The newly erupted teeth have not yet worn down their surfaces and there are many sulcus pitting gaps. The sulcus pitting is a structural defect in the development of tooth enamel and is more common on the occlusal, buccolingual and lingual surfaces of the maxillary lateral incisors of the posterior teeth. These parts are the place to harbor all kinds of oral bacteria, and form plaque in them, food residues are also easy to stay, extremely difficult to clean, and are the parts where caries is most likely to occur. The effective method to prevent the caries of the sulcus is the sulcus closure. The mechanism of its action is to close the sulcus that has not yet been decayed at the early stage of tooth eruption, so as to play a barrier role and isolate the cariogenic factors of oral environment from the sulcus, thus preventing the occurrence of caries. The indications for the closure of sulcus are: narrow and deep sulcus with caries tendency and sulcus with early caries or suspected caries. It is appropriate to seal the milk molar at the age of 3-4 years old; the first permanent molar is closed at the age of 6-7 years old as early as possible; the bicuspid and the second permanent molar are generally not older than 12-13 years old. The first permanent molar, which is often referred to as “six-year-old teeth”, is one of the earliest permanent teeth to erupt in the oral cavity, and plays a very important role in chewing, and has a special significance in the dental row, which is called the “lock and key of occlusion”. However, when the first permanent molar is just erupted, the sulcus is deeper and the mineralization is not yet perfect, so the sensitivity to caries is higher. Because the occlusal surface is covered by the distal gingival flap and it is not easy to carry out oral hygiene at the back of the teeth, it is often decayed in the process of eruption, so parents should pay close attention to the eruption of “six-age teeth” of their children and carry out sulcus closure in time. Therefore, parents should pay close attention to the eruption of the child’s “sixth-age teeth” and carry out the gutter closure in time. The effect of gutter closure in preventing caries is remarkable, but it is only a supplement of caries prevention method, and other prevention methods should not be ignored. Avoid eating sticky food (such as chewing gum, etc.) as much as possible after sealing, and review once every six months, if the sealant falls off or caries occurs, it should be re-sealed or treated with filling in time.