Table 2. The change in surface roughness (µm) after irradiation in relation to the initial measurement (the observed variable is base - irradiation).
| Tissue | Treatment | n | Mean | Std | Median | 1. quartile | 3. quartile | p-valuea |
|---|---|---|---|---|---|---|---|---|
| Enamel | 70 Gy | 20 | -0.11 | 0.08 | -0.10 | -0.15 | -0.04 | < 0.001 |
| Dentin | 70 Gy | 20 | -0.07 | 0.06 | -0.09 | -0.11 | -0.02 | < 0.001 |
| Enamel | 2x35 Gy | 20 | -0.09 | 0.07 | -0.09 | -0.12 | -0.04 | < 0.001 |
| Dentin | 2x35 Gy | 20 | -0.07 | 0.05 | -0.10 | -0.10 | -0.07 | < 0.001 b |
a P-value t-test for dependent samples.
b Due to deviations from the normal distribution, the Wilcoxon Signed Rank test was used.