Anesthesia is used to allow patients to feel comfortable during dental procedures such as fillings, root canals and oral surgery.

There are two major forms of anesthesia: local anesthesia and general anesthesia. Local anesthesia is used far more frequently in dental procedures than general anesthesia.

Local anesthesia numbs the portion of the mouth where the dentist will be working. The dentist typically uses a needle to inject the anesthetic into the gum or inner cheek to block nerve endings and numb mouth tissues.

Examples of local anesthetics include lidocaine, prilocaine, mepivacaine and bupivacaine. In addition to the anesthetic, the solution that is injected includes other substances, such as:

• Vasoconstrictor. Narrows blood vessels, making the anesthetic’s effect last longer.
  
  
• Antioxidant. Prevents the breakdown of the vasoconstrictor.
  
  
• Sodium hydroxide. Adjusts the acidity of the solution to keep it working properly.
  
  
• Sodium chloride. Helps the solution enter the bloodstream.

Local anesthesia may be injected as either a block injection (which numbs an entire region of the mouth) or infiltration injection (which numbs a smaller area). Researchers are also investigating a more precise form of local anesthesia that only affects a single tooth. The numbing effect of local anesthetics lasts for between one and several hours.

Topical anesthetics are another form of local anesthetic. These medicines are applied as ointments, gels, sprays or adhesive patches to skin or mucous membranes. Some topical anesthetics come in flavors, such as cherry and bubble gum. They numb the area to which they are applied. Dentists may use topical anesthetics to numb an area before inserting a needle into the area for a local anesthetic.

Topical anesthetics typically are made up of the same solutions used for local anesthetics. However, the dose of the topical may be stronger, because less of the anesthetic infiltrates the tissue when given topically. A topical may numb the nerves down to 2 to 3 millimeters (about 1/10 inch) below the surface for 15 to 30 minutes.

General anesthesia puts patients to sleep so they are unconscious during the procedure. Under general anesthesia, patients do not feel any pain. Medications used as part of general anesthesia include benzodiazepines, barbiturates, opioid analgesics and neuromuscular blocking agents.

When general anesthesia is used, it will be provided by someone with expertise in delivering the anesthesia, monitoring the patient and responding to any complications. Such experts include anesthesiologists, dental anesthesiologists and oral surgeons.

Patients who receive anesthetics during dental procedures should feel very little or no pain or discomfort. Patients who feel the anesthetic wearing off or who feel it is not working should notify their dentist immediately. In many cases, a dentist will arrange a signal with a patient before the procedure to serve as an alert in case of pain. For example, patients may be asked to raise a finger or hand if they experience discomfort.

Researchers are investigating new anesthetic processes for dental treatments. A new method called electronic anesthesia delivers electrical impulses through electrodes as a means of blocking pain. This technique allows patients to avoid needles completely. Another new technique involves injecting anesthetic directly into the jawbone. Known as an intraosseous injection, it can help to numb teeth directly. It takes less time to take effect and patients experience no pain with less numbness. Intraosseous injection can be used for any dental procedure, including fillings and root canals. There is also a new device that allows a very controlled, slow delivery of local anesthetic as the needle is advanced. This results in a pain free injection.

In addition to anesthesia, other forms of sedation may be used to help calm patients during dental procedures. These include conscious sedation, nitrous oxide and others.