Table 1.

Mean calculus scores on days 0, 11, 18 and 25

Presence/absence of calculus	Initially plaque-free surfaces (Control)		Initially plaque-covered surfaces (Test)
	Mean	SE	Mean	SE
Day 0	0.00A* a**	0.00	0.00Aa	0.00
Day 11	0.00Aa	0.00	0.00Aa	0.00
Day 18	0.05Aa	0.01	0.26Bb	0.02
Day 25	0.12Ab	0.02	0.34Bc	0.02

^*Upper case letters regard to comparison between initially plaque-free surfaces and plaque-covered surfaces in each experimental period. Different letters demonstrate statistically significant differences (Wald test, p=0.05)

^**Lower case letters regard to within group comparison overtime. Different letters demonstrate statistically significant differences (Wald test, p=0.05). SE= Standard Error