Donnell 2015

Methods	Parallel RCT
Participants	Country of study: USA Setting: laboratory Condition: chronic temperomandibular disorder Prior management details: pain not adequately controlled by previous therapies for more than 1 year n = 24 Age range, mean (SD): active group 34.8 (13.7) years, sham group 35.6 (16.7) years Duration of symptoms: not reported Gender distribution: all F
Interventions	Stimulation type: HD‐tDCS Stimulation parameters: intensity 2 mA, 4 electrodes arranged at the corners of a 4 x 4 cm square centred over M1 Stimulation location: anode ‐ M1 contralateral to painful side Number of treatments: daily, x 5 Control type: sham tDCS
Outcomes	Primary: pain VAS; anchors not reported ‐ responder analysis only reported When taken: 1‐month follow‐up Secondary: AEs
Notes	Sources of funding: this project was funded by grants from the American Academy of Orofacial Pain and the University of Michigan Rackham Graduate School. Potential undisclosed COI: 1 study author (Biksom) worked for stimulation device manufacturer Soterix
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote “participants were randomized to the treatment or placebo group using the Taves covariate adaptive randomization method.”
Allocation concealment (selection bias)	Unclear risk	Comment: no mention of allocation concealment procedures
Adequate blinding of participants?	Unclear risk	Comment: 2 mA intensity. Evidence that blinding can be inadequate at intensity of 2 mA
Adequate blinding of assessors?	High risk	Comment: study described as single blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: no participant dropout
Selective reporting (reporting bias)	High risk	Comment: pain outcomes not presented for all follow‐up time points
Study Size	High risk	n = 24
Study duration	Unclear risk	1‐month follow‐up postintervention
Other bias	Low risk	Comment: no other bias detected