Toothache when lying down and relieved when sitting up may be caused by acute pulpitis of the tooth, and the pressure in the pulp cavity changes with the change of body position, as follows.
When the tooth suffers from acute pulpitis, the pulp blood vessel dilation and congestion, increased vascular permeability, fluid exudation, tissue edema, pain symptoms. When people lie down, lying position, the head blood supply is larger, the pulp vascular blood flow increases, resulting in increased pressure in the pulp cavity, pain aggravation, when people are sitting position, the blood flow is reduced, the pressure is also reduced, the pain can be relieved.
If it is acute pulpitis, you can get root canal treatment to solve the problem of toothache completely.
There may be other reasons for the toothache when you lie down, but when you sit up, there may be other reasons, so it is recommended that you go to the hospital in time to see a doctor to clarify the cause of the toothache and receive targeted treatment as soon as possible.