Table 1 General characteristics of included studies and assessment of the risk of bias according to the Newcastle−Ottawa Scale (NOS)

Akturk et al, 2021 [39]

Turkey

NR

80

32.5%

University

Dental Class I (42)

Dental Classe II (38)

*

*

**

4

Amaral et al, 2019 [14]

Brazil

8 to 12 [NR]

200

45.0%

Schools

Dental Class I (100)

Dental Class II (100)

**

*

**

5

Brin et al, 2006 [43]

Israel and Turkey

7 to 17 [11.3]

221

41.6%

Orthodontic clinic

Skeletal Class I (41)

Maxillary class II (68)

Mandibular class II (112)

*

*

**

4

Celikoglu et al, 2011 [13]

Turkey

9 to 15 [12.51]

525

48.8%

University

Skeletal Class I (162)

Skeletal Class II (186)

Skeletal Class III (177)

****

*

*

6

Durka-Zając et al, 2017 [15]

Poland

9 to 12 [9.83]

150

50.0%

Orthodontic clinic

Skeletal Class I (50)

Skeletal Class II (50)

Skeletal Class III (50)

*

*

*

3

Esenlik, Atak and Altun, 2014 [31]

Turkey

7 to 15 [NR]

321

48.6%

University

Skeletal Class I (107)

Skeletal Class II (152)

Skeletal Class III (62)

***

**

**

7

Goncharuk-Khomyn et al, 2020 [42]

Ukraine

15 to 17 [NR]

61

NR

University

Class I (23)

Class II (19)

Class III (19)

**

*

*

4

Gottimukkala et al., 2012 [33]

India

9 to 12 [NR]

100

50.0%

Private schools

Vertical growth pattern (50)

Horizontal growth pattern (50)

*

*

*

3

Goyal et al, 2011 [34]

India

8 to 10 [NR]

150

50.0%

University

Normal growth pattern (50)

Vertical growth pattern (50)

Horizontal growth pattern (50)

**

*

*

4

Haruki, Kanomi and Shimono, 1997 [40]

Japan

NR

53

43.4%

Orthodontic clinic

Dental Class II (27)

Dental Class III (26)

**

**

4

Jamroz et al, 2006 [41]

Netherlands

9 to 12 [11.3±1]

176

NR

University

Vertical growth pattern (107)

Horizontal growth pattern (69)

***

*

**

6

Janson et al., 1998 [16]

Brazil

7 to 10 [9]

40

50.0%

University

Vertical growth pattern (20)

Horizontal growth pattern (20)

*

*

**

4

Jeong and Yang, 1996 [38]

South Korea

8 to 13 [10]

333

50.8%

University

Dental Class I (182)

Dental Class III (151)

*

**

*

4

Jo et al., 2021 [5]

South Korea

8 to 14 [NR]

184

52.2%

University

Normal growth pattern (93)

Vertical growth pattern (49)

Horizontal growth pattern (42)

***

*

**

6

Kamble et al., 2014 [35]

India

8 to 14 [NR]

60

NR

NR

Normal growth pattern (20)

Vertical growth pattern (20)

Horizontal growth pattern (20)

*

1

Lauc et al., 2017 [6]

Bosnia and Herzegovina

7 to 15 [NR]

776

47.4%

University

Skeletal Class I (284)

Skeletal Class II (218)

Skeletal Class III (274)

***

*

**

6

Mahmood and Fida, 2018 [36]

Pakistan

9 to 16 [NR]

270

50.0%

University

Dental Class I (100)

Dental Class II (100)

Dental Class III (70)

***

**

*

6

Neves et al, 2005 [30]

Brazil

8 to 8.92 [NR]

60

50.0%

University

Vertical growth pattern (30)

Horizontal growth pattern (30)

***

*

**

6

Sukhia and Fida, 2010 [37]

Pakistan

7 to 17 [NR]

264

42.0%

University

Normal growth pattern (88)

Vertical growth pattern (88)

Horizontal growth pattern (88)

Skeletal Class I (132)

Skeletal Class II (132)

****

*

**

7

Uysal, Yagci and Ramoglu, 2005 [32]

Turkey

8 to 13 [10.90±1.62]

101

52.5%

University

Dental Class I (50)

Unilateral posterior crossbite (51)

*

**

**

5