“…All the studies were cross-sectional. When classifying articles according to dentition, 4 of them investigated primary dentition [Trikaliotis et al, 2011;Norberg et al, 2012;Bagherian and Sadeghi, 2013;Pikramenou et al, 2016], 6 investigated mixed dentition [Willerhausen et al, 2007;Costacurta et al, 2011;Subramaniam and Singh, 2011;Elangovan et al, 2012;Shahraki et al, 2013;Liang et al, 2016], and the remaining 4 investigated permanent dentition [Narksawat et al, 2009;Sadeghi et al, 2011;Frias-Bulhosa et al, 2015;Denloye et al, 2016]. Of the 6 studies investigating mixed dentition, 4 calculated both primary and permanent teeth [Willerhausen et al, 2007;Costacurta et al, 2011;Subramaniam and Singh, 2011;Elangovan et al, 2012], while 1 just calculated primary teeth [Liang et al, 2016] and the remaining 1 calculated permanent teeth only [Shahraki et al, 2013].…”