Table 3.

Risk of bias assessed for different studies

Author, year	Was there adequate randomization?	Were baseline conditions similar for different groups? (according to brands or being as-received or retrieved aligners)	Were baseline conditions similar for different groups?	Were experimental procedures similar for different groups?	Were operators blinded of grouping?	Were outcome data complete without missing?	Were all measured outcomes adequately reported?	Were there any reports of outcomes that were not adequately explained in methods?	Any other inconsistencyor source of bias
Schusteretal., (2004)	Yes	No	?	Yes	Yes	Yes	Yes	No	No
Eliadesetal., (2009)	Yes	Yes	?	No	?	Yes	Yes	No	No
Graccoetal., (2009)	Yes	No	?	No	?	Yes	Yes	No	No
Kopperud(2011)	Yes	No	No	Yes	No	Yes	Yes	No	No
Ansarietal.,(2014)	?a	No	?	Yes	?	Yes	Yes	Yes	No
Kotykaetal.,(2014)	Yes	No	?	Yes	?	Yes	Yes	No	No
Premarajetal.,(2014)	?	Yes	?	No	?	Yes	Yes	No	No
Bradleyetal.,(2015)	?	No	?	Yes	?	Yes	Yes	No	No
Afraz Walele(2016)	?	No	?	Yes	Yes	Yes	Yes	No	No
Raghavanetal.,(2017)	Yes	No	?	No	?	Yes	Yes	No	No
Al Naghbietal.,(2018)	Yes	No	?	No	?	Yes	Yes	No	No
Martinaetal.,(2019)	?	No	?	Yes	Yes	Yes	Yes	No	No
Fayyaz Ahmadetal.,(2020)	?	No	?	Yes	?	Yes	Yes	No	No
Nemecetal.,(2020)	?	No	?	No	?	Yes	Yes	No	No
El idrissietal.,(2020)	Yes	No	?	Yes	Yes	Yes	Yes	No	No
Katras(2021)	Yes	No	?	Yes	Yes	Yes	Yes	No	No

aNot explicitly stated, but it appears to be this way from the explanations. ?: Not explicitly given