Comparative Evaluation of Bleaching Efficacy on White Spot Lesions Managed With Resin Infiltration and...

Bleaching is often desired by patients, but with white spot lesions (WSLs), this procedure can be a cause of concern due to its action on demineralized enamel. Treating these WSLs before bleaching can be a treatment modality to alleviate the action of the bleaching agent. This study assessed the efficacy of a 40% hydrogen peroxide bleaching agent on demineralized enamel pre-treated with resin infiltration (RI) or casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) using a dynamic pH cycling model to simulate oral conditions.

Fifty-six human molar enamel samples were randomly divided into four groups after staining with coffee solution, based on the surface treatment before bleaching (n=14): Group I, sound enamel/control and no treatment (NT); Group II, untreated artificial caries (AC) and NT; Group III, AC and was treated with RI ICON® (DMG Chemisch-Pharmazeutische Fabrik GmbH, Hamburg, Germany); and Group IV had AC and was remineralized (CPP-ACP, GC Tooth Mousse; GC Corporation, Tokyo, Japan). AC was induced via dynamic pH cycling (12 hours demineralization solution/12 hours artificial saliva) over seven days. Groups III and IV were treated for seven days. All groups were then bleached using 40% hydrogen peroxide (Opalescence Boost™; Ultradent Products, Inc., South Jordan, UT, USA) for 40 minutes. Color changes (ΔE*) were measured using a spectrophotometer, and surface topography was analyzed using scanning electron microscopy (SEM) prior to bleaching and 14 days after bleaching. A one-way ANOVA and Tukey's post-hoc test for intergroup comparison were done.

All groups demonstrated color change beyond the clinical visibility threshold (ΔE*>3.3). Group IV demonstrated the least color change (5.18, p < 0.05). The bleaching efficacy in Group III was not significantly different from Group I. Group II exhibited the highest mean color change. The changes in enamel surface seen the least in surface treated groups were minimal compared to the untreated demineralized group (Group II). SEM analysis revealed that while bleaching caused significant surface irregularities and prismatic exposure in the untreated demineralized group (Group II), RI and CPP-ACP pre-treatments mitigated this damage, with CPP-ACP samples exhibiting the smoothest post-bleaching surface topography.

RI is the most effective treatment modality for enhancing esthetic outcomes, while CPP-ACP provides better protection to the enamel damaged by the bleaching agent, although the color change after bleaching is less than in a window of a seven-day treatment period in this study.