Is a dog’s mouth really cleaner than ours?
Angel Ngo 10 -1
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Purpose
To find out whether there is more bacteria in a dogs mouth or a humans mouth. This will help me to uncover the truth on the myth that a dogs mouth is cleaner than humans.
Research
What is bacteria?
Bacteria are microscopic single-celled organisms which do not have a nucleus.
Some examples include E-Coli and Staphylococci
Bacteria: Human Mouth
- There are over 600 different kids on bacteria in our mouths.
- About 100 million in every millilitre of saliva.
- Most of this will however not harm us, due to stomach or saliva enzymes.
- The minority of bacteria in our mouths can cause things like gum disease and tooth decay.
Bacteria: Dog Mouth
- Many of the species of bacteria found in human mouths are also found in dog mouths
- However many other species can only reside in dog mouths and vice versa.
- Some of the types of bacteria that reside in a dogs mouth can be harmful to the dog and its owner.
- Dogs teeth are covered with a biofilm in which many forms of bacteria reside in. These are not harmful.
Professional Opinions/News Articles
- According to one woman dogs mouths and saliva are much cleaner than a humans and if you have a cut, and they lick it, it will heal much faster.
- Veterinarian Marty Becker, however, says this is not true. He believes that the myth comes from a dogs practice of licking their own wounds, which helps in the healing process.
- He also suggests however that bacteria in a dogs mouth is ‘species specific’ meaning that the bacteria in a dog will not effect humans in any way. And vice versa for human bacteria.
Past Experiments
- Myth Busters experiment proved that there was MORE bacterial growth from the human mouth, but however the bacteria in the dog mouth may be more harmful.
Aim
To find whether or not a dogs mouth has more bacteria than a human mouth does.
Variables
Control Variables: temperature of incubator, materials used to collect samples, test subjects, conditions of travel for samples
Independent Variable: the species of mouth in which saliva samples are collected
Dependent Variable: amount of bacteria colonies
Hypothesis
Through research and personal opinion, the canine mouth will have less bacteria than that of the humans.
Materials/equipment
- cotton buds
- sterile containers
- test subjects (dog and human)
- agar plates
- water
Safety precautions
- wear gloves to prevent bacteria on hands
- control the dog
Method(s).
- Gather equipment and test subjects
- Let dog drink water
- Hold dog down and take a swab with the cotton bud from the dogs mouth.
- Put cotton bud into sterile container
- Repeat steps 2-4 with human test subject
- Repeat steps 2 -5 twice more.
- Take swabs carefully out of container.
- Swipe swabs onto the agar plates. Don’t forget to label the plates.
- Incubate the plates at 37 degrees Celsius for two days.
- Observe the plates.
- Record results.
Results
No results. Experiment concluded.
New Experiment: Dissolving Paracetamol
Purpose
To find out how fast a normal paracetamol tablet will dissolve in different types of liquids. This will help me figure out which drink will allow people who find it hard to swallow a tablet to take the medicine.
Research:
Acidity of different liquids
To test acidity, we find the pH levels of the liquid. pH is the indicator of the acid or alkaline condition of a liquid.
Readings of less than 7 indicate the liquids acidity.
Readings of 7 are neutral.
Readings of more than 7 indicate alkalinity.
pH levels of different liquids:
Water - 7
Orange Juice - 4
Coca-Cola - 3
Black Tea - 6
With this information, we can see that Orange Juice and Coca-Cola are quite acidic, while water is neutral and tea is only slightly acidic.
Dissolving paracetamol
In discussion with a pharmacist, i was able to discover that paracetamol does not dissolve in water well. I also now know that certain medications will lose some of its effectiveness when dissolved in a liquid. However this is not what i am testing. The pharmacist suggests swallowing tablets in liquids like juice, which will help in digesting the tablet. She also suggests that paracetamol tablets are not made to be dissolved and will not dissolve well. Also, the liquid will most likely soften the tablet instead of actually dissolving it.
Aim
To find how fast paracetamol dissolves in different liquids.
Variables
Control Variables: amount of liquid, temperature of liquid, type/brand of paracetamol tablet, shape of glass, brand of liquid (e.g do not interchange between different brands of orange juice)
Independent Variable: type of liquid
Dependent Variable: time it takes for tablet to dissolve
Hypothesis
The paracetamol will dissolve the fastest in Coca-Cola and the slowest in water.
Materials/Equipment
- 4 clear tumblers/glasses
- 12 Paracetamol tablets
- Water (cold)
- Orange Juice (cold)
- Coca-Cola (cold)
- Stopwatch
Safety Precautions
- Do not stir the liquid
- Do not swallow any of tablets
Method
- Pour 50mL of one of the liquids into a glass.
- Drop a paracetamol tablet into the liquid.
- Start the timer when the tablet hits the liquid.
- Record the results once the tablet has dissolved completely.
Results
Note: If the tablet does not dissolve within 10 minutes, timer will be stopped and the time will be marked as >10.
Test 1
| Liquid | Time |
| Water | >10 |
| Orange Juice | >10 |
| Coca-Cola | >10 (12 minutes) |
Test 2
| Liquid | Time |
| Water | >10 |
| Orange Juice | >10 |
| Coca-Cola | >10 (12 1/2 minutes) |
Test 3
| Liquid | Time |
| Water | >10 |
| Orange Juice | >10 |
| Coca-Cola | >10 (12 minutes) |
Photos:
Discussion
During my experiment, there were quite a few things i observed and found quite interesting in the results. My hypothesis was mostly correct in saying that Coca-Cola would break down the tablet the fastest, because of its pH level. Water came in second and orange juice came in last. As most of the tablets did not break down in the first 10 minutes very well, i observed the tablets for another 5 minutes to compare how much the tablet had dissolved compared to the other liquids.
As seen in the results, Coca-Cola broke down the tablet the most and the fastest. When doing the experiment, the tablet in the water and orange juice sunk to the bottom of the glass and broke down there. However, when it came to the Coca-Cola, the tablet sunk to the bottom and floated back to the surface in a matter of seconds. The tablet them started to break down.
As seen in images 1-3 (taken at around 5 minutes), the tablet broke down gradually in the water. Parts of the tablet started to break away from its usual structure. At the end of the experiment, i felt the broken down tablet, and it was indeed very soft. The water did not actually ‘dissolve’ the tablet, but softened it intensely. The same could be said for the orange juice. However i was surprised that the tablet was still almost completely intact in the tablet shape at the end of the 10 minutes, unlike the water, for which as can be seen in images 4-6, which transformed into an abnormal shape, very different to what it started out as. There are no images of the orange juice because it was quite hard to capture the tablet in the opaque liquid. The tablet in the Coca-Cola broke down quite differently to that in the water and the orange juice.
After floating to the surface, you are able to actually here the Coca-Cola fizzing away at the tablet. The Coca-Cola broke away the tablet in very small pieces and actually dissolving some of the pieces into the liquid. Much of the tablet however didn’t dissolve. Out of the three, the Coca-Cola broke down the tablet the best, as seen in images 7-12. The whole tablet was completely broken down into the smaller pieces (seen in the images) at 12 minutes.
The reliability of an experiment depends on the amount of times you repeat the experiment. The results for these repeated experiments should all be roughly the same. My experiment was very reliable as the it was repeated 3 times and the results were all approximately the same. However, my experiment could have been more accurate, by using a smaller amount of liquid and using a more accurate measuring cylinder. These things would have made my experiment more accurate. The experiment was not valid as the paracetamol tablet did not dissolve. The aim of the experiment should have been to observe how the different liquids break down a tablet, instead of dissolving it.
If i were to do this experiment again, there would be some things i’d improve. I would use a wider variety of liquids, including coffee, tea and milk because it would increase the types of liquids i could use to compare the rate of the tablet breaking down. I would also use a more accurate measuring cylinder to increase accuracy.
This experiment has helped me to decide what liquid dissolves a paracetamol tablet the fastest. Coca-Cola was found to be the liquid that best broke down the tablet, followed by water and orange juice. I found that my research was mostly correct in that paracetamol tablets do not dissolve well and are not designed to dissolve. The tablets did however break down in the liquids. I also found that the acidity level of the liquid also played a big role in dissolving the tablet. The pH level of the Coca-Cola showed that it was very acidic, which resulted in the tablet dissolving in a faster pace.
Conclusion
In this experiment it was found that paracetamol tablets do not dissolve well in liquids. However, the liquids did break down the tablets. Coca-Cola broke down the tablet the most and the fastest, while water came in second and orange juice last. The acidity of the liquid did in fact effect how much it broke down the tablet.
Bibliography
ABC News (2005), Myth: Dogs Have Cleaner Mouths Than Humans, Place of Publication Unknown <http://abcnews.go.com/2020/Health/story?id=1213870> (Accessed March 17th)
Arnold.P (2010), Mouth Bacteria, It’s a Jungle In There, Place of Publication Unknown, <http://www.brighthub.com/science/genetics/articles/45935.aspx#ixzz1GS3DWOvl> (Accessed March 16th)
Excel Water(Year Unknown), pH - Acidity of Drinking Water, Place of Publication Unknown <http://www.excelwater.com/eng/b2c/ph.php> (Accessed April 7th)
Myth Busters: Episode 39 - Chinese Invasion Alarm. 2005, Discovery Channel, Australia, October 19th (television program)
Pet Care GT(Year Unknown) , Bacteria In A Dog Mouth, Place of Publication Unknown <http://www.petcaregt.com/dogcare/bacteriainadogmouth.html> (Accessed March 18th)
Pico Technology(Year Unknown), Testing the pH Level of Common Drinks Using DrDAQ as a pH Meter, Place of Publication Unknown <http://www.picotech.com/experiments/ph_of_drinks/results.html> (Accessed April 7th)
