Teeth Whitening is actually a bleaching process that lightens discoloration of tooth enamel.
Many do it yourself teeth whitening products are available, including whitening toothpastes, over-the counter gels, strips and trays, and whitening agents available at your local super store, pharmacy are online. Do it yourself Teeth Whitening will remove most stains with a gentle action that whitens your teeth. As the active ingredient in the gel (carbamide peroxide), is broken down, oxygen acts upon the stained organic deposits, which oxidizes them into a white color. Here are some I found on eBay.