The eruption of third molars, commonly known as wisdom teeth, occurs in the back of the jaw. Because of their position, these molars can develop roots that lie close to major sensory nerves, creating a risk of injury during their development, impaction, or removal. While nerve damage is a serious concern, it is considered a rare complication in dental procedures, particularly in the lower jaw.
Nerves at Risk Near Wisdom Teeth
The two sensory nerves most commonly involved are the Inferior Alveolar Nerve (IAN) and the Lingual Nerve (LN), both branches of the trigeminal nerve, which handles sensation in the face. The IAN runs inside a bony channel, the mandibular canal, within the lower jawbone. This nerve is responsible for providing sensation to the lower teeth, the lower lip, and the chin.
The roots of the lower wisdom teeth frequently develop directly adjacent to, or sometimes appear to wrap around, the canal housing the IAN. This proximity makes the nerve vulnerable during surgical manipulation of the tooth or surrounding bone. The Lingual Nerve (LN) provides general sensation and taste to the front two-thirds of the tongue. It travels along the inner side of the jaw, closer to the soft tissue, placing it at risk of injury during procedures.
How Nerve Injury Occurs
Nerve injury related to wisdom teeth can happen through two primary mechanisms: direct trauma during surgery or damage from the tooth’s pathology itself. Surgical extraction is the most frequent cause of nerve injury, which can involve several forms of trauma. The nerve may be stretched, compressed, or bruised by the instruments used to remove the tooth or the surrounding bone.
Surgical trauma can also involve the partial or complete laceration of the nerve. Damage may also occur from the injection of local anesthetic if the needle directly contacts or irritates the nerve sheath, or if the solution causes a chemical injury. The risk increases with deeply impacted teeth, especially when the roots appear linked with the IAN canal on preoperative imaging.
Non-surgical causes of nerve injury relate to the wisdom tooth’s development and surrounding pathology. An impacted tooth can exert chronic pressure on a neighboring nerve, leading to dysfunction. Furthermore, an abscess or cyst around the tooth causes localized inflammation and swelling. This swelling compresses the nerve, or the infection itself can directly harm the nerve tissue.
Recognizing the Signs of Damage
Nerve damage manifests as altered sensation, collectively referred to as paresthesia. Symptoms often present immediately following a procedure, once the effects of the anesthetic have worn off. The specific area affected helps identify which nerve is involved: IAN damage typically results in changes to the sensation of the lower lip and chin.
Lingual Nerve injury affects the sensation of the tongue and may include an altered sense of taste on that side. Patients may report persistent tingling (“pins and needles”), which is paresthesia, or complete numbness (anesthesia). Sometimes, patients experience dysesthesia, a painful, burning, or electric-shock-like sensation in response to a normal stimulus. Report any persistent loss or alteration of sensation lasting more than a few hours after the procedure to the treating clinician.
The severity of the injury is classified based on the damage to the nerve fibers, which guides the prognosis. A temporary injury, where the nerve is merely bruised or compressed, is the most common and is expected to resolve completely. More significant injuries involving damage to the nerve’s internal structure can lead to longer-lasting symptoms. The most severe cases involve the partial or complete severing of the nerve, which has the lowest likelihood of full spontaneous recovery.
Recovery and Management
Fortunately, the majority of nerve injuries sustained during wisdom tooth procedures are temporary, resolving within a few weeks to several months. Recovery occurs as the nerve sheath heals and the nerve fibers regenerate. Initial management involves close observation to track sensory return and may include anti-inflammatory medications to reduce swelling around the affected nerve.
If symptoms persist beyond the expected recovery time (typically three to six months), a specialist referral is necessary. Treatment for persistent nerve damage may involve prescribing medications like B vitamins or certain anti-convulsants to manage neuropathic pain and support healing. In cases of severe sensory loss, surgical intervention, such as microsurgery to repair or graft the damaged nerve, may be considered. Intervention is generally most successful when performed within the first few months following the injury.