I had my family take turns spitting in a cup until there was about 1-½ inches of spit in the cup. I dipped 12 toothbrushes into the cup and let them sit in plastic bags for 2 days. I divided the toothbrushes into four groups: control group (doing nothing), water group (rinsing the toothbrush in hot tap water for 10 seconds), Aqua Blast group (soaking a toothbrush in Aqua Blast for 10 minutes) and dishwasher group (placing toothbrush in top rack of dishwasher using Cascade soap). I pressed each toothbrush into a petri dish with nutrient agar solution. I repeated the experiment 2 more times. My Dad supervised me during the experiment and I wore protective gloves.
I took pictures of the petri dishes at 30 hours and 75 hours. Using a scale of 1 to 10, I rated the amount of bacteria where 1 had no bacteria and 10 had a lot of bacteria. I completed tables and charts and computed the average amount of bacteria for each group. By assigning numerical values, I was able to determine which method worked best at cleaning a toothbrush and eliminating germs.
The Aqua Blast did work better at cleaning a toothbrush and eliminating germs than plain water; however, I was surprised that the dishwasher method worked best. I was also surprised that rinsing your toothbrush off with water was not much better than doing nothing at all to your toothbrush after brushing. Most people simply rinse their toothbrushes off with water; I think they would change their habits if they saw the results of my experiment. I concluded that the dishwasher method was best, was more cost effective and may be safer for you and the environment.
This project was to determine the best way to clean your toothbrush.
Science Fair Project done By Kathleen M. Farrelly