Wisdom tooth infections - Pericoronitis.

- Why does the infection occur? | How is it treated? | Incidence rates - Statistics | If you've experienced pericoronitis, does your tooth need to be extracted?

1) What is pericoronitis?

"Pericoronitis" refers to a bacterial infection located in the soft tissues that surround the crown portion of a partially erupted tooth. Most cases involve wisdom teeth.

  • The "crown" of a tooth is its non-root portion. That part that normally shows above the gum line.
  • A "partially erupted tooth" is one whose crown portion has only part way penetrated through the gum tissue (see picture below).
  • This partially-erupted positioning may be just temporary because the tooth is still in the process of erupting (coming in). Or, in the case of a partially-erupted impacted tooth (a tooth's whose eruption process can proceed no further), a permanent one.

Where does the word "pericoronitis" come from?

The term breaks down as follows:

  • "Peri" means "around."
  • The "coron" portion of the word refers to the "crown" of the tooth.
  • The suffix "itis" refers to the presence of inflammation.

All together, the term pericoronitis refers to the presence of inflammation in the tissues that surround a tooth due to an infection associated with its (submerged in the gums) crown portion.

2) Details about Pericoronitis. -

a) What causes it? - It's caused by bacteria.

The underlying process/problem associated with pericoronitis is an infection, typically caused by ordinary oral bacteria (like those routinely found in dental plaque).

A partially erupted wisdom tooth.

It's the gum relationship around a partially-erupted tooth that allows pericoronitis to occur.

The scenario involved is one where bacteria have been allowed to colonize the space (sac) that exists between the crown portion of the tooth and its surrounding gum tissue.

  • This space exists because the positioning of the tooth is one where it is still mostly submerged in the gums (the tooth is only "partially" erupted).
  • The bacterial colony has formed because this sac is essentially impossible for a person to clean.

The bacterial colony may have (and probably has) been present for an indefinite period of time. However, no symptoms are noticed because the person's body defense mechanism (immune system) has been able to keep it in check.

However, if some type of event is able to tip this balance (illness, gum tissue trauma, increased numbers of bacteria or a better food supply for them), an active phase of infection (redness, tenderness, pain, swelling) can be triggered.

How often will pericoronitis form? - Transient vs. persistent episodes.

As long as a tooth remains partially erupted and is impossible to effectively clean, a person may experience repeated episodes of pericoronitis with that tooth.

  • Transient - In cases where the tooth is in the process of coming in, the problem should just be a transitory one. Once the tooth fully clears the gum line, it should be possible to properly clean (brush and floss). If so, no more episodes of infection should occur.
  • Persistent - In cases where the tooth is both partially erupted and impacted (meaning no further progress through the gum tissue will occur), the person can expect to experience repeated infections.

b) Why does pericoronitis form?

The crown portion of a tooth forms within a pouch termed the follicular sac (drawn in tan in our illustration).

Pericoronitis is an gum infection that surrounds a wisdom tooth.

The infection is harbored in the developmental sac (tan) around the tooth.

The sac is penetrated.

At that point in time during the eruption process when a tooth first pokes through the gum tissue, the integrity of its developmental sac is lost and bacteria from the mouth easily flood into this space and colonize it.

The sac is a non-cleansable area.

Unfortunately, there is no way for a person to effectively clean this space. And due to this inability, from time to time it is possible for the bacteria it harbors to cause an active infection, which then spreads to adjacent tissues surrounding the wisdom tooth (as illustrated in our picture).

Pericoronitis around a lower wisdom tooth.

The initial formation of infection around a lower partially erupted wisdom tooth.

d) What are the signs and symptoms of having pericoronitis?

The signs of pericoronitis include:

  • Redness, tenderness and swelling in the gum tissue immediately surrounding the wisdom tooth.
  • The swelling can extend into the face and neck and may make it difficult for the person to open their mouth.
  • There can also be moderate to severe pain, an unpleasant mouth odor, and even a bad taste coming from the infected area.
Some cases can be life threatening.

Due to the anatomy of the region, it's possible for an infection located in the soft tissues surrounding a lower wisdom tooth to spread rapidly and extensively in the region of the throat and neck.

If so, the extended tissues may interfere with the person's ability to breathe and swallow, thus causing a potentially life-threatening situation. These cases may require hospitalization and possibly surgery to drain the infection.

Especially for this reason, if you notice the signs and symptoms of developing pericoronitis, you should advise your dentist sooner rather than later.


How is pericoronitis treated?

This condition needs to be evaluated and treated by your dentist. In most cases they will:

  • Reduce the bacterial load in the infected area by scraping or irrigating (flushing) away as much accumulated debris as is possible.
  • Place you on a course of oral antibiotics. It usually takes on the order of 24 hours for oral antibiotics to start to create their affect.
  • Prescribe an antibacterial oral rinse (frequently chlorhexidine) that you can use to clean the infected area and reduce its bacterial load.
  • If access exists, show you methods by which you can flush out the space between the tooth and gum tissue (the area that harbors the bacteria causing the infection) using an "irrigating" (blunt-tipped) syringe.

In the case that a decision is made that your wisdom tooth should be extracted, your dentist will need to wait until your infection has resolved before the procedure can be performed. In relatively routine cases, and where a course of antibiotics is taken and irrigation is performed, a time frame of at least a week is usually required.

A dental x-ray showing where pericoronitis occurs.

X-ray diagram showing where the infection initiates.

4) Statistics - How frequently do people experience pericoronitis?

  • Friedman's (2007) [page references] review of published literature concluded that the incidence rate for a person experiencing pericoronitis in association with a wisdom tooth falls along the lines of 6 to 10%.
  • Research frequently cites pericoronitis as being the most common reason for wisdom tooth removal. Some studies place this number as high as 40 to 59% of cases. (Faculty 1997)

As we explain below, experiencing a single episode of pericoronitis does not necessarily constitute a valid reason to extract a wisdom tooth. The tooth's outlook in regard to its ability to ultimately fully erupt (clear the gum line) should be the basis on which the decision is made.

If you experience pericoronitis, does your tooth need to be pulled?

a) All teeth are just partially erupted at some point.

Just like every other tooth that comes in, even wisdom teeth that eventually fully erupt into normal and proper alignment go through a transitional period where they are only "partially erupted."

That's because it takes some time for a tooth to fully penetrate through the gums and achieve its final positioning. And during that time frame when the wisdom tooth is only part way through the gums, it is at risk for developing pericoronitis.

b) Partially erupted teeth are not necessarily impacted teeth.

When a dentist evaluates a patient that has pericoronitis they need to determine whether the tooth's partially erupted status is simply a transitory phase of the normal eruption process. Or if it's instead impacted (meaning the tooth will always remain partially erupted).

In the first case, the dentist's approach will be to actively manage the patient's current condition (prescribe antibiotics, irrigate the area, etc...). It's expected then, over time as the tooth more fully erupts, that its potential for additional episodes will diminish.

In the latter case, where the impacted tooth's positioning is not expected to resolve normally and therefore it will always remain at risk for recurring infections, the wisdom tooth should be extracted.


Topic Menu ▶  Wisdom Teeth (third molars).



Sore gums

There are times when I can see just a part of my wisdom molar. From time to time it seems to disappear and the gums in that area get really sore. I'm afraid of having a tooth pulled.


You're on the right page. From your description it would seem that what you have noticed is repeated episodes of pericoronitis.

Your tooth "disappears" due to the swelling of the gum tissue around it. The pain and swelling are all symptoms of an infection surrounding your tooth because you cannot clean it properly.

You can only see a part of your tooth because it is just "partially" erupted. And it's because your tooth has not fully penetrated your gums that you can not clean it (remove bacterial accumulation from around it) effectively.

The only question is whether the tooth will finally erupt (come through) the gums properly or not (is in it's impacted).

If the tooth is impacted (meaning is stuck in that position), you'll continue to experience episodes of pericoronits. (Everything we have mentioned here is explained in greater detail above on this page.)

The solution is to have the tooth taken out. The process of tooth removal really isn't all that bad, or painful. For some people, the use of sedation medication for their procedure can place them more at ease.

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