In-Vitro Model Development and Evaluation of Whitening Regimens

Objectives: To develop a model for testing the efficacy of different whitening regimens combining various product forms.
Methods: Pre-stained bovine enamel blocks from Therametics Technologies, INC. were brushed with a 1:1 mixture of toothpaste, containing hydrated silica, and DI water to achieve an initial L-value of ~60. Groups of 6 teeth were secured in custom trays and baseline L*a*b* values were recorded using a Spectroshade device. Two regimens were evaluated: 1) 5% w/v hydrogen peroxide (HP) toothpaste and 3% w/w HP pen, and 2) 1% w/w monoperoxysulfate (MPS) toothpaste and 0.1% w/w HP pen with a 410nm light tray. A regimen-treatment cycle consisted of 1) two brushings with HP toothpaste followed by an overnight 3% HP pen application, or 2) brushing with MPS toothpaste followed by a 10-minute light exposure with the 0.1% w/w HP pen, repeated twice. Brushing was conducted for 2 minutes at 120 strokes-per-minute with a 1g nurdle of toothpaste and 5mL of artificial saliva (AS). An even distribution of the pen’s formula was applied across each tooth followed by either sitting overnight with AS or applying the 410nm light tray for 10 minutes. Spectroshade recorded L*a*b* values after each treatment.
Results: Whiteness changes (ΔW) were measured for each group. For regimen 1), the improvement in the whitening index versus baseline (ΔW) after three cycles were measured: full-product regimen (ΔW = -8.81), toothpaste (ΔW = -4.48), and pen (ΔW = -6.07). For regimen 2) the ΔW after five cycles were measured: full-product regimen (ΔW = -12.56), toothpaste (ΔW = -7.17), and pen with light (ΔW = -8.46).
Conclusions: In-vitro models effectively evaluated new whitening regimens. Results demonstrated regimen 1) provided effective whitening over three treatments and regimen 2) produced greater overall efficacy, when compared to the individual products.