Antimicrobial Research Series: The Power of Mouthwash

By Division I student Elliot

Do you ever wonder what mouthwash actually does other then making conversations with you more enjoyable? Luca, Theo, and I wanted to know the answer to this question.

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At the end of April our class was split up into groups, each group came up with a different question that they were to answer with provided tools. Our group used 5 petri dishes, one positive control, one negative control, and three petri dishes with bacteria and different amounts of mouthwash. Our positive control was bacteria collected from the back of my mouth with a q-tip, and the negative control was just mouthwash spread on a petri dish.The negative and positive controls are important to see if the mouthwash was actually making a difference in the petri dishes compared to the positive control. The other three petri dishes were spread with bacteria from my mouth and then applied to the petri dishes with different amounts of mouthwash. We spread one with  25%, one with 50%, and 100%, these stood for different amount of drops we put on the dish we would put the certain amount of drops on the dish and swirl it around. I then wrapped the dishes with the sealing tape, so that our results wouldn't be affected by any outside bacteria getting in.

Over the course of a couple weeks we took pictures of the progress of the bacteria. We made sure that we handled the dishes with sterile gloves and with great care, so our results wouldn't be affected.  We had done this project three times, due to contaminated petri dishes previously, we made very strict rules about the handling of the dishes.

“It was interesting to see how different concentrations affected the growth of bacteria,” researcher Theo Cooper said. The 25% and 50% dishes had almost the same amount of bacteria, covering a good ¼ of the dish,  just in different sized colonies, but you can clearly see the difference between 25% and 100%, 100% had much less bacteria, from this result we could conclude that mouthwash does make a difference to the amount of bacteria that forms in your mouth.. The differences between the positive control and the 100% also demonstrated the difference that mouthwash has, even the 25% dish was a large difference from the positive control. In the future I would like to see what difference toothpaste makes to the amount of bacteria on your teeth.

So that mouthwash sitting on your sink should continue to be used, for the sanity of your friends, and for your health.