Table 1 Theories concerning TMD origin [27]

Mechanical displacement (by Costen)

Lack of support in lateral teeth or functional occlusal premature contacts lead to direct eccentric positioning of the condyle in the glenoid fossa; this leads to pain, ear symptoms, adverse muscle activity and TMD

Trauma theory (by Zack and Speck)

The principal factor of TMD is micro-/macro-trauma; trauma can cause structural alternation to the muscles or directly to the joint structures

Biomedical (by Reade)

Disorder is initiated by trauma; specific factors (malocclusion, parafunctions, occupational activities) cause the progression of the symptoms

Osteoarthric (by Stegenga)

Osteoarthrosis is a main cause of TMD; muscular symptoms and systemic diseases are secondary to TMJ pathology

Muscle (by Travell and Rinzler)

Masticatory muscles are the primary etiologic factor to TMD; myalgia (caused by chronic myospasm) is secondary to parafunctions and can refer pain to TMJ

Neuromuscular (by Ramfjord)

Occlusal problems cause TMDs, the loss of occlusal equilibrium leads to the incoordination of muscles and spasms

Psychophysiological (by Schwartz and Laskin)

TMD occurs outside of the physical factors; psychosocial factors play a crucial role in TMD pathogenesis – the main factor of hypertension and overcontraction of the muscle is due to the parafunctions performed to relieve stress

Psychosocial theory (by Dworkin)

Emotional disturbances induce hyperactivity of the muscles and lead to parafunctional habits and occlusal anomalies; the muscle contractivity is accentuated with teeth clenching, and repeatability leads to pain