Table 4: ∆b means (standard deviation) according to bleaching agent and enamel thickness for each time evaluated.

Bleaching agent Enamel thickness Time
∆b1 ∆b2 ∆b3
10% Carbamide
Peroxide		 0 mm enamel (D) *-18.18 (3.61) a *-24.94 (3.85) a *-25.20 (5.23) a
0.5 mm enamel (0.5E) *-13.87 (2.62) b *-20.84 (3.38) b *-25.18 (3.18) a
1 mm planned enamel (1E) *-11.87 (1.65) b *-18.65 (2.99) bc *-23.59 (3.04) ab
1 mm unplanned enamel (aprismatic) (1AE) -7.70 (2.70) c *-14.70 (4.50) c *-22.49 (3.65) b
35% Hydrogen
Peroxide		 0 mm enamel (D) -9.46 (2.07) a -19.90 (3.13) a -23.79 (5.68) a
0.5 mm enamel (0.5E) -4.47 (1.33) b -11.97 (2.02) b -21.86 (2.95) ab
1 mm planned enamel (1E) -4.29 (2.07) b -11.84 (3.26) bc -18.57 (2.17) b
1 mm unplanned enamel (aprismatic) (1AE) -5.16 (1.49) b 10.59 (3.37) c -19.19 (3.11) b

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).