Table 3: Risk of bias in the included studies.
| Study | Bias | Authors' judgement | Support for judgement |
| McMillan, et al. [15] | Random sequence Generation (selection bias) | Unclear risk |
Q: "Subjects were randomly assigned to one of the experimental treatment groups. A, B, or C, which were stratified by age" C: No information is provided on how the random sequence was generated |
| Allocation concealment (selection bias) | Unclear risk | No information is provided on how allocation was concealed | |
| Blinding of participants and personnel (performance bias) | Low risk | Double dummy design was used | |
| Blinding of outcome assessment (detection bias) | Low risk | The other clinician (ASM), who conducted all pain measurements was not present during the trigger point location process and was blinded to patient symptoms and treatment | |
| Incomplete outcome data (attrition bias) | Low risk | No withdrawals from the study. | |
| Selective reporting (reporting bias) | Unclear risk | All outcomes have been reported but the author did not report more important patient relevant outcomes such as mastication efficiency and quality of life. | |
| Other bias | Low risk | None | |
| Venancio, et al. [47] | Random sequence generation(selection bias) | Low risk | Q: "The patients were divided into three groups by random draw" |
| Allocation concealment (selection bias) | Unclear risk | No information is provided on how the allocation is concealed. | |
| Blinding of participants and personnel (performance bias) | High risk | The study did not report blinding, however blinding is not possible due to the nature of the intervention, but we judge the risk of bias as high due to the outcomes being subjective and are likely to be influenced by lack of blinding. | |
| Blinding of outcome assessment (detection bias) | High risk | The study did not report blinding, however, blinding is not possible due to the nature of the intervention, but we judge the risk of bias as high due to the outcomes being subjective and are likely to be influenced by lack of blinding. | |
| Incomplete outcome data (attrition bias) | Low risk | Q: "Only one patient abandoned treatment due to a back problem" | |
| Selective reporting (reporting bias) | High risk | Data on pain duration and frequency are not reported. The author did not report more important patient relevant outcomes such as mastication efficiency and quality of life. |