Table 1. Two-way ANOVA for ΔE.

Source of variation	df	Sum of squares (SS)	Mean SS	F	P value
Material	2	85.546	42.773	144.163	< .001*
Treatment	3	20.172	6.724	22.663	< .001*
Time	1	72.897	72.897	245.693	< .001*
Material * staining medium	6	23.901	3.984	13.426	< .001*
Material * time	2	14.461	7.230	24.370	< .001*
Staining medium * time	3	2.609	0.870	2.931	.035*
Material * staining medium * time	6	5.257	0.876	2.953	.009*

df: Degrees of Freedom (N-1), F: variation between sample means / variation within the samples

^*denotes significance