The addition of fluoride and calcium to carbamide peroxide-based whitening agents can minimize mineral loss in tooth enamel during bleaching treatments, according to a study to be published in the September 2010 Quintessence International (Vol. 41:8, pp. e157-e165).
A group of Brazilian researchers divided sound enamel slabs into six groups (n = 10):
Placebo gel
Whiteness (10% carbamide peroxide, FGM)
Opalescence F (10% carbamide peroxide plus fluoride, Ultradent)
Pola Night F (10% carbamide peroxide plus fluoride, SDI
Experimental gel 1 (10% carbamide peroxide plus fluoride)
Experimental gel 2 (10% carbamide peroxide plus calcium)
The samples were submitted to six-hour gel applications daily for 14 days and stored in remineralizing solution after treatment. Enamel microhardness measurements were performed at baseline and after bleaching. In addition, the analytical concentrations of fluoride and calcium and the pH of the water used to rinse the bleached surface were analyzed using ion-selective electrodes, atomic absorption spectroscopy, and pH meter, respectively.
The researchers found that enamel surface microhardness significantly decreased after bleaching with nonenhanced 10% carbamide peroxide. The chemical analyses suggested that fluoride uptake was promoted by the high-concentrate fluoride bleaching gels (Opalescence F, Pola Night F, and experimental gel 1), while fluoride loss occurred with nonenhanced 10% carbamide peroxide bleaching gels (placebo gel and Whiteness). The carbamide peroxide agent enhanced with calcium (experimental gel 2) also prompted calcium enamel uptake.
