Is A Dog's Mouth Cleaner Than a Human's?

Abstract

For my science Fair experiment, I wanted to figure out if a dogs mouth is cleaner than a humans. Not only did I just want to figure out if one subjects mouth was cleaner, I wanted to see if age, gender and time of the day mattered when I swabbed my subjects. I swabbed four people and four dogs mouths so altogether 8 subjects. I chose to do this experiment because I have 3 crazy dogs that are always eating something they are not supposed and I was curious to see if their mouths were actually going to be cleaner than mine! I swabbed my subjects in the morning and night to see if I would get different results. My hypothesis was that the dogs mouths would be dirtier because it just seemed impossible for them to have a cleaner mouth than people with all of the things they are eating.

For my experiment I started off with swabbing the humans and people in the morning time on January 8. I made sure that before I swabbed anyone, we didn’t eat yet or brush our teeth. I went into the lab for each test I did. For my people I used my Dad (person 1),Mom (person 2) , Brother (person 3), and myself (person 4). My parents are the oldest and my brother is older than me so that is how I used age. My mom and I are girls and my brother and dad are boys and that is gender. Everyone swabbed there mouths in the time frame of an hour and a half. Person 3 swabbed there mouth at 5:55 AM, Person 2 swabbed there mouth at 6:11 AM, Person 1 swabbed their mouth at 7:25 AM, and Person 4 swabbed their mouth at 7:16 AM. Dog 1 got swabbed at 7:27 AM, Dog 2 got swabbed at 7:28 AM, Dog 3 got swabbed at 7:30 AM and Dog 4 got swabbed at 7:35 AM. I did my night swabs on January 14 and went into the lab to test them on January 15th. Every Person and dog swabbed the same times as the morning swabs to keep it consistent. The only difference is that It was at night time instead of the morning. I got my agar plates and put the swabs on it in a back and forth motion being sure to get every part of the swab. I labeled the dishes so I knew which one was which and they got put underneath the incubator. The morning swabs were underneath the incubator for 6 days total. The night swabs were underneath the incubator for 6 days also. After the morning swabs were in the incubator, I put them on a 36 mm times 36 mm grid paper and counted how many squares each dish took up. I did the same for the night time swabs.

I got my results in for my morning swabs. I divided all of the averages by 10,000 to get square cm. For the morning, Person 1 had the cleanest swab of (7.2cm2 in the morning), followed by my person 4 of (43.2cm2 in the morning), person 2 of (54cm2 in the morning) and than person 3 of (57cm2). For the dogs, dog 1 had the cleanest mouth of (3.4cm2 in the morning) followed by dog 2 of (309.6cm2 in the morning), dog 3 of (381.6cm2 in the morning) and than dog 4 of (403.2cm2 in the morning ). For the night time swabs Person 1 mouth was the cleanest of (7.2cm2 at night), followed by Person 2 of (11.4cm2 at night), than Person 3 of (17.3cm2 at night) and finally Person 4 of (72cm2 at night). For the dogs swabs at night Dog 3 had the cleanest mouth at (360cm2 at night) followed by Dog 2 with (396cm2) then Dog 1 with (430cm2 at night) and finally Dog 4 at (432.2cm2). I also wanted to see if age mattered. Person 3 and Person 4 were the youngest but Person 4 the second cleanest mouth and Person 3 had the dirtiest mouth for morning and night swabs. Person 2 and 1 had very clean mouths so it turns out that maybe the older you are the cleaner your mouth is. Also, I wanted to see if gendre mattered. Person 3 and 1 are male and Person 1 had the cleanest mouth when Person 3 had the dirtiest. Person 2 and 4 are female and had clean mouths. For the dogs, all of them are girls and from different breeders. Dog 4 is the oldest, then Dog 1, Dog 2 and Dog 3 is the youngest. It is crazy how Dog 3 month was the third dirtiest in the morning but had the cleanest mouth at night time.

For my experiment I was to answer “Is a dogs mouth cleaner than a humans?” The answer is no. A dogs mouth is not cleaner than a humans. I know this because all of the dogs that were tested, had higher numbers than in bacteria than all of the humans. My hypothesis was correct because I said that a dogs mouth would be dirtier than a humans. I believe my experiment was accurate because it was very consistent and I tried my best to make my information as true as possible. I learned in this experiment how to use petri dishes and how to swab something correctly. If I could make my experiment more accurate, I would have tried to find a better way to count bacterial colonies because it was very hard to count very small little spaces between each colony.

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