Whitening Effect of Toothpaste on Various Stains

Researched by Michael B.


The purpose of this experiment was to determine which toothpaste whitens stained teeth the best.

I became interested in this idea when I realized that all the major toothpaste brands claim that they whiten teeth the best, I wanted to see which one is really the most effective.

The information gained from this experiment will help consumers choose the best whitening toothpaste.
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My hypothesis was that Colgate toothpaste would be the most effective at whitening teeth.

I base my hypothesis on the fact that Colgate was the first A.D.A. approved toothpaste in the U.S.A.  It is said to be the most effective at removing plaque and plaque is what stains teeth.
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The constants in this study were:

  • The quantity of stains used (50mL)
  • The amount of time the teeth will be kept in the stains (48 hours.)
  • The quantity of toothpaste used (1cm)
  • The pressure and number of strokes with the toothbrush (100 strokes)
  • The type of toothbrush
  • The type of tooth and its preparation
  • The substances used to stain the teeth (Coffee, and Kool-Aid.)

The manipulated variable was the type of toothpaste used to whiten the teeth (Crest Baking Soda and Peroxide, Colgate Extra Whitening, Western Family.) 

The responding variable was the color of the stained teeth after being brushed. 

To determine the color of the teeth I will be using a dentistís shade guide.
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1 Shade Guide
12 Teeth

Needle Nose Pliers
 100 mL Dixie Cups
200 mL coffee
200 mL strawberry Kool-Aid
5ft wax paper
1 Crest toothbrush
100 mL Crest Baking Soda and Peroxide
100 mL Colgate extra whitening
100 mL Western Family toothpaste


1. Gather materials.
2. Put on latex gloves.
3. Analyze the color shade of each tooth by matching it up with the right color on the shade guide. 
4. Fill graduated cylinder with 50mL of Folgers coffee.  Brewed according to the instructions on the container.
5. Carefully pour coffee into a Dixie cup. 
6. Carefully place one tooth into the Dixie cup and mark it C1.
7. Let it sit for exactly forty-eight hours.
8. Take the tooth out of the coffee and place it into a zip lock bag that is marked C1.
9. Repeat steps four through eight on six of the teeth, except mark the cups C2, C3, C4 and so on.
10. Repeat steps two through nine on six of the teeth, using Kool-Aid.  Brewed according to the instructions on the container.   Except mark the cups K1, K2, K3, K4 and so on.
11. Record the color of all the teeth after being stained by matching it with the correct color on the shade guide.
12. Take two teeth from the coffee group and put them in another Dixie cup marked "Coffee and whatever tooth whitener will be used on those teeth."  Do this to all the coffee stained teeth.
13. Repeat step thirteen on the Kool-Aid stained teeth also except mark cup with Kool-Aid and the toothpaste that is being used on the tooth.  Do this to all the teeth.
14. Brush the stained teeth with the assigned toothpaste. 
15. Do this by holding the tooth with needle nose pliers and brushing the tooth 100 strokes on the face of the tooth.
16. Compare the tooth to the shade guide by matching it with the correct color on the shade guide.  Record the data found.
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The original purpose of this experiment was to determine which toothpaste whitens stained teeth the best.

The results of the experiment were the coffee stained teeth were whitened the most by the Western Family brand toothpaste.  The Kool-Aid stained teeth were whitened the most with Colgate Extra Whitening.  The toothpaste that whitened the teeth the least was Crest Baking Soda and Peroxide.  Overall Western Family whitened the best, then Colgate, and then Crest.

See the table and graph.

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My hypothesis was that Colgate Extra Whitening toothpaste would be the most effective at whitening the stained teeth.

The results indicate that this hypothesis should be rejected.  Although Colgate Extra Whitening whitened the Kool-Aid stained teeth the best Western Family Cool Fresh whitened teeth the best overall.  The average whitening of all the teeth shows that Western Family Cool Fresh whitened 2.75 more shades on a dentists shade guide than Colgate Extra Whitening.  Colgate Extra whitening whitened 3.5 more shades than Crest Baking Soda and Peroxide.

These findings will benefit the average person who is looking for the best deal on a type of toothpaste that whitens teeth the best. 

Because of the results of this experiment, I wonder if the amount of toothpaste applied to the teeth would affect the results.  Also, I wonder if the Colgate and Western Family would work as well with a deeper stain.

If I were to conduct this project again I would use more stains and more cleansers.  There would also be more teeth in each group.
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 Toothpaste is a thick substance that consists of a binder (usually it is gum tragacanth), fluoride, flavoring oils, and a liquid to give the toothpaste plasticity.  Stains that occur on teeth are most often plaque stains.  These and other stains can be whitened using tooth-whitening processes.

Since the beginning of time humans have had problems with their teeth.  The ancient Greeks, Romans, and Egyptians used various remedies for toothpaste and tooth extraction.  In the Middle Ages barbers and jewelers practiced dentistry.  The Surgeon Dentist was the first book published that dealt with dentistry.  Pierre Fauchard published it in 1738.  American colonists in the 1600ís and 1700ís were considered to have the worst teeth in the world.  It was a result of a poor diet and inadequate cleaning habits.  Dentistry finally became a profession in the 1800ís.  X-rays were invented in 1885.  Fluoride was put in toothpaste to reduce tooth decay in the 1950ís.

Anatomy Of The Tooth
The human tooth is made up of many different parts.  The part of the tooth called pulp is the innermost part of the human tooth.  It is made up of connective tissue, blood vessels, and nerves.  Blood vessels nurture the tooth whereas the nerves send sensations of pain to the brain.  Dentin is a very hard yellow material that makes up most of the tooth.  It is harder than bone and is mostly made of mineral salts, water, and some living cells.  Enamel lies over the dentin is the outer most covering of the crown.  Cementum lies over the dentin in the root of the tooth.  The periodontal ligament consists of small fibers.  These fibers extend through the cementum.  The tooth is a very complicated human tissue. 

Causes of Stains
 There are many causes for tooth stains but perhaps the most common is plaque.  It is a sticky film that is made up of saliva, food particles, and bacteria.  Plaque is a source of toxic material that takes part in the discoloring, and decay of teeth.  Also inadequate cleaning habits and poor diet results in the discoloration of teeth.

 Almost all toothpastes contain fluoride, a chemical compound made up of fluorine; fluoride helps to resist tooth decay.  Binders are put into toothpaste to hold the toothpaste together.  Most binders are made up of gum tragacanth, seaweed derivatives, or cellulose derivatives.  Flavoring oils are put in the toothpaste to flavor it.  The flavoring oil consists of saccharin, or cyclamate.  Both oils are often used together.  Liquid is added for plasticity.  The liquids are glycerin and water.  Tooth powders are almost identical to toothpaste except tooth powders do not contain liquids or binders.

Bleaching Agents For Teeth
 When teeth start to age they tend to turn yellow.  This and other sorts of stains can be removed by whitening processes.  There are at home bleaching processes that take anywhere from three to six weeks, depending on the stain.  The carbamide peroxide level is about 10% to 22% and is used in a custom tray that should be worn twice a day for one hour.  Bleaching done by a dentist has a much stronger carbamide peroxide level, which can range from 34% to 44%.  Because of such a high level of carbamide peroxide only a professional should do this process.  Power bleaching is the most powerful form of bleaching that is still used today.  This has the highest level of peroxide (30% to 50%.)  It is used for those with severe discoloration.  This type of bleaching takes about 35 minutes depending of the stain.  Power bleaching lasts anywhere from one to seven years, depending on personal habits.

 As you can see there are many ways to whiten teeth.  You can bleach your teeth at home or have them bleached by the dentist.  Those are just some of the tooth whitening processes.
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Bercuson, David Jay.  "Early Dentistry,"  World Book Encyclopedia.  1998.  PP.144-145

"Branches of Dentistry,"  World Book Encyclopedia.  1998.  143-144.

"Cleaning the Teeth,"  World Book Encyclopedia.  1998.  PP.85-86.

Dental Forum.  "Choosing the Right Tooth Whitening Process,"  http://dentistry.about.com, 11/9/00.

"Dental Hygiene,"  World Book Encyclopedia.  1998.  PP.143

"Parts of a Tooth,"  World Book Encyclopedia.  1998.  PP.84-85

"Toothpaste and Dentifrice,"  Microsoft Encarta Encyclopedia Deluxe 2000.  Year 2000.
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First I would like to thank my mother for driving me around and buying all my materials.  Also I would like to thank Dr. Holbrook for giving me teeth and helping with my experiment.  Mr. Newkirk did a great deal of explaning things to me on how to make my project.

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