28 December 2022

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Correlation between using remineralization agents, bleaching efficacy

Lara Figini

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Traditional whitening procedures that involve the supervision of a dentist include home whitening, professional office whitening and a combination of both techniques.

In the outpatient technique, hydrogen peroxide is almost always used as a bleaching agent, in concentrations typically between 30% and 40%.

The effectiveness of the bleaching process is influenced by many factors, in particular by the concentration of the agent, the pH value, the application time, the activation by light and heat and the presence of a catalyst.

However, whitening processes, especially when applied with high concentrations of active ingredients, raise concerns as they can cause microstructural changes in tooth enamel by influencing the physicochemical properties of dental tissue.

Literature studies have shown that bleaching leads to changes in the mineral content of the enamel, causes an increase in the porosity of the enamel surface and a decrease in the elastic modulus, fracture toughness, abrasion resistance and microhardness of the enamel.

Materials and methods

In a study published in the European Journal of Oral Science in December 2022, the authors evaluated the effect of additional application of remineralization agents on whitening efficacy, enamel mineral changes and post-whitening color stability. 

A total of 112 dentin-enamel blocks were prepared from bovine teeth.

After the first color measurements, the following types of treatment were performed:

• Group 1, negative control (no treatment)
• Group 2, positive control (bleach only: 37.5% hydrogen peroxide)
• Group 3, bleaching followed by application of 2% sodium fluoride NaF and xylitol
• Group 4, application of a mix of bleaching agent + NaF
• Group 5, bleaching followed by application of CPP-ACPF amorphous calcium-casein phosphopeptide-calcium phosphate fluoride paste
• Group 6, application of a mix of whitening agent + CPP-ACPF
• Group 7, whitening followed by application of nHAP+F fluoride nanohydroxyapatite paste
• Group 8, application of a mix of whitening agent + nHAP+F.

Researchers repeated color measurements after immersion in distilled water for seven days and again after staining with coffee solution for 14 days.

The CIELAB-based whiteness index was used to evaluate whiteness and the CIEDE2000 color difference formula was employed to evaluate color stability.

The chemical investigation was performed using scanning electron microscopy with energy dispersive spectroscopy and X-ray diffraction analysis.

Results

The experimental groups showed significant increases in whitening compared to the negative control. Staining after bleaching did not result in statistically significant differences between the various groups.

Energy dispersive spectroscopic analysis revealed that bleaching protocols had no impact on baseline levels as well as Ca/P ratio.

The combined use of bleaching agents with remineralization agents did not affect the bleaching efficacy and did not provide an additional contribution.

Conclusions

From the data of this study, researchers concluded that the application of remineralization agents such as fluoride, CPP-ACPF and nHAP after in-office whitening or mixing them in the whitening gel does not compromise the whitening efficacy, but it also makes no further contribution to the mineral content of the glaze or to the color stability.

For additional information on this study: The impact of remineralization agents on dental bleaching efficacy and mineral loss in bleached enamel.