Teeth Brushing Bacteria Science Fair Project Abstract

In the teeth brushing bacteria science fair project, 9 year old Jason from Colorado in the USA wanted to know if taking an extra minute to brush his teeth made a difference in the amount of bacteria that remained in his mouth.
 
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SHOULD YOU TAKE A MINUTE?
 
HYPOTHESIS
If you brush your teeth for two minutes there will be fewer bacteria on your teeth than if you brush your teeth for one minute.
 
MATERIALS
18 sterile Petri dishes
2 bottles of nutrient agar
18 sterile swabs
Masking tape
Toothbrush
Toothpaste
Distilled water
Timer
 
TEETH BRUSHING BACTERIA SCIENCE FAIR PROJECT EXPERIMENT
First, I prepared 18 sterile Petri dishes by filling them with nutrient agar. I labeled them with a zero, one or two. I stored the dishes in the refrigerator until it was time to use them.
 
For each session, before I brushed my teeth, I wet a sterile swab with distilled water and swabbed my molars on the bottom left side of my mouth. I took the swab and inoculated the agar in the Petri dish labeled “0”. Then, I put toothpaste on my toothbrush, set the timer for one minute and brushed my teeth. After one minute, I rinsed my mouth and swabbed my molars on the bottom left side of my mouth with a wet sterile swab and inoculated the agar in the Petri dish labeled “1”. I then brushed my teeth for 1 more minute and swabbed the same teeth with a wet sterile swab and inoculated the Petri dish labeled “2”. I repeated this session a total of 6 times when I would normally brush my teeth. Bacteria growth was visible after 2 days.
 
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image of teeth brushing bacteria science fair project experiment image of teeth brushing bacteria science fair project experiment image of teeth brushing bacteria science fair project experiment
 
CONCLUSION
My hypothesis was that if you brush your teeth for two minutes there will be fewer bacteria on your teeth than if you brush your teeth for one minute. The results of my experiment show that my hypothesis is correct. The Petri dishes that were inoculated before I brushed my teeth have the most bacteria growth. The Petri dishes that were inoculated after I brushed my teeth for one minute have less bacteria growth than no brushing, but more bacteria than brushing for two minutes. The Petri dishes inoculated with bacteria after I brushed my teeth for two minutes had the least bacteria. These results are clear to the naked eye.
 
If you brush your teeth for two minutes you should have less bacteria on your teeth. If you have fewer bacteria on your teeth you should have less chance for tooth decay.
 
WHAT I WOULD DO DIFFERENTLY NEXT TIME
Next time, if I do another teeth brushing bacteria science fair project, I would take more samples in case some of them didn’t grow. I also would like to see if eating sugar right before you brush your teeth makes a difference in how much bacteria is in your mouth. Finally, I would buy a black display board and not try to paint a white one black. Paint makes it warp and it won’t stand up.

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