Table 5. Mean, standard deviation among study groups for lightness.
| Study groups | Stained-water | Stained-acid | Polished-water | Polished-acid | P value$ |
|---|---|---|---|---|---|
| VM | 64 (1.63)* | 62.9 (1.91) | 68.8 (0.71)* | 69 (0.95)* | < .01 |
| LU | 59.5 (1.79) | 60.3 (2.26) | 67.4 (1.15) | 67.5 (0.47)* | < .01 |
| EN | 58.2 (1.46) | 57.7 (1.1) | 65.1 (0.37)* | 64.7 (0.42)* | < .01 |
| SH | 63.9 (1.49)* | 64.5 (0.9) | 68.9 (0.42)* | 68.06 (0.34)* | < .01 |
| CU | 56.7 (0.86) | 57.3 (1.7) | 63.01 (0.73)* | 62.7 (0.41)* | < .01 |
*denote significant effect of simulated tooth brushing (t test).
§showing effect of storage and surface treatment using ANOVA (P value).