Every parent wants their child to have no caries, but in reality it is rare to find a child without a single tooth decay. Most of children’s caries are sulcus caries. The surface layer of the baby teeth and the first permanent teeth are not calcified enough, the acid resistance is poor, and the cuspid surface is not worn out yet, which makes the developmental sulcus obvious and deep, and the food residue is easily deposited on these weak parts of the tooth surface, leading to the occurrence of caries. If we can prevent the sulcus caries at an early stage, we can greatly reduce the prevalence of dental caries in children. The best way to prevent sulcus caries is to close the sulcus. The process of closing the sulcus is not complicated, firstly, clean the tooth surface, then treat the enamel around the sulcus with weak acid, wash and blow dry, then fill the sealant in the sulcus of the biting surface, after it penetrates into the sulcus, then make it harden and solidify, so as to form a solid and smooth plane in the biting surface. Without the sulcus, the caries-causing bacteria in the mouth naturally lose the breeding environment, and at the same time, the original bacteria in the sulcus die due to the lack of foreign nutrition, and cannot produce acid and cause caries, so as to stop the teeth from being damaged. The operation of the fissure closure is simple, only takes a few minutes, does not destroy the teeth, no pain, does not affect chewing and taste after filling, and is easily accepted by children. The resin is non-toxic and harmless, and does not affect the chewing function of the person, but also can adapt to the oral environment, even if the gutter sealant falls off, the resin that penetrates into the enamel has a certain protective effect on the teeth. Vulcanization is mainly applied to milk molars, permanent molars and permanent premolars. The best time to seal is when the crown is fully erupted and the caries has not yet occurred. The protection of “six-year-old teeth” is especially important. Sixth-aged teeth are permanent teeth that erupt at the end of the baby’s milk teeth at the age of 6. Because of the early eruption time and long usage time, plus the rich sulcus on the teeth, it is very easy to occur caries. Therefore, it is extremely important to protect them. The sulcus closure can also be used for the milk molars of children aged 3 to 4 years old and the second permanent molars of teenagers aged 12 to 13 years old. If you do not pay attention to oral hygiene and do not brush your teeth, the plaque will accumulate a lot and you will also get caries. After three months of the closure, it is necessary to go to the hospital for a review to see if there is any dislodgement, and if there is dislodgement, it is necessary to determine whether it needs to be done after the doctor’s examination.