Non-vital bleach method using 3.5% hydrogen peroxide with titanium dioxide

Objectives: To establish a safer and more effective bleaching method for discolored pulpless teeth, we examined bleaching from the intracoronal dentin side using a bleaching agent containing 3.5% hydrogen peroxide solution with titanium dioxide with irradiation by a halogen lamp. Methods: A bleaching agent containing 3.5% hydrogen peroxide with titanium dioxide (Pyrenees®, Mitsubishi Gas Chemical Company, Inc., Japan) was applied to the intracoronal dentin of ten extracted human teeth and irradiated for 10 minutes with a high-power halogen lamp (Hyperlightel, Kuraray Medical Inc., Japan) from the palatal side. After irradiation, the color of the buccal enamel surface was measured using a spectrophotometer (SE 2000, Nippon Denshoku Industries, Japan) to evaluate the bleaching effect using the CIE L*a*b* color coordinate system. Color measurements were taken before the bleaching treatment (L*0, a*0, b*0), at 5 minutes (L*5, a*5, b*5), and at 10 minutes (L*10, a*10, b*10) after the treatment. Results: The L*5 and L*10 levels were significantly higher than the L*0 level. The a* levels gradually increased, but did not rise significantly above the pre-treatment levels. The b*5 and b*10 levels were significantly lower than the b*0 level. On average, ΔE*ab5, and ΔE*ab10 were 3.8 (SD±1.58), and 6.2 (SD±2.29), respectively. These levels confirm the high effects of the bleaching. Conclusions: Based on these results, we concluded that a 3.5% hydrogen peroxide solution containing titanium dioxide can be used safely for bleaching of a discolored pulpless tooth and provides a strong bleaching effect. Furthermore, conventional walking bleaching takes several days, whereas treatment with the new bleaching agent can be completed in a short time.