The “sixth-aged teeth”, scientifically known as the first permanent molars, are the teeth that erupt in the distal middle part of the second molar at the age of about six. The eruption of the “sixth age teeth” increases the chewing area of the children’s dentition, maintains the occlusal relationship between the upper and lower jaws and the height of the lower third of the face, while the force generated during chewing can also stimulate the growth and development of the jaw bone. The chewing power of “six-year-old teeth” decreases after the caries, which is not good for food chewing and nutrition digestion and absorption, and also affects the development of jaw bone. If the tooth is lost in advance due to caries, it may cause the ectopic eruption of other teeth and cause the disorder of bite. Therefore, it is very important to protect the “sixth age teeth”. The “six-year-old teeth” erupt early and there are many sockets and gaps on the occlusal surface when they first erupt, which is the weak link of calcification in the process of tooth development, and because of the poor awareness and ability of children to maintain oral hygiene, the occlusal surface of the “six-year-old teeth” becomes the site of caries. The occlusal surface of the “sixth age teeth” becomes the site of caries. Children suffering from dental caries often refuse dental treatment because of the fear of pain, therefore, it is especially important to prevent the occurrence of dental caries. The World Health Organization recommends a method to protect the newborn permanent teeth to the children all over the world – the method of sulcus sealant: that is, the sulcus sealant made of polymeric synthetic material is coated on the acid-etch treated sulcus, using its viscosity and permeability to quickly solidify into a film to close up the sulcus prone to caries, which is equivalent to covering the teeth with a protective shield to prevent sulcus caries by isolating the external erosion. This method is easy to operate, without any pain, and if it does not fall off, its effect of caries prevention reaches more than 90%, and this new method of protecting teeth is also recommended by our dental prevention organization.