1.Why do I need to close the sulcus? There are many natural micro and narrow sulci and fissures on the occlusal surface of the newly erupted premolar and molar teeth, whether they are milk teeth or permanent teeth, and because the sulci are deep and narrow, the toothbrush cannot brush the bottom of the sulci cleanly, so the sulci are prone to caries. The sulcus sealant is used by the doctor to seal and fill these sulci. Protecting the occlusal surface of premolar and molar can effectively prevent the caries of the sulcus in the long term. 2.Appropriate age for the closure of sockets: 3-4 years old for milk molars, 6-7 years old for the first permanent molars, 11-13 years old for premolars and second permanent molars. Usually the teeth reach the occlusal surface before they are suitable for sulcus closure. Usually it is done within 4 years after eruption. If the decay of the baby’s milk teeth is serious, his permanent teeth have a higher rate of caries and should be closed as soon as possible. 3.How many years can the treatment of gully closure last? According to the domestic and foreign reports: about 90% of the teeth can be kept for one year after the treatment; about 42% of the teeth can be kept intact after five years. Due to many factors, such as children with moisture, the retention time after closure is not exactly the same. Therefore, it is important to conduct regular review after the closure treatment. A review should be conducted 6 months after fossa closure treatment, and then once a year. Observe the retention of the closure. If there is dislodgement, it is necessary to re-seal. Generally, if the sealant can be maintained for 3-5 years, with the abrasion of the sulcus is no longer too deep or has been ground flat, the sulcus closure has effectively played a role in the prevention of dental caries.