The reason why a toothache is painless with saliva is because cold water reduces the high pressure in the pulp cavity and provides pain relief.
The phenomenon of a toothache being relieved by a mouthful of saliva is known as “hot pain relief” and is most commonly seen in acute septic pulpitis.
The reason for this phenomenon may be due to the lesion of the dental pulp, resulting in the generation of gas in the pulp cavity, the gas is heated by the expansion will cause high pressure in the pulp cavity, resulting in severe pain. At this point, cold water can cause the gas to contract, reducing the pressure and relieving the severe pain.
It should be noted that the relief of cold water on toothache is only temporary, when the local temperature is restored, it will still hurt. Therefore, it is recommended to go to the hospital in time for targeted treatment to open the pulp drainage and root canal treatment.