RESUMEN
BACKGROUND: The evidence on the relationship between anxiety and depression and patients with distinct subtypes of temporomandibular disorder (TMD) is uncertain, so a thorough review study on the topic is still missing. OBJECTIVES: This systematic review investigated the distribution and severity of anxiety and depression in patients diagnosed with different subtypes of TMD. METHODS: The study is registered in PROSPERO (CRD42020150562) and it followed the PRISMA 2020 Statement. We searched in PubMed, Web of Science, Scopus and SciELO databases (last search: 12 March 2021) and the reference list from the included studies. Study eligibility criteria consisted of: (i) patients diagnosed with TMD using the Research Diagnostic Criteria (RDC/TMD) or Diagnostic Criteria (DC/TMD) instruments; (ii) assessment of anxiety and/or depression with validated psychological instruments and (iii) allocation of patients into a minimum of two distinct TMD subtypes with at least one group having myofascial pain (comparison group). Analyses were carried out using RevMan 5.3.5 statistical package and random- or fixed-effects models (α = 0.05). The quality of evidence was assessed based on review authors' judgment derived from a 10-item appraisal tool for prevalence studies and with the Newcastle-Ottawa scale. RESULTS: Of the 4086 records identified in total, 24 were eligible for inclusion; meta-analyses were conducted with 20 studies. In total, 3678 subjects were included in the review. Most of the studies found that patients with myofascial pain showed similar occurrence and severity of anxiety/depression as compared to other subtypes of TMD, although the average prevalence seemed to be higher among the diagnoses consisting of myofascial pain (muscular TMD). Despite the moderate-to-high heterogeneity, anxiety and depression were more frequently distributed within patients with myofascial pain (p = .001). TMD patients without myofascial pain presented less severe levels of anxiety and depression than patients with only myofascial pain (p ≤ .01). The type of psychological instrument seems to affect the assessment of both anxiety and depression emotional states. CONCLUSION: The findings of this review suggest that patients with myofascial pain are more anxious and more depressed than patients with other subtypes of TMD. IMPLICATIONS: Considering that anxiety and depression are differently distributed within the TMD population, a proper assessment of the psychological state of patients seems essential to offer an adequate treatment and management of each specific subtype of TMD.