Tooth decay is also known as dental caries in medical terms. If the cavity is already rotten and empty, it is usually not suitable for simple medication, and surgical treatment should be considered. The principle of surgical treatment is to remove the infected tissues, and if the nerve is injured, root canal treatment is needed to protect the normal pulp tissues and preserve the healthy tissues as much as possible, as well as to repair the cavities and restore the function and beauty of the teeth. Commonly used procedures for restoring dental caries include silver amalgam filling, composite resin direct paste restoration, and inlay restoration: 1.Silver amalgam filling: after thoroughly removing the necrotic tooth tissue, make a certain cavity shape. Through friction and mechanical latching, the amalgam filling is adapted to the cavity wall and shape to obtain retention. The filling should have a certain thickness and strength in order to have enough resistance to counteract the various forces during chewing; 2. Direct paste restoration with composite resin: composite resin is currently the more ideal filling material. Using composite resin for restoration of tooth defects can form adhesive cementation with dental tissues, which is suitable for the restoration of anterior teeth and large area of caries damage. Moreover, the color of this material is similar to that of the teeth, and it is more beautiful after repairing; 3.Inlay restoration: inlay is a kind of retaining body that can be embedded inside the tooth body to restore the form and function of the defective part of the tooth body. It is suitable for cases with large defects in the dental tissue. The advantage of inlay is that it is aesthetic and has excellent mechanical properties, and can play a good role in restoring the morphology of the occlusal surface and the contact relationship with the adjacent surface, so as to eliminate food embedding. However, when it is not possible to perform the above procedure on a tooth that is already rotten and empty, it can be extracted if necessary, under the advice of the doctor and at the will of the individual, in order to avoid the spread of the lesion to the surrounding teeth.