Bleaching agents used as a gel contain which peroxide components?

• A. carbamide peroxide and hydrogen peroxide
• B. ammonium persulfate
• C. calcium peroxide
• D. sodium hypochlorite

Answer: (A)

Peroxide species that oxidize and break down stain molecules are what drive whitening gels. In dental bleaching products, the peroxide component is either hydrogen peroxide itself or carbamide peroxide, which rapidly decomposes to hydrogen peroxide and urea. This dual option explains why gels can be formulated with either of these two compounds—the active bleaching action comes from hydrogen peroxide released during or after application.

Ammonium persulfate isn’t a peroxide in the sense used for whitening gels; it’s a different oxidizing salt sometimes seen in other products. Calcium peroxide and sodium hypochlorite are not used as the peroxide components in typical enamel-safe gel whitening formulations—calcium peroxide is a slower, less practical solid source for gels, and sodium hypochlorite is a strong indiscriminate oxidizer used for disinfection/endodontic purposes, not cosmetic whitening gels.