The effect of bleaching on enamel susceptibility to acid erosion and demineralisation

Abstract

I In nt tr ro od du uc ct ti io on n The purpose of this in vitro study was to determine if enamel that had been bleached by carbamide (urea) peroxide gel (CPG) was at increased risk of either acid erosion or demineralisation (early caries) than un-bleached enamel. M Me et th ho od ds s Human incisors were employed. The samples were randomly assigned to one of 4 groups; a) 10% CPG, b) 16% CPG, c) 22% CPG and d) 10% CPG with xylitol, fluoride and potassium. Each specimen was moistened with saliva and the appropriate formulation placed for 2 hours for a total of 40 hours of exposure. In order to ensure that bleaching had taken place, tooth shades were monitored using the Shade-Eye device. Following the bleaching process, one half of the specimen was subjected to an erosive challenge, the other to a demineralisation system with one half of each sub-sample retained as a non-bleached control. Samples were assessed longitudinally with quantitative light-induced fluorescence (QLF) and at the conclusion of the study with transverse micro-radiography (TMR) R Re es su ul lt ts s Erosion was detected in all samples (∆Q 126±23.4), in both bleached and non-bleached areas. There was no statistical difference between the bleached and non-bleached areas either within the treatment groups or between them. Caries-like lesions were detected on all samples; TMR revealed sub-surface lesions on all teeth and QLF data supported this (∆Q 89±18.9). Following statistical analysis there were no differences detected between the bleached and non-bleached areas, nor between the different concentrations of the bleaching solution. C Co on nc cl lu us si io on n These results suggest that tooth bleaching with carbamide (urea) peroxide (using commercially available concentrations) does not increase the susceptibility of enamel to acid erosion or caries.

Effect of Delaying Toothbrushing During Bleaching on Enamel Surface Roughness: An In Vitro Study

“…In addition, according to some studies, bleaching with these gels does not increase enamel susceptibility to caries or acidic erosion or increase the odds of demineralization. [21][22][23][24] However, some studies have reported significant increases in enamel surface roughness subsequent to the use of bleaching agents. 8,9 Some of the complications of applying bleaching agents in tooth hard tissues are changes in tooth chemical structure, demineralization and decreases in the mineral content including calcium and phosphate, 14,25,26 decreases in the fluoride content of enamel, 11 and changes in the micromorphology of enamel.…”

Review of the effects of peroxide on enamel and dentine properties

“…Further, bleaching human enamel and dentine with 10-22% CP for 2 h  20 treatments did not increase their susceptibility to acid erosion or caries lesion formation as measured by quantitative light-induced fluorescence and transverse microradiography. 91 This latter result of no increase in caries susceptibility of enamel after bleaching was confirmed by Al-Qunaian 92 in an in vitro microbial caries model following treatments with either 10% CP, 20% CP plus fluoride or 35% HP and by Kraigher et al 93 in rat molars in vivo following treatment with 10% CP (1 h/day for 14 days).…”

Influence of study design on the impact of bleaching agents on dental enamel microhardness: A review

“…Also, some studies found mineral loss, loss of fluoride, increased susceptibility to erosion or caries, increased surface roughness, reduced enamel micro tensile strength, reduced fracture stability or a decrease in abrasion resistance of bleached dental hard tissues [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. On the other hand, there are other studies, which did not confirm these observations [18][19][20][21][22]. Beside this, no clinical studies or case reports in the literature have documented macroscopically or clinically visible damage due to vital bleaching or clinically relevant tissue destruction.…”