Medium caries is only caries, does not involve the nerve inflammation does not need to kill the nerve, just need to clean the tooth decay, clean the infected dentin, and then filling can be. When the caries develops to the dentin deep layer, close to the pulp, has produced pulp symptoms, only need to kill the nerve treatment. Patients with moderate caries must go to the hospital in time for treatment, if not treated, with the prolongation of the course of the disease, the depth of caries is getting deeper and deeper, from moderate caries to deep caries, and finally to the pulpitis symptoms, this time will need to kill the nerve treatment.