Fossa sealing refers to the method of preventing fossa caries by applying fossa sealing material to the fossa pitting on the occlusal and buccolingual surfaces of the crowns of the teeth without damaging the dental tissues, when it flows into and penetrates the fossa it cures and hardens to form a protective barrier covering the fossa, which is capable of preventing caries-causing bacteria and acidic metabolites from attacking the dentin. Fissure sealing is a painless and non-invasive method, and the technique has been used internationally for more than 50 years. The sealing material used for fossa sealing is called fossa sealant, which is cured and tightly bonded to the fossa wall and has a certain degree of resistance to chewing pressure, which is not a hindrance to eating, and the fossa sealant is non-toxic and harmless to the human body after it is cured. The sealant can usually be retained for a long time. Just after the sealing, it is best to do a review in 3-6 months, and then every year when you do the routine oral examination, you should also check the sealed teeth, in order to find out if there is any sealant falling off, so as to make up for it in a timely manner. The principle of fissure sealing to prevent fissure caries is to use polymer material to fill the fissure of the teeth, so that the surface of the teeth becomes smooth and easy to clean. On the one hand, after the fissure is closed, the original bacteria in the fissure are cut off from the source of nutrition and gradually die; on the other hand, the caries-causing bacteria from the outside can no longer enter, so as to achieve the purpose of preventing fissure caries. Role The occlusal surface of the large back teeth (the side that chews food) in every person’s mouth is uneven, and the concave part is called the fossa. If the development is not good, these grooves are very deep, food and bacteria are embedded in them, and caries (also called “insect teeth” and “tooth decay”) will occur easily, which is called fissure caries in medicine. According to the oral epidemiological survey, more than 90% of the caries in China’s adolescents occur in the fossa area. The “six-year-old teeth” is the fossa caries site, it is the earliest eruption time of the permanent molar, its chewing function is the most powerful, but also the most prone to caries, and even cause premature loss, so the protection of children’s first permanent molar teeth is very important. Fissure sealing is the most effective way to prevent fissure caries in permanent molars. Scope of application Indications There are many factors involved in deciding whether or not fossa sealing is necessary, the most important of which are the shape and evaluation of the fossa. 1) Deep sockets, especially those that can catch the probe (including suspected caries). 2) The patient’s other teeth, especially the contralateral tooth of the same name, are carious or predisposed to caries. Optimal timing The optimal timing for fissure sealing is when the tooth is fully erupted and caries has not yet occurred. (1) Children’s teeth erupt and reach the occlusal plane, generally within 4 years of eruption. 2) Molar teeth are 3-4 years old, first permanent molar teeth are 6-7 years old, second permanent molar teeth are 11-13 years old, and bicuspid teeth are 9-13 years old. 3) For children with disabilities who have poor oral hygiene, relaxation of the age of fossa sealing may be considered although they are older or the teeth have been erupting from the mouth for a longer period of time. Non-indications 1) Teeth that are already carious or have been filled. (2) Teeth that have not fully erupted and part of the occlusal surface is covered by the gums. (3) The occlusal surface has no deep fossa or pitting, and the self-cleaning effect is good. 4) Children are uncooperative and cannot cooperate with normal operation. Generally speaking, middle-aged and old people have passed the susceptibility period of fossa caries, and some of them have already got caries. At the same time, the fossa of the posterior teeth with the abrasion of chewing food, the fossa gradually becomes shallow or disappears, so it is generally not necessary to do fissure closure. Basic operation The method of fissure sealing is very simple, which can be completed by cleaning the teeth, acid etching, rinsing and drying, applying sealant and curing several steps. However, it should be emphasized that fissure sealing needs to be operated by professionals and requires the necessary instruments and equipment. Clinical effect Evidence-based medical research shows that fissure sealing is an effective method of preventing fissure caries, and the use of resin-based fissure sealant can effectively reduce the incidence of caries in permanent molars. The caries prevention effect of fissure sealing is directly related to the retention rate of sealant, so the operation must be strict and standardized.