Temporomandibular joint dysfunction (TMD) is an umbrella term characterised by orofacial pain with involvement of structures such as the temporomandibular joints (TMJ), mastication muscles, and related anatomical regions. According to data provided by the American Academy of Orofacial Pain (AAOP), 75% of the population of the United States has or has presented signs and / or symptoms of TMD. The literature relating to the epidemiology of TMD also highlights a different prevalence of these disorders in relation to sex, with a strong female representation (female: male relationship about 4:1), and at the age group taken into consideration, with a more frequent onset of the pathology between the ages of 25 and 40 (down to 2-4% among those of senile age).

The greater susceptibility of women towards TMD has been associated with possible factors such as greater sensitivity to emotional stress, greater body care, and therefore greater diligence and request for professional services and/or treatment. However, the evidence of a higher prevalence of TMDs in women during the fertile period has led scholars to speculate on the existence of hormonal involvement, and in particular of estrogen hormones. The etiological cause of TMD still remains unclear, however, recent studies showed that psychosocial factors should be considered cofactors in the etiology of TMD. Biological interactions, psychosocial status, and environmental factors are complex causes, and moreover the scientific literature does not provide evidence of malocclusion and TMD relations, but recently it was showed that there is dysregulation of the autonomic nervous system (ANS) in patients suffering from TMD. TMD patients, in fact, showed consistent functional/structural changes in the thalamus and the primary somatosensory cortex. Additionally, functional and structural changes were frequently reported in the prefrontal cortex and the basal ganglia in TMD. In addition, these subjects show a higher frequency of psychiatric disorders (anxiety, depression, alexithymia, and catastrophizing). Sometimes the Central Sensitisation starts from a peripheral injury and/or dysfunction; frequently, this is the case of chronic TMD in which muscle, dental occlusion, or temporomandibular joint (TMJ) dysfunction can be considered peripheral triggers. In recent studies, many therapies are investigated for potential treatment of TMD, including the use of drugs, sometimes associated with bite or oral devices. Gnathology treatments, in particular conditions without muscular tension, are often the strategised therapies. Moreover, therapies with natural factors are becoming increasingly popular. Lastly, as explained above, the psychological support could be optimal in subjects in which TMD has become chronic.

The aim of this Special Issue is to collate original research that investigates and compares different therapeutic strategies in patients with TMD. Review articles discussing the current state of the art are also welcomed.

Potential topics include but are not limited to the following:

• Pharmacologic therapies (such as FANS, opioids, benzodiazepines, and steroid drugs)
• Natural therapies (natural agents such as arnica, cuprum metallicum, etc.)
• Use of oral devices (such es equilibrators, bite, sublingual device, orthodontics appliances)
• Physiotherapy
• Psychological support
• The role of gonadal hormones in TMD