Table 2.

The Newcastle–Ottawa quality assessment scale

Study (author, year, ref.)	Selection	Comparability	Outcome
Shimazaki et al., 2007[26]	**	**	**
D'Aiuto et al., 2008[11]	****	**	**
Khader et al., 2008[27]	***	*	**
LI et al., 2009[29]	**	*	**
Morita et al., 2009[30]	**	*	**
Kushiyama et al., 2009[28]	*	**	**
Andriankaja et al., 2010[16]	***	**	**
Nesbitt et al., 2010[33]	**	*	*
Benguigui et al., 2010[31]	****	**	**
Han et al., 2010[32]	***	**	**
Timonen et al., 2010[34]	***	*	*
Bensley et al., 2011[35]	**	*	**
Kwon et al., 2011[13]	**	**	**
Chen et al., 2011[36]	**	**	*
Han, 2012[46]	**	**	**
Fukui et al., 2012[37]	***	**	***
Tu et al., 2013[40]	**	*	*
Sora et al., 2013[39]	***	**	***
Furuta et al., 2013[38]	****	*	**
Lamonte et al., 2014[41]	****	**	**
Thanakun et al., 2014[43]	**	*	*
Alhabashneh et al., 2015[44]	***	**	***
Minagawa et al., 2015[47]	***	**	**
Iwasaki et al., 2015[45]	**	**	**
Jaramillo et al., 2017[50]	***	**	**
Kumar et al., 2016[49]	***	**	***
Gomes-Filho et al., 2016[48]	***	**	***
Musskopf et al., 2017[52]	***	**	**
Kikui et al., 2017[51]	***	**	**
Kim et al., 2018[55]	***	**	**
Pham, 2018[57]	***	**	**
Koo and Hong, 2018[56]	**	**	**
Nascimento et al., 2018[62]	***	**	***
Abdalla-Aslan et al., 2019[60]	***	**	***
Kim et al., 2019[61]	***	**	**