Whitening toothpastes differ not only smell, taste and color, but the composition. These pastes can be divided into two groups: the content of bleaching chemicals and pastes which have high abrasiveness.
Toothpastes first group contain in their composition the strong oxidants (hydrogen peroxide, or urea). These substances, getting on tooth enamel, actively produce oxygen free radicals. As a result, pigments (through which the enamel becomes yellow) are oxidized and become colorless as the teeth become white. The advantage of such pastes is a quick result. But these pastes pretty quickly destroy tooth enamel. Therefore, the use of toothpaste containing bleaching chemicals should be only after consultation with the dentist and under his control.
Toothpastes with a high content of abrasives are recommended for intensive cleansing pigmented enamel in smokers, people abusing coffee and strong tea. These pastes contain abrasives incorporating: dicalcium phosphate, silica or alumina. These substances may range from 20 to 40 percent of the total volume of the toothpaste. Abrasives remove plaque from the tooth enamel using physical effects, like sandpaper. As a result, the teeth become whiter. But clearing the plaque, they abrade the top layer of enamel. Moreover, such damage enamel paste (resulting in teeth become sensitive), they also have a negative impact on the gums. Most of all sold whitening pastes, fall into this group. The size of the abrasive particles is index RDA. Pasta with RDA above 250, experts do not recommend using more than two times a week.