Impacted wisdom teeth

What are impacted wisdom teeth?

Wisdom teeth are molar teeth, which are the last to erupt into the mouth, usually after the age of 15 years, or even much later. They are four in number – one each situated in the four corners of the mouth, behind the second molar teeth and have no clearly defined shape or form unlike the other permanent teeth. They are often called wisdom teeth as they erupt at an age when the person is in the transition phase from childhood to adulthood. The remaining 28 teeth normally erupt into the oral cavity by the age of 13 years.

Wisdom teeth are considered impacted when they are unable to erupt into their normal functional positions, mainly due to lack of space for their eruption. Approximately 20% of the population has impacted wisdom teeth. Less than 5% of the population has sufficient room to accommodate the wisdom teeth. Of the other permanent teeth in normal individuals, very few are found impacted except the canines.

What are the causes for impaction of wisdom teeth?

It has been found that during the process of evolution, the jaws are progressively becoming smaller in size and the braincase is expanding at the expense of the jaws. This is said to occur because with the passage of time, man is increasingly using his brain whereas the use of the jaws for chewing has been progressively on the decline, as the diet we are having has become refined and soft. Hence the chewing efficiency of the jaws is not put to full use. Masticatory force (force exerted while chewing) has been found to be contributory to jaw growth. Soft diet thus adversely affects jaw growth. An underdeveloped jaw will not be able to accommodate all 32 teeth. This reduces the space for the wisdom teeth, which erupt last, to erupt into place. Evolutionary trends also point to a gradual reduction in the number of teeth, though this may occur only over a considerable period of time.

Another important factor, which predisposes to development of impacted wisdom teeth, is heredity. It has been found that parents who have impacted wisdom teeth are likely to pass on the trait to children. However, this may only be a very small part of the evolutionary design.

Certain disease conditions such as rickets, endocrine dysfunction, anemia, achondroplasia, cleidocranial dysostosis, Treacher Collins syndrome etc. have also found to be associated with impacted teeth. Here, impactions of teeth other than that of the wisdom teeth are also found frequently.

What are the problems associated with impacted wisdom teeth?

Infection is the most common problem encountered associated with impacted teeth. It may range from a localized gum infection to acute, extensive, life-threatening infections involving the head and neck. Localized gum infections tend to recur intermittently when complete eruption of the tooth is not possible. Recurrent infections (which may be subacute and not painful for the patient) will frequently lead to gum disease and decay on adjacent teeth, which can ultimately result in the loss of these teeth in addition to the wisdom teeth.

Sometimes wisdom teeth erupt in abnormal positions and angulations making them non-functional, as they are unable to contact their corresponding opposing wisdom teeth. In such situations, frequent cheek biting or tongue biting can result from the abnormal positioning causing injuries to the cheeks and tongue while chewing. Besides this, the unsupported upper wisdom tooth also starts over-erupting, lengthening out from the supporting gums, thereby leading to food trapping, decay and gum infections in the region.

There are situations when the wisdom teeth do not erupt at all into the mouth. They lie buried within the gum tissue or bone. Often, patients do not experience problems in such situations. There are also instances where wisdom teeth are totally absent in certain individuals.


 What can happen if impacted wisdom teeth are not treated?

Serious problems can develop from partially blocked teeth such as infection, which may turn life threatening and possible crowding of, and damage to adjacent teeth and bone. Another serious complication can develop when the sac that surrounds the impacted tooth fills with fluid and enlarges to form a cyst causing an enlargement that hollows out the jaw and results in permanent damage to the adjacent teeth, jawbone and nerves. Left untreated, a tumor may develop from the walls of these cysts and a more complicated surgical procedure would be required for removal.
Rare instances have been found when the impacted wisdom teeth remain asymptomatic without causing any problems. However, no prediction can be made as to when an impacted molar will cause trouble, but trouble will probably arise, and that too at inconvenient times. When it does, the circumstances can be much more painful and the teeth can be more complicated to treat. Here, the tooth cannot be removed until the infection or other complications have been treated. This means loss of more time and added expense along with some added risk. It's best to have impacted teeth removed before trouble begins.

How are impacted wisdom teeth treated?

X-rays of the wisdom teeth are made to help assess the positions, shapes and sizes of the crowns and roots, the surrounding bone and the nerve, which usually runs below the roots of the teeth. X-rays also help in identification of associated disease conditions such as cysts and tumors in relation to the teeth, apart from aiding in planning of the surgical procedure.

In certain cases of impacted teeth, where there seems to be adequate space available for eruption, the dental surgeon may advise a pericoronal flap excision (removal of the gum tissue overlying the impacted tooth) and observation. In such cases, the tooth may erupt into place after the procedure. However, in many cases, infection of the overlying gum tissue has been found to recur. Here, there is no other choice other than the removal of the offending wisdom tooth.

In light of the clinical experience that most impacted teeth will ultimately give rise to some type of problem or disease, it is generally felt that preventive removal of impacted third molars is indicated. Because complications are significantly reduced when the impacted tooth has no associated disease conditions, and because difficulty of removal increases with age, it is recommended that impacted teeth be removed early. It is best done as soon as it becomes apparent that there is insufficient space or that they are not positioned for normal eruption. Generally, this will occur somewhere between the ages of 16-18. At this age, the roots of the developing tooth are usually between one half to two thirds formed and the bone is less dense, which makes their removal easier and the post-operative recovery smoother. A young patient usually is also in optimal general health, which facilitates safe anesthesia and rapid, complete healing. In older patients, removal before complications develop is key to shorter recovery and shorter healing time, besides minimizing discomfort after surgery.

Before the removal of the impacted wisdom tooth, the patient is normally put on a course of antibiotics and anti-inflammatory drugs to eliminate existing infection and inflammation in the area. The removal of an impacted tooth is normally a minor surgical operation, lasting 10 - 45 minutes. It often requires incision of the gum, cutting the tooth and probably some removal of bone too. The oral surgeon may provide anesthesia options of local anesthesia, intravenous sedation, or general anesthesia to make the procedure more relaxing for the patient. The surgical wound is often sutured with silk (non-absorbable) or with absorbable suture materials. Some surgeons advise extraction of the corresponding upper wisdom teeth also during the same sitting.

When taken up under local anesthesia (LA), removal of impacted teeth is done on one side at a time. This allows a patient to chew on the other side, facilitates faster healing and recovery. In certain situations, impacted wisdom teeth on both sides are removed under general anesthesia (GA) as a single procedure. If the impacted teeth are very deeply situated, or if they have abnormal shapes and forms making the procedure difficult to undertake, GA may again be required for surgical removal. If the surgical procedure is found to be complex, then the dental surgeon may refer the patient to an oral and maxillofacial surgeon, who is trained in surgical treatment of such problems.

After the surgery, the patient is asked to continue the antibiotics and anti-inflammatory drugs which should be meticulously taken by the patient without break in order to facilitate better wound healing without complications. The patient is given pressure packs to bite on over the surgical area and ice packs to be placed over the jaw, immediate post-operatively. The patient is advised to rinse the mouth with ice-cold water about half an hour after the procedure, after the gauze / cotton pressure dressings in the area are removed. After 12 hours have elapsed, the patient may start having warm foodstuffs. However, it would be ideal if the patient has semi-solid or liquid food (yogurt, eggs, fruitjuice, milkshakes, protein supplements etc.) for about a day or two after the surgery, after which he/she may have normal food, without disturbing the surgical area. The patient should also abstain from smoking and drinking during the post-surgical phase, to facilitate better healing and to avoid complications. The patient may also rinse the mouth with luke-warm saline twice or thrice a day after the 24-hour period.
Partial Odontectomy
In certain cases, the roots have been intentionally retained during the surgery to ensure that the mandibular nerve (very often lies very close to the roots of the wisdom tooth and rarely looped around them) & the distal root of the lower second molar are not injured. Such procedures are also carried out if the mandible is very thin / fragile or in situations where a lot of bone cutting is to be carried out to remove the whole tooth with the roots. Such situations can affect the integrity of the mandible at the angle possibly leading to a fracture. In these cases, the possible outcomes are:
          * roots remain vital and are retained
          * resorption (disintegration) of the retained roots
          * supra-eruption of the retained roots  (may be removed later through a relatively minor & complication free surgery)
          * recurring pain &/or infection (necessitating elective surgical removal)

A rare case of impacted molars

Prophylactic Odontectomy

This is a procedure carried out during the early stages of formation of the wisdom teeth. In such situations, the root will not be fully formed and surgical removal of these teeth in the early stages of development are very often free of difficulties and complications. Radiographic evaluation during early stages - for instance at the age of 13 or 14 yrs. of age will help the surgeon to assess the pattern of eruption of the wisdom teeth and also help assess whether they are likely to be impacted.

What are problems the patient faces after surgical removal of impacted wisdom teeth?

Swelling, mild pain, mild bleeding (ooze) from the surgical site and restriction in mouth opening are common problems, which the patient faces after surgical removal. This may be associated with tenderness in the area and difficulty while swallowing. Normally these problems are found to gradually increase after the surgery reaching the maximum by 12–24 hours post-operatively. These problems gradually decrease over the next one-week almost disappearing totally, after suture removal after 1 week in case of non-absorbable sutures. There may be instances where problems persist for longer periods.

The patient should report back to the surgeon if the following problems are seen persisting or increasing even after a period of 4 days after surgery – bleeding, severe pain, swelling, restriction in mouth opening, loss of sensation over the chin and lips, inability to chew properly, jaw joint pain etc.

Are there any complications or risks associated with the surgical removal?

In rare instances, numbness or odd sensation of the lower lip, chin or tongue may occur. The nerves involved are sensory so there is no change in appearance or function. Numbness can last from a few days to several months and in extremely rare instances can be permanent. However, recovery is usually uneventful. Usually X-rays made prior to the surgical procedure helps predict the possibility of involvement of the nerve with respect to the surgery. However, this is not applicable in all cases. Very occasionally, a filling in the tooth next to an impacted tooth may be dislodged or the adjacent tooth broken, in spite of immaculate care and technique. Filling of the ensuing defect may solve the problems once the surgical wound heals. Rarely, pain and/or sensitivity of the adjacent second molar tooth may also occur, which can be totally rectified. It will not cause any hollowing of the cheeks as many people suspect.
Potential complications include postoperative infection, temporary numbness from nerve irritation, jaw fracture, and jaw joint pain. An additional condition, which may develop, is called dry socket. This happens when a blood clot does not properly form in the empty tooth socket, or is disturbed by an oral vacuum (such as from drinking through a straw or smoking), the bone beneath the socket is painfully exposed to air and food, and the extraction site heals more slowly.
It is always important to discuss about the procedure with the surgeon, prior to surgery, so that the patient is able to clear all doubts that he/she might have concerning the surgery.


The wisdom teeth, being positioned far behind all the other teeth, are difficult to clean while brushing and flossing. As a result, in spite of normal eruption and positioning, wisdom teeth are increasingly associated with problems such as decay and gum infections. About 50% of the population needs to have their wisdom teeth removed (made “wisdomless”) before the age of 40 years, in spite of not having them impacted, in many cases. As these teeth do not play a very important role in chewing, their removal does not compromise the chewing efficiency of individuals. On the contrary, removal of wisdom teeth have found to improve the chewing efficiency by eliminating problems in the gums behind the second molar teeth and facilitating better oral hygiene measures in the area which may not be otherwise possible. Hence, once removed, wisdom teeth are not generally replaced. It is extremely important for all individuals to get the status of their wisdom teeth assessed early by a dental surgeon, so that necessary treatment if indicated, may be instituted before much damage is done.

Dr. Prasanth Pillai K.S., MDS (OMFS), FICD, FICOI, FIBOMS