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.
Nope: Neither will really whiten your teeth. Baking soda is abrasive and may remove some surface stains, but it does not really whiten your teeth. Excessive use may actually wear your enamel away. Professionally dispensed products are the strongest and best way to whiten your teeth. ...Read more.