Structural analysis of the enamel subjected to pre- and post-bleaching agents

Impact of microabrasion and a remineralizing agent before in-office bleaching on hydrogen peroxide permeability, color alteration, and enamel morphology

OBJECTIVE

This in vitro study evaluated hydrogen peroxide (HP) penetration into the pulp chamber, bleaching efficacy, and surface enamel morphology of human teeth subjected to enamel microabrasion (MA) combined with in-office bleaching (IOB), with or without the application of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) remineralizing agent.

METHODS

Forty sound premolars were randomly divided into four groups: no treatment (NT), IOB only (IOB), MA followed by IOB (MA+IOB), and MA followed by CPP-ACP and then IOB (MA+CPP-ACP+IOB). HP concentration in the pulp chamber was measured using UV-Vis spectrophotometry, while bleaching efficacy was assessed with a digital spectrophotometer. Surface morphology was analyzed using scanning electron microscopy (SEM), and data were statistically analyzed.

RESULTS

The NT group exhibited lower HP penetration compared to experimental groups, while MA+IOB showed higher HP levels than IOB and MA+CPP-ACP+IOB. All experimental groups demonstrated significant color changes, except NT. The MA+IOB group displayed more grooves on enamel surfaces than the MA+CPP-ACP+IOB group, which had remineralizing agent deposits.

CONCLUSION

Combining MA and IOB increases HP penetration into the pulp chamber, but using CPP-ACP after MA can mitigate this effect without compromising bleaching efficacy.

CLINICAL SIGNIFICANCE

Employing a CPP-ACP remineralizing agent post-microabrasion can help reduce HP levels in the pulp chamber while maintaining effective whitening.

Effect of CPP-ACP on efficacy and postoperative sensitivity associated with at-home vital tooth bleaching using 20% carbamide peroxide

OBJECTIVES

To evaluate CPP-ACP effect on colour change and tooth sensitivity (TS) associated with at-home vital tooth bleaching using 20% carbamide peroxide (CP).

METHODS

A randomised double-blind placebo-controlled clinical trial was conducted to measure the TS and tooth colour change of 24 patients at 3-day, 7-day, 14-day and 30-day periods. The participants were instructed to apply 20% CP (7 days-04 h each) followed by the application of either CPP-ACP or non-active placebo paste, delivered by the bleaching custom tray (7 days-30 min each). Lightness (L*), redness (a*) and yellowness (b*) were measured using a digital spectrophotometer and the overall colour changes ∆E were calculated. ∆E and TS values were statistically analysed. The level of statistical significance was established at p = 0.05.

RESULTS

No significant differences were detected between CPP-ACP and placebo groups regarding the ∆E. The ∆E measurements presented significant differences within CPP-ACP groups between 3-day vs. 14-day and 30-day measurements. The CPP-ACP application reduced significantly the TS reported by the participants at 3-day when compared with the placebo group.

CONCLUSION

The application of CPP-ACP paste during at-home tooth bleaching with 20% CP was beneficial since its use reduced the TS and presented no deteriorating effect on the colour change.

CLINICAL RELEVANCE

The current findings are of importance for clinicians to manage TS reported by patients when a high CP bleaching agent is used.