In vitro evaluation of a novel 6% hydrogen peroxide tooth whitening product

Summary Objectives. The aims of this study were to evaluate the in vitro tooth whitening effects of a novel 6% hydrogen peroxide containing tooth whitener Xtra White (XW) on extrinsic stain and intrinsic tooth colour and the effects on enamel and dentine microhardness. In addition, to determine the levels of peroxide found in tooth pulp chambers after treatment with XW in vitro. Methods. Extrinsic stain changes were determined by measuring colour changes of tea stained hydroxyapatite discs after treatment with water, placebo gel, XW or Colgate Simply White (CSW). Intrinsic tooth colour changes were determined by treating extracted human teeth in vitro with a placebo gel, XW or CSW for a simulated two weeks use and measuring colour differences with a chroma meter. Teeth treated with placebo gel and XW were cross-sectioned and the subsurface enamel and dentine was polished and the microhardness determined. The peroxide concentration found in extracted tooth pulp chambers was determined spectrophotometrically. Results. XW gave significantly more extrinsic stain removal ðp , 0:0001Þ and an increase in tooth whiteness ðp , 0:05Þ than a placebo gel, but was not significantly different to CSW. There were no significant differences in subsurface enamel and dentine microhardness values for the placebo and XW treated teeth. The mean concentration of peroxide found in the tooth pulp chambers was 0.44 mM, which is over 3000 times below the concentration reported to cause pulpal enzyme damage. Conclusions. XW has been shown to be an effective tooth whitening product in vitro with support for its safety on subsurface enamel and dentine together with its safety on tooth pulp tissue.