A tooth extraction can cause nerve damage, a complication known as paresthesia or neuropathy. Although infrequent, this is a documented risk associated with dental surgery, especially when removing teeth close to major sensory nerves in the lower jaw. Nerve injury can result in an altered or lost sensation in the face, lips, or tongue. Paresthesia refers to an abnormal sensation that persists beyond the expected recovery time of the anesthetic.
The Specific Nerves at Risk
The anatomical location of the lower teeth places two specific nerves at the greatest risk of injury during extraction, particularly for lower wisdom teeth or molars. These nerves are branches of the trigeminal nerve, which transmits sensory information from the face and mouth to the brain. Their proximity to the surgical site makes them vulnerable to trauma.
The Inferior Alveolar Nerve (IAN) is a primary concern. It runs through a bony tunnel within the lower jaw, called the mandibular canal, providing sensation to the lower teeth, lip, and chin. If a tooth’s roots are positioned near the IAN canal, the extraction process can bruise or stretch the nerve fibers.
The Lingual Nerve (LN) runs near the inner surface of the jawbone, often close to the third molar region. This nerve is responsible for general sensation and taste perception for the front two-thirds of the tongue. Because the LN travels in soft tissue, it is susceptible to injury from surgical instruments or manipulation of the gum flap.
The relationship between the IAN, LN, and the roots of the third molars determines the specific risk level for the patient. Modern imaging, such as Cone-Beam Computed Tomography (CBCT), is often used to map nerve pathways before complicated extractions to minimize contact.
Mechanisms Leading to Nerve Injury
Nerve injury during extraction results from mechanical and chemical processes around the surgical site. Mechanisms include direct physical trauma, compression, or effects related to the anesthetic. These factors can cause varying degrees of damage, from temporary disruption to a complete tear.
Direct trauma occurs when surgical instruments, such as drills or forceps, inadvertently contact the nerve tissue. This is common when removing bone around an impacted tooth or sectioning the tooth. Instruments can cause bruising, stretching, or laceration of the nerve fibers.
Compression injuries often result from the force applied during removal. The nerve may be squeezed between the tooth root and the bone. Post-procedure damage can occur if swelling (edema) or a hematoma (collection of blood) forms and exerts pressure on the nerve bundle. Even retracting the soft tissue flap to access the tooth can cause a stretching injury to the lingual nerve.
Chemical or anesthetic injury is less frequent than mechanical trauma. Damage can happen if the local anesthetic needle penetrates the nerve sheath, or if the solution causes neurotoxicity. High concentrations of certain anesthetic agents have been associated with this complication.
Recognizing the Signs of Damage
Symptoms of nerve damage are sensory and involve altered feeling in the areas supplied by the affected nerve. The primary indicator of injury is the persistence of these sensations beyond the expected recovery time of the local anesthetic. Patients should monitor their sensations closely following the procedure.
One common sign is paresthesia, an abnormal sensation like tingling or “pins and needles.” This indicates the nerve is irritated but still transmitting signals. Paresthesia is often felt in the lower lip and chin (IAN affected) or the tongue (LN affected).
A more concerning sign is anesthesia, the complete loss of sensation or numbness in the affected area. If a patient cannot feel touch or temperature in their lower lip, chin, or tongue, it indicates a significant disruption of nerve function. Loss of tongue sensation can also impair taste perception.
A distinct and painful symptom is dysesthesia, described as an unpleasant abnormal sensation, such as burning, shooting, or an electric shock feeling. This nerve pain can severely impact daily activities and suggests a more complex injury. If any altered sensations persist for more than 24 to 48 hours, immediate follow-up with the surgeon is warranted.
Recovery and Treatment Options
The prognosis for nerve injuries is generally favorable, as most cases involve temporary damage that resolves spontaneously. The mildest form, known as neuropraxia, is a temporary block of nerve conduction without structural damage and often heals quickly. Recovery for temporary injuries typically occurs within a few weeks to several months as the nerve repairs itself.
Initial management is conservative and involves close monitoring. The surgeon may recommend anti-inflammatory medications, such as ibuprofen, to reduce swelling and alleviate pressure on the nerve. For nerve discomfort, medications targeting neuropathic pain, such as certain antidepressants or antiepileptics, may be prescribed.
If altered sensation persists beyond six to eight weeks, a specialist referral to an oral and maxillofacial surgeon or neurologist is recommended. If symptoms last six months or longer, the likelihood of spontaneous, complete recovery diminishes, and the damage may be considered long-lasting or permanent. Persistent symptoms require a thorough neurosensory examination to determine injury severity.
For the most severe injuries, such as a completely severed nerve or failure to recover after an extended period, surgical intervention may be considered. Microsurgery to repair or graft the nerve is a specialized option, usually reserved for cases showing no improvement after nine months. The decision to pursue surgery depends on the exact nature and location of the damage.