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Mouthwash Science Fair Experiment
Transcript of Mouthwash Science Fair Experiment
5 2" inch petri dishes
5 3g pouches of powdered agar
pot and stove
absorbent paper (water color paper)
Listerine cool mint mouthwash
ACT mint fluoride rinse
Crest total care mouthwash
pen or pencil
If I use an antiseptic mouthwash (Listerine),
then the most oral bacteria will be killed because it contains thymol and alcohol, which are substances that kill and prevent bacterial growth.
Independent Variable: Type of mouthwash.
Dependent Variable: Amount of bacteria.
Control Group: Group with no mouthwash used.
The amount of mouthwash.
The amount of oral bacteria applied to petri dishes.
The amount of time the bacteria is exposed to the mouthwash.
Method used to apply bacteria to the petri dishes.
The area that all of the petri dishes are kept.
The source of the bacteria .
Data/ Data Analysis
What type of Mouthwash kills the most oral bacteria?
My hypothesis was that an antiseptic mouthwash, such as Listerine, would prevent and kill more bacteria than a fluoride rinse, ACT, or a total care mouthwash, Crest. I based my hypothesis off of the fact that antiseptic mouthwashes are well known for their bacteria killing properties. The results indicate that this hypothesis should be considered incorrect because the total care mouthwash, Crest, prevented all bacteria growth, while Listerine had the most bacterial growth only behind the control. Because of the results of this experiment, I wonder if different types of total care mouthwash have the same efficiency at preventing bacterial growth. If I were to conduct this science fair project again I would test different types of total care mouthwash.
Preparing the Petri Dishes
Making the sensitivity
Setting up the experiment
1. Clean petri dishes with soapy water and let them air dry.
2. Pour 1/2 cup of water into a pot and boil it.
3. Measure 1 tablespoon of agar and put the 1 tablespoon into a clean coffee cup.
4. Add 2 tablespoons of sugar into the coffee cup.
5. Add three tablespoons of boiling water into the coffee cup and stir vigorously until the mix dissolves.
6. Pour the agar equally into the 5 petri dishes so that each dish is filled halfway with agar. Immediately place the covers on the petri dishes as soon as you pour the agar in.
7. Place the petri dishes in a stable environment and allow them to set ( or place them in a refrigerator over night.
1. Using the absorbent paper, cut 20 small 1 cm squares.
2. After doing this, pour some of the Listerine, Act, and Colgate mouthwash into separate disposable cups. Pour enough mouthwash to cover about 1/3 of each cup, and make sure to label each cup appropriately.
3. Label 5 of squares with an L for Listerine mouthwash using the permanent marker.
4. Soak these squares in the cup with Listerine mouthwash one at a time for 5 seconds, using the tweezers to take the paper out. After soaking the squares blot any excess liquid with a paper towel and put the squares off to the side.
5. Label 5 of the squares with an A for ACT mouthwash using the permanent marker.
6. Repeat step 4, but soak the squares labeled A in the cup with ACT mouthwash.
7. Label 5 of the squares with a C for Colgate mouthwash using the permanent marker.
8. Repeat step 4, but soak the squares labeled C in the corresponding mouthwash,Crest Mouthwash.
9. The remaining 5 squares will be used as for the control. These squares WILL NOT be soaked in any mouthwash at all.
1. Using a sterile swab, swab inside someone’s mouth, making sure to swab the first four front teeth along the gum line.
2. Remove the cover of one of the petri dishes and begin to rub the swab across the agar in a zigzag pattern.
3. Turn the dish around a quarter turn, and repeat step 2 to ensure maximum coverage of petri dish.
4. After doing this, dispose of the swab.
5. Repeat steps 1-4 four more times for a total of 5 petri dishes, making sure to swab the gum line of the same person each time, and also using a new swab each time.
6. For each petri dish, use the tweezers to put 1 sensitivity square that has been soaked in Listerine (L), 1 that has been soaked in ACT (A), 1 that has been soaked in Crest (C), and 1 that has NOT been soaked in any mouthwash on a single dish. Make sure to space the 4 sensitivity squares an equal distance away from each other.
7. After repeating step 6 for each of the 5 petri dishes, label all 5 of the petri dishes1-5 using a permanent marker.
8. Now, seal the covers of the petri dishes using clear tape.
9. Put all 5 of the petri dishes in a dark place with a stable, constant temperature, such as a closet. Make sure the area that you chose to put the petri dishes in is an area where your experiment will remain undisturbed.
Check the petri dishes every 24 hours for a 7 day (168 hour) period and record bacterial growth.
Alcohol and antimicrobial agents are the ingredients in mouthwash that kill oral bacteria (Johnson, 2012). Alcohol is commonly used in mouthwash to dissolve ingredients such as menthol, methyl salicylate, thymol, and eucalyptol. Mouthwashes that do not contain alcohol usually have ingredients like cetylpyridinium chloride (CPC), an antiseptic that destroys and cleanses bacteria (“Mouth Wash”, 2012). These antimicrobial agents kill bad breath and germs by disrupting the membranes of oral bacteria. By disrupting the membranes of bacteria, the agents can destroy the bacteria completely or inhibit the growth of the bacteria.
Listerine antiseptic mouthwash contains thymol, methyl salicylate, menthol, and eucalyptol as its active ingredients (“Cool”, 2012).
It also contains 21.6% alcohol as one of its inactive ingredients.
Thymol is an antiseptic substance that prevents plaque, inhibits the growth of oral bacteria, and helps prevent gingivitis. (“Ingredients”, 2012).
Act fluoride rinse is alcohol free and contains 0.05% sodium fluoride as its active ingredient (“ACT®”, 2012).
Sodium fluoride is mainly used to strengthen and protect teeth from cavities, but can also be used to prevent bacteria.
Crest total care mouthwash is alcohol free and contains 0.07% CPC (“Crest”, 2012). CPC, a newer ingredient in mouthwash, is a chemical that destroys and cleanses bacteria. CPC kills bacteria by traveling through lymph, the fluid in between cells, to get through layers of skin and disrupt the cell membranes of infectious organisms (Wilford, 2012).