What Causes TMJ Disorders?
TMJ disorders are predominantly caused by muscular dysfunction (85-90% of cases), with only 5% representing true intra-articular joint pathology. 1
Primary Etiological Categories
Muscular Causes (Most Common)
The overwhelming majority of TMJ disorders stem from problems with the muscles of mastication rather than the joint itself:
- Masticatory muscle dysfunction accounts for approximately 45% of all genuine TMD cases and represents the single most common cause 1
- Muscle-related disorders cause discomfort in the jaw region and are triggered by multiple factors 1
- Emotional factors including anxiety, fear, frustration, and anger elicit muscular tension and oral habits that contribute to TMD development 2
- Bruxism (tooth grinding) and clenching are positively associated with TMJ pain and myalgia, with 60% of TMD patients reporting clenching and 30% reporting bruxism 3
Intra-Articular Causes (Minority of Cases)
Only 5% of TMD cases involve true joint pathology, though these tend to be more severe: 1
- Internal derangement with displacement of the articular disc (with or without reduction) 1
- Inflammatory disorders including synovitis and capsulitis 1
- Arthritis (rheumatoid arthritis and osteoarthritis) 1
- Traumatic arthritis following injury 1
- Developmental anomalies including condylar hypoplasia and hyperplasia 1
- Fractures of the condyle or joint structures 1
- Ankylosis (both traumatic and end-stage) 1
- Neoplastic conditions affecting the joint 1
Contributing and Predisposing Factors
Trauma and Iatrogenic Causes
- Jaw trauma is positively associated with TMJ crepitus and limited mandibular range of motion 3
- Orthodontic treatment (20% of cases) and wisdom tooth removal (19%) are positively associated with TMJ clicking 3
- Orthognathic surgery (1%) is positively associated with TMJ pain 3
- Tracheal intubation (4%) contributes to TMD development 3
- Iatrogenic injuries can act as both initiating and predisposing factors 4
Psychological and Behavioral Factors
Depression, catastrophizing, and other psychological factors increase the risk of chronicity and are strongly linked to TMD: 5
- Mental behavioral or neurodevelopmental disorders are present in 33.76% of TMD patients, with anxiety (20%) and depression (13%) being most common 3
- Mental disorders show positive association with the degree of TMJ pain and myalgia 3
- Lack of patient self-efficacy reduces treatment success 6
- TMDs are linked with back pain, fibromyalgia, and headaches, suggesting a systemic component 5
Occlusal Factors
- Occlusal discrepancies (fulcrum/interferences) can cause TMD 7
- Malocclusion following dental procedures may contribute 6
- However, the role of occlusion remains controversial, as position, shape, structure and function of teeth influence TMJ health 7
Critical Clinical Context
Approximately 50% of patients presenting with TMJ-region symptoms have complications unrelated to the TMJ itself, emphasizing the importance of accurate differential diagnosis 1. The etiology is multifactorial and includes biologic, environmental, social, emotional, and cognitive triggers 8.
TMD affects 5-12% of the population with peak incidence at 20-40 years of age, and is more common in females (80.50% in one study), though the reason is not clearly known 5, 3, 4. Up to 30% of acute TMD cases may progress to chronic pain, highlighting the importance of early intervention 6.