Wisdom tooth extraction- Risks and Complications

Wisdom tooth surgery is probably the most common surgery done by Oral and Maxillofacial Surgeons. Almost every teenager experiences some degree of discomfort from their wisdom teeth. Some will promptly seek treatment and the most expedient option is to remove the offending tooth. After all, most wisdom teeth, even the fully erupted ones, are not critical to our masticatory function. However, like with any surgery, wisdom tooth surgery has its risks and complications and patients need to be cognizant of these before deciding to remove their wisdom teeth. 

Downtime

Wisdom tooth surgery can be rather painful postoperatively. For some patients, it can also cause significant facial swelling. While the surgery is not physically incapacitating, the early recovery period can be uncomfortable. As such, medical leave is usually given for the patient to rest at home. As such, the surgery is usually scheduled at a time when the patient is able to take a few days off from school or work. As the swelling subsides after 4-5 days, bruises may appear on the face. These bruises will then dissipate downwards into the neck before disappearing. Some patients respond very well to the surgery and present with none of the above sequelae. However, most patients do experience some discomfort which can be alleviated with painkillers.

Nerve injury

There are two nerves lying in the vicinity of the lower wisdom teeth. The inferior dental nerve (IDN) is a sensory nerve that enters the lower jaw bone just below the jaw joint known as the temporomandibular joint (TMJ) and runs internally within the bone to the front, exiting the bone through a hole between and below the roots of the first and second premolar, to enter the lower lip. Along the way, the nerve passes under the wisdom tooth and may run very close to it. This nerve provides sensation to the lower jaw including the lower lip. Wisdom tooth surgery requires the administration of local anesthetic to this nerve to block the transmission of sensation to the brain. In the process of removing the lower wisdom tooth, this nerve may be injured due to direct contact with instruments or indirect pressure through the tooth. This may result in numbness of the lip that persists beyond the effective duration of the local anesthetic. It is not 100% devoid of sensation, but a lower level of sensitivity. In the healing process, there may be some pins and needles sensation on the lip as well. In most cases, this numbness is temporary but in a few rare cases, it could be permanent. Fortunately, because this nerve runs within a canal in the jaw bone, its path can be visualized on radiographs. Taking the appropriate x-rays will enable us to assess the risk level and help in avoiding the nerve during surgery.

The second nerve is the lingual nerve (LN). This nerve runs in the soft tissue along the lower jaw and the under the tongue, providing sensation to the tongue. Injury to this nerve can occur during wisdom tooth surgery, resulting in numbness of the tongue on the same side. Most cases do recover but the incidence of full recovery is lower than that of the IDN. Unlike the IDN, the LN is not housed within bone and as such cannot be visualized on radiographs.

Injury to adjacent tooth

Removal of an impacted wisdom tooth that is tightly impacted against the adjacent tooth may result in injury to the latter because of either the drill used to remove bone to relieve the impaction, or the force of the instrument used to elevate the tooth out. In some cases, the adjacent tooth may have already been loosened due to lost of bone support due to the impacted wisdom tooth. Removal of the wisdom tooth may result in further loosening of the adjacent tooth. In the worst case scenario, the adjacent tooth may have to be extracted as well.

Bleeding

As with any surgery, post-operative bleeding is an accepted complication. This can be due to disturbance to the blood clot caused by excessive mouth rinsing and toothbrushing in the first 48 hours post-op. Late bleeding, e.g. one or two weeks after the surgery is usually due to infection of the wound.

Jaw fracture

It is uncommon for wisdom tooth surgery to cause fracture of the jaw but this can happen when the tooth is deeply embedded in an older patient. The bone structure of an older patient is denser and more brittle. The higher density of the bone requires use of greater force which once exceeded the strength of the bone, may cause a fracture.

Dry socket

An extraction socket required bleeding to start the healing process. In some cases, the socket has minimal bleeding after extraction. This can result in inflammation of the bone in the socket which can be very painful. Unlike an infection, there is no swelling or abscess.

Infection

Oral wounds are impossible to completely isolate as we can have to continue to eat, drink and talk after surgery. Sometimes, the wound may get infected. This typically happens about a week post-operatively, as the bacteria need some time to grow. As such, when is pain and swelling recur after subsiding for a few days, it is an indication that infection may have set it. The wound may need to be re-opened for drainage of pus. Antibiotics will be needed to help the body combat the infection.

Retained fragments

One of the characteristics of wisdom teeth is that they have no fixed anatomy. Some have single conical roots while others may have multiple divergent roots. As such, sometimes, a part of the root may break and be left inside. Decision to remove the root or to leave it alone depends on the proximity of the root to vital structures. For example, if the retained root is not infected but is very close to a nerve or the sinus, leaving it behind is usually the treatment of choice as removing it may cause more damage. Most un-infected retained roots do no harm but occasionally, some may become infected later and need removal.

TMJ pain

Removal of wisdom teeth requires the patient to open his mouth wide for the duration of surgery. Prolonged opening may result in displacement of the jaw joint disc. Post-operatively, these patients may develop clicking or pain of the jaw joints. This is usually self-limiting though some may require an occlusal splint therapy.

Understanding the potential risks and complications will help patients weigh the risk against the benefits of having surgery. However, doing research and asking friends is of limited use. Ultimately, you still need to seek a professional opinion to help give the risk that are specific to you that personal perspective, so as to make an informed decision.