Table 3. Vickers hardness of tested materials.
| Groups | Food simulating liquids (n = 12) | Mean ± SD |
|---|---|---|
| VMII (n = 48) | Air | 658 ± 69a |
| Distiled water | 596 ± 43a | |
| 0.02 M Citric acid | 623 ± 58a | |
| 75% Ethanol | 640 ± 86a | |
| VE (n = 48) | Air | 209 ± 21d |
| Distiled water | 237 ± 46d | |
| 0.02 M Citric acid | 182 ± 11d | |
| 75% Ethanol | 194 ± 25d | |
| LU (n = 48) | Air | 128 ± 12e |
| Distiled water | 132 ± 23e | |
| 0.02 M Citric acid | 137 ± 18e | |
| 75% Ethanol | 96 ± 8f | |
| PMZ (n = 48) | Air | 104 ± 21e,f |
| Distiled water | 115 ± 10e | |
| 0.02 M Citric acid | 119 ± 15e | |
| 75% Ethanol | 82 ± 11f |
Different superscripted letters indicate statistically significant differences of materials (P < .05).