Hesperian Health Guides
Where to Inject
You can deaden a nerve with an injection of local anesthetic:
- near the small nerve branch going inside the root of a tooth.
- near the main nerve trunk before it divides into small branches.
Smaller nerves branch off from the main nerve — much like branches of a tree leave its main trunk.
One small nerve then goes to each root of every tooth.
Inject an upper tooth near its roots. 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.
It is more difficult to inject the lower teeth.
The lower jaw bone is thicker. When you inject near the roots of a lower tooth, the anesthetic is not able to reach its nerve as easily.
Note: You can inject lower front teeth in young children, or very loose lower front teeth in adults, near their roots.
To make a lower tooth completely numb, you must block the main nerve (a) before it goes inside the jaw bone.
If you are treating a back tooth, you must give a second injection for nerve (b).