highly significantP < 0.001
The mean and standard deviation after the second cycle of bleaching was M=290 SD= 16.6, which showed decrease by 2.3% and was highly significant ( P < 0.001).
The mean and standard deviation after the second cycle of bleaching was M=290 SD= 16.6, which showed decrease by 2.3% and was highly significant ( P < 0.001).