Table 1: ∆E means (standard deviation) according to bleaching agent and enamel thickness for each time evaluated.

Bleaching agent Enamel thickness Time
∆E1 ∆E2 ∆E3
10% Carbamide
Peroxide		 0 mm enamel (D) *24.74 (5.22) a *34.60 (5.45) a 41.16 (5.95) a
0.5 mm enamel (0.5E) *19.03 (3.06) b *27.77 (3.97) b 36.80 (3.08) ab
1 mm planned enamel (1E) *16.64 (1.63) b *25.98 (3.43) bc *34.88 (3.38) b
1 mm unplanned enamel (aprismatic) (1AE) 11.19 (3.18) c 20.44 (5.21) c 31.55 (4.35) b
35% Hydrogen
Peroxide		 0 mm enamel (D) 13.39 (2.85) a 28.43 (3.93) a 37.31 (4.63) a
0.5 mm enamel (0.5E) 6.81 (1.68) b 16.49 (2.78) b 31.48 (3.42) b
1 mm planned enamel (1E) 6.96 (2.87) b 16.64 (3.85) b 25.14 (2.65) c
1 mm unplanned enamel (aprismatic) (1AE) 8.03 (1.93) b 14.86 (3.47) b 28.26 (4.12) bc

Means followed by different lowercase letters comparing thickness within bleaching agent and evaluated time indicate significant difference (p ≤ 0.05). *It differs from 35% hydrogen peroxide in the same thickness and time (p ≤ 0.05).