Table 4. Comparison of Mean Values Before and After the Treatment Within the Same Group Regarding Calcium Weight Percent (paired t-test) .
| Group | Time | Mean | SD | Difference | t | P | |
| Mean | SD | ||||||
| Control | Before | 68.87 | 2.11 | -0.07 | .05 | -3.13 | .035* |
| After | 68.94 | 2.13 | |||||
| Eggshell NPs only | Before | 67.91 | 2.81 | -7.70 | 4.52 | -3.81 | .019* |
| After | 75.61 | 2.66 | |||||
| Seashell NPs only | Before | 67.54 | 1.39 | -7.41 | .52 | -31.80 | 0.000* |
| After | 74.95 | 1.17 | |||||
| Eggshell NPS + Nd:YAG laser | Before | 66.71 | 1.31 | -9.50 | 4.60 | -4.62 | 0.010* |
| After | 76.20 | 4.00 | |||||
| Seashell NPs + Nd:YAG laser | Before | 68.84 | 1.42 | -7.18 | 0.96 | -16.80 | 0.000* |
| After | 76.02 | 1.83 | |||||
Significance level P ≤ 0.05, *Significant.