Expert: Walter Hintz - 2/21/2008

Question
I am conducting an experiment to test whether a dog, a human, or a cat has the most bacteria in their mouth for a science fair.I am having a difficult time finding information for my research paper. What is the common type bacteria can be found in a mouth? ALso, do you recommend anything else to research about? I am grateful for any information you can provide.

Answer
Hi Steph-marie;
 The reason you are having a problem with finding information about this topic is because even though it is a popular science fair project it does not lend itself to serious scientific research. This is because number of bacteria in a mouth has no scientific interest.  There are to many variables because the number of bacteria at any given moment varies.  A qualitive study on bacteria in mouths makes a little more sense. Although bacterial numbers are rather meaningless the type of bacteria present have more importance.
 If you design an experiment to find how many bacteria in the mouths and can control the sampling you will find little difference in the numbers and probably not much difference in the types of bacteria.
 I do not want to discourage you from doing this project since you can learn a lot about scientific method by doing it. Come up with a hypothesis and I will be glad to help you with the experimental design.  I would suggest that rather then a hypothesis comparing the numbers of mouth bacteria to one stating that the types of bacteria in a dog's (or cat's) mouth varies from those in a human mouth. Pick either a cat or dog to compare with a human.  Don't do both.
 If you wish to pursue this use my email.  waltjh@sbcglobal.net