Study Year of
publication 		Study design Selection Comparability Outcome/exposure Score
Alsaadi et al. [4] 2008 Cohort ★☆☆★ ☆☆ ☆★★ 4/9
Mozzati et al. [5] 2021 Cohort ☆☆☆★ ☆☆ ☆★☆ 2/9
Oczakir et al. [6] 2005 Cohort ☆☆☆★ ☆☆ ☆★★ 3/9
Petsinis et al. [7] 2017 Cohort ★☆☆★ ☆☆ ☆★☆ 3/9
Isidor et al. [14] 1999 Cohort ★☆★★ ☆☆ ☆★★ 5/9
Bertl et al. [24] 2019 Cohort ☆☆☆★ ☆☆ ★★☆ 3/9
Aboushelib et al. [25] 2017 Cohort ★☆★★ ☆☆ ☆★★ 5/9
Alsaadi et al. [67] 2008 Cohort ★☆☆★ ☆☆ ☆★☆ 3/9
Anitua et al. [68] 2018 Cohort ★☆★★ ☆☆ ☆★☆ 4/9
Czerninski et al. [69] 2013 Cohort ★☆★★ ☆☆ ☆★☆ 4/9
Hasanoglu Erbasar et al. [70] 2019 Cohort ☆☆☆★ ☆☆ ☆★☆ 2/9
Krennmair et al. [71] 2010 Cohort ★☆★★ ☆☆ ☆★★ 5/9
Peñarrocha-Oltra et al. [72] 2020 Cohort ★☆★★ ☆☆ ★★☆ 5/9
Siddiqui et al. [73] 2017 Cohort ☆☆☆★ ☆☆ ☆★☆ 2/9
van Steenberghe et al. [74] 2002 Cohort ★☆☆★ ☆☆ ☆★☆ 3/9
Maló et al. [75] 2016 Cohort ★☆☆★ ☆☆ ★★★ 5/9
Nicoli et al. [76] 2017 Cohort ★☆☆★ ☆☆ ★★☆ 4/9
Agustín-Panadero et al. [77] 2019 Cohort ★☆☆★ ☆☆ ☆★★ 4/9
Chatzistavrianou et al. [78] 2016 Cohort ☆☆☆★ ☆☆ ☆★★ 3/9
Chrcanovic et al. [79] 2019 Cohort ★☆☆★ ☆☆ ☆★☆ 3/9
Esposito et al. [80] 2003 Cohort ★☆★★ ☆☆ ☆★★ 5/9
Payne et al. [81] 1997 Cohort ☆☆☆★ ☆☆ ☆★★ 3/9
Reichart [82] 2006 Cohort ☆☆☆★ ☆☆ ☆★★ 3/9
Corigliano et al. [83] 2014 Cohort ☆☆☆☆ ☆☆ ☆★☆ 1/9
Alenazi [84] 2021 Case-control ★★☆★ ★★ ★☆☆ 6/9
Hernández et al. [85] 2012 Case-control ★★★★ ★★ ★☆★ 8/9
Khamis al. [86] 2019 Case-control ☆★☆☆ ☆☆ ★☆★ 3/9
Korfage et al. [87] 2016 Case-control ★★☆★ ★★ ★☆☆ 6/9
López-Jornet et al. [88] 2014 Case-control ★★☆★ ☆★ ★☆★ 6/9
Attard et al. [89] 2002 Case-control ☆★☆☆ ★★ ★☆☆ 4/9

0 to 3 stars = low-quality; 4 to 6 stars = medium quality; 7 to 9 stars = high quality.