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% hydrogen peroxide. Each specimen was bleached for a number of sessions with one session being defined as 3 x 10 mins exposure. Each 10-minute exposure period was preceded by a 6 second exposure to a plasma arc lamp.
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.
Conclusion: 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. This work was supported by a Shirley Glastone Hughes award from the BDA.