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Our teeth are one of the strongest parts of our body.
我们的牙齿是我们身体最强壮的部位之一。
They are made from proteins such as collagen, and minerals such as calcium.
它们由胶原蛋白等蛋白质和钙等矿物质组成。
In addition to helping us chew through even the toughest foods, they also help us speak clearly.
除了帮助我们咀嚼即使是最难吃的食物外，它们还帮助我们说话清晰。
Most adults have 32 teeth called permanent or secondary teeth; 8 incisors, 4 canines, also called cuspids, 8 premolars, also called bicuspids, 12 molars, including 4 wisdom teeth whereas children have 20 teeth.
大多数成年人有32颗牙齿，称为恒牙或副牙；8颗门牙，4颗尖牙也叫犬牙，8颗前磨牙，也称为双尖牙，12颗臼齿，包括4颗智齿，而儿童有20颗牙齿。
All eight of our incisor teeth are located in the front part of our mouth.
我们所有的八颗门牙都位于口腔的前部。
We have four of them in our upper jaw and four in our lower jaw.
八颗门牙分别是上颚有四个，下颚有四个。
They have sharp edges that help us bite into food.
它们有锋利的边缘，可以帮助我们咬进食物。
Whenever we sink our teeth into something, such as an apple, we use our incisor teeth.
每当我们咬东西的时候，比如一个苹果，我们就用我们的门牙。
The very first teeth we grow are incisors, appearing when we are around 6 months old.
我们长出的第一颗牙齿是门牙，在我们六个月左右的时候出现。
Canines are four teeth which sit next to the incisors.
尖牙是位于门牙旁边的四颗牙齿。
We have two canines on the top of our mouth and two on the bottom.
我们的上颚和下颚各有两个犬齿。
Canines have a sharp, pointy surface for tearing food.
犬齿有一个锋利的、尖尖的表面，用来撕裂食物。
Canines are also called cuspids.
犬齿也被称为尖牙。
Premolars are eight in number and sit next to your canines.
前磨牙有八颗，在尖牙旁边。
There are four premolars on top and four on the bottom.
上颚有四颗前磨牙，下颚有四颗。
Premolars are bigger than canines and incisors.
前磨牙比尖牙和门牙大。
They have a flat surface with ridges for crushing and grinding food into smaller pieces to make it easier to swallow.
它们有一个平坦的表面，上面有脊状突起，可以将食物碾碎和磨成更小的块，以便于吞咽。
Baby molar teeth are replaced by adult premolars.
婴儿的磨牙被成人的前磨牙取代。
Infants and young children do not have premolars because these teeth do not start to come in until around age 10.
婴幼儿没有前磨牙，因为这些牙齿直到10岁左右才开始长出来。
Molars are 12 in number and are our biggest and strongest teeth.
臼齿有12颗，是我们最大、最强壮的牙齿。
We have six on the top and six on the bottom.
上颚有六颗，下颚有六颗。
The large surface area of your molars helps them grind up food.
臼齿的大表面积有助于它们研磨食物。
When you eat, your tongue pushes food to the back of your mouth.
当你吃东西的时候，你的舌头把食物推到你的嘴巴后部。
Then, your molars break up the food into pieces small enough for you to swallow.
然后，你的臼齿将食物分解成小到可以吞咽的小块。
The molars include four wisdom teeth, which are the last set of teeth to come in.
臼齿包括四颗智齿，这是最后一组长出来的牙齿。
Wisdom teeth are also called third molars.
智齿也被称为第三磨牙。
They usually come in between the ages of 17 and 25.
他们通常在17岁到25岁之间萌出。
Not everyone has enough room in their mouth for this last group of teeth.
并不是每个人的口腔都有足够的空间来容纳这最后一组牙齿。
Sometimes, the wisdom teeth are impacted, meaning they are stuck under the gums.
有时，智齿会被阻挡，这意味着它们卡在牙龈下面。
This means they do not have enough space to grow.
这意味着他们没有足够的空间来成长。
If you do not have room for your wisdom teeth, you’ll likely have to have them removed.
如果你的智齿没有足够的空间，你很可能不得不拔掉它们。
Can you recall, which type of teeth are the first ones we grow?
你能回忆起，我们最先长出的是哪种牙齿吗？
