The effect of light on tooth whitening: a split-mouth design

Conflicting research exists on the effect that various lights have on in-office tooth whitening. The aim of this study was to determine whether a sodium arc bulb lamp used with 25% hydrogen peroxide shows significant differences in shade using a split-mouth design.

Forty-nine subjects meeting study criteria had anterior teeth whitened with a 25% hydrogen peroxide in-office whitening system. The light was used on a randomly selected right or left half of the mouth. The opposing side was whitening only with gel. Shades were recorded using a spectrophotometer before, immediately after, 1 and 2 weeks post-whitening. Sensitivity was also recorded using a visual analogue scale. Values were analysed with a Friedman test with a stepdown Bonferroni adjustment for multiple comparisons.

All teeth increased in lightness after whitening procedures. The only significant differences between use of the light and without use of the light were on the maxillary arch 1 week after whitening (P = 0.010). Sensitivity was greatest immediately after whitening but subsided within 1 week of whitening.

The use of a sodium arc bulb lamp with 25% hydrogen peroxide in-office whitening produces better results on maxillary teeth up to 1 week after whitening is completed. Subjects could not distinguish differences on each side of the mouth.