Table 2.

Newcastle-Ottawa scale for assessing quality of non-randomized studies categorized as low-quality (0 - 3 stars), moderate quality (4 - 6 stars), and high quality (7 - 9 stars)

Study	Year of publication	Selection (maximum 4 stars)	Comparability (maximum 2 stars)	Outcome (maximum 3 stars)	Total score/ quality
Misch et al [24]	1997	★★★★	★★	☆★☆	7 stars/high quality
Cordaro et al. [25]	2002	★★★★	★★	☆★☆	7 stars/high quality
Clavero et al. [26]	2003	★★★★	★★	☆★☆	7 stars/high quality
Silva et al. [27]	2006	★★★★	★★	☆★☆	7 stars/high quality
Raghoebar et al. [28]	2007	★★★★	★★	☆★☆	7 stars/high quality
Andersson et al. [29]	2008	★★★★	★★	☆★☆	7 stars/high quality
Cordaro et al. [30]	2011	★★★★	★★	★★★	9 stars/high quality
Altiparmak et al. [31]	2015	★★★★	★★	☆★☆	7 stars/high quality
Ersanli et al. [32]	2016	★★★★	★★	☆★☆	7 stars/high quality
Pereira et al. [33]	2019	★★★★	★★	☆★☆	7 stars/high quality