Table 2.

Grouping and coding of different variables.

	Group	Code	Description
No. 1	Control	N0	Unreinforced light cured composite resin
No. 2	ZrO2	Z3	Light cured composite resin reinforced with 3 wt.% (0.78 vol%) of ZrO2 NPs
		Z7	Light cured composite resin reinforced with 7 wt.% (1.88 vol%) of ZrO2 NPs
No. 3	TiO2	T3	Light cured composite resin reinforced with 3 wt.% (1.1 vol%) of TiO2 NPs
		T7	Light cured composite resin reinforced with 7 wt.% (2.58 vol%) of TiO2 NPs
No. 4	SiO2	S3	Light cured composite resin reinforced with 3 wt.% (2.27 vol%) of SiO2 NPs
		S7	Light cured composite resin reinforced with 7 wt.% (5.34 vol%) of SiO2 NPs