Influence of Erosion/Abrasion and the Dentifrice Abrasiveness Concomitant with Bleaching Procedures

Figures & data

Figure 1 Schematic of the erosive/abrasive protocol used.

Table 1 Mean and SD for Enamel Vickers Microhardness Values

Abrasiveness	Bleaching	Erosion	Time
			Initial	Final
Low	W/o	With	346.58 (18.63) A	266.04 (9.06) B
		W/o	338.21 (17.70) A	277.79 (7.09) B
	With	With	342.12 (19.80) A	257.79 (3.42) B
		W/o	344.34 (22.37) A	272.62 (7.47) B
High	W/o	With	343.48 (20.76) A	273.58 (17.22) B
		W/o	348.60 (17.14) A	275.60 (6.69) B
	With	With	339.58 (16.96) A	258.94 (3.95) B
		W/o	339.66 (15.52) A	275.04 (6.77) B

Notes: Erosion/Abrasion refers to the groups subjected to the erosive/abrasive cycle model, and W/o refers to those without erosion/abrasion. Uppercase letters show differences within lines between the initial and final measurements. There were no significant differences between bleaching and erosive/abrasive conditions (p>0.05) and also no significant differences between the abrasiveness tested (p>0.05).

Table 2 Mean and SD for Dentin Vickers Microhardness Values

Abrasiveness	Bleaching	Erosion	Time
			Initial	Final
Low	W/o	With	62.05 (4.60) Aa	42.36 (2.30) Ba
		W/o	63.14 (4.86) Aa	61.23 (4.34) Ab
	With	With	61.92 (3.81) Aa	42.11 (2.57) Ba*
		W/o	62.29 (4.50) Aa	60.83 (2.12) Bb
High	W/o	With	62.58 (3.30) Aa	42.11 (1.67) Ba
		W/o	62.47 (4.40) Aa	60.64 (2.96) Ab
	With	With	60.36 (4.29) Aa	37.17 (2.63) Bc*
		W/o	62.29 (2.90) Aa	59.99 (2.57) Bb

Notes: Erosion/Abrasion refers to the groups subjected to the erosive/abrasive cycle model, and W/o refers to those without erosion/abrasion. Uppercase letters show differences within lines, between the initial and final measurements. Lowercase letters shows differences within columns, for the erosive/abrasive and bleaching conditions. The asterisk (*) shows differences between the abrasiveness (low × high) for the same condition (bleaching and erosion/abrasion) tested.

Table 3 Mean and Standard Deviation for Surface Loss (µm)

Substance	Bleaching	Erosion	Abrasiveness
			Low	High
Enamel	W/o	With	0.89 (0.47) Aa	1.23 (0.56) Ba
		W/o	0.06 (0.03) Ab	0.08 (0.03) Bb
	With	With	0.80 (0.15) Aa	0.96 (0.24) Ba
		W/o	0.06 (0.02) Ab	0.08 (0.03) Bb
Dentin	W/o	With	3.17 (0.55) Aa *	3.66 (0.63) Ba *
		W/o	0.31 (0.10) Ab #	0.98 (0.16) Bb #
	With	With	2.21 (0.42) Aa **	3.56 (0.77) Ba **
		W/o	0.22 (0.06) Ab ##	0.31 (0.07) Bb ##

Notes: Uppercase letters show differences within lines between the low and high abrasiveness. Lowercase letters show differences within columns for enamel and dentin separately considering the erosive/abrasive cycle. For the bleaching factor, only dentin showed differences: asterisks show differences between the absence (*/#) and presence (**/##) of bleaching considering the same condition tested.

Figure 2 Enamel: (A) and (B) with bleaching and without erosion; (C) and (D) with bleaching and with erosion.

Figure 3 Dentin: (A) and (B) with bleaching and without erosion; and (C) and (D) with bleaching and with erosion.