LogFAQs > #968302985

Chemically, it doesn't make a lot of sense for activated charcoal to be able to penetrate into the enamel and and remove stains as:

1. Activated charcoal is a solid that tends to clump in comparatively large particles that would struggle to get anything but the most surface stains.
2. Activated charcoal does little to chemically break down organic molecules, and more or less works by "capturing" other molecules into it's porous structure. This would presumably mean it would be less effective at removing staining particles that are more chemically bonded to the surface of the tooth.
3. It's such a large and relatively hard particle that it produces a lot more abrasive action on the surface of the tooth, eroding away the enamel if used frequently.

Just use a bleaching agent that can penetrate into every nook and cranny and chemically break up the staining molecules and flush them out of the enamel or dentin.