Voiceover: So now that we've talked about
the mouth in general, let's put a
smile on that face and take a look at
the teeth in a little more depth.
What we have here is an image of the lower jaw.
Another term for the lower jaw is the mandible.
This is your mandible right here and then
this is your left side of the mandible
so I'll put left, and this is your right side
so you can follow along as we
talk about your teeth.
As you can notice here, things are
pretty symmetric, right?
I can draw a dividing line right down
the center and as we go through and
talk about every little tooth that we have,
we'll see that we have the same tooth
not just on the other side but also in your
upper jaw, also known as the maxilla.
This tooth right here?
We have a mirror image of it here,
and for this pair that we have,
there's two of them in your upper jaw.
Keep that in mind when we're going through
and doing the math at the end.
Every tooth has a specific function to it,
or every set of teeth.
Let's go through the different types
of teeth we have.
This first one we have is called the central incisor.
The central incisor.
Again, we have four central incisors in total.
We have the one I've pointed out here,
the second one here, and then
two others in your upper jaw.
The central incisor is mainly used for cutting.
This is the tooth that you use to cut your food.
The way you remember that is the reason
why we call these incisors, just like in
surgery we say we're about to make an incision,
is we're about to make a cut.
So the central incisors make incisions.
The same thing is true when we talk about
the lateral incisors.
We've got four of them in total,
just like the central incisors.
There's only one on this side
so I'll write 4 in total here.
Again, they're also used for cutting our food.
Now that we're done talking about our incisors,
let's move on to talk about our canines.
This is our canine tooth
and we've got 4 of them in total.
The canine tooth, they're also known as fangs
and you'll see why and
I'll show you in another image.
They're the sharpest, longest teeth that we have
and they're actually used for gripping.
They're for gripping.
You can imagine when you're going to a
restaurant and they give you a bread
basket at the beginning.
You put a piece of bread in your mouth
and you kind of pull away at it and you
tear it apart because your teeth,
the canine teeth that you have,
all 4 of them are gripping on the bread
that's in your mouth as your hand
pulls the rest of it away.
So I'll put 'pulling' in here just as a
little cue as well for how we use our canines.
Now that we're done with our canines,
we can talk next about our premolars.
So the premolars, we have two on each side,
which means that in total, we have 8 of them.
We have 8 premolars and the way to think
about what these guys do is in two parts.
One, if you see the word 'mola' over here,
that's a reference to the Latin word 'mola'
which just means to grind,
or it actually represents grindstone.
If you ever look at what a millstone is
or a grindstone, those are called 'mola'
in Latin and that makes sense because
our premolar teeth are used for grinding
down our food as we chew it.
The other thing to keep in mind
is this first part of the word, 'pre.'
We call is 'pre' because these two premolar
teeth come before these final three molar teeth.
So we have three molar teeth right here,
which means that we have a grand total
of, you guessed it, 12 teeth.
Just like the premolars, these guys
are here for grinding as well, to break down
our food as we chew on it for the
same Latin root we discussed above.
At this point, now that we've talked about
all the different types of teeth,
the interesting thing is that this
textbook picture of what your lower jaw
should look like is actually what it looks
like in only 28% of people in the population.
Why is that?
I've got a nice panoramic image here.
You might recognize somebody familiar
whose image was taken here
and it's nicely situated.
This is your right side and this is your left side.
This is actually a panoramic X-ray
of me looking right at you.
This is the front of my, as you now know them,
the central incisors and these are the
central incisors on my mandible down here.
For reference, this top bone that holds
your upper jaw is also known as the maxilla.
So why don't we clarify that?
This is my maxilla up here, and as you guys
already know, this is my mandible.
So I'll write mandible right here.
What's interesting is when you look at
the teeth that I have here, they're a
little different from the image we saw previously.
It's because if you count them,
here's my central incisor,
this is my lateral incisor, the canine,
this is my first premolar,
this is my second premolar,
that's my first molar and
this is my second molar.
There's something missing here,
and it's not just here, but it's actually
missing on this side, this side and this side.
I think you guessed it.
All four of my third molars are gone.
The reason why is because they were
my wisdom teeth.
Your third molars are called your wisdom teeth.
Often people get these removed.
In fact, 72% of people get these removed.
72% of our population removed the wisdom teeth.
There's actually a pretty simple explanation
for why that occurs.
If you take a look at the gums
that I have right here, so I'm just going to
draw a rough drawing of my gums,
and I'll try to make sure I exclude
my teeth as I do this little tracing right here,
but if you look at the gums that are
surrounding every tooth I have in my mandible
or my lower jaw right here,
they have just enough space for every tooth
to erupt or come out.
Let me color that in.
The way the tooth comes out is that
there's a small designated hole.
Let me draw one here for my second molar
or if I want to draw one in over here
for my lateral incisor, so that's the hole the
lateral incisor erupted or emerged out of.
The hole for the third molar
sometimes ends up being pretty small.
In fact, in 72% of people,
it ends up being pretty small.
The problem is that when my third molar
is here, let me just draw this third molar in,
and it wants to grow, naturally what you
would want to see happen is for the
third molar to go this way and then
out and erupt through that hole.
Unfortunately, this isn't what
happens in most people.
Instead, the third molar commonly tries
to erupt through your gum or
through your gingiva, which is an important term.
I'll write that down.
Your gums are also known as your gingiva.
If they try and erupt through your gingiva,
you can have things like inflammation
or tearing of the gum or gingiva,
or even an infection that occurs if it
happens for an extended period of time.
This commonly occurs in people within the
age group of about 17 to 25 years old.
That's why we call them wisdom teeth.
By the time you gain a little bit of wisdom,
you start having all four of your third molars
erupt right through your gingiva.
You want to get them removed before you
can have some type of bad reaction like
inflammation or infection that can occur
that can mess up the neighboring teeth
that have erupted or grew out so well.
That's pretty cool if you can recognize that
because the same X-ray that my dentist used
to see that my wisdom teeth were removed
correctly and safely, is something that you
can now read and interpret by yourself.