Table 3. Mean, standard deviation among study groups for surface colour.

Study groups	Stained-water	Stained-acid	Polished-water	Polished-acid	P value$
VM	0.88 (0.34)	1.02 (0.66)	1.37 (0.60)	1.29 (0.30)	.066
LU	1.22 (0.51)	1.23 (0.50)	0.8 (0.25)	0.94 (0.67)	.090
EN	0.89 (0.63)	0.83 (0.49)	0.66 (0.16)	0.78 (0.15)	.395
SH	0.99 (0.46)	1.44 (0.40)	0.71 (0.14)	0.73 (0.18)	< .002
CU	1.35 (0.41)	1.2 (0.36)	1.25 (0.29)	0.95 (0.25)	.224

^§showing effect of storage and surface treatment using ANOVA (P value).

Note: each group shows the degree of influence of toothbrush abrasion on the surface colour.