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

本质非常硬，但与釉质不同，它是多孔的。

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

如果你的釉质被磨掉了，你的本质和它的小管就会暴露出来。

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

有，味的东西和暴露的本质的碰撞就会导致疼痛。

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的范围内发生。

And the dentin acts as the selectively permeable barrier.

而本质则作为选择性渗透的屏障。

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，这是齿成分中的绝大部分组成物质。

If destruction continues into the dentin layer, then the caries lesion enlarges towards the pulp.

本质层的损害继续蔓延，缺损会延伸到。

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

本质的微管中的液体冲出齿，冲向糖那里。

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

分泌釉的成釉细胞以及分泌本质的成本质细胞。

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的过程，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。

But if the damage extends beyond the dentin, the bacterial invasion progresses causing excruciating pain as the nerves become exposed.

在此阶段，逐渐扩大的 蛀区并不会产生疼痛，但若损害扩大 超出了本质的范围持续侵入的细菌。

But decay is reversible until it reaches the dentin.

可是，在本质遭到腐蚀之前，腐蚀随都会发生。

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

它们的齿由外层的釉质以及内层坚硬、紧密的骨组织构成，这些骨组织被称为质。

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，开始腐蚀了才会对齿造成本质的伤害。这个候齿也就开始疼起来了。

That snack touching the outside of your exposed dentin has highly concentrated solutes in the form of sugar molecules.

那些接触到你暴露的本质外部的零食含有高度集中的糖分子形式的溶质。

Once bacteria are in the dentin it’s called infected dentin and usually requires a restoration or filling.

一旦本质中有细菌，就称为感染本质，需要修复或填充。

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的珐琅质。珐琅质所包覆的便是本质。

The outer wall of the pulp, contains odontoblasts which are cells that secrete a bonelike substance called dentin, which is filled with protein and minerals.

外层有成质细胞，它们可以分泌一种叫本质的骨样组织，其中充满了蛋白质和矿物质。

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.

本质中的小管对感觉神经也很重要，因为感觉神经可以通过它们从到达本釉质交界处。

At that point, the bacteria, which are normally too big to fit through the enamel diffusion channel, can penetrate all the way through the enamel to the dentin.

此，平太大无法进入釉质扩散通道的细菌，就可以从釉质一路渗透到本质。