My science explanation

Are dogs mouths cleaner than humans? You’ve probably heard the saying “Dogs mouths are cleaner than human’s”, but is that true? For our experiment, we used a Petri dish prepared with nutrient agar (a seaweed derivative with beef nutrients added) which is an ideal way to reveal the bacteria hiding all around you. Chemically, agar is a polymer made up of subunits of the sugar galactose, and is a component of the cell walls of several species of red algae that are usually harvested in eastern Asia and California. Agar, as opposed to regular gelatin (like that found in Jelly), is used for culturing bacteria. Agar, unlike gelatin, won't be degraded (eaten) by bacteria. Even though there may be more bacteria in dogs mouths than humans mouths, scientific research shows that dog’s mouths are actually more sterile than humans mouths. The study compared the bacteria cultured from oral swabs with the bacteria cultured from dog-bite victims, to determine which bacteria in the dog's saliva were responsible for causing infections. Dog’s mouths have more good bacteria in their mouths than in human’s mouths, since dogs clean themselves with their tongues and eat strange things. Humans, on the other hand, don’t clean themselves with their tongues, and clean their teeth twice a day, eliminating the use for more good bacteria in their mouths. So, if a dog bites you on one arm and a human bites you on the other arm, you have more chance of getting an infection from the human bite. In conclusion, petri dishes work by using the agar to grow the bacteria, since any other material or chemical would get “eaten” by the bacteria because of the ingredients that go into the agar, so the agar is more like a home for bacteria. Also, dog’s mouths are more sterile because of the amount of good bacteria in their mouths that completely overpower the bad bacteria, so you are more likely to get an infection from a human bite than from a dog bite.