Table 3.

Multiple linear regression analysis for percentage of output shades as outcome, considering both the veneer thickness and background shade as covariates.

Output Shade	Level	Coefficient	95% CI Lower	95% CI Upper	p-Value
A1
Veneer Thickness	0.50 mm	Reference
	0.75 mm	24.6619	21.6870	27.6369	<0.001
	1.00 mm	−8.6821	−11.657	−5.7071	<0.001
Background Shade	A1	Reference
	A2	−13.8000	−17.6169	−9.9831	<0.001
	A3	−10.7916	−14.6215	−6.9617	<0.001
	A3.5	−10.6049	−14.4482	−6.7617	<0.001
	A4	−11.9333	−15.7503	−8.1164	<0.001
A2
Veneer Thickness	0.50 mm	Reference
	0.75 mm	2.6793	2.0575	3.3011	<0.001
	1.00 mm	9.8073	9.1855	10.4291	<0.001
Background Shade	A1	Reference
	A2	2.173333	1.3755	2.9711	<0.001
	A3	2.043213	1.2427	2.8437	<0.001
	A3.5	0.224597	−0.5787	1.0279	0.583
	A4	0.253333	−0.5445	1.0511	0.533
B1
Veneer Thickness	0.50 mm	Reference
	0.75 mm	−48.8392	−50.9970	−46.6814	<0.001
	1.00 mm	−54.8312	−56.9890	−52.6734	<0.001
Background Shade	A1	Reference
	A2	3.4400	0.6715	6.2085	0.015
	A3	−0.8845	−3.6624	1.8933	0.532
	A3.5	4.5765	1.7889	7.3641	0.001
	A4	8.5867	5.8182	11.3552	0
B2
Veneer Thickness	0.5 mm	Reference
	0.75 mm	22.6229	20.1951	25.0507	<0.001
	1.00 mm	55.5749	53.1471	58.0027	<0.001
Background Shade	A1	Reference
	A2	3	−0.11491	6.1149	0.059
	A3	9.0195	5.8940	12.1449	<0.001
	A3.5	4.3956	1.2592	7.5320	0.006
	A4	1.5467	−1.5682	4.6616	0.329
B3
Veneer Thickness	0.50 mm	Reference
	0.75 mm	−0.1789	−0.2938	−0.0641	0.002
	1.00 mm	−0.1789	−0.2938	−0.0641	0.002
Background Shade	A1	Reference
	A2	0.1867	0.03932	0.33401	0.013
	A3	−0.0517	−0.1996	0.0961	0.492
	A3.5	−0.0501	−0.1984	0.0983	0.507
	A4	−0.0533	−0.2007	0.0940	0.477
B4
Veneer Thickness	0.50 mm	Reference
	0.75 mm	−0.4314	−0.6481	−0.2147	<0.001
	1.00 mm	−0.4714	−0.6881	−0.2547	<0.001
Background Shade	A1	Reference
	A2	0.3333	0.0553	0.6114	0.019
	A3	−0.2493	−0.5282	0.0297	0.080
	A3.5	−0.2451	−0.5250	0.0348	0.086
	A4	−0.2533	−0.5314	0.0247	0.074
C1
Veneer Thickness	0.50 mm	Reference
	0.75 mm	0.1345	−0.7897	1.0588	0.775
	1.00 mm	−1.0095	−1.9337	−0.0852	0.032
Background Shade	A1	Reference
	A2	3.8933	2.7075	5.0792	<0.001
	A3	0.1769	−1.0130	1.3668	0.770
	A3.5	0.8655	−0.3285	2.0596	0.155
	A4	1.1333	−0.0525	2.3192	0.061