The trigeminal nerve is the great nerve of the face and jaws. All the teeth are linked by branches of the same nerve. A pain may be felt in the upper jaw, when the cause is a tooth in the lower jaw. This is called a ‘referred pain’. It occurs when decay within a tooth is the source of the pain.
When pain is caused by decay that has spread to the area around a tooth, it is quite simple to locate it. An abscess is an example of this.
Careful examination by the dentist will discover which tooth is causing the problem.