Table 3.
Comparison of microhardness values (Vickers hardness number) by Kruskal-Wallis test and Mann-Whitney U-test
| Surface microhardness | Mean | SD | Minimum | Maximum | Kruskal-Wallis U-test P | Multiple group comparisons | P |
|---|---|---|---|---|---|---|---|
| Acid-etched group | 303.36 | 85.44 | 155.00 | 405.66 | <0.001 | Acid - Er:YAG | <0.001 |
| Er:YAG group | 418.14 | 43.81 | 330.33 | 515.33 | Acid - Er,Cr:YSGG | <0.001 | |
| Er,Cr:YSGG group | 423.59 | 29.17 | 345.50 | 512.00 | Er:YAG Er,Cr:YSGG | 0.320 |
SD: Standard deviation; Er:YAG: Erbium: yttrium-aluminum-garnet; Er,Cr:YSGG: Erbium, chromium-doped: yttrium, scandium, gallium, and garnet