The effect of hydrogen peroxide concentration on the outcome of tooth whitening: an in vitro study

Aim. This in vitro study examined the effect that various concentration of hydrogen peroxide (5–35%) had on tooth whitening. Method. Extracted third molars were sectioned and stained using a standardised tea solution to Vita shade C4. These stained specimens were then bleached with a series of gels containing 5, 10, 15 or 25% w/w hydrogen peroxide. Each specimen was bleached for a number of sessions with one session being defined as 3×10 min exposure. Results. The number of applications of the various concentrations of bleaching gel varied from 12 applications for the 5% gel to one application for the 35% gel. Plotting the number of applications against hydrogen peroxide concentration showed an exponential response curve. Conclusions. The concentration of hydrogen peroxide in a proprietary bleaching gel had a marked effect on the number of applications required to produce an optimal shade outcome.