Table 2. Comparison of microhardness and surface roughness between the composite resin materials before and after bleaching.

	Before	After	t value	P-value †
	Mean ± SD	Mean ± SD
Microhardness (VHN)
Ceram.x ® SphereTEC™ one	37.59 ± 4.28	37.5 ± 4.34	0.06	0.954
Filtek Z350 XT	27.67 ± 2.1	17.83 ± 1.36	16.55	<0.001 *
t	6.59	13.68
P-value ‡	<0.001 *	<0.001 *
Surface roughness (μm)
Ceram.x ® SphereTEC™ one	2.66 ± 0.26	2.11 ± 0.92	1.56	0.153
Filtek Z 350XT	2.62 ± 0.2	2.52 ± 0.24	1.39	0.199
t	0.4	-1.39
P-value ‡	0.693	0.194

^*Denotes statistically significant (p < 0.05), paired t test.

^†Paired t test.

^‡Independent sample t test.