Table 4.

Influence of surface conditioning methods, thickness of ZrO₂ specimens, and the cement type on ΔL^∗, Δa^∗, Δb^∗, and ΔE₀₀ values.

Measure	Cement type	Zirconia thickness (mm)	Linear regression results
			R 2	Constant	Coefficient of regression
ΔE 00	PO	0.7	0.020	6.59	−0.037	p = 0.332
		1.0	0.038	5.29	0.038	p = 0.185
	PC	0.7	0.670	4.06	0.374	p  < 0.001
		1.0	0.636	2.65	0.357	p  < 0.001
ΔL ∗	PO	0.7	0.007	7.22	0.014	p = 0.561
		1.0	0.029	6.35	−0.019	p = 0.244
	PC	0.7	0.854	−6.30	0.187	p  < 0.001
		1.0	0.618	−5.07	0.149	p  < 0.001
Δa ∗	PO	0.7	0.072	−1.26	−0.009	p = 0.065
		1.0	0.025	−0.19	−0.009	p = 0.281
	PC	0.7	0.637	−2.09	0.094	p  < 0.001
		1.0	0.948	−2.28	0.104	p  < 0.001
Δb ∗	PO	0.7	0.006	4.66	0.006	p = 0.595
		1.0	0.039	5.75	0.020	p = 0.180
	PC	0.7	0.625	−9.66	0.161	p  < 0.001
		1.0	0.597	−8.63	0.108	p  < 0.001

Abbreviations: PC, translucent cement; PO, opaque cement.

For coefficients of regression differing significantly from zero, corresponding p-values are highlighted with bold font.