Table 4.

Means and standard deviation values for surface roughness for all subgroups of the two composites in shade A2.

Variable	Material	Bleach	Mean	SD	Regression analysis for materials	Regression analysis for bleach agents
After first bleach	Durafil VS	Control	126.1	5.3	0.011*	0.39
		Beyond	137.6	13.2
		Luma	131	13.1
		Opal	127.5	6.5
	TPH3	Control	150.1	9.7
		Beyond	125.6	6.5
		Luma	143.3	6.6
		Opal	138	5.7
After second bleach	Durafil VS	Control	126.1	5.3	<0.001*	<0.001*

^*:Significant at P≤.05