A tooth is made up of 3 layers, the enamel, dentin and pulp. When the dentin is exposed the tubules pass on the hot and cold liquids to the nerve endings which gives out a sharp and a short pain. So this is called as sensitivity. Dentin sensitivity is caused by 3 reasons, one is erosion, attrition and abrasion. Erosion is caused by wearing of the enamel on the chewing surface, abrasion is caused because of applying more pressure on the tooth surface while brushing. Erosion is exposure of the enamel surface to the chemical action by the acidic drinks like the soft drinks. So that gives sensitivity, there is another factor that is receding gums. This happens even because of wrong brushing techniques and also with age.
![](https://s2.save4k.ru/pic/LRJ6hljNnAA/maxresdefault.jpg)