My aim is to answer some common questions about the numbing process at the dentist. Nobody likes it, including the dentist, but we are grateful for it.

First, even though many call it novocaine, nobody uses novocaine as a local anesthetic any longer. Many people were actually allergic to it. Most dentists in the USA use either lidocaine or articaine. Very few people are allergic to these anesthetics and they work better. Recently the Journal of American Dental Association (May 2011) published a paper that showed that articaine is almost 4 times more likely to make you numb than lidocaine. If you are a patient that has had difficulty getting numb, ask your dentist to use articaine. It will likely be more effective. 

Anesthetic does not always work. If your tooth is infected, the anesthetic is less likely to work. An infected tooth nerve is harder to numb. There are techniques to get a tooth like this numb, but it usually involves multiple injections. If it seems like your dentist, is giving a lot of injections, it is because he wants you to be comfortable and realizes this tooth may need a little (or a lot) extra.

Most local anesthetics are mixed with adrenaline or epinephrine. This substance makes the anesthetic last longer. It can also make your heart race. Some patients have had this reaction. It is usually prevented by being careful to not inject the anesthetic into a blood vessel. Even being careful it can still sometimes happen. If it does the heart racing usually lasts for about a minute. If you have heart problems, your dentist may use a local anesthetic that does not contain epinephrine, but you may need multiple injections as the anesthetic without epinephrine does not last very long.

We’re often asked how long the numb feeling will last. With most anesthetics, the tooth will be numb for 1-2 hours your lips and tongue will be numb for 3-5 hours from the time of injection. The numb feeling goes away as the blood flow carries it away from the injection site to be broken down or metabolized. Taking a walk or being active, assuming your dentist says it’s ok, will make the anesthetic effects go away more quickly. You may also ask your dentist to use Oraverse. It is injected after the procedure is completed and reverses the effects of the anesthetic. It will make the numbing go away twice as fast. It does cost $25-75 dollars to administer, and dental insurance does not pay for it.

Even though nobody likes it, thank goodness for local anesthetics.