1 Its cost, on average, is $650, compared to $400 for take-home trays and under $100 for over-the-counter bleaching trays or whitening strips. 2  Results can be unpredictable, depending on factors such as age, heredity and the type of staining that is present.
Plankton (singular plankter) are a diverse group of organisms that live in the water column of large bodies of water and that cannot swim against a current. They provide a crucial source of food to many large aquatic organisms, such as fish and whales.
Many animals, from single-celled Radiolaria to the eggs or larvae of herrings, crabs, and lobsters, are found among the zooplankton. Permanent plankton, or holoplankton, such as protozoa and copepods (an important food for larger animals), spend their lives as plankton.