Wisdom teeth, also known as the third molars, are the last teeth to grow. They are located at the end of the upper and lower gums, right in the back of the mouth.
Most people eventually have four wisdom teeth, but this can vary from none to four, and in rare cases, a person may have more than four.
Wisdom teeth normally appear in late adolescence or early adulthood, between the ages of 17 and 25 years.
The human mouth normally does not have room for 32 teeth, which includes the four wisdom teeth, so if wisdom teeth do come through, they may cause crowding, infections, ear pain, and swelling.
Wisdom teeth that do not have enough room to grow properly are known as impacted wisdom teeth. They do not fully erupt into the mouth.
As a result, they can grow in the wrong direction, coming out sideways, at a wrong angle, or only partially. This can affect nearby teeth.
There may be pain, and the other teeth may become damaged.
Even if no apparent damage occurs, the teeth can become more susceptible to disease. If a tooth remains just under the gum, known as tissue impacted, bacteria can collect. This can lead to infection.
For many people, wisdom teeth will eventually grow and settle down, and they will not need to be extracted as long as the person practices good oral hygiene.
However, wisdom teeth may need removing if:
- There is pain, swelling, pressure, and discomfort
- If it is clear that the teeth will not have room to grow or that they will cause damage to nearby teeth
- The teeth are partially erupted and decayed, which makes them harder to reach for cleaning
Do all wisdom teeth need extracting?
In the past, wisdom teeth were regularly removed, whether or not there was a problem. This is less common now in many countries, but in the United States, around 5 million people annually have all their wisdom teeth removed.
In the U.S., many dentists and oral surgeons believe that impacted wisdom teeth that are not causing any apparent problems should be taken out as a preventative measure, to reduce the risk of infection, gum disease, and tooth decay. They add that it is easier to extract a wisdom tooth from younger patients than older ones.
In 2007, Jay Friedman questioned this, in an article published in the American Journal of Public Health. He called the unnecessary removal of wisdom teeth a "public health hazard."
Friedman points out that 11 million patient days are lost each year, due to "standard discomfort or disability," following wisdom tooth removal. Over 11,000, says Friedman, are left with some degree of paralysis in the lip, cheek, or tongue.
He argued that this could be avoided if dentists were to remove the teeth only if they cause a problem.
Depending on how the teeth grow through, impacted wisdom teeth can have:
- Mesioangular impaction: The tooth is angled towards the front of the mouth
- Vertical impaction: The tooth does not break through the gum line
- Distoangular impaction: The tooth is angled towards the back of the mouth
- Horizontal impaction: The tooth is angled sideways at a full 90 degrees, and it grows into the roots of the molar next to it
An impacted wisdom tooth can cause a range of problems.
The overcrowding and pressure can lead to general crowding of the teeth and the patient may need orthodontic treatments to straighten crooked teeth.
The tooth may grow into a sac in the jawbone which fills with fluid, creating a cyst. The cyst can damage the jawbone, and the teeth and nerves nearby.
Rarely, a noncancerous tumor may form. Tissue and bone may have to be surgically removed.
The second molar, which is next to the wisdom tooth, becomes more prone to infection if something is pushing against it.
Even if there are no symptoms, impacted wisdom teeth can damage other teeth and can be more prone to infections.
More serious infections include cellulitis in the cheek tongue or throat or gingivitis, the gum disease that results when plaque releases toxins that irritate the gums.
To relieve symptoms, patients can:
- Use painkillers, but swallow them rather than leaving them on the sore tooth
- Use a mouthwash of warm water and a teaspoon of salt several times a day: This can reduce soreness and inflammation
- Use an antibacterial mouthwash, such as chlorhexidine
If the pain continues, medical attention should be sought.
A dentist may clean the teeth and prescribe antibiotics, but if the problem returns, the teeth may need removing.
If a wisdom tooth is painful or troublesome, or if it causes damage to other teeth or the jaw bone, it will be taken out.
An oral surgeon will need to see a patient if an existing medical condition puts them at a higher risk of complications.
Dentists cannot accurately predict which wisdom teeth are going to cause problems. However, the angle at which the tooth erupts and the extent to which it pushes against other teeth can offer a clue.
What to expect at the dentist
The dentist will probably take an x-ray to see how the roots lie and how the tooth is growing.
The removal may take place at a dentist's surgery or as an outpatient at the hospital.
How straightforward the operation is will depend on the position of the tooth or teeth to be removed.
After having the tooth or teeth removed, there may be pain and swelling for a few days. Painkillers such as ibuprofen can help sometimes antibiotics might be prescribed.
The dentist will advise on mouthwashes. If there are stitches, they may need to be removed about a week later. It is important to follow the dentist's post treatment instructions.
It is important to relax and to avoid alcohol and smoking for at least 24 hours, to make sure there are no bleeding problems.
Complications of surgery
Some patients have problems during or after the extraction of their wisdom teeth, but these are not usually serious.
Problems may include:
- Malaise, or a feeling of being unwell
- Bruising and discomfort
- Dry socket
- A hole between the mouth and the maxillary sinus
- A fistula between the mouth and the sinus, sometimes through the tooth socket
Nerve damage can occur in nearby teeth, when the wisdom tooth is removed. This can lead to numbness or paralysis in the lip, tongue, or cheek.
Some people may have an adverse reaction to medications.
A dry socket, or alveolar osteitis, is when a blood clot does not form properly in the socket left by the wisdom tooth. This can lead to a throbbing pain. It normally results from patients not following the dentist's instructions. It can result from smoking, rinsing the area too soon after surgery, or sucking on it.
Sometimes removing the wisdom tooth can cause a fracture in the maxillary tuberosity, which is just behind the upper wisdom tooth.
A lower jaw, or mandibular fracture, can occur during surgery or within 4 weeks after surgery.
It is important to practice good dental hygiene and to have regular checkups to minimize the risk of dental problems.