There are two kinds of bacteria observed on the teeth brush. Generally, these bacteria would cause cavities. It is wise to change your teeth brush regularly, otherwise it is useless to protect your teeth by using a teeth brush full of bacteria.

Take a look at the tooth plaque, thousands of bacteria contained in them. Aren't you shocked by these "tiny animals"? I hope these two images remind you to brush your teeth every day. Of course, you should brush them with clean teeth brush. 

Bacteria are everywhere, especially in the  moisture places. Have a look at the sponge, which you use to clean your plates everyday. You should pay attention to your sponge, otherwise the doctor would pay attention to you soon.

The cups can also provide suitable places for the bacteria to grow. Compared with other samples above, the cups have less bacteria. Maybe hot water or coffee help to decrease the number of bacteria. It is really a good way to kill bacteria through high temperature.

As reported, the keyboard, especially the ones used in public, contain a lot of bacteria. But it is hard to find bacteria on my sample, instead many small particles are found on the keyboard sample. These small particles have been prove to be salt by EDS and mapping. These small salt particles are probably formed from the sweat of hands. Based on my observation, the keyboard is more clean than your teeth brush. But you should also remember to wash youe hands after you use computer.

2.Analyzing Small Particles Collected From Keyboard Via Mapping and EDS

The following is an electron interaction model of  15kV and 20 kV accelerating voltage electron beam incident on filter paper. This model is based on the filter paper of a layer of  gold coating on the top. The thickness of the gold coating is 80nm for the modeling. And the substrate for the sample is Aluminum. Figure 8(a) is the modeling result for 20 kV accelerating voltage and Figure 8 (b) is the modeling result for 15 kV.