Table 4.

Synthesis of results according to Section 2.9.

Authors and Year	Results
Velly et al., 2010 [16]	According to the authors, the risk associated with baseline fibromyalgia was moderate. Centrally generated pain plays a role in TMJ disorders (TMJD) and muscle pain.
Hoffmann et al., 2011 [17]	According to the authors, TMJD-affected individuals were on average 41 years old and predominantly female (90%). Patients reported moderate-to-severe intensity of pain. In this case-control comparison study, a higher frequency of depression, fatigue and fibromyalgia is correlated to TMJD. Fibromyalgia was a comorbid condition
Karibe et al., 2011 [18]	Fibromyalgia patients and Neuropathy patients significantly reported greater pain intensity in the TMJ area.
Kindler et al., 2011 [19]	Central nervous system alteration could reflect TMJD
Alonso-Bianco et al., 2012 [20]	TrPs were identified by palpation, and patients referred to pain in these areas. The number of active TrPs was significantly higher in TMD patients than in FMS ones. Women with FMS referred to pain in these areas more than those with TMD. Significant differences within the center of gravity coordinates of TrPs were found in TMD and FMS. There are different TrPs localization between myofascial temporomandibular disorders (TMD) and fibromyalgia patients.
Suma et al., 2012 [21]	According to the authors, in fibromyalgia patients, TMD and pain remain a recurring problem and they need a correct diagnosis and management to resolve this problem. Often therapies are dictated by the cause as inflammation, trauma, aging or parafunctional habits.
De Rossi et al., 2013 [22]	According to the authors, many medicaments used for fibromyalgia could be used for TMJD.
De Siqueira et al., 2013 [23]	Sensorial anomalies were observed in neuropathic or somatic pain patients, as in fibromyalgia patients. According to the authors, the majority of patients had pain upon craniofacial muscle palpation. Persistent idiopathic facial pain and temporomandibular disorders were associated with a low threshold for pain perception. (p < 0.002)
Cassisi et al., 2014 [24]	Pain in fibromyalgia or TMJD is caused by CNS hypersensitivity. Pharmacological and non-pharmacological therapies have been suggested for the treatment of these conditions.
Jin et al., 2014 [25]	Masticatory muscle pain and TMJ pain could be associated with fibromyalgia, despite the internal derangements of the TMJ.
Dahan et al., 2015 [26]	There was a positive association between the number of comorbidities present and TMD pain duration (p < 0.01), also the presence of migraine was positively associated. TMD and fibromyalgia are associated with an increase of TMJ pain intensity and duration.
Eisenlohr-Moul et al., 2015 [27]	TMD and fibromyalgia showed a higher parasympathetic decline during a psychosocial assessment.
Furquim et al., 2015 [28]	TMD is managed by complex mechanisms by the autonomic nervous systems as is fibromyalgia.
Gui et al., 2015 [29]	TMD and fibromyalgia (FM) are not merely coexisting conditions, but they have a series of similar characteristics and predisposing triggering factors.
Cummiford et al., 2016 [30]	Transcranial direct current stimulation (tDCS) may produce analgesia by altering thalamic connectivity while there may be a placebo response. Stronger baseline functional connectivity between M1-VL (left primary motor cortex- ventral lateral) thalamus, S1-anterior insula (primary somatosensory cortices), and VL thalamus-PAG (periaqueductal) predicted greater analgesia after sham and real tDCS. Sham treatment (compared with baseline) reduced FC between the VPL (ventral posterolateral) thalamus, S1, and the amygdala. Real tDCS (compared with sham treatment) reduced FC between the VL thalamus, medial prefrontal, and supplementary motor cortices. Interestingly, decreased FC between the VL/VPL thalamus and posterior insula, M1, and S1 correlated with reductions in clinical pain after both sham and active treatments.
Fujarra et al., 2016 [31]	All patients showed TMD and muscle disorders, with limited opening and TMJ disc displacement. According to the authors, Myofascial pain could be associated with mouth opening limitation (p = 0.038); right disc displacement with reduction (p = 0.012) and jaw stiffness (p = 0.004) were predominant in the facial pain group. Myofascial pain without mouth opening limitation (p = 0.038) and numbness/burning were more common in the facial or generalized pain sample group.
Robinson et al., 2016 [32]	Chronic painful TMD is a central sensitivity syndrome related to the hypersensitivity of the CNS. Similar conditions are Chronic Fatigue Syndrome (CFS) and FM.
Losert-Bruggner et al., 2018 [33]	Patients with cranio-cervical disfunctions and craniomandibular disorders benefit from interdisciplinary treatment. Using myocentric bite splint therapy and therapy with oral orthosis in combination with neuromuscular relaxation measures, an improvement of physical symptoms was seen in 84% of CMD-FMS patients, and improvement of the symptoms in the jaw was achieved in 77% of cases.