Why Enamel Is Different From Every Other Tissue

One comment on r/ADHD picked up hundreds of upvotes for saying the thing everyone half-knows:

Once your enamel is gone, it’s gone for good. It doesn’t regenerate. r/ADHD

That’s true. It’s also stranger than it sounds, because your body repairs almost everything else without being asked.

Every other tissue has a repair crew. This one doesn’t.

Break a bone and cells arrive to knit it. Cut skin and it closes. Take out most of a liver and it regrows. Even a scratched cornea — clear, delicate, nothing like tough tissue — heals in a day or two.

Enamel is the exception, and the reason is that there are no living cells inside it. None. It’s the hardest substance your body makes and it’s not alive.

The cells that build it are called ameloblasts. They lay enamel down before the tooth ever appears, and then they die as it erupts. The body doesn’t keep any in reserve. It doesn’t make more later. Whatever enamel you had at the age of about twelve is the entire supply, for life.

This is why dentistry is a separate profession from medicine. Almost all of medicine works by helping the body do its own repair. In a tooth there is nothing to help. So dentistry became a repair trade instead — drilling, filling, crowning, replacing. A dentist isn’t treating a tooth so much as doing the job the tooth can’t.

Then why does anyone talk about remineralization?

Because two true things get mixed up constantly, and it confuses people who are paying attention:

Remineralizing? I thought tooth enamel was gone once it was gone. r/ADHD

Fair question. Here’s the split.

Structure doesn’t come back. Thickness lost to acid, scrubbing or grinding is gone. No cells, no rebuilding.

Mineral does move in and out, constantly. Enamel isn’t alive, but it is a crystal lattice sitting in fluid, and mineral leaves it whenever the mouth turns acidic and returns when conditions are right. That exchange runs every single day of your life. It’s the only lever anyone has.

So enamel doesn’t grow back and enamel can be remineralized are both correct. One is about architecture. The other is about topping up the material inside the architecture you still have.

Which is exactly what people ask next

Since you can’t grow enamel back, what are some good ways to protect your enamel? I know certain foods (and as you mentioned - abrasive products) can deplete tooth enamel, are there any that strengthen it at all? r/AskWomen

Three things move mineral in the right direction. Saliva does it all day for free, which is why a dry mouth is worse for teeth than most diets. Fluoride does it, and builds a slightly tougher crystal in the process. And hydroxyapatite does it by supplying the exact mineral enamel is made of — Japan has had it in toothpaste since the 1980s, and it has been turning up in pastes and sprays elsewhere for about five years.

What all three have in common is contact time. Mineral moves while the stuff is against the tooth, and stops when it’s rinsed off.

None of that regrows a tooth. All of it decides how much of the enamel you have stays where it is.

What burns through it fastest

Since the supply is fixed, what removes it matters more than what protects it.

Abrasives. This is the one people volunteer for:

your dentist is trying to make money off you. using abrassives is not worth it. tooth enamel doesn’t grow back so blasting is off with baking soda is crazy. r/LifeProTips

UltraBrite can really brighten your teeth, but you have to use it only once in a while because it’s abrasive. Enamel is very important and you don’t want to erode it…doesn’t grow back. r/beauty

Charcoal pastes, baking soda, whitening powders, hard brushing. All of them work by removing surface — and surface is the thing that isn’t coming back.

Acid, which softens enamel before anything touches it:

Be careful with that! It can damage the tooth enamel and once the enamel is gone it won’t come back and lead to tooth decay. r/AskWomen

The short version

You have one issue of enamel. It was finished before you had memories of getting it, by cells that died on the job.

Everything after that is maintenance on a fixed supply.