People often ask the question: My cavity doesn’t hurt or itch, can I just leave it alone? Is it possible for tooth decay to heal itself by brushing carefully? Just like a cold and fever, it will get better by taking medicine, and it will get better after a while without medicine. For this question, we know that any kind of disease that occurs in the human body contains two aspects. On one hand is the invasion and destruction of the disease; on the other hand is the resistance and repair of the body. It is the same with caries, while the bacteria invade, produce acid, demineralize and destroy the teeth, there is also its resistance and repair side, which is expressed as remineralization of the teeth, whether it is enamel or dentin. Remineralization means that the demineralized tooth tissue can be remineralized by the redeposition of minerals. These minerals can come from the dissolved minerals in the lesion or from saliva. Therefore, the process of caries lesion is actually a process of demineralization and remineralization alternately, and can be in a state of mutual balance to some extent. For example, the early caries of smooth surface is often restored to normal state due to better cleaning, so that the plaque cannot adhere for a long time. Although teeth have the ability of remineralization, it is relatively weak, and it can have some restoration ability only when there is only color change at the early stage of demineralization before cavity is formed; once substantial defect is produced, it is impossible to repair. This is why we have been actively promoting oral health care knowledge, making everyone aware, checking oral hygiene once every six months to a year, if early tooth demineralization problems are found, early prevention can reduce the occurrence of many cavities.