When the cavity of tooth decay is not very big, it is relatively easy to treat and the patient suffers little pain. The main treatment of tooth decay is to remove all the infected and necrotic hard tissues and then fill the cavity with composite resin. When tooth decay occurs, the first manifestation is demineralization of tooth surface, which makes chalky plaque appear on the surface of tooth enamel, and the surface of enamel will become rough and unsmooth, with the further expansion of decay, superficial cavity will be formed and black pigment will appear on the surface, in this case, patients usually do not have obvious pain, so many patients do not pay attention to it, and often the disease will be delayed, but the tooth decay cannot heal by itself. However, tooth decay is not able to heal by itself, it can only be formed as the cavity becomes bigger and bigger, and finally form toothache. Therefore, it is necessary to consult a doctor in time to treat the tooth decay to prevent further expansion of infection.