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

Table 4. Mean values and standard deviations of sound and demineralized enamel Ca/P weight ratios at baseline (T₀) and after bleaching (T_b) (weight percentage, wt %), according to μ-EDXRFresults.

Groups	Sound enamel				Demineralized enamel
	T₀		T_b		T₀		T_b
C	1.97	(0.11)^Aa	1.98	(0.07)^Ba	1.28	(0.04)^Aa ^*	1.96	(0.04)^Ab
HP	1.99	(0.07)^Aa	1.67	(0.05)^Cb	1.32	(0.05)^Aa ^*	1.68	(0.09)^Ba
HPF	1.92	(0.02)^Aa	2.29	(0.05)^Ab	1.22	(0.06)^Aa ^*	2.02	(0.08)^Ab ^*
HPC	1.94	(0.06)^Aa	2.32	(0.07)^Ab	1.20	(0.05)^Aa ^*	1.99	(0.04)^Ab ^*

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 4. Mean values and standard deviations of sound and demineralized enamel Ca/P weight ratios at baseline (T0) and after bleaching (Tb) (weight percentage, wt %), according to μ-EDXRFresults.

Table 4. Mean values and standard deviations of sound and demineralized enamel Ca/P weight ratios at baseline (T₀) and after bleaching (T_b) (weight percentage, wt %), according to μ-EDXRFresults.