Types of bleaching:
- mechanical decolorization and
- chemical degradation of chromogens (dyes)
What substances are used:
- Hydrogen and urea peroxides
Types of dyes:
- Large organic dyes
- Dyes with metal particles
Bleaching mechanism:
Hydrogen peroxide breaks the chemical bonds between dye molecules. As a result, the dye molecules remain lighter.
Dyes with metallic components are very difficult to fade, so in these cases mechanical masking of the paint with restorations (seals, veneers, crowns) is recommended.