Depth

Age range

Test control

5 - 20 years

20 - 35 years

35 - 50 years

50 years and over

10 cm

13.73 ± 1.48

31.38 ± 1.13***

28.02 ± 0.96***

31.15 ± 0.41***

21.30 ± 1.62**^aα

20 cm

12.82 ± 1.59

26.32 ± 1.47***

25.08 ± 0.85***^b

27.91 ± 0.77***^c

18.37 ± 0.84*^α

30 cm

14.36 ± 1.00

17.79 ± 1.51*

23.16 ± 0.31*** ^a

20.96 ± 0.80**^β

16.40 ± 1.11^γ