Local Anesthetic

 Local Anesthetic is a wonderful thing.  I can't imagine doing dentistry with out it.  Interesting to note that Lidocaine was first synthesized in l943 and used in minor dental surgery. 

Now let's take a little deeper look into how local anesthetic works. I will try and simplify the process so that you can have a basic understanding you can remove a tooth or do gum surgery with out feeling any type of sharp pain.  

First you have to understand how we can feel pain.  Pain is felt when a stimulus is initiated at the site of injury.  Let's use the example of your finger getting slammed by a car door when your little sister is not paying attention.  At the speed of light the nerve will conduct an impulse that will tract from the site of injury up to the brain where it will then communicate with all the other organs and tissues.  This will allow the body to protect itself from repeating the injury.  The network of nerves tracts throughout the whole body.  Now if you were to cut the communication flow from the site of injury where that impulse would not be able to make it back to the brain your body would not feel that pain.  And that's how local anesthetic works.  The brain does not get the intel that one of its members is in danger.  

The miracle of local anesthetic is that it is able to be injected into the soft tissue and through diffusion it is able to go into the nerve cell and block that pain impulse.  I can remember when I was little my family lived in Upstate New York.  There were many bridges called "draw bridges" that would allow boats to pass under the bridge.  The bridge would either be raised up high enough to allow the boat to pass or the bridge would split in the middle and raise up high in the sky.  This would allow the boats to pass but it would stop the flow of traffic for cars trying to pass over the bridge.  Local anesthetic also serves the same purpose.  It temporarily stops the flow of traffic to the brain.  After a few hours the effectiveness of the local anesthetic wears off and the impulse of the nerve is then allowed to flow again.  

There are times however when a patient comes in to see the dentist and for some reason the patient is having a hard time getting numb.  There are few reasons why this would happen.  Let me list a few:

1.  The local anesthetic is placed too far from the nerve

2.  There is something blocking the anesthetic (like bone)

3.  There is an infection in the area.  This enables the local anesthetic from being able to to enter the nerve

In order to administer local anesthetic successfully the dentist must have a knowledge of soft tissue, bone, and nerve anatomy as well as being able to reassure the patient everything will be ok.