Are Dog Mouths Cleaner Than Humans?

Whenever it comes to humans and dogs, a usual question that often is asked is, “Are dog's mouths cleaner than humans?” Dogs produce more saliva than we do, so some people believe that acutally do have a cleaner mouth. The problem is that dogs obviously don't brush there teeth, and take care of their mouth. We eat what we want, but we also floss, brush teeth, and use mouthwash. Dogs eat what they are given, and really have no way of cleaning their mouths without our help. So they don't have cleaner mouths.

To begin the project, we had cotton swabs and petri dishes. First we used a swab on each of our mouths, and inoculated the swab onto the petri dish. The same thing was done for the dogs onto two other dishes. They were placed in the incubator for a couple days so that the bacteria would grow on the nutrient agar.

When staining to find which kind of bacteria we could find in the two dogs (Willie and Sophie) mouths and ours, we used three different staining techniques: negative, gram, and capsule staining. As we did each stain, the aseptic technique was used, which includes using an inoculating loop or needle (depending on the circumstances), and a bunsen burner. Placing the needle or loop above the flame kills any left over bacteria that was on it. This helps prevent any contamination other further inoculation.

For negative staining, we used colonies from each petri dish, which included bacteria from everyone's mouth, and mixed it with a drop of nigrosin on a slide. Another slide is used to push the mixture across the initial slide. Negative staining is used to see the outline of the bacteria.

The next staining method was a gram stain. The stains that are used are crystal violet, Gram's iodine, ethanol, and safranin. Before staining starts, a smear must be fixed, which means it dries by applying heat to it. Use crystal violet for 30 seconds, then Gram's iodine for 10 seconds, and decolorize the stain with the ethanol. Finally, the smear is stained with the safranin for 30 seconds.

The last stain method was the capsule