It is a good habit to look at the mirror when brushing your teeth, not only to see if all your teeth are brushed against it, but also to find some problems. I believe that some people will inadvertently find black spots on their teeth, and they do not feel pain, what is going on? 1, pigmentation One kind is pigmentation, such as tobacco stains, tea stains, coffee stains, etc., which is difficult to brush off and can be removed by teeth cleaning. 2, tooth decay Another kind of tooth decay is deep or shallow, from the outside it looks like a black spot, usually located in the sulcus point gap (dotted or linear depression on the tooth surface). The culprit of tooth decay is certain bacteria in the mouth, but it takes time for them to destroy the tooth, from the initial discoloration to the final formation of cavity, usually takes 1.5 to 2 years. During this time, it is entirely possible to nip decay in the bud by paying more attention to our own teeth. Once the small black spots on the teeth are confirmed to be cavities, they should be repaired as soon as possible to stop the progression of the lesions. If we let it continue to develop, it will become obvious cavity, then the patient will be sensitive to the stimulation of food such as cold, hot, sour and sweet; when the damage further reaches the pulp (i.e. “dental nerve”), it will be painful and seriously affect the daily life. Clinically, we see many people wait until the toothache is unbearable before they go to the hospital. At this time, usually can not rely on simple fillings to solve the problem, may also have to do root canal treatment or even extraction of the affected teeth, denture repair, time-consuming and costly, people also suffer, can be called “small hole is not filled, big hole to eat suffering”. Normally, you should pay attention to self-examination, observe the changes of tooth color, shape and texture, and go to the specialist hospital regularly for comprehensive oral examination, if there is caries, it should be found and treated early. After repairing the caries, using fluoride toothpaste can play a certain protective and preventive role. On the one hand, fluorine ion can form a protective layer on the surface of the teeth to help resist the erosion of acidic substances and avoid the further development of caries; on the other hand, fluorine ion can act on other teeth to fight against some potential caries dangers and play the role of promoting the remineralization of teeth to avoid the further development of cavities.