. 2018 Oct 2;26:e20170589. doi: 10.1590/1678-7757-2017-0589

Table 2. Mean values and standard deviations of relative areas of phosphate (PO₄ ^3-) peak v4 (582-611 cm^-1) (in arbitrary units) of FT-Raman spectra of sound and demineralized enamel at baseline (T₀) and after bleaching (T_b).

Treatments	Sound enamel				Demineralized enamel
	^T ₀		^Tb		^T ₀		^Tb
C	3.69	(0.16)^Aa	5.77	(0.32)^Ab	1.38	(0.65)^Aa ^*	4.32	(0.26)^Ab ^*
HP	3.12	(0.29) ^Aa	2.89	(0.55)^Ba	1.73	(0.81)^Aa ^*	4.55	(0.31)^Ab ^*
HPF	3.31	(0.09) ^Aa	5.99	(0.39)^Ab	1.89	(0.35)^Aa ^*	5.79	(0.35)^Bb
HPC	3.17	(0.11) ^Aa	6.72	(0.87)^Ab	1.77	(0.87)^Aa ^*	5.89	(0.58)^Bb

Mean values followed by distinct letters differ statistically at 5%, according to three-way ANOVA and Tukey test (p<0.05). Uppercase letters compare treatments (in columns) and lowercase letters compare time (in row).

Asterisks (*) compare each enamel condition within time

C: control

HP: 35% hydrogen peroxide

HPF: fluoride-based bleaching agent containing 35% hydrogen peroxide

HPC: calcium-based bleaching agent containing 35% hydrogen peroxide

Table 2. Mean values and standard deviations of relative areas of phosphate (PO4 3-) peak v4 (582-611 cm-1) (in arbitrary units) of FT-Raman spectra of sound and demineralized enamel at baseline (T0) and after bleaching (Tb).

Table 2. Mean values and standard deviations of relative areas of phosphate (PO₄ ^3-) peak v4 (582-611 cm^-1) (in arbitrary units) of FT-Raman spectra of sound and demineralized enamel at baseline (T₀) and after bleaching (T_b).