|QUOTE (HUGOHL @ Thursday, May 16 2013, 22:01)|
| If the human mouth has so many bacteria, and biting someone tearing the skin causes so many diseases, how is it that we don't get them when we bite our lips or get a cut inside of our mouths? Or when we get a cut and suck our own blood? |
I assume it's to do with the fact that most of the bacteria is harmless. If it is a pathogen such as the common cold, the flu virus, herpes, or something along those lines, then we aren't affected because we already have the antibodies to defeat them whereas the person being bitten probably doesn't. The more damaging bacteria, like certain strains of strep, is where things become more complicated so I can't really answer that with 100% confidence.
My guess is that seeing as most bacteria in our mouth live on the surface of the teeth, a full-on bite to another person transfers more bacteria than a small bite in our own mouths; the idea being the surface area of two rows of teeth (front, back, and top) versus the surface area of, say, a molar (just front and top). Let's say each tooth surface has 1000 bacteria, 5 of which are streptococcus. The bite was done with two rows of six teeth (not exact, but they're the prominent ones), that's 60 bacteria transferred compared to just 5 from the one tooth.
Unfortunately, the question of what about the bacteria in our saliva is still present. We know that saliva has anti-bacterial properties so I'm assuming that it takes care of things itself. Also, the mouth is one of the fastest healing areas of the body so what little bacteria do get through is probably dealt with quite swiftly.
Wow, who would have known I could blabber on about bacteria and teeth like that? I really am the most boring person I know. Anyway, hope it's a good enough answer