Influence of Staining Solutions on Color Change and Enamel Surface Properties During At-home and In-office Dental Bleaching: An In Situ Study

Abstract

SUMMARY The purpose of this in situ study was to evaluate the influence of staining solutions (coffee and cola) on the color change, microhardness, roughness, and micromorphology of the enamel surface during at-home and in-office dental bleaching. One hundred and thirty-five enamel bovine blocks were prepared to perform the evaluations. Fifteen volunteers used an intraoral appliance with nine enamel blocks for 15 days. The enamel blocks were randomly assigned among the different groups according to the three treatments: in-office bleaching with high hydrogen peroxide concentration (Opalescence Boost PF 40%, Ultradent) for 40 minutes in three sessions (first, eighth, and 15th days of treatment), at-home bleaching with low carbamide peroxide concentration (Opalescence PF 10%, Ultradent) for 60 minutes daily for 15 days, and a control group (no bleaching agent applied). The enamel blocks were immersed daily in different staining solutions (coffee or cola) for 30 minutes for 15 days or were not submitted to staining (control) to obtain a factorial scheme (3×3) of the dental bleaching treatment and staining solution (n=15). The microhardness analyses (Knoop), roughness evaluations (Ra), surface micromorphological observations, and color measurements (using the CIELAB system and the VITA Classical scale) were made before and after the bleaching treatments to assess immersion in staining solutions. Mixed model tests showed that there was a decrease in enamel microhardness after exposure to cola compared with coffee and the control group (p<0.0001) for both bleaching techniques. Roughness was higher for the cola groups (p<0.0001), and there was no significant difference between the coffee and the control groups. Generalized linear models showed that when no staining solution was applied, lighter color scores were found for the VITA Classical scale (p<0.0001). Without the staining solutions, there was an increase in luminosity (ΔL) (p=0.0444) for in-office bleaching. Lower values of Δa (p=0.0010) were observed when the staining solutions were not used. The Δb (p=0.3929) did not vary significantly between the bleaching agents, but when cola was applied, the values were significantly higher than for the control (p=0.0293). Higher values of ΔE (p=0.0089) were observed for in-office bleaching without staining solutions, while lower values of ΔE were observed for the in-office associated with coffee immersion. Regardless of whether being submitted to bleaching, the enamel stained with cola showed a decrease in microhardness, an increase in roughness, and changes in the micromorphology. The efficacy of the bleaching agents was greater when no staining solution (cola or coffee) was used, and in-office bleaching showed greater color change than the at-home bleaching technique.

Changes in Optical Characteristics and Surface Topography of CAD/CAM Materials after Bleaching Applications: An AFM Evaluation

“…These results may be attributed to the different whitening mechanisms according to the different contents and longer total contact time of WP. In agreement with this result, previous studies showed that total bleaching time is more important than the concentration of the bleaching agent. The increase in contact time may cause more HP diffusion into the resin matrix leading to more hydrolysis of chemical bonds between the resin matrix and fillers, which may result in the removal of fillers.…”

Bleaching Stained Arrested Caries Lesions: In vivo Clinical Study

“…22 Existing literature reports that the bleaching efficacy may increase with several bleaching attempts or when associated with longer bleaching time. [23][24][25][26] Thus, metallic and deep stains might need further in-office bleaching treatment (more than one visit) or at-home bleaching for longer periods to produce clinically satisfactory results. However, careful consideration must be exercised in view of the possible increased incidence of sensitivity.…”

Effect of pigmenting agents on tooth enamel staining during immediate tooth whitening: an in vitro study

“…Previous studies showed that bleaching may increase enamel roughness 10,17 . However, the present study corroborates recent ones that do not show changes in topography or staining after the bleaching process, which is likely explained by the differences in the methodologies used.…”

“…Decalcification, porosities, and topographic changes in tooth enamel are promoted 16,17 , favoring discoloration and pigment build-up in teeth. However, the mineral loss is compensated by the remineralization properties of saliva 18 , which contains calcium and phosphate ions.…”