Pre- and post-depigmentation OPI scores and smile aesthetic scores were compared using Wilcoxon signed-rank test

ParameterPre-depigmentationPost-depigmentationp value
Mean and SDConfidence intervalMean and SDConfidence interval
OPI scores2.67 ± 0.492.4–2.90.33 ± 0.50.0631–0.6036< 0.001**
Smile aesthetic scores6.72 ± 0.326.5–6.97.91 ± 0.187.8–8.00.001**

OPI: oral pigmentation index; SD: standard deviation; ** indicates statistical significance