What Are the Three Layers of a Tooth?

December 04, 2020

What Are the Three Layers of a Tooth?

tooth, anatomy, structure, enamel, pulp, dentin

Your teeth are pretty amazing creations. Your permanent teeth emerge as a late-child and are designed to last, under amazing stress and constant use, for your entire life.

Designed to be hard as steel, yet with a supporting resiliency that both absorbs impact and transports nutrients they are a pretty cool piece of evolutionary engineering.

Like any part of the body, the full breakdown can get really complicated. But let’s leave the complications to scientists and researchers. To effectively take care of your teeth, you only need to understand the 3 basic parts: the outer layer, the central zone and the inner core.

Let’s take a brief and simple look at what these are:

The Protective Layer of a Tooth

The outer layer has two names; the exposed part that you see is called your “enamel” and then below the gums this layer is called “cementum” (for simplicity, we will refer to both sections as “enamel” in this article).

This layer is very hard, its hardness ranks between steel and titanium. In order to become so hard, it has to be composed almost entirely of minerals, the main mineral is a form of calcium called “hydroxyapatite.” As this layer is basically just minerals, there are no living cells, blood or nerves in your enamel. It is a dead, protective layer and so the body cannot regenerate or repair damaged enamel. It can, however, be repaired by remineralization. This is a function performed by the saliva in your mouth as well as by dental procedures and preparations. As a note towards the future, scientists are working on very promising technologies to “regrow” enamel which will be an enormous leap forward for dentistry.

Since the enamel is so hard, it has very little flexibility and could easily be cracked or fractured if it were not for the softer, and supportive, layer below called “dentin.”

The Main Supportive Layer of a Tooth

Dentin is the central zone of your tooth and lies just below the enamel. It is a softer layer (still pretty hard, don’t think of it as a marshmallow!) that provides flex and support to the enamel.

There are several important differences between enamel and dentin:

Enamel is “dead” and almost 100% composed of minerals but dentin is a mix of minerals, organic material and water. Its biggest component is the mineral hydroxyapatite (45%).

As it is living tissue, it is regenerated by the body throughout your life and it can transmit sensations (hot, cold, pain).

Unlike the very solid enamel, the dentin is porous and its structure is laced with many, many tiny tubes or channels called “dentinal tubules” that transport nutrients and transmit sensation through the tooth. This area makes up the majority of your tooth.

The dentin tubules are really important to your teeth. They are microscopic tubes or channels that start at the pulp and extend all the way out to the enamel.

They help in the support of your enamel (it is so hard that it would crack and fracture without the underlying softer and porous dentin layer). Outside of the core (the pulp) there aren’t any nerves or blood vessels. And so, the dentinal tubules are critical to transmit sensations and to provide a channel for nutrients to flow on. Think of the inner pulp as a loading dock, where blood vessels bring nutrients, and the dentinal tubules as transport channels for delivery.

Interestingly, the direction of flow in the tubules is important.

Fluids, and nutrients, should flow outward towards the enamel. When this flow reverses (such as when the enamel is eroded and the tubules become exposed) then bacteria and other gunk can penetrate into your teeth, the pulp and into the blood system. This reversal of fluid flow also prevents nutrition from getting to the tooth.

Understanding this “reverse flow” in the microscopic dentinal tubules should help you better understand how teeth decay and why strong dental enamel is so important.

This is also helpful for a better understanding of dental sensitivity. When the dentin is exposed, by enamel erosion and/or gum recession, these tiny tubules are now wide open to stimuli or pressure.

For example, imagine a channel of fluid. Then imagine a downward pressure on that channel which would push fluid through that tube. This pressure would of course push on the other end. This is not an accurate depiction of what goes on in your dentinal tubules, but it does give you an idea of how some stimulus would transfer through the exposed dentinal tubules to the nerves in the pulp, causing pain and sensitivity.

And so, your teeth get sensitive when the protective enamel layer is violated and the tubules are exposed. Hot and cold travels through the tubules and the nerves are stimulated. Pressure, such as from a toothbrush, pushes the fluids in the tubules and the nerves are again stimulated.

There is even something called “osmotic stimulation” which is a type of chemical flow that certain foods, like sugar, can trigger a flow and so irritate the nerves.

The Inner Nutrient Providing Layer of a Tooth

The pulp is at the base, or inner core of the tooth. It is composed of living tissue–with cells, nerves and blood vessels. Its main purpose is to provide nutrition to the tooth (dentin) and to assist in the formation of new dentin.

These 3 parts make up your tooth. A hard, protective outer layer (enamel or cementum), a softer, supportive and living inner zone (the dentin) and finally the inner base that supplies nutrition and transmits sensation (the pulp).

Hopefully, understanding this structure will also help you to “up your game” in take care of your teeth, especially the protective enamel that your body cannot regrow. Once that layer breaks down, the result is not only pain but it raises the risk of physical issues as bacteria passes into your body.

And, as a note of hope and a path of action, while the body cannot regrow enamel, the enamel can be remineralized. Some of this occurs naturally by your saliva.

But you can also remineralize and strengthen your teeth by using a toothpaste with nano-hydroxyapatite. This form of calcium remineralizes the enamel, thus building up strength and lessening sensitivity. It is important to also choose one that has forms of nano-hydroxyapatite that are proven to bond easily to your enamel–such as our OraRestore Pro-Mineralizer toothpaste. (It is LOADED with a clinically proven form on nano-hydroxyapatite). Check it out on our store: Great Oral Health Pro-Mineralizer Toothpaste.

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