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Table 2 Risk of bias of the included randomized clinical trials with the Cochrane risk of bias tool

From: What effect does functional appliance treatment have on the temporomandibular joint? A systematic review with meta-analysis

Trial Sequence generation Allocation concealment Blinding of participants/personnel Blinding of outcome assessors Incomplete outcome data Selective outcome reporting Other sources of bias
Arici et al. [39] Unclear—no randomization details provided information provided: “Thirty patients (17 girls, 13 boys) were randomly assigned to treatment with a fixed functional orthodontic appliance (Forsus nitinol flat-spring) for 6 to 9 months (mean, 7 months).” Unclear—no information provided. Unclear—blinding is impractical for both patients and clinician; outcome is objective, but was not assessed blindly. High risk—no mention of blinding throughout the paper; blinding could have been implemented. Low risk—no drop-outs or patient losses are reported. Unclear—it is difficult to judge whether selective reporting is a problem, as no protocol exists. Unclear—no definite issue identified (except for a possible confounder of vertical skeletal configuration type).
Cevidanes et al. [40, 41] Unclear—no randomization details provided: “The Class II subjects were randomly allocated to 2 subgroups, treated and control, to avoid bias in the group comparison.” Unclear—no information provided. Low risk—blinding is impractical for both patients and clinician; outcome is objective and was assessed blindly. Low risk—all images were coded and their order permutated to keep the analyst blind to subject identification group, and timing (T1 or T2). Low risk—no drop-outs or patient losses are reported. Unclear—it is difficult to judge whether selective reporting is a problem, as no protocol exists. Unclear—no definite issue identified (except for a possible confounder of vertical skeletal configuration type).
Franco et al. and Franco [47, 48] Unclear—no randomization details provided: “The sample was randomly dichotomized into 2 subgroups, treated subjects and untreated controls, to avoid bias in the group comparison.” Unclear—no information provided. Low risk—blinding is impractical for both patients and clinician; outcome is objective and was assessed blindly. Unclear—blinding is mentioned: “A double-blind procedure was used”. However, no details are given and this is not mentioned at all in study published subsequently as dissertation. Low risk—no drop-outs or patient losses are reported. Unclear—it is difficult to judge whether selective reporting is a problem, as no protocol exists. Unclear—no definite issue identified (except for a possible confounder of vertical skeletal configuration type).