Caries cavities should be divided into several aspects: 1, shallow caries is not a cavity, such as shallow caries enamel caries, manifested as enamel whitening, that is to say, manifested as enamel local surface demineralization, but the structure has not been destroyed, at this time we qualify as shallow caries, at this time he will not have a cavity; 2, the further development of dental caries into caries or deep caries there will be a tissue defect, this defect causative factors include: bacteria attached to the surface of the teeth by food acid production, acid production will cause the loss of minerals on the surface of the teeth after erosion, if it is very little mineral loss, is the acid production will lead to the loss of minerals. Factors include: bacteria attached to the surface of the teeth, relying on food for acid production, acid production of acid will be corroded on the surface of the teeth, corrosion leads to mineral loss, if it is a very small loss of some minerals, is the surface of the enamel of the shallow caries, with the loss of more and more minerals, the inside of the organic matter will be destroyed, this time the formation of caries holes, if this time do not go to intervene, the more and more bacteria, more and more acidic, and keep in the surface of the enamel, the more and more caries. If you don’t intervene at this time, the bacteria will accumulate more and more, the acidity is stronger and stronger, keep in the lower acidic environment, the cavity will be bigger and bigger, once the enamel caries is destroyed, into the dentin, the whole caries progress will be accelerated. So generally enamel defects we will see a relatively small, dentin defects will have a large cavity, this is the process of caries formation. Once the caries cavity is formed, for the classification of caries, it already belongs to the range of medium caries or deep caries, which is more serious compared to caries, and you need to go to the hospital for treatment in a hurry.