
The diagnostic classification of TMDs is not fixed or absolute. It is an evolving framework that reflects advances in clinical research, imaging, and pain science.
The classification system used in this article is partially derived from the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD), developed by the International RDC/TMD Consortium. I have also included additional categories outlined in the resource: “Orofacial Pain: Guidelines for Assessment, Diagnosis, and Management” by the American Academy of Orofacial Pain.
Why Diagnostic Classification Matters
A structured diagnostic approach helps answer a fundamental question: where is the pain or dysfunction coming from? Is it arising from the joint itself, the surrounding muscles, both the joint and the muscles, or a broader systemic or neurological process?
For patients, accurate classification provides clarity and reassurance. It helps explain why symptoms occur, why imaging findings may or may not matter, and what realistic treatment goals look like.
For dental professionals, proper classification prevents overtreatment, improves interdisciplinary communication, and ensures that care is directed at the true source of the problem.
It is also important to recognize that many individuals have more than one TMD diagnosis at the same time. Joint and muscle disorders frequently coexist, and symptoms may change over time. A systematic diagnostic framework enables clinicians to identify contributing factors rather than focusing on a single finding.
Broadly, TMDs are classified into three major groups:
Temporomandibular Joint (TMJ) Disorders
Disorders that primarily affect the jaw joints, articular disc, supportive ligaments, and bony structures. These conditions may present with pain, mechanical dysfunction, joint noises, or structural changes.
Masticatory Muscle Disorders
Disorders originating from the muscles of mastication. These conditions often cause pain with jaw movement, muscle tenderness, or limited function, and may sometimes overlap with systemic pain conditions.
Headache Attributed to TMDs
Headaches that arise secondary to pain-related TMDs.
Each group includes several distinct conditions with characteristic clinical features. This article presents the more commonly encountered conditions. I do not discuss the full spectrum of disorders that can affect the TMJs and associated structures.
Temporomandibular Joint Disorders
TMJ joint disorders originate from the joint structures themselves and are typically aggravated by jaw movement or function.
Arthralgia
Arthralgia refers to pain arising from the joint without clear evidence of active inflammation. Patients often report pain with chewing, talking, or yawning. Jaw opening may be limited, not because of a mechanical block, but because pain inhibits normal movement.
Arthritis
Arthritis involves joint pain accompanied by signs of inflammation or infection. Clinically, this may include swelling, redness, warmth, or tenderness over the joint. Arthritis is sometimes referred to as capsulitis or synovitis in clinical settings. Limitation of jaw movement may occur secondary to inflammation and pain.
TMJ Disc Displacement Disorders
Disorders involving the articular disc are among the most common TMJ conditions. The articular disc normally sits between the mandibular condyle and the articular eminence, allowing smooth, coordinated joint movement. Disc displacement occurs when this relationship becomes altered, most commonly in an anterior or anteromedial direction.
This abnormal positioning is thought to result from elongation or tearing of the ligaments that attach the disc to the condyle. Not all disc displacements cause pain or dysfunction; therefore, clinical correlation is essential.
Disc Displacement With Reduction
Disc displacement with reduction occurs when the disc is positioned anteriorly with the mouth closed, but it returns to its normal position during opening. Medial or lateral displacements of the disc may also occur. This reduction is often accompanied by clicking, popping, or snapping sounds. Many patients are asymptomatic, while others may experience intermittent discomfort or a sense of jaw instability.
Disc Displacement With Reduction With Intermittent Locking
Disc displacement with reduction with intermittent locking represents a more variable condition. In these cases, the disc sometimes reduces normally and sometimes does not. When reduction fails, patients experience episodes of limited opening, commonly referred to as a closed lock. Jaw noises may come and go, and patients may learn specific maneuvers to unlock the jaw.
Disc Displacement Without Reduction With Limited Opening
Disc displacement without reduction with limited opening is characterized by a disc that does not return to its normal position during opening. This results in a persistent mechanical restriction, commonly described as a closed lock. Patients often report a prior history of clicking that suddenly stopped. Pain is common, and jaw opening is typically less than 40 mm, even with assisted stretching. Deflection toward the affected side during opening is frequently observed.
Disc Displacement Without Reduction Without Limited Opening
Disc displacement without reduction without limited opening represents a later or adaptive stage. Although the disc remains displaced, jaw opening is no longer restricted. Patients usually have a history of prior locking, but current function is relatively normal, with assisted opening of 40 mm or greater.
Degenerative Joint Disease
Degenerative joint disease represents a breakdown of articular tissues accompanied by osseous changes involving the condyle and or articular eminence. It is best understood as the joint’s response to increased or altered loading over time.
Patients may present with joint noises (crepitus) that produce grinding or crunching sounds, limited jaw opening, and changes in their bite. Bilateral degenerative joint disease may result in an anterior open bite, while unilateral disease can cause a contralateral posterior open bite.
Osteoarthritis and Osteoarthrosis
When degenerative changes occur without pain, the condition is referred to as osteoarthrosis, indicating an adaptive or stabilized stage.
Osteoarthritis, by contrast, is characterized by persistent joint pain and inflammation. Imaging, particularly CT, may reveal condylar flattening, erosion, sclerosis, osteophyte formation, or subchondral cysts.
Systemic Inflammatory Arthritides
Systemic inflammatory arthritides can also involve the TMJs. Conditions such as rheumatoid arthritis, lupus, psoriatic arthritis, ankylosing spondylitis, and gout may cause joint pain, inflammation, and structural damage. In these cases, laboratory testing and referral to a rheumatologist are often appropriate.
TMJ Hypermobility Disorders
Hypermobility Disorders
Hypermobility disorders occur when the disc-condyle complex translates beyond the articular eminence. Clinically, this results in an open lock, where the mouth is stuck in a wide-open position and cannot immediately return to a closed position.
Luxation and Subluxation
When jaw closure requires clinician assistance, the condition is referred to as luxation or dislocation.
When patients can reduce the joint on their own, often with a simple maneuver, it is termed subluxation. These episodes may be momentary or prolonged and can be distressing for patients.
TMJ Hypomobility Disorders
Hypomobility disorders involve restriction of joint movement due to structural changes within the joint. These conditions typically feel firm and unyielding during clinical examination.
Intra-articular Adhesions
Intra-articular adhesions consist of fibrous bands, most commonly within the superior joint space. These adhesions restrict normal movement, resulting in a limited range of motion with marked deflection toward the affected side. They arise secondary to joint inflammation from trauma or systemic disorders, and are usually not associated with pain.
Ankylosis
Ankylosis represents a more severe form of hypomobility.
Fibrous ankylosis involves widespread fibrotic changes of the joint capsule and supporting ligaments, leading to progressive loss of jaw mobility.
Osseous ankylosis occurs when bone formation results in partial or complete fusion of the joint components. Imaging reveals obliteration of the joint space and abnormal bone proliferation, with severe restriction of jaw movement in all directions.
Developmental Disorders
Congenital and developmental TMJ disorders include:
Aplasia
Characterized by the absence of the mandibular condyle and underdevelopment of the articular fossa and eminence. It is typically present at birth and progresses with age. It results in significant occlusal disturbances, often including posterior open bite and deviation of the mandible toward the affected side. Treatment planning may involve long-term growth monitoring, orthodontic intervention, surgical reconstruction, and collaboration with craniofacial teams
Hypoplasia
Underdevelopment or incomplete formation of the mandibular condyle. It is less severe than aplasia, but still associated with facial asymmetry, altered jaw mechanics, and malocclusion. Patients may report difficulty chewing or a shift in their bite.
Hyperplasia
Excessive growth of the condyle, either unilaterally or bilaterally - not a tumor, but an overgrowth of normal bone-producing cells, which leads to progressive facial asymmetry, deviation of the mandible, and bite discrepancies such as unilateral posterior open bite or crossbite.
Overall, these conditions highlight that not all TMDs are pain-driven. Some present primarily as structural or developmental concerns requiring interdisciplinary care.
Masticatory Muscle Disorders
Masticatory muscle disorders are a common source of facial pain and are frequently mistaken for dental pathology.
Local Myalgia
Local myalgia occurs when pain is confined to a specific muscle. When pressure is applied to that muscle during evaluation, pain is felt only at that exact site. Patients often describe the sensation as sore, stiff, tight, aching, or fatigued, especially after activities that strain the jaw, such as prolonged chewing, clenching, or grinding. In many cases, this reflects muscle overuse or tension that has exceeded the muscle’s capacity to recover.
Myofascial Pain
Muscle pain, as described for myalgia. However, in myofascial pain, the pain extends beyond the palpating fingers but remains within the borders of the muscle being palpated.
Myofascial Pain with Referral
Muscle pain, as described for myalgia. In addition, in individuals with myofascial pain with referral, the pain pattern extends even further from the affected muscle. During an examination, pressing on a tense muscle band or trigger point may reproduce symptoms in a distant location beyond the boundaries of the palpated muscle. This helps clarify the diagnosis, particularly when patients report toothache-like pain that does not correspond to dental disease or otalgia (ear pain) in the absence of ear pathology.
Additional Muscle Disorders
Tendonitis, which involves pain originating from tendon structures such as the tendon of the temporalis muscle, which is palpated intraorally at its insertion on the coronoid process of the mandible.
Myositis, which reflects inflammatory or infectious muscle involvement.
Myospasm is an involuntary, tonic muscle contraction that results in limited opening and, in some cases, acute occlusal changes. For example, spasm of the lateral pterygoid muscle may pull the mandible toward the contralateral side, creating a posterior open bite on the affected side.
Muscle Pain Attributed to Systemic or Central Disorders
Not all masticatory muscle pain originates only from local muscle pathology.
Fibromyalgia involves widespread musculoskeletal pain and commonly includes the jaw muscles.
Centrally mediated myalgia is characterized by chronic, continuous muscle pain accompanied by sensations of stiffness, weakness, or fatigue. Patients may report a feeling of malocclusion that is not supported by clinical findings, limited opening, as well as otologic or sensory symptoms. These conditions typically do not respond well to treatments directed solely at the muscles and also require addressing central sensitization, which amplifies and sustains the pain experience.
Headache Attributed to TMDs
Headache attributed to TMDs is pain in the temple region related to a temporomandibular disorder. The headache is affected by jaw movement, function, or parafunction and can be reproduced by palpation of the temporalis muscles or movement of the TMJs. Importantly, this diagnosis is made only when the headache is not better explained by another primary headache disorder.
Clinical Pearls
Not all joint noises require intervention - the absence of pain and dysfunction may indicate stability
Disc displacement without reduction and persistent limited opening warrants a timely referral
Facial asymmetry or progressive occlusal change may indicate underlying developmental or degenerative joint disease
Recognize coexisting conditions: many patients present with both muscle and joint components
Chronic muscle pain unresponsive to local care may reflect systemic or centrally mediated processes
When in doubt, refer early: delayed recognition of inflammatory arthritides or developmental conditions can complicate outcomes
Conclusion
Temporomandibular disorders encompass a wide spectrum of joint, muscle, and developmental conditions. A diagnostic framework enables clinicians to deliver individualized, evidence-based treatment.
For patients, understanding the cause of symptoms provides clarity. The goal of evaluation is not only to name the condition but also to determine its cause, identify contributing factors, and develop an effective treatment plan for recovery.
Join me next time as I discuss the clinical evaluation of patients with temporomandibular disorders.
Until next time…
Dr. Chizobam Idahosa
© Diagnostic Classification of Temporomandibular Disorders (TMDs): A Guide for Dental Professionals and Patients. Dr. Chizobam Idahosa.
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References
Schiffman, Eric L. et al. “Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) for Clinical and Research Applications: recommendations of the International RDC/TMD Consortium Network* and Orofacial Pain Special Interest Group†.” Journal of oral & facial pain and headache28 1 (2014): 6-27.
Gary D. Klasser, Marcela Romero Reyes. Orofacial Pain: Guidelines for Assessment, Classification and Management. The American Academy of Orofacial Pain. 7th edition. Chicago IL: Quintessence Publishing Co., Inc.;2023
Okeson JP. Management of Temporomandibular Disorders and Occlusion. 8th edition. St. Louis, Missouri: Elsevier Mosby; 2020
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