Table 5. Comparison of Mean Values Before and After the Treatment Within the Same Group Regarding the Calcium/Phosphorus Ratio (paired t-test) .

Group	Time	Mean	SD	Difference		t	P
				Mean	SD
Control	Before	2.22	0.20	-0.01	0.01	-3.06	0.38
	After	2.23	0.21
Eggshell NPs only	Before	2.14	0.30	-1.00	0.64	-3.51	0.025*
	After	3.14	0.47
Seashell NPs only	Before	2.09	0.13	-0.91	0.08	-24.65	0.000*
	After	3.00	0.19
Eggshell NPS + Nd:YAG laser	Before	2.01	0.11	-1.29	0.75	-3.86	0.018*
	After	3.30	0.71
Seashell NPs + Nd:YAG laser	Before	2.21	0.15	-0.97	0.20	-10.88	0.000*
	After	3.19	0.31

Significance level P ≤ 0.05, *Significant.