Local anesthesia is commonly used in dentistry for procedures like fillings, extractions, or root canals. It temporarily blocks nerve signals in a specific area of your mouth, preventing pain. Understanding how long numbness lasts and how the body processes the anesthetic are common questions. Dentists use various types, including lidocaine, articaine, and bupivacaine, each with distinct properties.
How Long Will You Feel Numb?
The duration of numbness after dental anesthesia varies depending on the specific anesthetic and amount administered. Lidocaine typically causes tooth numbness for 1 to 2 hours, with soft tissue numbness lasting 3 to 5 hours. Articaine provides a similar duration, often 2 to 3 hours for routine procedures. For longer-lasting effects, bupivacaine might be used, providing numbness for 4 to 9 hours, and sometimes up to 12 hours for soft tissues.
The injection location also influences numbness duration. Anesthesia in the lower jaw, particularly for mandibular teeth, often lasts longer than in the upper jaw due to greater bone density, which can hinder anesthetic diffusion. Even after numbness fades, anesthetic molecules may still be present in your body at lower concentrations as they are gradually cleared.
The Body’s Process of Eliminating Anesthesia
After a dental procedure, your body breaks down and removes the anesthetic. Most dental local anesthetics, such as lidocaine, articaine, and bupivacaine, are amides. Amide-type anesthetics are primarily metabolized in the liver by specific enzyme systems. Articaine is unique among amides; about 90% is rapidly metabolized in blood plasma by plasma esterases, with only a small portion processed by the liver.
Once metabolized, the breakdown products and any remaining drug are filtered out, mainly through the kidneys and excreted in urine. A drug’s “half-life” refers to the time it takes for half of it to be eliminated from your system. Lidocaine has a half-life of approximately 1.5 to 2 hours, while articaine’s is about 20 minutes. Complete clearance typically takes several half-lives, meaning the anesthetic is present at declining levels even after numbness fades.
Why Anesthesia Duration Varies
Several factors contribute to the varying duration of dental anesthesia. The specific anesthetic type plays a significant role, as different drugs have distinct durations of action and metabolism rates. Dosage also matters; higher doses typically lead to longer numbness. An individual’s metabolism is another factor; faster metabolic rates may cause numbness to subside sooner.
A vasoconstrictor, such as epinephrine, is often included in the anesthetic solution to prolong its effect. Epinephrine constricts blood vessels in the area, slowing anesthetic absorption into the bloodstream, thereby keeping it localized longer and extending numbness duration. Without a vasoconstrictor, anesthetics wear off more quickly. Other influences include the injection site’s vascularity, with more vascular areas absorbing the drug faster, and patient factors like age, weight, and liver and kidney function, which affect how efficiently the body processes and eliminates the drug.
After the Numbness Fades
Once numbness from dental anesthesia begins to wear off, you might notice sensations as feeling returns to the treated area. Tenderness or soreness at the injection site is typical for a few days following the procedure. Your jaw muscles might also feel stiff or sore, especially if your mouth was open for an extended period during dental work.
To manage discomfort, over-the-counter pain relievers can be used. It is advisable to wait until numbness has completely disappeared before eating or drinking, especially hot foods or beverages, to prevent accidental biting of your cheek, lip, or tongue, or inadvertent burns. Gentle activities like walking or light jaw movements can help increase blood flow, potentially aiding in numbness resolution. If you experience prolonged numbness, tingling, or unusual sensations that persist, contact your dentist for evaluation.