Numbness persisting in the lower lip and chin after wisdom teeth removal is a recognized, though uncommon, complication known medically as paresthesia. Paresthesia is an altered sensation that can manifest as numbness, tingling, or a “pins and needles” feeling. While initial numbness is caused by the local anesthetic, any numbness lasting beyond the first 24 hours suggests a sensory nerve has been affected.
Identifying the Inferior Alveolar Nerve
The cause of this sensory change is the proximity of the lower wisdom teeth to the Inferior Alveolar Nerve (IAN). The IAN is a branch of the trigeminal nerve, the main sensory pathway for the face. It conveys sensations like pain, temperature, and pressure from the lower teeth, gums, chin, and lower lip.
The IAN runs through the lower jawbone (mandible) in a bony channel called the mandibular canal. The roots of the lower wisdom teeth are often positioned directly next to, or sometimes wrapped around, this canal. The incidence of IAN injury during lower wisdom tooth extraction is estimated to be between 0.4% and 8.4%.
Injury occurs when the nerve is physically disturbed during the extraction process. This disturbance can involve stretching the nerve while manipulating the tooth, compression by a surgical instrument, or trauma from instruments used to cut the bone. The risk increases significantly when the wisdom tooth roots are deeply embedded, have complex shapes, or visibly overlap the nerve canal on pre-operative imaging.
Understanding the Degrees of Nerve Injury and Recovery
The duration and extent of numbness depend on the severity of the nerve damage, which is categorized into three main types. The mildest and most common form is neuropraxia, similar to a nerve concussion. In neuropraxia, the physical structure of the nerve remains intact, but signal transmission is temporarily blocked.
Recovery from neuropraxia is typically spontaneous and fast, with sensation returning within days to a few weeks. A more moderate injury is axonotmesis, where the internal fibers (axons) are damaged, but the protective outer sheath remains preserved. Since the outer sheath guides regeneration, recovery can take several weeks to many months, as the nerve regenerates slowly.
The most severe injury is neurotmesis, which involves the complete severance or significant disruption of the entire nerve structure. This rare injury has a low chance of spontaneous, complete recovery. Neurotmesis often requires surgical intervention to restore function.
Monitoring Symptoms and Next Steps
If persistent numbness is noticed beyond the initial post-operative day, immediately contact the oral surgeon’s office. This prompt communication allows the surgeon to document the altered sensation and begin a structured monitoring protocol. The surgeon will conduct simple sensory tests, such as checking the ability to distinguish sharp versus dull touch, and mapping the exact area of altered sensation.
As the nerve heals, the numbness may change into other sensations, such as tingling, crawling, or burning. This phase of altered sensation is called dysesthesia and is a positive sign that nerve pathways are attempting to re-establish connection. Patients should actively track these changes, noting if the numb area is shrinking or if the intensity of the feeling is evolving.
If the numbness remains unchanged after one to two months, it is considered persistent and warrants further investigation. The surgeon may recommend specialized diagnostic tools, such as quantitative sensory testing, to precisely measure nerve function. Initial treatments for persistent cases include anti-inflammatory medications to reduce swelling or nerve-specific medications, like gabapentin, to manage unusual pain signals.
Sensory re-education, which involves gently stimulating the affected area with different textures, can be recommended to encourage the brain to relearn normal sensation. If numbness persists for many months without change, the surgeon may refer the patient to a microsurgeon for consideration of nerve repair. Early intervention is important, as the chances of successful functional recovery decrease the longer the nerve remains unrepaired.