Local anesthesia is a common practice in dentistry, designed to prevent pain during various dental procedures. Dentists achieve this by injecting a numbing medicine, often lidocaine, directly into the soft tissues of the mouth, such as the gums or inner cheek. This targeted approach ensures patient comfort by temporarily blocking nerve signals in a specific area. The numbing effect usually begins within minutes and can last for 30 to 60 minutes, or even several hours, depending on the anesthetic type and dosage.
Understanding Nerve Injury During Numbing
While generally safe, it is possible for a nerve injury to occur during a dental injection. Nerve damage can result from several mechanisms. Direct contact between the needle and the nerve sheath can cause trauma to the nerve fibers. The anesthetic solution itself can cause chemical irritation or neurotoxicity to the nerve. Pressure from a hematoma, a blood clot forming near the nerve after the injection, can also compress and injure the nerve.
The nerves most frequently affected by dental injections are the inferior alveolar nerve and the lingual nerve. The inferior alveolar nerve provides sensation to the lower lip, chin, and lower teeth. The lingual nerve, supplying sensation to the front two-thirds of the tongue and the floor of the mouth, is particularly vulnerable due to its anatomical path. Injuries to these nerves can lead to varied sensory deficits in the areas they supply.
Immediate Sensations During Numbing
If a dental needle contacts a nerve during an injection, a patient might experience an immediate, sharp, electric shock-like sensation. This feeling can radiate down the jaw or into the tongue, depending on which nerve is touched. This sensation is often fleeting and does not automatically indicate permanent nerve damage.
Experiencing such a shock can be alarming, but it often signifies a temporary contact with the nerve rather than lasting harm. It is important for patients to communicate this sensation to their dentist immediately during the injection. This allows the dentist to adjust the needle position if necessary, to minimize further irritation.
Recognizing Post-Injection Nerve Symptoms
After the immediate numbing effect of the anesthetic wears off, persistent or altered sensations can signal a potential nerve injury. One common symptom is prolonged numbness, known as paresthesia. This can manifest as a “pins and needles” feeling, tingling, or a burning sensation in the affected area, such as the lip, chin, tongue, or gums.
Another symptom is dysesthesia, which involves distorted or unpleasant sensations, sometimes including pain, in the area supplied by the injured nerve. Patients might also notice difficulties with speech, altered taste sensation, or inadvertent biting of the cheek or tongue due to reduced feeling. These symptoms can vary in intensity and duration and should be reported to the dentist if they persist for more than a day.
Recovery and Management of Nerve Injuries
Most nerve injuries resulting from dental injections are temporary. Approximately 85% to 94% of cases show complete recovery, typically within eight weeks. For injuries to the inferior alveolar nerve, recovery may be more likely than for the lingual nerve.
If a patient suspects a nerve injury, contacting their dentist promptly is the first step. Management often begins with observation, allowing time for the nerve to heal on its own. Medications like anti-inflammatories, such as ibuprofen, may be prescribed to manage symptoms and inflammation. In cases where symptoms persist for three months or more without improvement, referral to a specialist, such as an oral and maxillofacial surgeon or neurologist, may be considered for further evaluation. Surgical intervention is an option in rare, persistent cases, though success rates can vary.