乳牙知识

You sleep at night with your milk tooth beside your bed or under your pillow forthe tooth fairy to come and take it and give you a gift in return. Ever wondered whydo you have these brittle1 milk teeth， which we lose as we grow up？

晚上睡觉时，你把乳牙放在床边或枕头下，让牙仙来取走它，并给你一份礼物作为回报。你有没有想过为什么你会有这些随着年龄的增长而换掉的易碎的乳牙？

Why are they called Milk Teeth？

为什么叫乳牙？

We all have milk teeth during the process of growing up. They are the first set ofteeth that come out. When a baby is born， it is born without any teeth， since the skull2and the jaws3 of the baby are not yet developed. As the baby grows， the skull and jawbegins to develop. Thus， the first set of teeth or the milk teeth start to come out. Buteven then， the skull and jaw of a child is still developing. It is not yet developed as inthe case of adults. Thus， the milk teeth start falling at the age of 6 or 7.

我们成长的过程中都有乳牙。它们是长出来的第一副牙齿。一个婴儿出生时并没有牙齿，因为婴儿的头骨和下颌还没有发育。随着婴儿的成长，婴儿的头骨和下颌开始发育。因此，第一副牙齿或乳牙开始长出来。但即便如此，儿童的头骨和颌骨仍在发育中。它还没有像成年人那样发育成熟。因此，乳牙在6、7 岁时开始脱落。

Milk teeth， when they fall， provide the space and guide the permanent4 teeth toerupt5. The milk teeth shape the jaw bones and muscles. Thus when they fall off，they leave that space for the permanent teeth to grow in and give the jaw bones andmuscles the correct structure6. Therefore， milk teeth help in developing the oralcavity7 of a child. Milk teeth also help in the development of a child’s speech andin chewing food. The roots of these milk teeth provide a solid8 space and structurefor the permanent teeth to grow.

乳牙脱落时，为恒牙提供空间，引导恒牙长出。乳牙塑造了颌骨和肌肉的形状。因此，当它们脱落时，它们会为恒牙的生长留下空间，并赋予颌骨和肌肉正确的结构。因此，乳牙有助于儿童口腔的发育。乳牙还有助于儿童的言语发育和咀嚼食物。乳牙的根部为恒牙的生长提供了坚实的空间和结构。

The skull of a baby is very small to hold the 32 permanent teeth which adultshave. Thus， a child till the age of 6 will have 20 primary teeth. As they keepdeveloping the jaw， the milk teeth start becoming loose9. Then they eventually fall ofone by one， making way for the permanent teeth to come out. The roots of the milkteeth provide an opening for the permanent teeth to come up， with proper spacingbetween each tooth. Thus at the age of 6 or 7， the jaw of the child is developed andthus the milk teeth start to fall off.

婴儿的头骨很小，容纳不下成年人的32 颗恒牙。因此，一个6 岁的孩子将会有20 颗乳牙。随着颌骨的不断发育，乳牙开始松动。然后它们最终会一个接一个地脱落，为恒牙的长出腾出位置。乳牙的根部为恒牙的生长提供了一个开口，每颗牙齿之间有适当的间距。因此，在6、7 岁时，孩子的颌骨发育成熟，乳牙开始脱落。

What happens after the milk tooth has fallen？

乳牙脱落后会发生什么？

A permanent tooth starts taking the place of the fallen milk tooth. This toothbegins to push its way up through the gums10. This happens after the age of 6 whenthe child starts developing the first set of incisor11 and molar12 teeth. The two centralincisors or the two teeth on the upper jaw and two on the lower jaw are the first onesto drop and the first set of permanent teeth to come out.

一颗恒牙开始代替脱落的乳牙。这颗牙齿开始从牙龈往上挤。这发生在6 岁以后，那时孩子开始发育第一组门牙和臼齿。中间的两颗门牙，也就是上颌的两颗和下颌的两颗，是最先脱落的牙齿，也是最先长出恒牙的位置。

What to do with the fallen milk tooth？

脱落的乳牙怎么办？

Many countries have many traditions about the fallen milk tooth. The falling offof the primary tooth and gaining the permanent set of teeth is seen as a veryimportant sign of entering into adulthood. In some countries people believe that themilk tooth should be thrown in a specific13 place and a wish should be made. In theWestern countries people believe in leaving the tooth under their pillows at night orbury them in the ground， and the tooth fairy will come and collect it， giving some giftin return.

关于脱落的乳牙，许多国家有不同的传统。乳牙的脱落和恒牙的长出被认为是进入成年的一个非常重要的标志。在一些国家，人们认为应该直接把乳牙扔在一个特定的地方，然后许愿。在西方国家，人们相信晚上把乳牙放在枕头下或埋在地下，牙仙会来收集它，并给一些礼物作为回报。

Fun Facts about Milk Teeth

关于乳牙的有趣事实

On an average， we lose 14 milk teeth from the age of 6 to 13—seven from the upper and seven from the lower jaws.

If your milk tooth is loose， never try to pull it out. Let it take its own time to come out and leave the roots undamaged.

Humans have 20 milk teeth and 28 to 32 permanent teeth. Mammals14 likedogs and cats have two sets of teeth—one is their entire set of baby teeth which theylose in a few months， and next is their entire new set of permanent teeth.

Dolphins and other whales have only one set of teeth.

平均而言，我们在 6 岁到 13 岁之间会掉 14 颗乳牙———上颌和下颌各 7颗。

如果你的乳牙松动了，千万不要试图把它拔出来。让它自己慢慢脱落，从而让它的根不受伤害。

人类有20 颗乳牙和28 到32 颗恒牙。像狗和猫这样的哺乳动物有两副牙齿———一副是它们在几个月内会脱落的全部乳牙，另一副是它们全新的恒牙。

海豚和其他鲸鱼只有一副牙齿。