First, to help us understand the basic tooth structure, let's see how a tooth develops . . .
When a tooth is first formed, it is nothing more than "germ cells," cells from a specialized layer of developmental tissue that forms within the bone.
The first part of the tooth that forms in the bone is the outer shell of the enamel.
As the tooth fully develops within the bone, before it comes through the surface, it starts growing the tooth root. It does this because the blood flow that goes into the middle of the tooth starts laying down calcium, phosphorous, magnesium and other minerals that help the tooth to grow.
Finally, the developing tooth starts erupting into the mouth.
When the tooth first comes into the mouth, it does not have a fully developed root structure. It is not completely developed until about the age of 15 to 20 years. At that point, the root starts changing, and begins to fully calcify itself.
Now, let's look at a mature tooth . . .
The mature adult basic tooth structure has several different parts to it. The first is the outer layer of enamel, which is a very hard, crystalline material that acts as a protective helmet or shell. It breaks apart foods during the act of chewing, it can resist grinding and abrasion, and it helps protect the tooth throughout life.
The enamel is also resistant to acid and chemical attacks during the process of digestion, but the entire basic tooth structure is not made up of enamel, because enamel is very rigid and brittle. If the entire tooth were made of enamel, it would fracture very easily. The enamel is there as a thin protective shell, protecting the rest of the basic tooth structure from the outside environment.
Inside the enamel shell are the tooth's dentin tubules, which is continuous with the root structure. The entire inner part of the tooth develops over time with millions of tubules that run throughout the entire inner part of the tooth, from the inner blood flow to the outer environment of the tooth structure.
The purpose of these tubules is to carry calcium and other minerals from the blood delivery system into the large surface area of the tooth root for the root's growth and development.
In the middle of the tooth is the "pulp," or nerve. This supplies the blood vessels, the blood cells, and the living tissue to the inner part of the tooth.
Around the outer part of the tooth is the periodontal ligament, an immune membrane that is part of an elaborate oral immune system.This membrane is designed to protect the inner environment of the body (the bone and blood system) from the outer environment, with all its microbes and bacteria that can harm us. Additionally, it has a multitude of criss-crossing ligaments that act as a suspension system, helping to absorb the shock and force of biting and chewing for the protection of the more fragile bone. This ligament, or immune membrane, is probably one of the most important aspects of our entire oral system.
Surrounding this whole basic tooth structure is the bone, with its blood flow, blood vessels, and lymphatics that supply health to the entire structure of not just the immune membrane, but also the inner part of the tooth and the bone itself, so that it can last a lifetime.
The immune membrane provides the immunity. The blood flow inside the tooth provides the minerals necessary to deposit and grow a root structure , as well as provide changes throughout time to fully calcify this tooth root.
As a nerve inside of a tooth goes through time, with increasing stimulus and change, the tooth root becomes increasingly calcified. In older people, even if they have had no dental treatment, their x-rays show that the blood flow going through the vessels into the tooth is very constricted because of these changes. The more trauma or stimulus, such as dental drilling or biting stress, the more likely this blood flow is going to be constricted as it circulates into the tooth structure, and the more likely many of the dentin tubules will be sealed off, fully calcified.
As the tooth changes throughout life, more of this calcification occurs, so that many times a tooth in its natural state will have no living cells, not even within the nerve or the blood system. At that point it is a totally calcified structure.
This doesn't mean that the tooth is dead. A calcified tooth and its living parts--the outer immune membrane, the bone--are still intact, as long as the system has been kept healthy. This is what truly supplies health to the tooth itself (the outer blood flow in the bone to the immune membrane), and allows the tooth to do its basic job and function throughout life.The next page will discuss how you may be able to avoid root canals.
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