Comparison of brightness changes over the period of use of dentifrice
| Group | Before | 3 days | 1 week | 2 weeks | p-value1 | p-value2 | ||
|---|---|---|---|---|---|---|---|---|
| ΔL* | Con. | 30 | 4.37±3.77a | 4.27±3.54a | 4.30±3.60a | 4.17±3.29a | 0.222 | <0.001 |
| Exp1 | 33 | 4.42±4.05a | 3.55±2.85b | 3.15±2.72bc | 2.97±2.51c | <0.001 | ||
| Exp2 | 29 | 4.59±3.42a | 3.97±2.88a | 3.17±2.56b | 2.66±2.57c | <0.001 | ||
| p-value3 | 0.121 | 0.002** | 0.14* |
Values are presented as mean±standard deviation. 1Repeated measures ANOVA. 2Repeated measure ANOVA (between subject effects). 3Repeated measure ANOVA (differences between groups over time). abcSame letters means there is no significant difference between times by Tukey’s multiple comparison at a=0.05 in each group.
