Hypothesis

If toothbrushes are stored in different conditions such as outside and inside the washroom and in less hygienic conditions such as near the toilet places then that will cause it to have more bacterial growth because it is more prone to bacterial buildup.

Variables

Dependent variable: The amount of bacteria that will grow on the toothbrushes in these places.

Independent variable: The different places in where the toothbrushes are stored (countertop covered and uncovered, outside of the washroom uncovered and covered, up high, next to the toilet with lid open and lid flushed closed.

Controlled variables: The type of toothbrush, the brand and amount of toothpaste, the duration and technique of brushing the teeth, the age of each participant.

Procedure

1.  Preparation of materials: 4 people each person will brush their teeth using each of the eight toothbrushes when stored in there conditions, 32 toothbrushes there is 8 toothbrushes per person in the storage conditions, 32 petri dishes for bacteria culturing, agar powder to put into the petri dishes, sterile cotton swabs to swab the bacteria off the toothbrushes, heat mat/incubator for the bacteria to grow, distilled water to moisten the swabs,  and a microscope to look at bacteria when done growing.

2.  Dividing the toothbrushes among the 4 people which is 8 toothbrushes per person, every toothbrush is marked after each person's name  to track which toothbrush belongs to each person and where it goes and then bagged up until use.

3.  The first 4 toothbrushes were then stored in the first storage condition (washroom countertop uncovered) ; they were then used for seven days in the morning after breakfast and in the evening after dinner for 2 minutes each time brushed. This would continue for each of the next 7 storage conditions Countertop (covered) Outside the bathroom (uncovered) Outside the bathroom (covered) Under the bathroom drawer Up high, Next to the toilet (lid open),Next to the toilet (lid closed).

4.  Bacterial Sampling and Swabbing Process: After brushing with the toothbrushes for 7 days it is time to swab the bacteria off the toothbrushes, the agar mixture is made and poured into the petri dishes, after cooled off a sterile cotton swab will be moistened with distilled water and then rubbed on a toothbrush in a back and forth motion and making sure there is no cross contamination, soon after the cotton swab will be put Ontario the agar in the petri dish in a zigzag motion to ensure it is evenly spread across the agar. Afterwards, the petri dishes are labeled and placed on the heat mat at 37 degrees Celsius and then repeated for all 32 toothbrushes separately after being in the storage condition.

5.  Incubation and growth: After dishes are prepared, they are placed on a heat mat and covered with an insulated box to ensure heat; the temperature is set to 37 degrees celsius, the petri dishes are in there for around a week or so until bacteria starts to be noticeable.

6.  Observe each and every dish for observations such as size, shape, and colour.

7.  Write down results based on what is shown in observations to conclude which toothbrush collected the most bacteria.

Observations

During the experiment the bacteria growth varied depending on the places the toothbrushes were stored. The toothbrushes that were placed by the toilet with the lid flushed open and closed collected the most bacteria and to see this we looked through a microscope to identify the colour, shape, size and amount of bacteria on each petri dish.The colonies ranged from 4 to 7 colonies per petri dish, they were oval and circular shaped, they ranged from light browns to dark browns,the size ranged from around 1mm-4mm, and lastly the texture ranged from smooth to flat and rough. Overall the closer you have your toothbrush to the toilet the more bacteria buildup there will be, but if you use a toothbrush cover it will minimize bacterial growth.

Analysis

The results of the experiment showed that the places beside the toilet flushed closed and open had the highest bacteria levels. This shows that bacteria from the toilet can spread to close by surfaces possibly through airborne particles released when toilet is flushed. Although flushing the toilet with the toilet did reduce bacteria buildup slightly it did not prevent contamination completely. Other locations where the toothbrushes where stored such as the ones with covers on them had the least amount of bacteria buildup on them because they had less surface contact. This supports the idea that the place where you put your toothbrush has a significant role in bacteria exposure and buildup. One potential theory is that bacteria would have grown more on the ones with the lids on them due to humidity that traps bacteria cells or the way that your bathroom is cleaned.

Conclusion

In conclusion this experiment demonstrates that storing a toothbrush beside or close to your toilet will increase bacteria contamination even if the lid is closed. To reduce bacteria buildup or exposure is to store your toothbrush as far away from the toilet as possible or even outside of the washroom with a lid on the toothbrush. These findings highlight the importance of storing your toothbrush to reduce bacteria buildup and help with better oral hygiene.

Sources Of Error: Sources of error that could have affected my results of my science fair project could have been the the people not brushing their teeth properly or even missing the times they were supposed to brush their teeth, another thing that could have affected my results could have been for the toilet flushing one of the toothbrushes. The people may have forgotten to close the toilet lid when flushing. 

Acknowledgments to my science fair teachers and my dad for helping me along the way of this science fair journey!