Science project


Research Questions

  • Do whitening toothpastes really whiten teeth?
  • What ingredients in whitening toothpastes help to whiten teeth best?

Who doesn’t want a bright sparkling smile? But several things can cause teeth to lose their luster including coffee, tea, soda, and cigarettes. Also poor dental hygiene and age can cause teeth to turn yellow or brown. Many toothpastes today claim to whiten teeth. These toothpastes contain special abrasives that gently polish teeth and chemicals, such as sodium tripolyphosphate, that help break down or dissolve stains.


  • 5 white ceramic tiles, unfinished
  • coffee
  • bowl
  • masking tape
  • marker
  • 4 whitening toothpastes
  • 5 toothbrushes
  • stopwatch
  • paper
  • pencil

Experimental Procedure:

  1. Gather the necessary materials.
  2. To simulate stained teeth, place the ceramic tiles in a bowl and cover with coffee. Let the tiles soak for a couple of days. Then remove the tiles and let them dry completely (about one or two days). Label four of the tiles with the type of toothpaste that will be used on each tile. Label the fifth tile water.
  3. One at a time, place a dab of toothpaste on a toothbrush and brush for two minutes.
  4. Then rinse the tile. Repeat with each toothpaste and corresponding tile. Be sure to use similar amounts of each toothpaste and similar brushing techniques. On the fifth tile, brush using water only. Let the tiles dry.
  5. Compare the tiles. Order the tiles from darkest to lightest. Record your observations.
  6. Repeat steps 3 and 4 27 more times to represent using the toothpaste twice a day for two weeks.
  7. Analyze your data and draw your conclusion.

Terms/Concepts: enamel: protective covering on a tooth dentin: hard bonelike tissue that makes up most of a tooth; Many whitening toothpastes claim to make teeth whiter, but do they? The outer layer of the tooth is called the enamel. Underneath the enamel is a layer called dentin. Dentin is what produces the color of teeth. To actually change the color of the dentin a bleaching process must occur. However, whitening toothpastes can help to remove stains on the enamel by gently scratching the surface and with chemicals that help to remove stains.


“Tooth Whitening Methods: What You Need to Know about Tooth Whitening” by Shawn Watson at “Best Whitening Toothpaste” at “Do Teeth Whitening Toothpastes Really Work?” by Terry Ross at “Tooth Whitening: What you should know” at

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