“…Of the 16 articles focusing only on Miller class III GRs, nine of them [ 7 , 31 , 35 , 38 , 39 , 57 , 61 , 62 , 64 ] treated single GRs, six studies [ 6 , 53 , 56 , 58 – 60 ] included multiple GRs, and one study [ 67 ] included single or multiple Miller class III GRs. In the rest of articles, different kind of GRs were treated: single Miller class I, II and III GRs were treated in nine studies [ 40 , 41 , 44 , 48 , 50 , 51 , 63 , 65 , 66 ], whereas multiple Miller class I, II, III and IV GRs were treated in five articles [ 45 , 46 , 52 , 54 , 68 ], and single and multiple Miller class I, II and III GRs were treated in other seven articles [ 14 , 42 , 43 , 46 , 47 , 49 , 55 ] (Table 2 ).…”