Table 2 Evaluation of included studies according to revised tool for assessing risk of bias in randomized trials (RoB 2)
Bovali et al. 2014 [24] | Gunay et al. 2016 [25] | Bolla et al. 2011 [26] | Årtun et al. 1997 [27] | Nagani et al. 2020 [28] | Bazargani et al. 2012 [29] | |
Random sequence generation | LOW | SOME CONCERNS | SOME CONCERNS | HIGH | LOW | LOW |
Allocation concealment | LOW | LOW | HIGH | LOW | LOW | SOME CONCERNS |
Blinding of participants and personnel | HIGH | HIGH | HIGH | HIGH | HIGH | HIGH |
Blinding of outcome assessment | LOW | HIGH | HIGH | HIGH | HIGH | LOW |
Incomplete outcome data | LOW | LOW | LOW | LOW | LOW | LOW |
Selective reporting | LOW | SOME CONCERNS | LOW | HIGH | LOW | LOW |
Other bias (why) | Indirect reteiners were bonded with chemical curing, direct ones – with light curing, which may both influence chairtime and survival rate. | Extraction had longer reteiners (to premolars) | Uneven no. of participants study groups. Different bonding materials were used. | Clinical procedures were performed by different clinicians. The study group has been expanded from an earlier study. | In case if detachment of retainer was noticed during the visit, the subject was allowed to approach immediately for repair and bond failure was recorded in the upcoming visit. | NONE |
Risk of bias judgement | LOW | SOME CONCERNS | HIGH | HIGH | SOME CONCERNS | LOW |
Salehi et al. 2013 [30] | Arash et al. 2020 [31] | Scribante et al. 2011 [32] | Rose et al. 2002 [33] | Gelin et al. 2020 [34] | Kartal et al. 2020 [35] | |
Random sequence generation | LOW | HIGH | SOME CONCERNS | SOME CONCERNS | LOW | LOW |
Allocation concealment | LOW | SOME CONCERNS | SOME CONCERNS | SOME CONCERNS | LOW | LOW |
Blinding of participants and personnel | HIGH | HIGH | HIGH | HIGH | HIGH | HIGH |
Blinding of outcome assessment | SOME CONCERNS | SOME CONCERNS | HIGH | SOME CONCERNS | SOME CONCERNS | HIGH |
Incomplete outcome data | LOW | SOME CONCERNS | LOW | LOW | LOW | LOW |
Selective reporting | LOW | SOME CONCERNS | SOME CONCERNS | SOME CONCERNS | LOW | LOW |
Other bias (why) | The study included patients during growth period. | The study included patients during growth period. Regression analysis was performed for statistically non-significant results. | No sample size calculation. | The study included patients during growth period. No data concerning drop-out is reported. | NONE | Patient’s age was not provided. |
Risk of bias judgement | SOME CONCERNS | HIGH | HIGH | HIGH | LOW | LOW |
Scribante et al. 2020 [36] | Sfondrini et al. 2014 [37] | Sobouti et al. 2016 [38] | ||||
Random sequence generation | SOME CONCERNS | LOW | LOW | |||
Allocation concealment | LOW | LOW | LOW | |||
Blinding of participants and personnel | HIGH | HIGH | HIGH | |||
Blinding of outcome assessment | LOW | SOME CONCERNS | SOME CONCERNS | |||
Incomplete outcome data | LOW | LOW | LOW | |||
Selective reporting | LOW | LOW | LOW | |||
Other bias (why) | NONE | NONE | ||||
Risk of bias judgement | LOW | LOW | SOME CONCERNS | |||