What are “wisdom teeth”?

Wisdom teeth are the third permanent molars. There are four wisdom teeth in total, two upper and two lower third molars. It is believed that they are referred to as wisdom teeth because they erupt later in life when the person attains the mature wisdom.

How and when do wisdom teeth form and erupt?
Wisdom teeth are the last teeth to start forming in the human dentition. The age at which they erupt is highly variable compared to the other teeth and it can be as early as 16 years old or until late twenties. Luckily, wisdom teeth are the most commonly congenitally missing teeth, meaning that they do not form at all. This is probably due to natural selection because of the softer diet that is consumed nowadays which negates the need for third molars. It is important to know that third molars may be present even if you do not see them in your mouth. This is because they are often unerupted or impacted. What this means is that there is no enough space for the third molars to erupt into the mouth so they remain buried under the gums and/or jaw bone. Wisdom teeth are the most commonly impacted teeth and the reason is they are the last teeth to erupt into the mouth and usually there is not enough space for them. The only way to find out if you have impacted wisdom teeth is to be examined by a dentist who might recommend taking a panoramic x-ray or any other kind of radiograph to evaluate third molars. Wisdom teeth may be detected early during orthodontic screening and the orthodontist is usually able to determine whether there is enough space for them to erupt in the future or not.

Symptoms of impacted wisdom teeth
Usually there are no symptoms at all, especially if the teeth are deeply impacted in bone. Symptoms are more often if wisdom teeth are “partially impacted” meaning that only a small part of the tooth is exposed in the mouth while the rest of it is buried underneath the gums. Sometimes, this partial impaction results in a “food trap” meaning that food can be trapped in that area because it is difficult to clean. Over time this may cause tooth decay in the second molars, the teeth that are in front of third molars. Chronic food impaction may also result in gum infections in that area causing swelling of gum tissue forming what is called an operculum. The operculum may extend over the surface of second molars and can be very painful especially if it gets between teeth when biting. Some people report “pressure” on their back or front teeth when third molars start coming out but the force third molars exerts on other teeth is thought to be insignificant. Wisdom teeth may also cause discomfort even if they are completely erupted because the cheeks tend to get trapped and even bitten by them during eating.

Wisdom teeth and crowding
It was once believed that the eruption and impaction of wisdom teeth may result in crowding of front teeth especially the lower incisors. Most studies demonstrated that lower incisors tend to get crowded during late teens to early twenties due to late growth of the jaws rather than wisdom teeth. However, many dentists and orthodontists still recommend the removal of wisdom teeth to maintain the alignment of lower incisors after orthodontic treatment. In other cases, wisdom teeth may prevent proper eruption and alignment or second molars and this can be one of the indications for their removal.

Indications for wisdom teeth removal
This is one of the controversial topics in the field of dentistry and oral surgery because some people strongly believe that third molars must be extracted if they are impacted while others believe they should not be if there is no clear indication to remove them.

Indications for wisdom teeth removal include:
-    Chronic pain and/or discomfort
-    Inability to maintain good oral hygiene in that area because of their presence
-    Increased risk for tooth decay of the adjacent teeth
-    Restoration of adjacent teeth is complicated by their presence
-    Alignment or uprighting of second molars
-    Periodontal indications to maintain alveolar bone around the adjacent teeth
-    Recurrent gingival inflammation and overgrowth (operculum)
-    Facilitating orthodontic treatment (if space is needed to move teeth)

Contraindications for removal of wisdom teeth:
-    Close proximity to the mandibular nerve or border of mandible in the absence of pain or other symptoms
-    Prevention of lower incisor crowding as the only reason for removal
-    Poor prognosis or loss of adjacent teeth like second molars because third molars can be used to substitute those teeth
-    Systemic health conditions contraindicating the surgery (example: bleeding disorders, radiotherapy, etc…)

1.    Full medical and dental evaluation:

comprehensive medical and dental history should be obtained to rule out any contraindications or possible complications

2.    Sedation and anesthesia:
Removal of wisdom teeth is often carried out under sedation especially if all four wisdom teeth are to be removed in the same visit. Usually, a patient is partially awake during sedation but is in a low anxiety state that facilitates the procedure. It is administered by intravenous, oral or inhalation drugs. Sedation should be controlled by a surgeon or specialist to ensure the safety of the patient. Local anesthesia is then performed by giving needle injections to numb the nerves around the wisdom teeth.

3.    Wisdom teeth removal:
Removal of third molars depends on their location, depth of impaction and other anatomic factors. The procedure may require cutting through the gums and/or jaw bone to provide access for the tooth which is then removed using special instruments. It is also sometimes necessary to cut and section the tooth to facilitate its removal.

4.    Sutures:
After the removal of wisdom teeth the extraction sites are usually sutures to encourage healing and to prevent bleeding and infections. Sutures are removed few days after the surgery unless they are resorbable (dissolvable).

Patient recovery post wisdom teeth removal:
Usually the patient is not aware of the procedure due to sedation, recovery from sedation occurs within an hour or so. Recovery may be associated with nausea and vomiting. Pain killers and antibiotics may be prescribed. Pain and swelling for a few days after the procedure is normal but should be followed up to rule out infections.

Possible complications and risks of wisdom teeth removal:

1.    Swelling and pain
2.    Bleeding
3.    Dry socket: infection of the socket caused by smoking, poor oral hygiene, diabetes and other factors. It starts 1-3 days after surgery as deep throbbing jaw pain. Examination reveals food debris and dead grey yellowish tissues in the extraction site. It is treated by cleaning and rinsing the extraction site and antibiotics may be prescribed.
4.    Fracture of the jaw (very rare)
5.    Fracture of adjacent teeth or crowns
6.    Nerve damage causing partial or complete lip numbness: numbness after the procedure is common and usually resolves. Numbness may take weeks or months to resolve completely. If numbness persists for more than a year then it indicates permanent nerve damage and usually does not resolve.
7.    Bone infections (osteomyelitis)
8.    Septicemia and generalized infections
9.    Bony defects in extraction sites

Wisdom teeth extraction cost
The cost depends on the number of teeth to be extracted and whether sedation will be used or not. The typical cost for four wisdom teeth extractions plus sedation is about 2000 USD. This is usually partially or fully covered by the medical insurance.