Table 2. Ra surface roughness (µm) after surface pre-treatment.
| Surface pre-treatment | n | Mean | SD | Min | Max |
|---|---|---|---|---|---|
| PO (polishing unglazed zirconia) | 10 | 0.06a | 0.02 | 0.05 | 0.09 |
| BR (bur roughening) | 10 | 1.25e | 0.24 | 0.85 | 1.64 |
| PP (cleaning) | 10 | 0.24b | 0.05 | 0.16 | 0.34 |
| HF (hydrofluoric acid etching) | 10 | 0.32c | 0.05 | 0.24 | 0.39 |
| AA (alumina air-abrasion) | 10 | 0.51d | 0.09 | 0.39 | 0.67 |
| CJ (CoJet-Sand air-abrasion) | 10 | 0.60d | 0.08 | 0.40 | 0.69 |
Welch's variance-weighted one-way ANOVA showed a significant difference in mean Ra value among the groups (p < 0.001); the Games-Howell post hoc test showed that means with the same superscripted letter were not significantly different (p > 0.05).
SD, standard deviation; Min, minimum value; Max, maximum value.