Table 2 Means and standard deviations of CIE L*a*b* values of human enamel and dentine and of all ceramic materials and shades for the two different thicknesses analyzed

1

86.89 ± 3.56

− 1.22 ± 0.38^AB

7.57 ± 2.05^abcd

2

82.67 ± 6.70

− 0.92 ± 0.57^AB

12.78 ± 4.99^abcdef

1

65.61 ± 3.21^αβγ

− 2.35 ± 0.51

6.46 ± 2.34^aef

2

66.54 ± 4.35^αβγ

− 0.58 ± 1.21^ACDEF

12.08 ± 2.34^aghijk

1

70.29 ± 2.08

− 0.32 ± 0.48

11.00 ± 3.43^b

2

72.40 ± 2.98

0.23 ± 0.72^C

14.87 ± 4.05^bg

1

69.56 ± 2.49^α

− 0.24 ± 0.59

9.89 ± 3.55^ce

2

70.76 ± 3.30^α

0.32 ± 1.03^BD

12.83 ± 3.38^ch

1

73.31 ± 1.55

0.40 ± 0.71

12.54 ± 3.21

2

74.42 ± 2.14

1.28 ± 1.03

15.26 ± 3.19^di

1

67.07 ± 2.71^β

− 1.53 ± 0.50^A

8.46 ± 2.41^df

2

67.86 ± 2.92^β

− 0.10 ± 0.62^E

10.96 ± 1.80^ej

1

69.59 ± 3.70^γ

− 0.88 ± 0.89^B

10.48 ± 2.57

2

70.01 ± 3.58^γ

0.47 ± 0.96^F

13.04 ± 2.19^fk