My teeth hurt when they touch cold water

If your teeth hurt when they come into contact with cold water, this is most likely a symptom caused by tooth sensitivity. Tooth allergy has a relatively large impact on patients. After all, teeth are often in contact with various foods. If teeth are allergic, the patient's diet will be greatly restricted. There are many causes of tooth sensitivity. Here we will introduce to you the common causes of tooth sensitivity!

1. Neurological theory

It is believed that there are pulp nerve endings in the dentin, so sensation can be transmitted from the surface of the dentin to the pulp. However, there is no consensus on morphological and functional observations. Many scholars believe that only a part of the unmyelinated nerves in the odontoblast layer of the dental pulp enters the pre-dentin and the inner layer of the dentin, and no nerve structure is found in the outer 2/3. Many experimental results also do not support the view that "the nerves' responses to various stimuli are direct." Potassium chloride, histamine, acetylcholine, etc. do not cause pain when acting on superficial dentin; local anesthetics acting on the dentin surface cannot reduce the sensitivity of dentin.

2. Dentin fiber conduction theory

It is believed that the protoplasmic processes of odontoblasts contain acetylcholine, which can cause nerve conduction and produce pain after stimulation. Opponents believe that experimental interference with human odontoblasts did not reduce dentin sensitivity, indicating that odontoblasts do not have the characteristics of sensory organs and may only play a passive role in dentin hypersensitivity.

3. Fluid kinetic theory

It is believed that the pain caused by air, hypertonic solution or temperature stimulation is because these stimuli cause the fluid in the dentinal tubules to move, mechanically stirring the contents of the pulp, and then indirectly exciting the free nerve endings therein, transmitting impulses and producing pain. The energy accompanying the movement of the fluid can be converted into electrical signals by the receptors in the dental pulp. Approximately 25% of the volume of dentin is occupied by free fluid, which is similar in composition and properties to other body fluids and communicates with the pulp tissue fluid. Dentinal tubules are capillaries with a diameter of 0.8 to 2.5 μm; therefore, the effects of fluid dynamics depend on the permeability of dentinal tubules or the condition of the dentin surface. Stimuli that cause dentin fluid to move outward include air drying, hypertonic solutions and cold stimulation. Stimuli that cause dentin fluid to move inward include mechanical stimulation or heating. Dentin exposure is very sensitive in the early stage, and the sensitivity is naturally relieved later due to the deposition of minerals in the dentinal tubules or the formation of reparative dentin by the pulp.