Table 4. Masking ability of the zirconia specimens on the opaque porcelain sintered Co-Cr alloy substrate.

		Thickness (mm)
		0.7	1.0	1.2	1.5
Shade of zirconia	1M1	Ta<Yb	Ta<Yb<Wc	Ya < Wb < Tc < Oc < Bd	Wa = Ba < Ta < Ob < Yc
	1M2	Ba < Wa < Yb < Oc < Td	oa < bb < Wc < Yd < Te	ba < Ob < Wc < Yd < Te	oa < wb < yc < Tc < Bd
	2M1	Oa < Wb < Yc	Wa < Ta < Oa < Yb < Bc	wa = oa < bb < Yc < Tc	oa < wa = ya < Bb < Tc
	2M2	Ba < Ta	Oa < Yb < Wc < Tc,d < Bd	oa < wb < Tc < Yd < Be	oa < yb < wc < td < Be
	2M3		Oa < Bb < Tc < Wc < Yd	Ba < Wa < Tb < Ob < Yc	Oa < Bb < Wc < Tc < Yd
	3M2	oa < Wb < Bc < Td < Ye	wa < ba < yb < Tc < Od	Wa < Yb < Bc < Td < Oe	ba < wb < yc < td < oe
	4M2	wa < tb < yc < Bd < Oe	ba < wa,b < yb < oc < td	wa < tb < yb < oc < bc	ya < wb < tc < bd < oe
	5M2	Wa = Ya < Oa < Ba < Tb	Ba < Ta < Oa < Yb < Wb	wa < ta < bb < Yb < Oc	ta < Ba < Oa < Wb < Yc

^*W(w), Y(y), T(t), B(b) and O(o), respectively, represent the ΔE values of different groups using try-in pastes in shades of white, yellow, transparent, bleach and opaque; Capital letters (W, Y, T, B, O) mean 2.6 ≤ ΔE < 5.5; Lowercases (w, y, t, b, o) mean ΔE < 2.6; Same superscripts represent no statistical difference between the groups.