. 2015 Jan 20;2015:581731. doi: 10.1155/2015/581731

Table 1.

The mean ΔE ± SD after tooth bleaching with and without plasma and P values using Student's t-test.

Observation times	Bleaching agents	N	Mean ΔE ± SD		t-test P values
Observation times	Bleaching agents	N	Plasma	Without plasma	t-test P values
10 min	15% CP	20	17.82 ± 1.74	5.87 ± 0.81	0.000^*
20 min	15% CP	20	23.48 ± 2.30	6.98 ± 0.93	0.000^*
30 min	15% CP	20	29.91 ± 1.74	8.30 ± 1.15	0.000^*

CP: carbamide peroxide, ΔE: overall color changes, and SD: standard deviation.

^*ΔE values show significant differences between the two groups (P < 0.05).