Table 2 General information of recruited studies

Blake et al. (1995) [20]

CCT

S:n = 30(M12,F18;12.8 ± 2.3y)

N:n = 33(M16,F17;13 ± 2.5y)

SL bracket (Speed, Strite inductries) vs non-SL bracket

Root resorption in percentage (periapical radiograph)

(11,21),(12,22),(13,23),(14,24)

S:20.9 ± 4.36 month

N:20.6 ± 4.6 month

Scott et al. (2008) [21]

RCT

S:n = 32 (M12, F20;16.19 ± 3.68y)

N:n = 28 (M19, F9; 16.38 ± 5.28y)

SL brackets vs non-SL bracket (Synthesis, Ormco)

Root resorption in millimeter (periapical radiograph)

Mandibular right central incisor

S:8.5 ± 2.1 month

N:8.1 ± 2.7 month

Pandis et al. (2008) [22]

Cohort study

S:n = 48(M17,F31;13.29 ± 1.57y)

N:n = 48(M12,F36;13.14 ± 1.73y)

SL bracket (Damon2, Ormco) vs Non-SL bracket (Microarch, GAC)

Root resorption in millimeter (panoramic radiographs)

Maxillary incisors

S:26.89 ± 5.94 month

N:25.97 ± 6.65 month

Leite et al. (2012) [17]

CCT

n = 19(20.6y,min11,max30) S:n = 11(M6,F5) L:n = 8(M2,F6)

SL bracket (EasyClip) vs non-SL bracket (3 M)

Root resorption in millimeter (CBCT)

(11,21),(12,22),(13,23),(14,24)

6 month

Liu et al. (2012) [18]

Cohort study

S:n = 35(M7,F8;15.13y)

L:n = 35(M9,F6;14.93y)

SL bracket (Damon3, Ormco) vs non-SL bracket

Root resorption in millimeter (periapical radiographs)

(11,21),(12,22),(13,23),(14,24)

S:20.4 ± 5.04 month

N:16.8 ± 2.66 month

Jacobs et al. (2014) [23]

Cohort study

S:n = 139(M56,F83;12.6 ± 2.3y)

L:n = 74(M23,F51;12.1 ± 2.2y)

SL bracket (SmartClip 3 M) vs non-SL bracket (Victory,3 M)

Root resorption in percentage (panoramic radiographs)

Maxillary and mandibular incisors

S:20.7 ± 4.9 month

N:18.1 ± 5.3 month

Chen et al. (2015) [19]

Cohort study

S:n = 35(M17,F18;13.52 ± 2.84y)

L:n = 35(M16,F19;13.42 ± 2.50y)

SL bracket (Damon3, Ormco) vs Non-SL bracket (3 M)

Root resorption in millimeter (periapical radiographs)

(11,21),(12,22),(13,23),(14,24)

S:20.53 ± 3.62 month

N:20.34 ± 3.40 month