Teeth whitening gels are the most widely used home dental bleaching products. A teeth whitening gel oxidizes and removes stains and shows result usually over a period of about two weeks. Some of this dental teeth bleaching gels have active ingredients designed to remove hardened stains, but they also tend to cause irritation and serious discomfort when they are not used carefully or a poor quality dental bleaching gel is being used. While you will not have to worry about any of the teeth whitening gels that accompany the teeth whitening kits, there is no certain product that are very effective when it comes to the removal of even moderate stains and discoloration. Therefore, unless you have very, very mild stains on your teeth and thus need little help in attaining a whiter smile, the teeth whitening trays and their gels need to be considered the best option.