in the best working condition?

TWO MILLS

Come, children, listen to the story Uncle Ned told to me. It was the
story of a long time ago when Uncle Ned was a little boy. One day his
mother took him on her knee and said, "Ned, do you know that your mouth
is like a little mill?" It is. The mill grinds corn. Your teeth grind
your food. Look in the mirror. Are your teeth all alike? Some of the
teeth in your mouth are to bite the food into bits, and others are to
grind it fine so that it will not hurt your stomach.

You have twenty now because you are a little boy and do not need any
more. When you have grown to be a man you will have thirty-two teeth.
You will have more grinders in your mouth when you are a man than you
have now. The jaw teeth are called grinders, because they grind the food
you put into your mouth, just as the big mill stones grind the corn into
meal down at Grandpa's mill.

You wear clothes to keep your bodies warm, so the teeth need some
covering to keep out the cold. The enamel, a hard outer covering on the
teeth, keeps them from feeling the cold. Down in the middle of the tooth
is a place for the nerves of the tooth. When you break the covering on
the tooth the cold and hot things that you sometimes put into your mouth
will make the nerves ache. Sometimes things that are very sweet or very
sour hurt the covering on the teeth.

To use the teeth to crack nuts or ice will harm them, for it often
breaks the outer covering, and it will not grow again.

Your teeth should last you all your life if you will take care of them.
Grandpa's mill would not grind the corn well, nor would the mill last
long, if he did not take care of it and keep the big stone grinders
clean and free from grit and dirt. Your teeth must have just as good
care as the stones in the mill if you wish them to last you a long time,
and if you want them to grind your food fine.

This is why you must use your toothbrush, and wash your mouth out
regularly every day. If you do not keep your mouth clean, germs will
creep in and cause the little boy to have toothache. You are wondering
what the germs have to do with toothache.

These little germs always get into places that are not kept clean, and
when they get into the mouth they go to work, like so many little
carpenters, with pick and drill, and pick away the outer covering of
the tooth and then the tooth decays, and this causes toothache.

We all want to have pretty white tee