After the restoration of living pulp teeth, there are often problems of sensitivity to hot and cold stimuli, in my clinical experience, the possible causes are as follows: 1, the patient’s own reasons: that is, the pulp is not in a healthy state before restoration, but itself already exists tooth sensitivity, chronic pulpitis, pulp irritation state, the tooth was not found before restoration; 2, the cause of dental preparation: the amount of preparation is too large near the pulp, the preparation of water cold is not enough to produce too much heat ( especially when you can smell the burnt smell should be noted), the edge is located in the x-dentin bone boundary root side root dentin exposure area, the second production of restorations of live pulp teeth (previously restored teeth polished again, restoration of tooth allergy, the incidence of pulpitis multiplied); 3, temporary restorations causes: not made temporary restorations, temporary restorations off or loss of bonding, temporary crown during the cold, heat or chemical stimulation is too strong; 4, Restorative causes: sensitivity is basically inevitable if the restoration edges are not tightly fitted; 5. Bonding causes: excessive irritation of the bonding agent, excessive irritation during the bonding operation, bonding failure / or false bonding; 6. Other causes: patient’s allergic psychological constitution (compulsive and paranoid patients, women with menopausal psychological problems, patients with oral sensory abnormalities such as burning mouth syndrome). For the above reasons, measures to avoid dentin sensitivity: 1. exclude the possibility of pulp problems before restoration, if necessary, first pulp inactivation; 2. control the quality of the dental preparation, standardize the dental cutting and grinding techniques, after the preparation of the teeth before taking the mold can be used to protect the dentin, such as strong rinse; 3. must make temporary restorations, to ensure the stability of the temporary restorations and can be mixed in the temporary bonding material dentin desensitization paste for bonding 4. ensure the precision and marginal fit of the final restoration; 5. standardize the bonding operation and choose a less irritating type or brand of bonding agent (individual brands of bonding agents have strong pulpal irritation); 6. avoid excessive hot, cold and chemical stimulation within one month after the restoration is worn, and use desensitizing toothpaste; 7. provide psychological counseling in conjunction with the diagnosis and treatment of possible other related diseases (generally difficult to achieve). . The problem of dentin sensitivity after restoration not only causes pain to the patient, but also distress to the restorative surgeon and frustrates his self-confidence. Personally, I believe that prevention should be the main focus, and once it occurs it is quite difficult to deal with. It is important to pay sufficient attention during treatment planning, restoration design, clinical operation and post-prosthetic maintenance, and to take preventive measures to avoid it.