Table 1 Basic information of non-extraction and extraction groups

Age (y)

26.97 ± 6.96

27 (10)

0.399^a

Initial crowding (mm)

1.23 ± 2.02

1.68 (3.39)

0.188^a

Overbite (mm)

3.13 ± 2.14

1.61 ± 1.68

0.004^b*

Overjet (mm)

3.62 ± 2.19

3.46 ± 1.68

0.757^b

Gender

1.000^c

 Female

22

21

 Male

8

9

Angle classification

0.174^c

 Class I

15

21

 Class II

14

7

 Class III

1

2

Sagittal skeletal classification

0.042^c*

 Class I

22

13

 Class II

5

13

 Class III

3

4

Vertical skeletal pattern

0.037^c*

 Hypodivergent

14

11

 Normodivergent

16

13

 Hyperdivergent

0

6