Chapter 9: Injecting Inside the Mouth
It is possible to treat a tooth without pain. You do this with an injection of local anesthetic. You must inject near the nerve, so to give good injections, you must know where the nerves are.
Injecting is a skill that develops with experience. The best way to learn is not from a book, but from a person who has experience giving injections.
Local anesthetic is an injectable medicine. When it touches a nerve, the tooth joined to that nerve feels numb or dead for about an hour. This usually gives you enough time to take out a strong tooth or to put a cement filling into a deep cavity.
WHAT YOU NEED TO INJECT
There are two kinds of syringes for injecting local anesthetic inside the mouth. One is made of metal and the other is made of glass. The metal syringe uses local anesthetic in a cartridge. The glass syringe uses local anesthetic from a bottle.
Use a new needle and a new cartridge of local anesthetic for each person.
Be careful! Do not touch the needle.
Your choice of which syringe to use depends on the local anesthetic you can get. Order needles to fit your particular kind of syringe.
You can deaden a nerve with an injection of local anesthetic:
1. near the small nerve branch going inside the root of a tooth.
2. near the main nerve trunk before it divides into small branches.
Bone in the upper jaw is soft and spongy.
Local anesthetic placed near the root of an upper tooth can go inside the bone and reach its nerve easily.
The same injection also makes the gums around that side of the tooth numb.
WHEN TO INJECT
Inject local anesthetic whenever the treatment you give may hurt the person. If, after you inject, the person says the tooth still hurts, be kind. Stop and inject again.
HOW TO INJECT*
1. Do not inject local anesthetic into an area that is swollen. This can spread the infection.
Also, pus inside the swelling stops the local anesthetic from working properly.
Instead, treat the swelling first and take out the tooth later.
2. If the person has a heart problem, do not inject more than 2 times in one visit. Also, it is best not to use an anesthetic with epinephrine on persons with heart problems. Use lidocaine only, or mepivacaine 3%.
3. Before you push the needle under the skin, be sure its pointed end is facing in the correct direction.
4. Before you inject the local anesthetic, wait a moment to see if any blood enters the syringe. (Note: only an aspirating syringe will do this.)
Pull back on the plunger. If blood comes inside, it means you have poked a blood vessel.
Pull the needle part way out and gently move it over to a different place.
If you inject local anesthetic into the blood vessel, there will be more swelling afterward, and the person may faint. If the person faints:
FOR GLASS SYRINGES:
Boil the syringe and needle in water for 20 minutes in a covered pot. Although it is not as important, it is also a good practice to boil your metal syringe.
FOR METAL SYRINGES:
Inject local anesthetic near the root of the tooth you want to treat.
Front teeth have one root. Back teeth have more than one.
For a tooth to become completely numb, the local anesthetic must touch the small nerve going to each one of its roots.
1. First decide where to inject.
Lift the lip or cheek. See the line that forms when it joins the gum.
The needle enters at the line where the lip or cheek meets the gum.
2. Push the needle in, aiming at the root of the tooth. Stop when the needle hits bone. Inject about 1 ml. of local anesthetic (1/2 of a cartridge).
Pull the needle part way out and move it over to the next root. Inject again,
If the tooth is to be taken out, leave 1/4 ml. for the next step.
3. If you are taking out a tooth, also inject the gums on the inside.
4. Wait 5 minutes for the tooth to become numb.
Injecting the Lower Teeth
When you block the nerve, it affects all of the teeth as well as gums on that side. However, it takes practice to do this successfully. Ask an experienced dental worker to help you learn how to give this injection properly.
Stand in such a way that you can see clearly where you need to inject. Ask the person to open wide.
1. First feel for the place to be injected.
Put your thumb beside the last molar tooth. (Wash your hands first!) Feel the jawbone as it turns up towards the head. Rest your thumb in the depression there.
2. Press against the skin with the end of your thumb.
The skin forms a V shape. Your needle must go into the V.
Hold the syringe on top of tooth number 4 and aim the needle at the ‘v’.
Push the needle in until it hits the jawbone, (about 3/4 of the length of a long needle). Pull back on the plunger of the aspirating syringe to check for blood.
Inject 1½ ml of local anesthetic (3/4 of a cartridge).
Try to feel your way: If you hit bone too early, pull the needle part way out and move it over so that it points more toward the back of the mouth. Try again.
If you do not hit bone, the needle is too far back. Pull it part way out, and point it more toward the front. Push it in again.
3. Give a second injection BESIDE the back teeth.
If you are going to fill or remove a back tooth, inject beside that tooth, where the cheek joins the gum.
Inject 1/2 ml of local anesthetic (1/4 of a cartridge).
This injection is not needed for front teeth.
It is enough to block the main nerve.
4. Wait 5 minutes for the tooth to become numb.
AFTER YOU GIVE AN INJECTION
Before you begin treatment, test the tooth and gums to be sure that they are numb. Wait 5 minutes for the anesthetic to start working. Ask the person how his lips feel - they should feel ‘heavy’ or numb. Then test the area.
Poke the gums between the teeth with a clean probe.
Watch the person’s eyes - you will see if you are hurting. If the person still feels pain, stop. Think about your injection technique, and inject again.
After you finish treatment, always talk to the person about what you have done. Tell the person what to expect, and how to be careful with the numb area of the mouth:
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