“The best method to prevent caries and reduce the rate of caries in the sixth age teeth is sulcus closure.” The so-called “sulcus closure” refers to an effective caries prevention method by applying a layer of adhesive resin on the occlusal surface of teeth to protect the enamel from the erosion of bacteria and metabolic products and to enhance the caries resistance of teeth. When the sulcus on the tooth surface is closed, the nutrient source of the bacteria originally existing in the sulcus is cut off, which plays the role of preventing the occurrence of caries on the one hand, and on the other hand, the sulcus closure can also prevent the development of the existing early caries, so it is used for treatment before the early caries becomes a cavity. Vulval closure plays a very important role in providing effective and high quality caries prevention measures. Therefore, as long as the sealant is retained intact, the desired caries prevention effect can be achieved.