Table 2 Mean values with standard deviations and 95% confidence intervals (CI) of dimensional dental casts variables at T0 and T1 achieved with the extrusion arch mechanics with mean differences^a

Arch Perimeter

78.66

4.84

75.63

5.86

− 3.02

3.07

− 4.79

− 1.25

.003*

Arch Length

29.07

2.46

26.84

2.92

− 2.23

1.85

− 4.79

− 1.16

.001*

Overjet

4.89

2.01

3.24

1.47

− 1.65

1.75

− 2.65

− 0.64

.004*

Overbite

− 1.28

1.46

1.79

1.23

3.07

1.57

− 2.17

− 3.97

< .0001*

Mesial intermolar distance

51.65

3.08

51.31

2.85

− 0.33

0.90

− 0.85

0.18

.188

Distal intermolar distance

55.05

3.49

54.69

3.66

− 0.36

1.08

− 0.98

0.27

.239

Incisors clinical crown height

9.11

0.74

9.44

0.92

0.33

0.64

− 0.08

0.58

.011*