Table 2.

Means and P value of surface roughness in micrometer (pre- and posttest)

Group	Mean±SD		Percentage increase	t	P
	Pretest	Posttest
Dash (B1)	0.329±0.082	0.378±0.082	14.80	8.10	0.000*
Pola Office (B2)	0.327±0.069	0.354±0.078	8.25	6.38	0.000*
Opalescence Boost (B3)	0.328±0.075	0.347±0.075	5.79	6.04	0.001*

*Highly significant. SD: Standard deviation