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Why Is There Still Cold and Hot Stimulus Pain After Root Canal Treatment

Why Is There Still Cold and Hot Stimulus Pain After Root Canal Treatment

Ⅰ. Causes of hot and cold stimulus pain after root canal treatment


Tooth tissue is composed of tooth enamel, dentin, cementum and dental pulp. Studies on the nerve distribution of dentin have shown that there are nerve distributions in the early dentin, mineralized dentin and dentin tubules. Dentin has a positive effect on irritation, the only sensation produced is pain. The fluid dynamics of the transmission mechanism of dentin pain is that there is liquid in the dentin tubules, and the liquid flows from the outside to the inside during cold stimulation; the liquid flows from the inside to the outside during thermal stimulation, and the flow of liquid causes dentin cells relax or contract, thereby affecting peripheral nerve endings.


Regarding the nerves of the dental pulp, most of them are myelinated nerves, which conduct pain. The nerve axons from the parietal nerve layer in the dental pulp can be distributed in the dentin tubules at the pulp and dentin boundary. In addition, from the persepective of anatomical structure, there are lateral accessory root canals in the root canal system, and it is difficult to remove them completely during root canal treatment.


Ⅱ. A series of pains caused by pressure changes after root canal treatment


During clinical root filling, if the filling is empty, air will remain in the root canal, and the filling of the pulp cavity will form a closed space in the root canal. When the external heat and cold stimulation acts on the tooth, the dentin tubules will be caused by thermal expansion and contraction. And pressure changes in the root canal. These pressure changes can cause a series of pain. In summary, there are the following points:


1. The pressure changes in the root canal act on the collateral root canal and the pulp tissue at the anatomical apical foramen, causing pain.


2. The pressure change in the root canal acts on the inner wall of the root canal, which puts pressure on the dentin tubules, changes the flow of liquid in the tubules, and causes pain.


3. The pressure change in the root canal acts on the root tip area, and the inflammation in the root tip area is not completely eliminated, causing pain.


4. Cold and heat stimulation directly acts on the hard tissues of the tooth. Due to the principle of thermal expansion and contraction, the internal pressure of the dentin tubules is changed so that the fluid in the tubules flows, causing pain.


The above are reasons why there is pain after root canal treatment.

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