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.
Rating Newest Oldest. Best Answer: Buying an expensive tooth brush may help keep your teeth cleaner, but using an over the counter whitening system will whiten and brighten your smile! Bleaching your teeth for one to 4 weeks will not harm your teeth and the result will last for a long time.There are also a number of dentist assisted whitening methods that work well including take home tray bleaching and in office whitening.eport Abuse. Lemon juice, baking soda or baking powder can also be used for teeth whitening. Rubbing the bark of walnut tree brightens the teeth. Strawberries are natural teeth whiteners, simply rub them directly on your teeth or mash into a paste and apply.