1. Toothpaste Brand vs. Bacteria in your mouth
By: Nick Merriman

2. Question:
How does the brand of toothpaste you use (Prevident 5000 Plus, Pepsodent, Tom’s of Maine All Natural Organic) affect the number of bacteria on your teeth when brushing for 2 minutes in the morning with the same toothbrush.

3. Hypothesis:
If you change the brand of toothpaste you use then the Prevident 5000 Plus will remove more bacteria than Pepsodent or Tom’s because it is prescription strength toothpaste.

4. Toothpaste Brands

5. Variables Manipulated: brand of toothpaste
Controlled: amount of time brushing (2 minutes), type of toothbrush, amount of toothpaste used (1 squeeze), time of day (morning)
Responding: number of bacteria colonies on your teeth

6. Materials Prevident 5000 Plus: Dry Mouth Pepsodent
Tom’s of Maine Natural Organic
6 sheep blood agar culture plates
6 sterile swabs
6 sterile inoculating loops
toothbrush
timer

7. Materials

8. Procedure
Step 1-On the first day when you wake up note the time and brush your teeth for 2 minutes with Prevident 5000 Plus
Step 2-Use the sterile swab to go over your top teeth and your bottom teeth
Step 3-Using the swab, make a circle on the blood agar about the size of a quarter
Step 4-Using the sterile loop spread a streak through the circle area you swabbed , and continue spreading the material out in 3 different directions on the plate. This will let you see and be able to count the separate colonies of bacteria.

9. 2 minutes is a long time…..

10. Swabbing for the culture

11. Inoculating the agar

12. Procedure continued….
Step 5: Place the blood agar culture in an incubator for 32 hours at 37 degrees Celsius (body temperature)
Step 6: Count the number of visible
Bacterial colonies growing on the plate and record.
Step 7: On the second repeat steps 1-6 for trial #2
Step 8: On the third and 4th day repeat steps 1-7 with Pepsodent
Step 9: On the fifth and sixth day repeat steps 1-7 with Tom’s of Maine

13. 32 hours later…….lots of bacteria

14. Experimental Data Number of Bacterial Colonies on Culture
(cfu = colony forming units)
Trial #1
Trial #2
Average
Prevident5000
1337 cfu
1363 cfu
1352 cfu
Pepsodent
629 cfu
520 cfu
524.5 cfu
Tom’s of Maine
1354
1283 cfu
cfu

15. Conclusion
My hypothesis was incorrect. The Pepsodent cleaned your teeth the best, not the Prevident 5000 Plus. The low was 520 cfu for the Pepsodent. The high was 1363 cfu for the Prevident 5000 Plus. The difference between the two points was 843 cfu. Therefore I have learned that Pepsodent cleans your teeth the best of these three brands. To take this experiment to the next step, you could explore the different types of bacteria.