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

分泌釉成釉细胞以及分泌本质成本质细胞。

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

如果你釉质被磨掉了，你本质和它小管就会暴露出来。

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

一些变成成质细胞——这些细胞形成质，纤维质，是齿核心部分。

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.

在这层外层下，还有另一层物质做本质，它没有釉质。本质下面是齿内层，做髓，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，患者常会感到疼痛，但本质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本质管道中。

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

酸性物质会先腐蚀掉冠表层珐琅质。珐琅质所包覆便是本质。

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

它们齿由外层釉质以及内层、紧密骨组织构成，这些骨组织被称为质。

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

“伪”不是由我们齿材料——本质和珐琅质——构成。

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

这些生长因子会提示干细胞修复本质，这是齿成分中绝大部分组成物质。

But decay is reversible until it reaches the dentin.

可是，在本质遭到腐蚀之前，腐蚀随时都会发生。

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

有时，甜味东西和暴露本质碰撞就会导致疼痛。

Inside the enamel is the dentin.

珐琅质所包覆便是本质。

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.

本质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髓到达本釉质交界处。

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

成本质细胞则需要更复杂过程，但与成釉细胞不同，它们不会消失，会在我们有生之年继续分泌本质。

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

本质非常，但与釉质不同，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.

外层由釉质包围，几乎完全由磷酸钙组成，釉质之下，有一层更加强韧本质，部分由有机纤维组成，它们能够使齿强韧。

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

骨质和本质脱矿可以在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，要等到酸性物质通过本质，开始腐蚀髓了才会对齿造成本质伤害。这个时候齿也就开始疼起来了。

And the dentin acts as the selectively permeable barrier.

而本质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.

本质微管中液体冲出齿，冲向糖那里。