Sock it in normal/tap water for 7/8 hours or Keep the bristles under the hot water until they soften. Use your fingers to test the softness by gently rubbing them along the bristles. Once they feel soft to your touch, you can brush your teeth.
A toothbrush also has bristles.
All bristles are safe,
Yes ,the bristles and the handles of toothbrush are made of the same material that is nylon.
The capitol of a toothbrush (most important part) is the bristles. Why am I answering this?
Nylon.
Yes ,the bristles and the handles of toothbrush are made of the same material that is nylon.
Helpful Friction.
I'm assuming that they are attached on a small board. I would expect the plastic of the toothbrush to be put over the board and the piece over the board would have holes to allow the bristles to come through the plastic.
it stands for the stiffness of the bristles but the lower the number the softer or harder?
No. The bristles of the brush will damage the soft tissue inside.
No
It is generally safe to use alcohol, such as vodka, to disinfect a toothbrush. There should not be any significant chemical reactions with the plastic handle or nylon bristles, but it may not be as effective as other disinfectants. It's important to thoroughly rinse the toothbrush before using it again.