A dental study with a rinse that whitens your teeth: Inclusion criteria: * Be 18 years of age or older * Have four healthy natural upper front teeth free of fillings, bondings or crowns / caps * There will be a total of 4 short visits. * A stipend in the amount of $45 will be provided upon completion of the research study. Its a double blind study so there is 50% chance that you will be in placebo. Call Valerie at 617 636 4099 at Tufts University Boston MA if you are interested.