Table 1.

Extraction of the studies' results.

Author/ Year/ Country/ Study design	Participants			TMJ Disorders evaluation	Anxiety evaluation	Statistical analysis	Results
	Source of sample	Sample size	Age (years)
Solberg et al. (28) United States of America Case-control	University of Minnesota School of Dentristy	TMJ Disorders: 29 Controls: 29	Mean age for TMJ disorders and controls: 14–63 years	Histories, regional examinations, dental and lateral transcranial oblique radiographs for all patients	Minnesota Multiphasic Personality Inventory (MMPI)	t-test p < 0.001	Half of the symptom group showed clinical signs of greater anxiety than the matched control group as measured by the MMPI. The control group was essentially free of elevated levels of anxiety.
Moss and Adams (29) United States of America Case-control	Subjects were recruited from the community through radio advertisements and as referrals from local dentists	TMJ Disorders: 20 Controls: 10	Mean age for TMJ Disorders: 28.7 (19–41) years Mean age for Controls: 25.8 (22–32) years	TMJ pain and TMJ sound of click	Spielberger State-Trait Anxiety Inventory (STAI)	One-way ANOVA p < 0.05 post hoc	The results of the STAI indicated that there were no differences among groups in relation to state anxiety.
Southwell et al. (30) Scotland Case-control	Prosthetics Department at the Edinburgh Dental Hospital	TMJ Disorders: 32 Controls: 32	Mean age for TMJ Disorders: 36 ± 15.8 years Mean age for Controls: 36.2 ± 19 years	Classic triad of symptoms.	Eysenck Personality Questionnaire (EPQ); Spielberger State Trait Anxiety Inventory (STAI); Pennybaker Inventory of Limbic Languidness (PILL).	t-test p < 0.005	TMJ patients showed higher state and trait anxiety levels on the Spielberger scales, but only the trait difference was significant (P < 0–0.05). When females were compared, the only significant difference between TMJ patients and controls was in trait anxiety (TMJ mean - 43-2, control mean = 34-8; t = 2-80, P < 0–0.05)
Schroeder et al. (31) Germany Case-control	Department of the Clinic of Dental Surgery (Charité) and Institute of Physiology	TMJ Disorders: 30 Controls: 25	Range for TMJ disorders and controls: 19–66 years	Dysfunction Index proposed (32); orthopantomographic examination to assess the structure of the TMJ; examination of their occlusion and electromyographical investigation.	Scale ranging from 1–5 (from very relaxed to extremely tense) after the electromyographical investigation and the Hospital Anxiety and Depression Scale questions (HADS) (33).	Kruskal-Wallis-Test P < 0.05	Anxiety developed as conditioned reactions to pain. In agreement with this interpretation, patients with high anxiety values more often reported their mood during the experiment as tensed or stressed than did those with low anxiety values.
Zarh et al. (34) United States of America Case-control	TMJ clinic at University Hospital and Clinic, Iowa City, Iowa College of Dentistry, University of Iowa, Iowa City, Iowa.	TMJ Disorders: 98 Controls: 98	Range for TMJ disorders and controls: 18–65 years	Clinical examination (tenderness of muscles of mastication on palpation, tenderness of TMJ on lateral palpation, audible sounds in the TMJ on opening and closing, etc.)	The Crown Crisp Experimental Index (CCEI)	The paired Student t test	TMD patient in this study is more anxious about bodily concerns than the non TMD subject Stockstill and Callahan (35) United States of America Case-control	From several dental care facilities in the Lincoln, Nebraska, area, including a dental college clinic and several private practitioners.	TMJ Disorders: 47 Controls: 49	Mean age for TMJ Disorders: 33.8 ± 9.95 Mean age for Controls: 32.9 ± 10.2	Patients who had been in treatment for 1 year or less (Clinical history)	Taylor Manifest Anxiety Scale	Student's t-test Mann-Whitney U test P < 0.05	No significant differences were found between the subsamples (anxiety: i[58] = 0.687, P = NS)
Curran et al. (36) United States of America Case-control	Orofacial Pain Center at the University of Kentucky, College of Dentistry and university population (including introductory psychology courses for researcb credit)	TMJ Disorders: 23 Controls: 23	Mean age for TMJ Disorders: 26.9 years Mean age for Controls: 27.4 years	Research Diagnostic Criteria for Temporomandibular Disorders (RDC);	State-Trait Personality Inventory (STPI); Emotion Assessment Scale (EAS);	t-tests p < 0.05	The patients with TMD also indicated greater anxiety based on the trait measure of the STPI than did the control subjects (TMD X = 23.83, MC X = 19.35) [t/45] = 2.40, P < 0.03). The patients with TMD indicated greater levels of anxiety X = 24.70| relative to control subjects X = n.87) (¡[45] = 2.55, P < 0.02) on the EA
Jones et al. (37) Canada Case-control	Department of Dentistry at Victoria Hospital, London, Ontario, Canada;	TMJ Disorders: 36 Controls: 39	Mean age for TMJ Disorders: 31.86 ± 11.40 Mean age for Controls: 22.28 ± 6.37	Research Diagnostic Criteria for Temporomandibular Disorders (RDC); The Temporomandibular Joint Pain and Dysfunction Index (TMJPDI)	Positive and Negative Affect Scale (PANAS); Visual Analog Scale (VAS) on 15 cm; The Symptom Checklist 90–Revised (SCL-90R);	t-test ANOVA MANOVA SPSS/PC+ p = 0.05	The TMD group showed significant negative relationships between cortisol response and self-reported symptoms of anxiety. The TMD group showed greatly increased salivary cortisol concentrations to almost 12 nmol/l in response to the stress protocol.
Sirirungrojying et al. (38) Case-control Thailand	Dental Hospital, Faculty of Dentistry, Prince of Songkhla University	TMJ Disorders: 62 Controls: 67	Mean age for TMJ Disorders: 31.5 ± 10.9 years Mean age for Controls: 33.5 ± 10.2 years	Criteria of the American Academy of Craniomandibular Disorders	SCL-90 Questionnaire	t-test p < 0.05	Significant difference between TMD patients and dental patients at P < 0·05. Thus, the TMD patients in the study were more depressed and anxious than the other group.
Velly et al. (39) Canada Case-control	Jewish General Hospital (JGH) and the Montreal General Hospital (MGH), Montreal, Quebec, Canada.	TMJ Disorders: 83 Controls: 100	Mean age for TMJ disorders and controls: 18–60 years	Extra-oral and intra-oral clinical examinations; Research Diagnostic Criteria for Temporomandibular disorders (RDC/TMD)	The symptom check list 90 revised questionnaire (SCL-90R)	ratio test p = < 0.05	A mid-level of phobic anxiety appeared to be related to chronic pain. Higher levels of anxiety, but not depression, were associated with chronic miofacial pain. Manfredini et al. (40) Italy Case-control	Section of Prosthetic Dentistry, Department of Neuroscience, University of Pisa, Italy	TMJ Disorders: 87 Controls: 44	Mean age for TMJ disorders and controls: 25.8 (19–66) years	Research Diagnostic Criteria for Temporomandibular disorders (RDC/TMD) axis-I categories	Self-report questionnaire PAS-SR (version of SCIPAS).	One-way ANOVA Post hoc test P < 0.05	Myofascial pain subjects presented significantly higher scores PAS-SR domains investigating of anxiety. Myofascial pain patients showed the highest prevalence of anxiety psychopathology when compared with TMD-free.
Pallegama et al. (41) Democratic Socialist Republic of Sri Lanka Case-control	Oral Medicine Clinic at the Dental Hospital of the University of Peradeniya, Sri Lanka.	TMJ Disorders:38 Controls: 41	Mean age for TMJ Disorders: 29 ± 10.3 Mean age for Controls: 27.3 ± 8.2	Protocol adopted from the one used by Liu et al.	The self-evaluative, Spielberger's state and trait anxiety inventory (STAI)	Chi-square test Hapiro–Wilk test Levene's test Box's M-test Bonferroni post-hoc test P < 0.05	Multiple comparisons among the three groups revealed that the patients with TMD exhibited significantly higher levels of trait anxiety than controls (P < 0.01) Muscle related TMD patients all together showed significantly raised trait anxiety levels and neuroticism scores compared with healthy individuals.
Saheeb and Otakpor (42) Nigeria Case-control	Department of Oral and Maxillofacial Surgery at the University Benin Teaching and Hospital Benin City, Nigeria.	TMJ Disorders: 24 Controls: 24	Mean age for TMJ Disorders: 43.9 ± 15.9 Mean age for Controls: 44.1	Research Diagnostic Criteria for Temporomandibular disorders (RDC/TMD)	State-Trait-Anxiety Inventory (STAI); Hospital Anxiety and Depression Scale (HADS); The 28- item General Health Questionnaire (GHQ-28).	Chi-square test (x2) P < 0.05	This study identified a significantly higher prevalence rate of psychiatric among the temporomandibular joint pain and dysfunction patients compared with a control group. In 25% generalized anxiety and 12.5% dysthymia as the main comorbid psychiatric diagnoses in these patients.
Xu et al. (43) China Cross-sectional	Temporomandibular Joint Treatment and Joint and Oral and Maxillofacial Pain Center, School of Stomatology, Peking University	TMJ Disorders: 338 Controls: 1,338	Mean age for TMJ disorders and controls: 29.5 ± 10.5 (18–65) years	Patients in TMD treatment	SCL-90 Questionnaire	t-test ANOVA P < 0.05	The anxiety score of TMD patients was higher than the control population. This difference is statistically significant (p < 0.05)
Fernandes et al. (44) Brazil Cross-sectional	Undergraduates in Dentistry at University of Brasilia	TMJ Disorders: 225 Controls: 75	Mean age for TMJ disorders and controls: 17–25 years	Auto-applicable questionnaires Fonseca's Index	Spielberger's Trait–State Anxiety Inventory	Kruskal-Wallis and Pearson correlation p < 0.001	Pearson's Correlation Test, allowed to verify that the degree of TMD showed a positive correlation (r= 0.1872; p < 0.01) for both trait-anxiety ad state, that is
							increase in TMD is directly proportional to the increase in the level of anxiety
Vedolin et al. (45) Brazil Case-control	Bauru School of Dentistry (University of São Paulo, Brazil).	TMJ Disorders: 29 Controls: 16	Mean age for TMJ Disorders: 20 years Mean age for Controls: 19.5 years	Research Diagnostic Criteria for Temporomandibular disorders (RDC/TMD)	Beck Anxiety Inventory (BAI) (derived from the Cornell Medical Index)	Tukey's test Mann–Whitney test Friedman's test Chi-squared test	There was no difference between groups in anxiety and stress at any time (P > 0.05). When comparing the levels of anxiety and stress between times in each group, T2 had higher values, although not statistically significant for both groups.
Giannakopoulos et al. (8) Germany Case-control	Department of Prosthodontics of the University Hospital of Heidelberg	TMJ Disorders:131 Controls: 91	Mean age for TMJ disorders and controls: 42 ± 15.4	Research Diagnostic Criteria or Temporomandibular disorders (RDC/TMD)	Hospital Anxiety and Depression Scale (HADS)	One-way ANOVA t-tests	Using the HADS scale to measure anxiety, this study showed that anxiety does not seem to be significant for chronic TMD patients.
Lajnert et al. (46) Croatia Case-control	Dental Polyclinic, School of Medicine in Rijeka, and Clinic for Psychotrauma of the Rijeka University Hospital Center	TMJ Disorders: 60 Controls: 30	Mean age for TMJ disorders and controls: 38.5 ± 12 (22–67) years	Research Diagnostic Criteria for Temporomandibular disorders (RDC/TMD)	Emotions Profile Index Life Events Scale	Kolmogorov-Smirnov test. One way ANOVA with Scheffe post hoc (p = 0.05). Pearson's coefficient of correlation (r).	The acute patients self-perceive higher levels of anxiety in relation to the control group; Acute pain is often coupled with anxiety. Patients suffering from the TMD's exhibit higher levels of anxiety compared to the healthy ones.
Monteiro et al. (47) Brazil Cross-sectional	São Paulo State University, Sagrado Coracão University and Thathi COC University	TMJ Disorders:49 Controls: 101	Mean age for TMJ disorders and controls: 17–30 years	Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD)	Spielberger's Trait–State Anxiety Inventory (STAI-T and S).	Chi-square test p < 0.05	The correlation between trait-anxiety levels and chronic orofacial pain degrees was significant and positive (p = 0.0154; p < 0.05).
Bezerra et al. (48) Brazil Cross-sectional	Center of Biological and Health Sciences (CCBS), University of Paraíba (UEPB), in Campina Grande	TMJ Disorders: 210 Controls: 126	Mean age for TMJ disorders and controls: 18–38 years	DMF Anamnestic Index	Anamnesis Index and the State-Trait Anxiety Inventory (IDATE).	Pearson's Chi-square Fisher Exact tests Confidence interval 95%	It was observed a higher prevalence of anxiety of moderate/high level for TMD individuals and of low level for TMD free individual.
Boscato et al. (49) Brazil Cross-sectional	Individuals in the Midwest region of Santa Catarina, a developed state of Brazil	TMJ Disorders: 247 Controls: 321	Mean age for TMJ disorders and controls: 35–74 years	Clinical examination	Hospital Anxiety and Depression Scale (HADS) (Seven itens for anxiety (HADSa)	Chi-squared test Poisson regression P ≤ 0.05	TMD occurrence increased with the anxiety level (P = 0.001). Women had a higher risk of presenting TMD, as well as individuals with mild and high levels of anxiety. that there is an increased risk of TMD in women and
							individuals with higher levels of anxiety. Strong association between TMD and psychological factors as higher levels of anxiety resulted in moderate and severe TMD with statistically significant difference.
Smriti et al. (50) India Cross-sectional	VSPM's Dental College	TMJ Disorders: 28 Controls: 122	Mean age for TMJ disorders and controls: 18–25 years	Self-administered anamnestic questionnaire (modified version of Helkimo's anamnestic index)	Zung self-rating scale	Chi-square	This study has a statistically significant association between TMD degree and anxiety.
Lemos et al. (51) Brazil Cross-sectional	Academics of undergraduate course in Dentistry of a public university in northeastern Brazil	TMJ Disorders: 50 Controls: 85	Mean age for TMJ disorders and controls: 18–25 years	Adapted anamnestic questionnaire; Clinical examination	Hospital Anxiety and Depression Scale (HADS)	Chi-square Fisher's exact test p < 0,05	In the sample evaluated, anxiety was associated with jaw locking (p = 0.031), fatigue during chewing (p = 0.025) and difficulty moving the jaw (p = 0.031).
de Oliveira et al. (52) Brazil Cross-sectional	Medical University Hospital of the Federal University of Uberlândia	TMJ Disorders: 125 Controls: 41	Mean age for TMJ disorders and controls: ≥18 years	Fonseca's questionnaire	Anamnesis Index and the State-Trait Anxiety Inventory (IDATE).	Chi-square tests via Monte Carlo simulation (p = 0.142)	Chi-square test indicates that TMD severity is independent of the trait anxiety. However, TMD severity is associated with the severity of state anxiety (p = 0.0410)
Yu et al. (53) China Cross-sectional	Pilots from Shenzhen Airlines	TMJ Disorders: 205 Controls: 411	Mean age for TMJ disorders and controls: 31.4 ± 5.9	Clinical examination contained TMD screening per Research Diagnostic Criteria for TMD (RDC/TMD).	Trait Anxiety section of Spielberger State-Trait Anxiety Inventory (STAI-T).	Kruskal–Wallis; Chi-square test and multiple logistic regression models p ≤ 0.05	The STAI-T score in TMD group was significantly higher compared with non-TMD. Thus, subjects with higher anxiety were more likely suffering from TMD.
Schmidt et al. (54) Brazil Case-control	Dental Clinic in the interior on the state of Rio Grande do Sul	TMJ Disorders: 20 Controls: 20	Mean age for TMJ disorders and controls: ≥18 years	TMD diagnosis performed through the specialized dental team	Young Schemes Questionnaire–reduced form (YSQ–S2), Beck Anxiety Questionnary (BAI):	Mann-Whitney e Wilcoxon p = 0.05	The statistics showed significant differences between the presence of more anxiety symptoms in the group with DTM, by applying the Mann-Whitney and Wilcoxon (p = 0.0191). Based on the findings of this study, it is clear that, despite being a maxillofacial pathology, TMD is inevitably associated with psychological factors such as anxiety.
Reissmann et al. (17) Germany Case-control	Departament of prosthodontics and materials science, University of Leipzig. Departament of prosthodontics, Martin Luther University Halle-	TMJ Disorders: 320 Controls: 888	Mean age for TMJ Disorders: 39.4 ± 15.4 Mean age for Controls: 40.4 ± 11.8	German version of Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD)	State-Trait Anxiety Inventory (STAI)	Logistic regression analysis Students' t-test	Trait anxiety was more pronounced in TMD patients than in controls (t test: p < 0.001). The patient's trait anxiety was more often classified as moderate or severe. In the logistic regression analysis, a one-point increase in STAI-Trait summary scores resulted in 1.04–fold higher odds of having pain-related TMD (p < 0.001) compared to controls.
Sójka et al. (55) Poland Cross-sectional	Poznań University of Medical Sciences	TMJ Disorders: 90 Controls: 181	Mean age for TMJ disorders and controls: 21.28 (35–37, 39–42, 44, 45, 47–49, 53, 55, 56) years	Diagnostic Criteria for Temporomandibular disorders axis I (DC/TMD)	Four-Dimensional Questionnaire (4DSQ); Sense of coherence orientation to life questionnaire	Spearman rho correlation and Mann-Whitney P < 0.05	About one-third of the students in this study presented symptoms of TMD and perceived more intensively symptoms of anxiety.
Staniszewski et al. (56) Norway Case-control	National TMD project in Bergen, Norway	TMJ Disorders: 44 Controls: 44	Mean age for TMJ Disorders: 44 Mean age for Controls: 46	Investigation of the severity and duration of symptoms, both for pain and dysfunction, analyzing pain intensity and duration, and functional impairment (general and jaw-specific).	Hospital Anxiety and Depression Scale (HADS) and a 2-item version of the Coping Strategies Questionnaire.	Wilcoxon signed rank test; linear multiregression between; and linear correlation P < 0.05	Anxiety scores and pain catastrophizing scores were significantly higher in the TMD group compared to Controls.
Tay et al. (6) Singapore Cross-sectional	Military dental centers of Singapore Armed Forces (SAF).	TMJ Disorders: 742 Controls: 1,301	Mean age for TMJ disorders and controls: 24.18 ± 7.18 years	Research Diagnostic Criteria for TMD (RDC/TMD) Symptom Questionnaire (SQ) to assess pain characteristics, history of headaches, jaw joint noises as well as closed / open jaw locking in the past 30 days.	The Depression, Anxiety and Stress Scale-21 (DASS-21).	Spearman correlation test p < 0.05	Specific type and number of TMD symptoms impacted OHRQoL and psychological states differently. Associations between number of TMD symptoms and quality of life, depression, anxiety and stress were significant but weak.
Bastos et al. (5) Brazil Case-control	Department of Dentistry of the Federal University of Rio Grande do Norte (UFRN), Natal, Brazil	TMJ Disorders: 60 Controls: 60	Mean age for TMJ disorders and controls: 33.29 ± 13.68 years	Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD)	Anxiety (Beck Anxiety Inventory [BAI]; the State-Trait Anxiety Inventory [STAI-S and -T]; the Hospital Anxiety and Depression Scale [HADS])	X2 test Student t test Odds ratio (OR) analysis Non-conditional logistic regression	Anxiety was observed by a higher percentage of TMD participants (75 percent; p < 0.001) in the HADS test. According to STAI-S and -T, the majority of TMD patients experienced anxiety (55.6%). In terms of BAI, the majority of anxious people had TMDs (63.9%).
do Patrocinio et al. (7) Brazil Cross-sectional	Dental students at the Federal University of Campina Grande, Patos, Brazil.	TMJ Disorders: 144 Controls: 41	Mean age for TMJ disorders and controls: 21.4 (18–38) years	Fonseca's questionnaire	The State-Trait Anxiety Inventory [STAI-S and -T];	Chi-square Fisher exact P = 0.05	Statistical analysis revealed that the presence or absence of TMJ dysfunction had no effect on state (p = 0.297) or trait anxiety (p = 0.484). In terms of anxiety-related outcomes, it was discovered that most undergraduates had moderate state-anxiety based on the results of the State-Trait Anxiety Inventory - STAI.
Nguyen et al. (16) Vietnam Cross-sectional	Participants were randomly selected based on sex and residence living in Danang, Vietnam.	TMJ Disorders:75 Controls: 104	Mean age for TMJ disorders and controls: 65–74 years	Orthopantomography set at 73 kV, 10 mA, and 17.6 s with a CC-detector sensor (Soredex Cranex D, Tuusula, Finland).	Self-reported 7-item Generalized Anxiety Disorder Scale (GAD-7)	SPSS Kruskal-Wallis test Spearman's test P < 0.05	Positive correlations were found between limitation of mandibular function and anxiety (r = 0.304, p < 0.001). TMJ osseous changes were not correlated with anxiety.