The whitening products available in the dental care section of pharmacies, grocery stores and discount stores fall into the following categories: toothpastes, gels and adhesive strips. Products that claim whitening are considered cosmetics and are not regulated by the Federal Drug Administration. Therefore their claims are not subject to verification of effectiveness.
All toothpastes can be considered whitening because the act of brushing will remove stains. In order for a product to be truly effective in whitening, it must contain oxygenating agents such as carbamide peroxide or hydrogen peroxide. These react with the pigments in the tooth. The longer they remain in contact with the tooth the better it whitens. Gels work better than liquids and toothpastes.
Adhesive strips work better than gels unless the gels can be placed in a tray that adapts extremely well to the teeth. "Store bought" trays do not fit well. The shelf life of the oxygenating agents is short which means they could lose their effectiveness before opening. Always check the manufacture and expiration dates. This fact, together with the lack of contact time is the reason toothpastes are poor whiteners. Yellow and brown stained teeth, due to age, will lighten the best. There are some that just won’t respond to whitening. Also fillings and crowns (caps) do not lighten and may appear darker after teeth have been lightened. Whitened teeth may occasionally need to be touched up to maintain the selected shade.