In vitro study on the Prevention of Re-Staining After Office-Bleaching

Objectives: The re-staining after tooth bleaching is the great concern clinically.  The purpose of this study was to evaluate the effect of sodium fluoride (NaF) solution and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste on the prevention of re-staining after in-office bleaching in vitro.

Methods: Fifty bovine teeth were stained with the black tea and bleached by an in-office beaching material (TiON In Office, GC, Japan). The teeth were divided in five groups, with 10 teeth in each group (n=10). They were applied with 0.2%, 2% NaF solution, CPP-ACP paste (MI Paste, GC, Japan), CPP-ACP paste containing fluoride (MI Paste Plus, GC, Japan) for 1 hour, or without application served as control group. Then, each tooth was immersed into the black tea again. CIE L*a*b* of the stained surface of each tooth was measured by a dental color meter (Shade Eye NCC, Shofu, Japan) after bleaching, at 1/3/ 6 hours and 1/2/3/7 days after immersion, and the changes in color were evaluated. Other specimens were prepared and the bleached and stained surfaces were observed by a scanning electron microscope (SEM) at each period.

Results: Color change was increased gradually by immersion in the black tea in all groups. The color changes of all experimental groups were less than that of control group. Significant difference was not found in the SEM images among all groups at each period.

Conclusions:  It was suggested that application of NaF and CPP-ACP was expected to be able to prevent from re-staining after office-bleaching.