. 2020 Jun 22;10:10016. doi: 10.1038/s41598-020-66733-z

Table 2.

Initial, final and variation of Knoop hardness (%) after bleaching procedures (Mean ± SD).

Group	Knoop Hardness (KHN)
Group	Initial*	Final*	Δ KHN (%)^¶
Carbamide peroxide	^A 121.44 ± 30.36^a (95% CI 103 to 140)	^B 99.48 ± 27.20^b (95% CI 82.6 to 116)	−18.72 ± 4.21^d
Bromelain	^A 144.13 ± 44.19^a (95% CI 117 to 172)	^B 140.05 ± 43.86^ab (95% CI 113 to 167)	−2.92 ± 1.5^c
Ficin	^A 145.19 ± 20.80^a (95% CI 132 to 158)	^B 153.96 ± 23.54^a (95% CI 139 to 169)	5.92 ± 2.5^a
Papain	^A 136.95 ± 18.51^a (95% CI 125 to 148)	^B 162.31 ± 21.46^a (95% CI 149 to 176)	18.58 ± 3.4^b
Negative control	^A 143.55 ± 41.33^a (95% CI 118 to 169)	^B 146.75 ± 41.65^a (95% CI 121 to 173)	2.51 ± 2.2^a

*Data analyzed through a Two-Way Repeated Measures ANOVA test. Different uppercase letters indicate statistically significant differences in the same row (p < 0.05). Different lowercase letters indicate statistically significant differences in the same column (p < 0.05). ^¶Data analyzed through a One-Way ANOVA test. Different lowercase letters indicate statistically significant differences (p < 0.05).