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.
The Dentist's Guide to a Basic Teeth Cleaning. Professional teeth cleaning by a certified dental hygienist aims to remove plaque, tarter and stains that have accumulated on the teeth. Even with routine brushing and flossing of your teeth and gums, tarter can develop. The professional cleaning of teeth is a crucial part of good oral hygiene and is needed periodically to maintain the health of your teeth and gums.