Are the large number of microorganisms found in the mouth a cause for concern? Explain

No, not generally, it depends what species they are.

If they were, then we should have started being concerned several million years ago.

 

Too late now.

No, the mouth is just the opening of a hole that goes through the middle of us like the hole in a doughnut - technically all the bugs in our mouths and intestines are outside our bodies!

Supose there are no deep cuts inside the mouth leading to the stomach, we will digest almost any bacteria or microbe that enters into the stomach (pH 2) when we swallow or eat. We won't get rid of the microbes so it is the body's defense system to digest harmful bacteria.

Basically you can assume that every portion of your body that is sufficiently wet (yes, including the stomach) harbors bacteria. If they are not pathogens it is generally a good thing as they limit the resources for pathogens by merely being (and living) there.

NO, the normal flora of bacteria in the mouth actually help to keep the harmful bacteria from attaching to the mucosa.

There are more microbial cels in and on our body than human cells. The numbers in/on respective parts are more likely to be functional than concerning.

We've coevolved with them for millions of years, so no. Although, I know thrust (an oral yeast infection, basically) can get out of control in people with poor hygiene, weak immune systems and spread down the esophagus, potentially causing problems. That, and I knew a guy who got a really nasty infection from punching someone in the mouth and cutting his hand on his teeth.

Thrush not thrust