1 concentration gradient The difference in the concentration of a chemical across a membrane. 2  cytoplasm The living substance inside a cell (not including the nucleus). 3  diffusion The movement of particles (molecules or ions) from an area of higher concentration to an area of lower concentration.
Not all stains can be lightened by over-the-counter or professional bleaching, and your dentist will be able to give you guidance. If you have sensitive teeth, gum disease or teeth with worn enamel, your dentist may discourage tooth whitening.
In-office bleaching provides the quickest way to whiten teeth. With in-office bleaching, the whitening product is applied directly to the teeth. These products can be used in combination with heat, a special light, or a laser. Results are seen in only one, 30- to 60-minute treatment.ith in-office bleaching, the whitening product is applied directly to the teeth. These products can be used in combination with heat, a special light, or a laser. Results are seen in only one, 30- to 60-minute treatment.