Effect of strong tooth-bleaching with 38% hydrogen peroxide on marginal seal of dental restorations using self-etch...

The purpose of this study was to evaluate the distance and/or thickness of dye penetration at enamel and cementum/dentin margins of restorations before and after vital bleaching. Class V cavities were prepared on extracted human premolars and restored with light-cured resin composite using either AQ-Bond or Single-Bond2 adhesives. Four conditions: no bleaching (control), restored before bleaching (RB), bleached and immediately restored (BIR), bleached and stored in artificial saliva for 7 days then restored (B7R), were used for each adhesive group. After soaking in basic fuchsin dye for 24 hours, all specimens were vertically sectioned through the middle of restorations to measure the distance and/or the thickness of dye penetration. No microleakage was found either on enamel and cementum/dentin margins of control group using AQ-Bond. Whereas leakage was found in the control group using Single-Bond2 and bleached groups. Statistically significant differences in leakage distance and/or thickness were found among groups at the cementum/dentin margin (P < .05). Dye could penetrate into the pulp chamber of BIR (60%) and B7R (15%) specimens.

The negative control or leakage-free group is very important when discussing the effects of bleaching on marginal seal or microleakage. Bleaching using 38% H₂ O₂ increases the microleakage distance and dye penetration area of cementum/dentin margin more than that of enamel margin. The bleached tooth is not a good substrate for reliable bonding and complete seal and it is also a channel for external stimuli reaching the pulp.