Effect of a New Bleaching Gel on Tooth Whitening

Objectives: To evaluate the tooth-whitening capability of a unique tri-barrel hydremide-peroxide bleaching gel (Kör, Evolve Dental).
Methods: Bovine teeth were mounted into a custom acrylic arch-shaped-mounting device. Four groups of 10 teeth were mounted in two mounting devices containing 5 teeth each (n=10). Teeth were immersed in a solution of black tea for six days and baseline readings (CIE Lab) were obtained using a spectrophotometer (Easyshade Compact, VITA). Groups 1 (Kör Max Ultra Kit) and 2 (Opalescence Boost 40% and Opalescence PF 15% CP, Ultradent) had bleaching gel applied to the teeth to simulate a combination of home and in-office bleaching (Combined). Groups 3 (Kör 16% CP) and 4 (Opalescence PF 15% CP, Ultradent) simulated home bleaching (Home) using custom trays fabricated following manufacturer instructions. Spectophotometer readings were performed at the end of active bleaching (Immediate) and at three months post-bleaching (3 months). All samples were stored in artificial saliva at 37°C between active bleaching. The delta E and delta b data were evaluated with ANOVA and unpaired t-test/Bonferroni correction (alpha=0.0125). Delta L was analyzed with Mann-Whitney U/Bonferroni correction due to the large variability of the data (alpha=0.0125).
Results: Opalescence had significantly greater delta E and b immediately post-bleaching for both Combined and Home bleaching. However, three months post-bleaching, Opalescence was only significantly greater than Kör with delta b and Home bleaching. There was no significant difference in delta E, b, or L between Immediate and 3-month bleaching times per bleaching gel, except for delta b and Combined bleaching with Opalescence.
Conclusions: Immediately post-bleaching, the use of Opalescence gel resulted in greater change in delta E (less discolored) and delta b (less yellow) but no change in delta L (lightness) compared to Kör. However, in general, the differences between the two bleaching gels were less significant after three months post-bleaching.