Dehn Invariants of two space-filling tetrahedra

Question

Here are vertices for two space-filling tetrahedra.

$A = ((0, 0, 2),(0, 4, 2),(1, 2, 2),(2, 2, 0))$
$B = ((0, 3, 3),(1, 4, 2),(3, 2, 4),(1, 0, 2))$

Dihedral angles for A: {Pi/4, ArcCos[-(1/Sqrt[6])], Pi/6, ArcCos[-(1/Sqrt[6])], Pi/6, ArcCos[-2/3]}
Dihedral angles for B: {Pi/3, ArcCos[-1/(2 Sqrt[3])], ArcCos[1/(2 Sqrt[3])], Pi/3, Pi/2, Pi/6}

How do these end up producing Dehn Invariant 0?