Table 3: ∆a means (standard deviation) according to bleaching agent and enamel thickness for each time evaluated.

Bleaching agent Enamel thickness Time
∆a1 ∆a2 ∆a3
10% Carbamide
Peroxide		 0 mm enamel (D) -5.54 (1.88) a -4.13 (3.01) b -0.14 (2.99) b
0.5 mm enamel (0.5E) *-7.36 (2.13) a *-8.49 (2.36) a -5.89 (2.51) a
1 mm planned enamel (1E) *-6.08 (1.74) a *-7.41 (3.09) a -6.18 (3.51) a
1 mm unplanned enamel (aprismatic) (1AE) -5.81 (0.78) a *-9.03 (1.48) a -9.61 (2.00) a
35% Hydrogen
Peroxide		 0 mm enamel (D) -3.80 (1.09) a -4.33 (2.23) b -2.00 (3.34) b
0.5 mm enamel (0.5E) -2.62 (0.71) a -5.41 (1.62) a -5.24 (1.92) ab
1 mm planned enamel (1E) -2.17 (1.00) a -5.15 (2.44) a -6.71 (3.77) a
1 mm unplanned enamel (aprismatic) (1AE) -4.02 (0.95) a -7.07 (2.06) a -6.59 (2.07) a

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).