The pulp is an "endodontic" tissue. in other words it is a tissue contained within the tooth, often called the "endodontium." Endodontic health and disease are very intimately related to the scope of dental therapy. There was a time when treatment of the endodontium was performed primarily by specialists called Endodontists. That specialty still exists today, but more and more these procedures are being performed in the general dental practice.
The vast majority of pulp issues are treated within our office. And that includes all of the things which a dentist must do to protect the pulp tissue as well as advanced endodontics in which the pulp is removed and the chamber sealed up. When that last task proves to be too difficult, I am not afraid to refer the case to the endodontists who have the experience to treat the more advanced cases.
For anyone who has reached this page without reading the section "Hard Tissues of the Tooth", I would recommend that you take a moment to review the dentin before going any further. For those who already read the section on the dentin, you know that the pulp and the dentinal tubules are intimately connected and must be discussed together.
The Properties of the Pulp
I will not draw a picture of the actual cells within the pulp for you, nor can I show you a microscopic image of the pulp - living cells do not survive the process of preparing microscope slides! But if you use your imagination you can see these cells with your minds eye. Look at the image to the right, and now follow along with the description below:
The cells within the center of the tooth make up a tissue which, collectively, is called the pulp tissue. If you can picture how those cells are arrayed within this small chamber, think of the outer perimeter of the pulp being a layer of cells, each of which is connected to a single dentinal tubule. Then imagine a network of nerve fibers fanning out along that perimeter and connected to every single one of those cells.
Then, in the center, you have the blood vessels and nerves to supply the proper nutrition to these important perimeter cells, and finally the connective tissue in the center to hold it all together.
Another important aspect of this image is where the pulp enters the root at the apex (another fancy way of saying the tip of the root.) The blood vessels and nerves enter into the tooth by way of this very small, constricted, apical foramen (another fancy of way of saying an opening at the tip of the root.) They are drawn in blue and red under the tooth.
So what do we have here?
We have very highly organized tissue inhabiting a very small space, supplied with blood and nerves that enter through a very small hole.
The Purpose of the Pulp
As you will recall, the primary purpose of the pulp was to construct the dentin, and the tubules within the dentin itself. Like a honey bee laying down the walls of the honeycomb, cells called odontoblasts lay down the dentin and create the tubular hard tissue. When the cells are "done" they stay there, connected to the end of the tubule, with a foot like object projected into the tubule to pick up any changes in the properties of the water within the tubule.
By the way, the fluid within the tubule comes from the fluid within the pulp itself.
The ongoing purpose of the pulp is two fold:
- To continue to make more dentin if stimulated to do so by advancing decay or dental trauma
- this is an important ongoing feature that will "wall off" the pulp with secondary dentin formation in the face of decay travelling towards it
- To send a message to the brain, if even a single tubule deforms ever so slightly under the pressure of chewing.
- this is an important way to let the brain know what your teeth are in contact with, and to coordinate the muscles of chewing properly.
- see the section on "Occlusal Trauma" in this Learning Center to learn more.
In health, the pulp does not exhibit any symptoms at all. But if the dentin is exposed, the tubules will react accordingly to hot or cold, sweets or metal. That is a product of the pulp itself, working in concert with the dentinal tubule complex. If the pulp is inflamed however, the reactions are magnified significantly
Inflammation of the Pulp ("Pulpitis")
If the pulp is stimulated, damaged, or irritated accordingly then it becomes inflamed. By the way, any medical word that ends in "itis" means "inflammation." We will not go into details here about what causes a pulpitis, that will be in the section appropriately title "Disease, Diagnosis, and Treatment."
But to give you a little glimpse
- tooth decay that advances into the dentin and follows the tubules toward the pulp will eventually yield a pulpitis
- chronic or acute occlusal trauma, banging the tooth and bending the tooth can pulp up the pulp
- fracture of the tooth
- failing restorations that are allowing leakage of oral fluids, bacteria, and cells into the dentinal tubules
For the purposes of this discussion, when the pulp becomes inflamed, i.e. when you present a pulpitis, the tissue begins to swell. And there in lies a major problem - this chamber is so confining that the swelling has no place to go, so the intra-pulpal pressure increases.
Once again, I have no pictures to show you. So lets pretend that we are standing within the pulp chamber and the dentin around us has decay that is invading our tubules and travelling toward us. Inflammation ensues which means that blood vessels open up, and fluid pressure increases around us within our small chamber. The intra-pulpal pressure presses against the odontoblast/nerve network that surrounds us and the pressure within each of the dentinal tubules increases as a result. Similarly, the pressure exudes out the apical foramen and increases within the periodontal ligament that surrounds the tooth.
If we can remove the irritant, the cause of this inflammation, the situation will resolve, the choke hold on the blood vessels will loosen and everything will go back to normal without any long term cellular damage. That is a reversible pulpitis.
The pulp can stand this pressure for a while, but if it has to endure it for too long, the blood vessels that enter through the apical foramen get pinched off and we start losing our supply of fresh blood - a medical condition known as ischemia that damages cells. This would yield an irreversible pulpitis
The clinical symptoms and signs of reversible and irreversible pulpitis are very distinct and different. We will review them in far more detail when we begin to discuss "Dental Disease, Diagnosis, and Treatment" in that section.
Now lets go on to the next soft tissue associated with your tooth - the gingiva
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