Table 2.

Risk of Bias table. “+” low risk of bias; “?” some concerns; “-” high risk of bias.

First Author, Year	1	2	3	4	5	6
Asgari 2018 [37]	+	?	+	+	+	?
Beckwee 2017 [41]	?	+	+	+	+	?
Benedetti 1997 [66]	?	?	+	+	+	?
Bjersa 2014 [62]	+	?	+	+	+	?
Bjersa 2015 [38]	+	?	+	+	+	?
Chen 2021 [55]	?	?	+	+	+	?
Chiu 1999 [42]	+	?	+	+	+	?
Cuschieri 1985 [63]	?	+	+	+	+	?
da Silva 2015 [35]	+	?	?	+	+	?
Elboim-Gabyzon 2019 [43]	+	+	+	+	+	+
Engen 2015 [44]	?	?	+	+	+	?
Erden 2022 [45]	+	+	-	-	+	+
Erden 2016 [36]	+	?	+	+	+	?
Erdogan 2005 [46]	?	+	+	+	+	?
Ferreira 2011 [40]	?	?	+	+	+	?
Fiorelli 2011 [2]	+	+	+	+	+	+
Forogh 2017 [56]	+	+	+	+	+	+
Galli 2015 [57]	+	+	+	+	+	+
Gregorini 2010 [58]	+	?	+	+	+	?
Hamza 1999 [67]	+	?	?	+	+	?
Ilfeld 2021 [34]	+	+	+	+	+	+
Jahangirifard 2018 [61]	?	+	+	+	+	?
Kara 2011 [48]	+	?	+	+	+	?
Kurata 2022 [47]	+	+	+	+	+	+
Laitinen 1991 [68]	?	?	+	+	+	?
Lima 2011 [39]	-	?	?	?	?	-
Mahure 2017 [59]	+	?	+	?	+	?
McCallum 1988 [64]	?	+	+	+	+	?
Navarathnam 1984 [65]	?	?	+	+	+	?
Parseliunas 2020 [49]	+	+	+	+	+	+
Rakel 2003 [60]	?	?	+	+	+	?
Sezen 2017 [50]	?	?	+	+	+	?
Silva 2012 [13]	+	?	+	+	+	?
Smedley 1988 [51]	+	?	+	+	+	?
Solak 2007 [69]	?	?	+	+	+	?
Stubbing 1988 [70]	?	?	+	+	+	?
Wang 2014	+	+	+	+	+	+
Yu 2020 [52]	+	+	+	+	+	+
Zhang 2017 [53]	+	?	+	+	+	?
Zhang 2018 [54]	?	?	+	+	+	?

1. Risk of bias arising from the randomization process. 2. Risk of bias arising from deviations from the intended interventions. 3. Risk of bias arising from missing outcome data. 4. Risk of bias arising from the measurement of the outcome. 5. Risk of bias arising from the selection of the reported results. 6. Overall risk of bias.