This amazing structure is created by two types of cells: ameloblasts that secrete enamel and odontoblasts that secrete dentin.

分泌牙釉釉细胞以及分泌牙本牙本细胞。

If your enamel is worn away, your dentin and its tubules can be exposed.

如果你牙釉被磨掉了，你牙本和它小管就暴露出来。

Some become odontoblasts — these cells make dentin, the tough, fibrous core of the tooth.

一些变牙细胞——这些细胞形牙，坚硬纤维牙，是牙齿核心部分。

Just below that tough outer layer, there's another layer called dentin that's not as hard. And below that, there's the inner layer of the tooth, called the pulp, which has blood vessels and nerves inside it.

在这层坚硬外层下，还有另一层做牙本，它没有牙釉坚硬。牙本下面是牙齿内层，做牙髓，里面有血管和神经。

That's the stage when individuals usually experience pain, although pain can also occur when the caries lesion involves the dentin layer since sensory nerve fibers travel through tubules in the dentin.

在这个阶段，患者常感到疼痛，但牙本层受累产生龋坏时也可能有疼痛产生，因为感觉神经也分布在牙本管道中。

First, the acid eats away the very hard outer layer of yourtooth, called the enamel. Inside the enamel is the dentin.

酸性先腐蚀掉牙冠表层珐琅。珐琅所包覆便是牙本。

They are made up of an outer layer of enamel, and an inner layer of hard, dense, bony tissue called dentin.

它们牙齿由外层牙釉以及内层坚硬、紧密骨组织构，这些骨组织被称为牙。

They're false in that they're not made of what our teeth are made of: dentin and enamel.

“伪牙”不是由我们牙齿材料——牙本和珐琅——构。

These growth factors cue stem cells to generate dentin, the bonelike substance that teeth are mostly made of.

这些生长因子提示干细胞修复牙本，这是牙齿分中绝大部分组。

But decay is reversible until it reaches the dentin.

可是，在牙本遭到腐蚀之前，腐蚀随时都发生。

And sometimes, the combination of sweet stuff and exposed dentin equals pain.

有时，甜味东西和暴露牙本碰撞就导致疼痛。

Inside the enamel is the dentin.

珐琅所包覆便是牙本。

These tubules are important for sensory nerves as well, which use them to travel through the dentin from the pulp to the dentin-enamel junction.

牙本中小管对感觉神经也很重要，因为感觉神经可以通过它们从牙髓到达本釉交界处。

Odontoblasts use a more complex process, but unlike ameloblasts, they stick around, continuing to secrete dentin throughout your life.

牙本细胞则需要更复杂过程，但与釉细胞不同，它们不消失，在我们有生之年继续分泌牙本。

Dentin is pretty hard, but unlike enamel, it's porous.

牙本非常硬，但与牙釉不同，它是多孔。

Teeth manage both by having two layers: a hard external cap of enamel, made up almost entirely of a calcium phosphate, and beneath it, a tougher layer of dentin, partly formed from organic fibers that make it flexible.

外层由坚硬牙釉包围，几乎完全由磷酸钙组，牙釉之下，有一层更加强韧牙本，部分由有机纤维组，它们能够使牙齿强韧。

The demineralization of cementum and dentin can occur in a pH range of 6.2-6.8.

牙骨和牙本脱矿可以在pH6.2到6。8范围内发生。

But the cavity doesn't really start to hurt until it gets through the dentin to the soft pulp. That'swhen you get a toothache.

但是，要等到酸性通过牙本，开始腐蚀牙髓了才对牙齿造本伤害。这个时候牙齿也就开始疼起来了。

And the dentin acts as the selectively permeable barrier.

而牙本则作为选择性渗透屏障。

The fluid in your dentin's microtubules rushes out of your tooth towards the sugar.

牙本微管中液体冲出牙齿，冲向糖那里。