Ex-vivo testing of hydrogen peroxide tooth whitening

Objectives:

To test the effectiveness of blue light on hydrogen peroxide tooth whitening using extracted human teeth and stained bovine models. To examine how effective bovine model systems are at predicting whitening results.

Methods:

40 extracted human incisors and 40 stained bovine incisors were used to test the Philips Zoom! whitening system. The bovine samples were first stained in a solution of tea and coffee by complete immersion for 7 days at 37^oC. The samples were randomly assigned to 2 groups (each with 20 human and 20 bovine) then one group was tested in ambient light, and the other group was tested under the Philips Zoom! Whitespeed lamp on full power setting (190mW/cm² at 465nm). Zoom! gel comprising of 25% hydrogen peroxide and chemical activator was applied at each time interval, as per the manufactures instructions. The colour of the individual teeth was measured using a Konica Minolta CR-321 chromameter at each time point after rinsing and dab drying the tooth. Descriptive statistics were calculated for  L*, a*, and b*, as well as changes from baseline (DL*, Da*, Db*, and DE). An analysis of variance (ANOVA) was performed yielding the least square means and 95% confidence intervals.

Results:

The mean DE values are shown in the figure together with the 95% confidence intervals for both types of teeth and for illuminated and non-illuminated cases.

Conclusions:

The Philips Zoom! whitening procedure based upon 25% hydrogen peroxide and blue light illumination produces a change in colour (DE ) of 7-10 units after 3 consecutive 15min treatments when tested ex-vivo on human and bovine teeth. The blue light significantly enhances the whitening effect. The whitening of the stained bovine teeth is >3 times faster than that of the extracted human, since the added stain is more superficial.