Table 2 General characteristics of the studies included in the systematic review and meta-analysis

Heidari et al. 2022 [37]

cross-sectional

Split-mouth

8–10

(9.08 ± 0.58)

47

Maxilla(25)

Mandible(22)

Plaster casts

11.85 ± 5.81 m(6-24 m)

midline, molar and canine relationship, facial growth pattern, Canine’s inclination, space loss, crowding

Maxilla: 0.54

Mandible: 0.58

Mosharrafian et al. 2021 [13]

cross-sectional

Split-mouth

6–8

(7.30 ± 0.68)

50

Maxilla(25)

Mandible(25)

Plaster casts

13.54 ± 6.28 m

(6-24 m)

midline, molar and canine relationship, facial growth pattern, space loss, crowding

Maxilla: 1.32

Mandible: 1.40

Kobylńska et al. 2019 [36]

longitudinal study

Split-mouth

5–7

(6.64 ± 1.01)

44*

Maxilla(16)

Mandible(14)

Plaster casts

1,3,6,12 m

midline, inter-arch tooth alignment, Angle’s class, vertical bite, lateral teeth contact, radiological assessment, space loss

Maxilla: 1.156

Mandible: 1.000

Lin et al. 2017 [9]

longitudinal study

Split-mouth

5–7

(6.0 ± 0.42)

9

Maxilla(9)

Plaster casts

81 m

arch width, arch length, intercanine width, intercanine length, and arch perimeter, space loss

Not mentioned

Alexander et al. 2015 [34]

longitudinal study

Split-mouth

7.7–8.2

226

Maxilla(111)

Mandible(115)

Direct intraoral measurement

9 m

facial growth pattern, space loss

Maxilla:(Leptoprosopic/End-On:1.75 ± 0.31; Leptoprosopic/Class I:0.89 ± 0.16; Mesoprosopic/Euryprosopic/End-On:+0.07 ± 0.03; Mesoprosopic/Euryprosopic/Class I:+0.11 ± 0.05)

Mandible:(Leptoprosopic/End-On:1.38 ± 0.26; Leptoprosopic/Class I:1.71 ± 0.43; Mesoprosopic/Euryprosopic/End-On:1.59 ± 0.43;

Mesoprosopic/Euryprosopic/Class I:0.08 ± 0.04)

Lin et al. 2011 [15]

longitudinal study

Split-mouth

6–9

(6.0 ± 0.74)

13

Maxilla(13)

Plaster casts

12 m

arch width, arch length, intercanine width, intercanine length, arch perimeter, space loss

Maxilla: 0.82.

Macena et al. 2011 [33]

longitudinal study

Split-mouth

6–9

20

Maxilla (12)

Mandible (8)

Plaster casts

3、6、10 m

arch length, arch hemi- perimeter, space loss

Maxilla: 0.2^&

Mandible: 1.0^&

Park et al. 2009 [32]

cross-sectional

Split-mouth

5–10

13

Maxilla(13)

Digitized

plaster casts

12 m (8-23 m)

space loss, arch width, arch length, arch perimeter, the inclination and angulation

Maxilla: 0.57 ± 0.83

Kim et al. 2008 [35]

cross-sectional

Split-mouth

6–10

6

Maxilla(3)

Mandible(3)

Digitized

plaster casts

Maxilla: 15.3 m (6-23 m)

Mandible:

13.6 m (9-20 m)

space loss, arch width, arch length, arch perimeter, the inclination and angulation

Maxilla: 0.43

Mandible: 1.78

Lin et al. 2007 [31]

longitudinal study

Split-mouth

4–7

(5.9 ± 0.74)

19

Maxilla(19)

Plaster casts

6 m

arch width, arch length, intercanine width, intercanine length, and arch perimeter, space loss

Maxilla: 1.08

Padam et al. 2006 [30]

longitudinal study

Split-mouth

6–9

40**

Mandible(30)

Plaster casts

2、4、6、8 m

arch length, arch perimeter, arch width, space loss

Mandible: 1.83^&