Tooth decay is known as dental caries in medicine, which can be caused by oral environment, dietary factors, and the host’s own factors, etc. It is recommended to consult a doctor in time. 1. Oral environment: There are many kinds of bacteria in the human mouth, which are normally in a balanced state. However, if infections and poor oral environment occur, the balance may be out of balance, leading to the proliferation of a certain kind of bacteria, which triggers plaque and induces the emergence of dental caries. 2. Dietary factors: For people who often eat sweets and have poor oral cleaning, the bacteria in their mouths can break down the residual sugar to produce a large amount of lactic acid, leading to tooth damage and thus triggering dental caries. 3. Host’s own factors: Different patients have different dental morphology, structure, tooth arrangement, antibacterial and buffer components, so the degree of susceptibility to caries is not the same. Patients with dental caries should seek medical treatment in time, and carry out appropriate treatment under the guidance of doctors, avoiding blind judgment on their own, so as to avoid delaying the condition.