Does Whitening Toothpaste Work?

Research Questions:

• Which whitening toothpaste whitens the fastest?
• Which whitening toothpaste makes your teeth the whitest?

Try this whitening toothpaste for a whiter smile!” Have you ever wondered whether whitening toothpaste actually works? And even if it does, is it better to use an expensive brand of whitening toothpaste than an inexpensive brand? This science project answers these questions and more.

Materials:

• Large bowl
• Instant coffee
• Boiling water
• Five white stone tiles
• Masking tape
• Permanent markers
• Four different brands of whitening toothpaste
• Four identical toothbrushes

Experimental Procedure:

1. Fill the large bowl with coffee by mixing together boiling water and instant coffee. Use the package directions to make sure that you are using the correct proportions.
2. Carefully slip the five stone tiles into the bowl, making sure that the coffee does not splash out.
3. Leave the tiles in the coffee for 24 hours to stain them. Then remove them from the bowl and let them dry for another 24 hours.
4. Use masking tape and a permanent marker to label each of the toothbrushes and each of the tiles with the name of one of the toothpastes.
5. Brush each of the first four tiles for two minutes, using a different toothpaste and toothbrush for each tile. Make sure to brush the entire surface, both side to side and in a circular motion. At the end of the two minute period, rinse the tile.
6. Rinse the last tile with water without brushing it at all.
7. Organize the tiles so that they go from darkest to lightest. Record the order in a notebook.
8. Repeat this brushing process exactly 14 times on each tile. (This simulates twice-a-day brushing for two weeks.) Rerecord the order between each brushing.
9. Analyze your data. Which toothpaste whitened the fastest? Which toothpaste made the tiles the whitest at the end of the “two weeks”?

Terms/Concepts: Carbamide Peroxide; Enamel; Which substances stain teeth the most?; What whitening agents are in the various types of toothpastes, and how do they work?

References:

First Place Science Fair Projects for Inquisitive Kids, by Elizabeth Snoke Harris. Pp. 116-117.