Caries is a common disease, to protect your teeth we need to start from childhood, at present, one of the best methods to prevent caries is: Vulcanization. It is painless for children to have their teeth closed. Therefore, its acceptability is much greater than the dental treatment after the caries. The cost is also not high and it is a good method to prevent caries. The occlusal surface of the grinding teeth is the frequent site of caries. The occlusal surface of the newly grown teeth is uneven, and there are many grooves and sockets on these surfaces, which are deep and easy to accumulate caries-causing bacteria, thus causing the occurrence of caries. The sulcus closure is an effective method to prevent the occurrence of caries by removing the tooth tissue and applying a layer of bonding resin on the point gap and fissure of the tooth surface to protect the tooth enamel from the erosion of bacteria and metabolites. When the sulcus of the tooth surface is closed, the cariogenic environment of the oral cavity is isolated, and the source of nutrition of the bacteria existing in the sulcus is cut off, so that the occurrence and development of caries can be stopped. Molar teeth with deep sockets are suitable for early sulcus closure, and some children with other teeth caries or tendency to caries are also suitable for sulcus closure. The most suitable time for closure is from 3 to 4 years old for milk molar, from 6 to 7 years old for the first permanent molar and from 12 to 13 years old for the second permanent molar. The age of fissure closure can be extended from 7-8 years old to 20 years old, and even to adults according to the situation. The caries prevention effect of fossa closure is certain, as long as the sealant coating is kept intact, it can prevent caries adequately. Although it is very effective, it is not necessary for everyone to have it, and it is not necessary if the teeth are well developed. It should be clear that the so-called significant reduction of the occurrence of caries is within the scope of a certain group of people, it does not mean that your child will not get caries if he/she has had a gutter closure. If your child can cooperate well with the doctor, you can have the molar teeth sealed now. If not, wait until the first permanent molars (sixth age teeth) are closed at the age of 7 years.