The Effect of an Electric Toothbrush Versus Manual Toothbrush on The Removal of Denture Stains 

Researched by Christian H.


The purpose of this experiment was to determine the effect of an electric toothbrush versus a manual toothbrush on the  removal of stains on dentures. 

I became interested in this idea because I wanted to find out which toothbrush actually works better and I wanted to find out a little bit more about dental hygiene as a career option. 

The information gained from this experiment would help people to understand which is a better choice for a toothbrush.



My hypothesis was that an electric toothbrush would clean more effectively on stains, compared to a manual toothbrush. 

I based my hypothesis on the book Dental Health which stated, "Electric toothbrushes are small enough to reach into inaccessible areas and clear away stains and plaque more effectively than hand brushes."


The constants in this study were:

  • Amount and type of stain
  • Amount of time stains are on dentures
  • Kind of dentures
  • Kind of toothpaste
  • Amount of toothpaste
  • Amount of pressure by brush 
  • Amount of time brushing occurred
  • Temperature of water 

The manipulated variable was the kind of toothbrush used. 

The responding variable was the stain removed from dentures. 

To measure the responding variable I used a colorimeter to determine the whiteness of the cleaned dentures.


electric toothbrush
1 manual toothbrush
2 dentures
1 tube crest tooth paste
1 digital timer
1 triple beam balance
1 graduated cylinder


1. Start with clean dentures.
2. Use a graduated cylinder to pour 50 ml each of coffee, grape juice, and tea into a large container. Mix stains thoroughly. 
3. Stain dentures for one hour in the mixed stain in a container. 
4. Put one gram of Crest cavity protection toothpaste on the toothbrush. 
5. Place dentures on triple beam balance, set to 100 grams. 
6. Apply pressure to brush until triple beam balance equalizes to 100 grams.
7. Brush for two minutes.
8. Repeat steps 4-7 with other toothbrush on the right side.
9. Measure the amount of whiteness with a colorimeter.
A. Put one tooth on colorimeter
B. Push "sample" on computer
C. Test 3 times on one tooth 
D. Do the same with the next teeth



The original purpose of this experiment was to find out whether electric or manual toothbrushes worked better on the cleaning of dentures.

The results of the experiment were that a manual toothbrush worked better. 

See the table and graph


My hypothesis was that an electric toothbrush would work better.

The results indicate that this hypothesis should be rejected because a manual toothbrush worked better. 

Because of the results of this experiment, I wonder if I had used a different amount s of toothpaste would the results be different.

If I were to conduct this project  again I would do more  trails  and use a stronger amount of stains. 

Research Report


Clean teeth are important for your health, appearance, and digestion. To have clean teeth you have to brush and floss every single day to prevent tooth decay and other damage that can happen to your mouth.

Parts of a Tooth
Enamel is a hard material that covers your teeth. Enamel is one of the hardest part of your teeth. Dentin is another important tooth material, which is inside the enamel in your teeth. Dentin is a yellow structure. The dentin is Nerves inside of the tooth. When you get a cavity it leaves the dentin open and this is where pain comes from. The pulp is in the center of the tooth. Pulp contains blood vessels and nerves. The pulp protects the nerves so they can send messages to your brain. Cemetum is the material that covers the root of the tooth and also attaches the teeth to the jaw.

Cause of Cavities
Bacteria constantly grow in your mouth on teeth, gums, lips, and tongue. Some bacteria can be harmful but most are not, some are even helpful. Certain bacteria stick to hard surfaces like enamel that covers your teeth. If this bacteria is not removed, build-up can occur and grow. As colonies form, more bacteria of different types attach to the colonies growing on the teeth enamel. They form a sticky invisible film, called plaque which creates acid that dissolves holes, causing cavities. 

Mineral salts in your saliva help add hardness to teeth, however they are prone to attack by acids. Acid causes mineral salts to break down. Plaque forms on teeth that donít get washed. Acid is created when bacteria eat sugar. This acid produces plaque that canít be easily washed away by saliva. Acid eats tooth enamel and then tiny holes appear which get bigger. This also causes a cavity.

Brushing teeth alone is not enough to clean all the plaque from the surface of your teeth. In the space between your teeth and your gum line are two spots that a toothbrush canít reach well and plaque canít be removed easily, this is a reason why you should floss every day.

Why Does it take so Long to for a Toothache to Occur?

Itís important to see your dentist before a cavity forms so the plaque that canít be removed by brushing or flossing can be remove by the dentist with special tools. 

The body sends pain messages through nerve fibers. While acid is attacking the enamel you canít feel anything, but once acid has created a cavity it attacks dentin under the enamel, so nerve fibers in the dentin begin to send out a message that something is wrong. When that happens you feel tooth pain and you know for sure that you have a cavity.

Clean Teeth

Dentists advise people to brush their teeth after every meal and use dental floss every day to clean the area under the gum line. Bacteria digest certain foods, particularly sugars that form enamel acids. Brushing and flossing remove bacteria and acids. 

Dentists advise parents to teach and help children from ages two to three to brush their teeth so they can start learning the proper techniques. A parent should help their child brush their teeth until they are old enough to do it alone. Parents should schedule oral health appointments around their childís first birthday. The dentist will check for cavities in primary teeth. You should allow a child to discuss any fears he or she might have about the dentist. 

People should go to the dentist at least once a year for a check up. Children should start going after their deciduous teeth have erupted.
Dentists treat diseases at an early age. They also provide services to help people learn how to clean teeth better. In a check up dentists examine teeth, gums, and other tissues to look for diseases. Dentists may X-ray teeth. That helps them locate tooth decay that canít be seen on the surface. It also shows abnormal formations with the jaw or any other tissue that support teeth. 


Brushing your teeth is important. Just take a couple minutes out of the day and brush and floss. You will have a clean mouth and a nice smile.



"Causes of Cavities," Cavities 11-20-02

"Child Oral Health," Oral Health 12-3-02

"Health Tips and Fun Facts," Save Your Smile 12-3-02

"Seal out Decay," Sealants 12-3-02

Seigel, Dorothy. "Dental Health" United States, Chelsea House Publishing, 1994. Pp. 70 and 78

Simon, Charnon. "Dental Hygientist" United States, Capstone Press, 1998. Pp.7, 8, 10, and 13

Wellek, Charles. "Teeth," The World Book Encyclopedia .1998,Volume  19



I would like to thank the following people for helping me with my science project.

I would like to thank my mom and dad for wanting me to try my hardest and wanting me to do my best.

Another person I would like to thank is Tom Eislie for letting me use the colorimeter at Tree Top to find the results for my experiment.

I would also like to thank Mr. Ken Newkirk for helping me make my science project the best it can be.

The last person I would like to than is Mrs. Carol Helms for giving me advice all the way through my science project and helping me with documents on the computer

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