Dr Amelia Chew
Consultant, Prosthodontics Unit, Department of Restorative Dentistry, National Dental Centre Singapore

Temporomandibular joint disease is a common source of non-dental orofacial pain in urbanised, high-stress populations like Singapore but it is prone to be under diagnosed in primary care settings due to the overlap of symptoms with neurological, otolaryngological and dental conditions. The National Dental Centre Singapore shares how early recognition in primary care can prevent chronicity and enhance outcomes.

INTRODUCTION

What it is

Temporomandibular joint disease (TMD) refers to a diverse group of conditions affecting the temporomandibular joint (TMJ), the masticatory muscles, and associated anatomical structures. TMD is a common yet often under-recognised condition that can lead to significant morbidity due to pain, functional limitation and impact on quality of life.

TMD encompasses both articular and muscular pathologies and is generally categorised into three broad groups:

1. Myogenous TMD: involving the masticatory muscles
2. Arthrogenous TMD: involving the joint structures such as the articular disc or condyle
3. Combined TMD: where muscular and joint pathologies coexist

Aetiology

TMD is a multifactorial condition with diverse biological, behavioural, mechanical and psychosocial contributors. No single aetiological factor explains all cases; rather, the interaction of several risk factors determines onset severity and chronicity. The aetiology can broadly be categorised into the following domains:

1. Biomechanical Factors

• Parafunctional habits: Bruxism (grinding), clenching, nail-biting and gum chewing impose excessive, repetitive strain on the masticatory muscles and TMJ.
  
  
• Trauma:
  • Macrotrauma: Blunt injury to the jaw, whiplash, or mandibular fractures can result in structural damage to the joint or disc.
  • Microtrauma: Repeated minor stresses (e.g., chronic bruxism) may lead to inflammation, disc displacement, or degenerative joint changes.
     
• Joint hypermobility: Patients with ligamentous laxity (e.g., Ehlers-Danlos syndrome) may be predisposed to disc displacement and joint instability.

2. Muscular and Functional Factors

• Myofascial pain: Overactivity or dysfunction of masticatory muscles (masseter, temporalis, medial/lateral pterygoids) can lead to localised pain, muscle spasms and trigger points.
  
  
• Fibromyalgia: Fibromyalgia and TMD frequently coexist, and they share overlapping pathophysiology and symptomatology.

3. Psychological and Behavioural Factors

• Stress and anxiety: Strongly associated with increased muscle tension, clenching and parafunctional activity.
  
  
• Depression and somatisation: Patients with psychological distress may have heightened pain perception or difficulty coping with chronic symptoms.
  
  
• Sleep disorders: Sleep bruxism and poor sleep quality are linked to increased risk of TMD.

4. Inflammatory and Degenerative Joint Disorders

• Osteoarthritis (OA): Degenerative changes in the TMJ can lead to joint pain, stiffness and crepitus. OA may be primary or secondary to trauma or disc displacement.
  
  
• Rheumatoid arthritis (RA): Inflammatory arthritis such as RA, psoriatic arthritis or juvenile idiopathic arthritis can involve the TMJ, leading to synovitis, joint erosion and functional limitation.

Prevalence and Relevance in Singapore

Local studies and clinical observations suggest that TMD affects up to 25-30% of the adult population in Singapore at some point in their lives, with higher prevalence in females aged 20-40 years. While many cases are self-limiting, a subset develops chronic symptoms requiring medical or dental intervention.

In urbanised, high-stress populations such as Singapore, there is growing recognition of TMD as a prevalent condition with both physical and psychosocial dimensions. From a public health perspective, TMD is a common source of non-dental orofacial pain.

Due to the overlap of symptoms with neurological, otolaryngological and dental conditions, it is frequently underdiagnosed or mismanaged, particularly in primary care settings. For clinicians, early recognition, appropriate referral and coordinated management are critical in preventing chronicity and enhancing outcomes.

WHAT TO LOOK OUT FOR

SYMPTOMS AND CLINICAL FEATURES

TMD symptoms can vary widely between patients and may be musculoskeletal, articular, or referred in nature. They often fluctuate in intensity and may present acutely or chronically, aggravated by maximum mouth opening, biting hard food or teeth grinding. They may also present unilaterally or bilaterally.

1. Pain-Related Symptoms

• Jaw pain: Dull, aching discomfort in the jaw joint or surrounding muscles
• Facial pain: Often unilateral and may radiate to the temples, cheeks or neck
• Ear-related pain (otalgia): Non-otologic inorigin; can mimic middle ear pathology
• Headaches: Typically tension-type or in the temporal region; sometimes mimicking migraines

2. Joint Sounds

• Clicking: A single, distinct sound during opening or closing, often associated with disc displacement with reduction
• Popping: Louder and more abrupt than clicking
• Crepitus: Grating or gravel-like sound, usually associated with degenerative changes (e.g., osteoarthritis)

3. Functional Limitations

• Limited mouth opening: May be due tomuscle spasm, disc displacement without reduction or joint effusion; often <35 mm interincisal opening
• Locking:
  • Open lock: Inability to close the mouth fully
  • Closed lock: Difficulty opening the mouth

4. Ear and Auditory Symptoms

• Ear fullness or pressure
• Tinnitus: Ringing in the ears without underlying auditory pathology

5. Associated Psychosomatic and Systemic Symptoms

• Sleep disturbances: Poor sleep quality, often related to nocturnal bruxism or pain
• Anxiety, stress or depression: Commonly reported in chronic TMD patients
• Neck and shoulder pain: May be due to muscle coactivation or postural strain

DIAGNOSIS AND REFERRAL

Patients with persistent or severe symptoms shouldbe referred to a dental specialist (e.g., oral and maxillofacial surgeon or orofacial pain specialist) for further evaluation.

1. Clinical History

• Pain characteristics:
  • Location: Preauricular, jaw, temple, face
  • Quality: Dull, aching- Duration and frequency: Intermittent vspersistent
  • Exacerbating factors: Chewing, stress,jaw movement
  • Diurnal variation: Morning pain (bruxism),evening pain (muscle fatigue)
• Joint sounds:
  • Clicking, popping or crepitus withmovement
• Functional limitations:
  • Jaw stiffness, locking or restricted opening
  • Deviation or deflection on opening
• Associated symptoms:
  • Ear symptoms (fullness, tinnitus, non-otologic pain)
  • Headache, neck or shoulder pain
  • Parafunctional habits (e.g., clenching, grinding)
  • Psychosocial stressors, sleep disturbances

2. Physical Examination

• Mandibular range of motion
  • Normal opening: 40-50 mm (interincisal)
  • Restricted opening: <35 mm may suggest disc displacement or muscle spasm
• Palpation
  • TMJ tenderness: Palpate bilaterally in the preauricular area
  • Masticatory muscles: Masseter, temporalis, medial/lateral pterygoid
  • Cervical muscles: Sternocleidomastoid, trapezius
• Joint sounds
  • Auscultate or palpate for:
    > Clicking or popping: Suggests disc displacement with reduction
    > Crepitus: Often seen in degenerative joint disease

3. Imaging

• Panoramic radiograph (OPG)
  Often used as a first-line screening tool, panoramic imaging helps assess gross bony abnormalities, condylar asymmetries, fractures and degenerative changes.

However, it lacks sensitivity for soft tissue structures and early joint pathology.

• Magnetic resonance imaging (MRI)
  Used for evaluating soft tissue structures, including the articular disc, joint effusion, synovitis and muscle pathology. It is most useful in diagnosing disc displacement with or without reduction and inflammatory joint conditions.
  
  
• Cone beam computed tomography (CBCT)
  CBCT offers high-resolution 3D imaging of osseous structures at a lower radiation dose than conventional CT. It is ideal for assessing condylar morphology, bony remodelling, ankylosis, and degenerative joint disease.

TREATMENT AND MANAGEMENT

1. Conservative Management (first-line and most effective in majority)

• Patient education and reassurance
• Soft diet and activity modification
• Heat or cold therapy
• Pharmacologic therapy: NSAIDs, muscle relaxants or low-dose tricyclic antidepressants
• Occlusal splints (e.g., night guards) for bruxism
• Physiotherapy: Jaw exercises, posture correction, manual therapy
• Ultrasound therapy
• Traditional Chinese Medicine and acupuncture

2. Psychological Interventions

• Cognitive behavioural therapy (CBT) for stress and pain management
• Biofeedback

3. Advanced or Refractory Cases

• Botulinum toxin injections to masticatory muscles for myogenous TMD
• Intra-articular injections: e.g., corticosteroids or hyaluronic acid
• Arthrocentesis or arthroscopy for internal derangement
• Open joint surgery in rare, severe or structural TMJ pathology

CONCLUSION

Temporomandibular joint disease is a prevalent and impactful condition that spans across medical and dental disciplines.

Awareness among primary care and medical practitioners is key to early recognition, conservative management and appropriate referral. In Singapore’s increasingly stress-driven society, early intervention can prevent progression to chronic pain syndromes and improve patient outcomes.

REFERENCES

1. Natu, V. P., Yap, A. U., Su, M. H., Irfan Ali, N. M., Ansari, A., & Duric, M. (2018). Temporomandibular disorder symptoms and their association with quality of life, emotionalstress, and sleep quality among South-East Asian youths. Journal of Oral Rehabilitation, 45(10), 756–763. https://doi.org/10.1111/joor.12690

2. Yap, A. U., Tan, K. B. C., & Chua, E. K. (2003). Sleep bruxism, anxiety, and psychosocial factors in TMD patients. Journal of Oral Rehabilitation, 30(3), 263–270. https://doi.org/10.1046/j.1365-2842.2003.01034.x

3. Yap, A. U., & Lee, C. H. (2021). Number and type of temporomandibular disorder symptoms: Their associations with psychological distress and oral health–relatedquality of life in youths. Journal of Oral Rehabilitation, 48(3), 270–278. https://doi.org/10.1111/joor.13120

4. Yap, A. U., Chua, E. K., & Tan, H. H. (2002). Study of TMJ clicking and associated factors among young adults in Singapore. Journal of Oral Rehabilitation, 29(6), 521–528.https://doi.org/10.1046/j.1365-2842.2002.00898.x

Dr Amelia Chew is a Consultant Prosthodontist in the Department of Restorative Dentistry, National Dental Centre Singapore. She has clinical experience in restoration and replacement of teeth. She specialises in complex rehabilitative care including full-mouth reconstruction, dental implants, maxillofacial prosthetics, and aesthetic prosthodontics.

A dedicated clinician and educator, Dr Chew is also a Clinical Teacher of the Prosthodontics Residency Programme at the Faculty of Dentistry, National University of Singapore.

GP Appointment Hotline: 6324 8798