Association between Stress at Work and Temporomandibular Disorders: A Systematic Review

Table 2

The analysis of certainty of the evidence. Imported from GRADEpro Guideline Development Tool (GDT) (https://gdt.gradepro.org/app/#projects).

Certainty assessment							Impact	Certainty	Importance
No. of studies	Study design	Risk of bias	Inconsistency	Indirectness	Imprecision	Other considerations
12	Observational studies	Very serious^a	Very serious^b	Very serious^c	Not serious	Publication bias strongly suspected^d	Seven studies found an association between stress and DTM or TMD signs and symptoms, and five studies found no association.	⨁◯◯◯; Very low

CI: confidence interval. ^aTwelve studies did not adjust for the confounders. Observational studies are at risk of bias because of differences in prognosis in exposed and unexposed populations (Guyatt et al., 2011//guidelines 4). ^bThere was great heterogeneity of instruments used for stress and TMD: 7 out of 12 studies used nonvalidated scales for stress (Nishiyama et al., 2012; Perelman et al., 2015; Saruhanoğlu et al., 2016; Han et al., 2018; M G et al., 2018; van Selms et al., 2019; van Selms et al., 2020) and 2 for TMD (Rantala et al., 2003; M G et al., 2018). Overall, only 3 articles employed valid instruments for both stress and TMD (Tay et al., 2019; Amorim and Jorge, 2016; Amalina et al., 2018). There was inconsistency among study findings: seven of selected articles found an association between TMD or TMD signs and symptoms and stress (Rantala et al., 2003; Perelman et al., 2015; Amorim and Jorge, 2016; Han et al., 2018; M G et al., 2018; Tay et al., 2019; van Selms et al., 2020), and 5 did not find an association (Nishiyama et al., 2012; Martins et al., 2016; Amalina et al., 2018; van Selms et al., 2019; van Selms et al., 2020). ^cThe evidence is from some types of categories of workers, with limited applicability to all workers. The majority of the evidence is from studies that evaluated stress in general, but not work stress (considered in only two studies: Amorim and Jorge (2016) and Amalina et al. (2018)). ^dObservational studies are more prone to publication bias than RCTs or clinical trials due to the nonmandatory registration in databases (Guyatt et al., 2011/guidelines 5).