Even six-year-old children now know that their teeth should be closed because they are most susceptible to dental caries. However, experts remind that in fact, the adjacent surfaces of teeth are also very easy to have worm teeth, and it is difficult to detect them, so people should be more vigilant and floss more after meals can be effectively prevented. It is difficult to take into account the gap between teeth by brushing. In daily life, the outer side, inner side and occlusal surface of teeth can be cleaned by brushing, but because the bristles of toothbrush cannot effectively enter the gap between two adjacent teeth, food residues remain on the adjacent part of teeth after brushing, leading to adjacent surface caries. The adjacent surface caries is very common in the clinic, because it occurs on the adjacent surface of the teeth, the patients can hardly find it by themselves, and often wait until they have conscious symptoms (such as tooth loss, pain, etc.) before they go to the hospital, at this time, the lesion is more serious, and even develops into pulpitis and periapicalitis, which is more harmful. Adjacent surface caries is related to periodontal disease and food embedding The occurrence of adjacent surface caries is mainly related to periodontal disease, food embedding and bad restoration and other factors. In patients with periodontal disease, there are mostly bone loss and gum atrophy between adjacent teeth, and after eating, there are easily food, soft scale and plaque adhering residue, causing tooth decay. Food embedment refers to the poor adjacent relationship or abnormal gap between adjacent teeth, resulting in food being embedded or retained in the gap between adjacent teeth when eating or chewing, which is not easy to remove and clean. The embedded food will be decomposed by bacteria, decay and deteriorate, and promote the adjacent surface caries. Adjacent surface caries is also closely related to bad fillings and bad restorations, such as overhang of fillings, poor fit of restorations, and excessive convexity of restorations, etc., which will easily cause plaque accumulation on the adjacent surface and cause tooth adjacent surface caries. Poorly made removable teeth and bad wearing habits (such as not cleaning the denture and not taking out the denture at night, etc.) are also likely to cause adjacent surface caries. The use of dental floss and tooth brush can effectively clean the adjacent surface caries occurs in a hidden location, which is difficult to treat and the effect of filling is also poor, so the prevention and treatment of adjacent surface caries focuses on prevention. To maintain oral health is a long-term work, we should establish the concept of lifelong care of the oral cavity, do oral hygiene examination once every six months, use dental floss and toothbrush to clean the adjacent surface of teeth, and promote oral health.