Abstract
ObjectivesThe aim of this study was to evaluate the influence of different bleaching gels on the masking and caries-arresting effects of infiltrated and non-infiltrated stained artificial enamel caries lesions.Materials and methodsBovine enamel specimens (n = 240) with each two sound areas (SI and SC) and each two lesions (DI and DC) were infiltrated (DI and SI), stained (1:1 red wine-coffee mixture,70 days), and randomly distributed in six groups to be bleached with the following materials: 6%HP (HP-6), 16%CP (CP-16), 35%HP (HP-35), 40%HP (HP-40), and no bleaching (NBl,NBl-NBr). Subsequently, specimens were pH-cycled (28 days, 6 × 60 min demineralization/day) and all groups except NBl-NBr were brushed with toothpaste slurry (1.100 ppm, 2×/day, 10 s). Differences in colorimetric values (ΔL, ΔE) and integrated mineral loss (ΔΔZ) between baseline, infiltration, staining, bleaching, and pH cycling were calculated using photographic and transversal microradiographic images.ResultsAt baseline, significant visible color differences between DI and SC were observed (ΔEbaseline = 12.2; p < 0.001; ANCOVA). After infiltration, these differences decreased significantly (ΔEinfiltration = 3.8; p < 0.001). Staining decreased and bleaching increased ΔL values significantly (p ≤ 0.001). No significant difference in ΔΔE was observed between before staining and after bleaching (ΔEbleaching = 4.3; p = 0.308) and between the bleaching agents (p = 1.000; ANCOVA). pH-cycling did not affect colorimetric values (ΔEpH-cycling = 4.0; p = 1.000). For DI, no significant change in ΔZ during in vitro period was observed (p ≥ 0.063; paired t test).ConclusionsUnder the conditions chosen, the tested materials could satisfactorily bleach infiltrated and non-infiltrated stained enamel. Furthermore, bleaching did not affect the caries-arresting effect of the infiltration.Clinical relevanceThe present study indicates that bleaching is a viable way to satisfactorily recover the appearance of discolored sound enamel and infiltrated lesions.
Highlights
In recent years, the aesthetic demands for brighter and whiter teeth by patients have increased [1]
To create artificial enamel caries lesions with pseudo-intact surface in the uncovered areas (demineralized/negative control area (DC) and demineralized infiltrated area (DI)), specimens were stored in a demineralization solution (2.5 ml solution/mm2 enamel surface) [19]
After bleaching, DC was significantly brighter than DI (p ≤ 0.001). pH-cycling did not affect colorimetric values (ΔEpH-cycling = 4.0; p = 1.000)
Summary
The aesthetic demands for brighter and whiter teeth by patients have increased [1]. Dentists often have to deal with extrinsic or intrinsic staining as well as non-cavitated initial lesions— known as white spot lesions (WSL). The latter frequently being associated with fixed orthodontic treatments [2]. A WSL prevalence up to 97% has been reported [2]. Successful masking of a WSL by remineralizing regimes only seems to be related to the severity of lesion. Initial WSL can often be completely remineralized naturally since fixed elements—increasing the plaque retention—have been removed. By the additional use of fluorides, e.g., in form of fluoride varnish remineralization
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