Local anesthesia is commonly used in dentistry to ensure comfort during procedures. This technique temporarily blocks sensations in a specific area of your mouth, making treatments manageable and free from discomfort.
How Dental Numbing Works
Dental local anesthetics temporarily block nerve signals, preventing pain messages from reaching the brain. These agents work by reversibly binding to and inhibiting voltage-gated sodium channels on nerve cell membranes. This prevents sodium ions from flowing into the neuron, which is necessary for transmitting pain. Common active ingredients include Lidocaine, Articaine, Mepivacaine, and Bupivacaine, all of which typically end with “-caine.” The anesthetic solution is injected close to targeted nerves, diffusing through tissues to temporarily interrupt their ability to carry messages.
Nerves Numbed in the Upper Jaw
In the upper jaw (maxilla), specific nerves are targeted for numbing due to the bone’s porous nature, which allows anesthetic to diffuse easily. The Posterior Superior Alveolar (PSA) nerve numbs the maxillary molars, excluding the mesiobuccal root of the first molar in some cases. This block also affects the surrounding cheek-side gum tissue.
For the premolars and the mesiobuccal root of the first molar, the Middle Superior Alveolar (MSA) nerve may be targeted, along with associated buccal gum tissue. The Anterior Superior Alveolar (ASA) nerve block provides numbness to the incisors and canine teeth, as well as the labial (lip-side) gums in that region. For numbing the palatal (roof of the mouth) tissue, the Greater Palatine nerve is targeted for the posterior palate, and the Nasopalatine nerve for the anterior palate behind the front teeth.
Nerves Numbed in the Lower Jaw
Numbing the lower jaw (mandible) often requires a nerve block due to its denser, less porous outer bone layer. The Inferior Alveolar Nerve (IAN) block is the most common technique for the lower jaw, numbing all lower teeth on one side, including molars, premolars, canines, and incisors. This block also affects the tongue-side gum tissue, the lower lip, and the chin on the same side.
The Lingual Nerve, which runs close to the IAN, is often numbed during an IAN block, providing anesthesia to the tongue and lingual gum tissue on that side. For the buccal (cheek-side) gum tissue of the lower molars, a separate Buccal Nerve block may be administered. The Mental and Incisive Nerves, terminal branches of the IAN, provide sensation to the lower anterior teeth, chin, and lower lip.
Numbing for Common Dental Procedures
The choice of nerve block depends on the dental procedure and the area requiring treatment. For instance, a filling on a lower molar requires an Inferior Alveolar Nerve (IAN) block. This comprehensive block often includes the Lingual nerve, providing anesthesia for the tongue and inner gum tissue.
When an upper front tooth requires a filling or a crown, an Anterior Superior Alveolar (ASA) nerve block is used to numb the incisors and canines, along with the adjacent gum tissue. For extractions of upper back teeth, a Posterior Superior Alveolar (PSA) nerve block is administered to anesthetize the molars and their buccal gums. Procedures like root canals on lower teeth also rely on the profound numbness provided by an IAN block.
Deep cleanings, particularly for gum disease, may involve various infiltration injections or nerve blocks, depending on the specific areas of the gums that need treatment.
What to Expect During and After Numbing
When receiving a dental injection, you may feel a slight pinch as the needle enters, followed by a sensation of pressure or stinging as the anesthetic solution is delivered. Dentists often apply a topical numbing gel beforehand to minimize discomfort at the injection site. The numbing sensation begins within a few minutes, described as a tingling or heaviness in the affected area.
The duration of dental numbing ranges from one to three hours for soft tissues. For more extensive procedures or when using longer-acting anesthetics like Bupivacaine, numbness can last from four to eight hours or even longer.
As the anesthetic wears off, you will gradually regain sensation, sometimes accompanied by tingling, itching, or a “pins and needles” feeling. It is advisable to avoid eating or drinking hot beverages until full sensation returns to prevent accidental biting of the numb cheek or lip, especially for children.