Table 3. Mean (standard deviation) of surface roughness (Ra) as a function of group and time.

Group	Time
	Initial	Final
	Mean (standard deviation)	Mean (standard deviation)
No bleaching	0.07 (0.01)Aa	0.07 (0.01)Ac
7.5% HP	0.07 (0.01)Ba	0.13 (0.01)Aa
7.5% HP + Chi	0.07 (0.01)Ba	0.10 (0.01)Ab
7.5% HP + Ca	0.07 (0.01)Ba	0.13 (0.01)Aa
7.5% HP + Ca + Chi	0.07 (0.01)Ba	0.10 (0.01)Ab

Distinct letters (uppercase horizontally and lowercase vertically) indicate statistically significant differences (p≤0.05). p(group<0.0001; p(time)<0.0001; p(interaction)<0.0001.