Dental Cysts Of The Jaw

What Is A Cyst?

A cyst is a space-occupying lesion that can be formed in either the hard or the soft tissues of the body. In most cases the center of the cyst is filled with necrotized material and pus. As these cysts grow, they put pressure on adjacent structures like blood vessels and nerves and, in fact, may even obliterate them altogether.

Think of these cysts like balloons that slowly continue to grow and as they grow they keep destroying the surrounding structures to find the necessary space. As a result, of this destruction, patients may experience numbness, hard and soft swellings (depending upon the nature of the cyst), destruction of bone and the roots of the teeth they lie against, and eventually they may even cause the teeth to fall out altogether.

Why Do Cysts Form In The Mouth?

Some of these cysts may be formed because some part of the epithelium (the soft tissue cells lining the bone) gets entrapped into the bone during development. Others may be formed in response to inflammation, infection or trauma and still others may be formed without there ever having been an obvious reason.

Cysts by themselves do not cause any symptoms whatsoever and only start to cause trouble once they have been secondarily infected. The other symptoms that appear are associated with the destruction they cause.

If a cyst is found to be self-contained and causing no apparent symptom or destruction then there is no reason to remove it.

Periapical Cyst

This is by far the most common type of cyst found in the oral cavity. There are several distinguishing features which make it quite easy to identify a periapical cyst. The origin of a periapical cyst is from the necrotized pulp tissue.

This can occur in several ways. Dental caries which have not been treated can extend to the pulp, causing it to become infected and eventually leading it to necrotize. The same can also happen through a blow, fall or any other trauma to the teeth.

This cyst is detected on a standard periapical X-ray of the tooth, however, it can also be recognized in an OPG of the entire mouth.

A periapical cyst is very similar in radiographic appearance to a periapical abscess that also presents itself with very similar symptoms. An untreated periapical cyst can also grow to a size large enough to cause the destruction of neighboring teeth and can even cause a displacement in their position.

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The cyst can be distinguished from the abscess by the presence of pus, presence of symptoms of acute inflammation or through the presence of a necrotic pulp tissue. In some cases, however, it can be quite difficult to distinguish between the two since both basically exhibit the symptoms of inflammation.

From a treatment point of view, the presence of both indicates that the affected tooth has to undergo a root canal. An abscess will resolve in due course of time whereas a cyst may persist. Depending upon its size and location, it may then have to be removed.

More Common Cysts Found In The Jaw 

Dentigerous Cyst

A dentigerous cyst is a type of cyst that is associated with un-erupted teeth in the jaws. The mechanism that leads to the development of this cyst is well understood. It involves the developing cells around the crown of the teeth to proliferate and to start to accumulate fluid between themselves the crown of the tooth.

Thus, characteristically, this type of cyst will always be attached to a tooth. Since the cyst is developmental in origin and does not have any inflammatory component, it is frequently completely asymptomatic.

A dentigerous cyst can grow to a very large size, sometimes taking up almost half of the jaw. The diagnosis of this cyst is usually done during routine X-rays taken during a check-up or during treatment for some other involved tooth.

A lot of doctors advise removal of all un-erupted teeth due to the risk of developing a dentigerous cyst, however, it should be remembered that the chances of this happening are close to no higher than one percent.

Since the cyst can grow to a very large size, it can actually weaken the entire jaw structurally and make it more prone to develop fractures.

Eruption Cyst   

An eruption cyst is a kind of dentigerous cyst that occurs in a very specific kind of situation. Here the tooth erupts through the bone but remains lodges inside the gingival tissue. The cyst around the neck of the tooth frequently becomes blue in color because of bleeding into the cyst and this color permeates through the gingival to become visible outside.

It is because of this reason that the cyst is erroneously referred to as an eruption hematoma as well. The good thing about the cyst is that it is very short lived and does not require any treatment whatsoever. The cyst resolves on its own as soon as the tooth erupts into the oral cavity.

Residual Cyst

As the name suggests, a residual cyst is a periapical cyst that has not resolved even though the tooth with which it was associated has been extracted. This happens in a small number of cases and when it does, it is an indication that the cyst needs to be surgically removed.

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Conclusion

The appearance of cysts is very similar to tumors of the jaw, at least on radiographic appearance. As a result, if the doctor is unsure whether the lesion on the radiograph is a cyst or a tumor, it is better to err on the side of caution and order a biopsy.

Better imaging techniques and the use of cone beam CT scans has also made it easier to see the entire extent of the cyst, the structures it is affecting, any structures present inside the cyst and plan the best approach for treatment.

Also, cysts are an entirely different entity from tumors and do not indicate any likelihood of a person developing/ not developing a tumor in the future.