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Polyether rubber impression material is elastic irreversible impression materials, mainly constituted by the copolymerization of tetrahydrofuran and ethylene oxide polyether rubber composition. 1960s, the material was first applied in Germany, after 40 years of development, has become an elastomer impression materials widely used in clinical work. It has the advantages of strength, elastic recovery, rapid solidification, high dimensional stability, good hydrophilicity, and during the course of the reaction does not produce byproducts. Polyether rubber impression materials commonly used in the preparation without severely undercut precision impression, the accuracy was significantly higher than the condensation type silicone rubber and polysulfide rubber impression materials. However, in the polyether rubber impression material is made to take an impression the prosthesis fabrication failure caused due to the deformation of the stamper. To get an accurate impression of the goals and aspirations of clinicians, therefore, the impression of precision and dimensional stability is extremely important. Each prosthesis in the clinical work stamper is removed from the mouth, the need to be placed into the irrigation mode chamber reperfusion unified by the technician, remove the stamper to the process of perfusion model, the models will inevitably be subject to the influence of indoor temperature, humidity, placed temperature, humidity and time impression can not be ignored. The subject's experimental group selection of the the commercial polyether rubber impression materials: Polyjel (?) NF TM polyether rubber impression material (Dentsply, Germany, referred to as PO) and Impregum TM < / sup> Soft polyether rubber impression material (3M Company, Germany, referred to as IM), the comparison group selection clinically used silicone rubber: the Express TM XT hydrophilic addition silicone rubber stamp molding material (3M Company, Germany, referred to as EX). Take an impression with the above three impression material, the measured temperature, humidity and storage time stamp or change the size of the model to calculate the size of the rate of change of the comparative analysis in order to evaluate the changes in the impression of precision. Methods (1) recommended standards of the International Organization for Standardization (ISO4823) stainless steel mold to the system to take an impression. Stamper were placed in five different humidity: 30%, 50%, 70%, 90%, water, the temperature was set to 23 ° C. After standing for 24 hours, using a universal tool microscope to measure the length with a horizontal line in the middle horizontal line length and the standard mold of each sample to calculate the percentage of die size changes. (2) using the standard mold made to take an impression, an impression is stored at a temperature of 4 ° C, 16 ° C, 23 ° C, 32 ° C, 40 ° C environment, select the above experiments the impression most accurate humidity Storage humidity After standing for 24 hours, using a universal tool microscope to measure the size stamper calculated die size changes. (3) to simulate three-unit fixed bridge making metal molds, made impression. The stamp is stored in the highest accuracy of the above experiment the temperature and humidity environment, the plaster model is perfused at 7 different time points, respectively. Using the universal tool microscope to measure the size of the plaster model to calculate the percentage of dimensional change. Results (1) polyether rubber IM, PO impression of storage size change under different humidity there is a statistically significant difference (p lt; 0 .05), dimensional changes when soaked in water, stored in a humidity of 70% minimum dimensional changes. The size change hydrophilic silicone rubber EX impression is stored in five kinds humidity difference were statistically significant (p lt; 0 .05), stored in 30% humidity dimensional changes, size changes when soaked in water minimum. (2) polyether rubber IM, PO impression of store size change under different temperature differences were statistically significant (p lt; 0 .05), dimensional changes stored in a 40 ° C environment, stored in 23 ℃ environment in size changes smallest. Impression of silicone rubber EX stored in a 4 ° C environment with an impression of the rest of the temperature of stored dimensional changes were statistically significant (p lt; 0 .05), and the size change. (3) in 70% humidity and a temperature of 23 ° C environment, each impression in 1h, 6h the irrigation-mode model size change was no significant difference (p> 0 .05) minimum irrigation mold model size changes. Model size change in 72h 168h irrigation mode was no significant difference (p> 0 .05), and filling the mold plaster model size change. The irrigation mode the rest of the time points plaster model of dimensional changes were statistically significant (p lt; 0 .05). Conclusion (1) two polyether rubber PO and IM stored in humidity 70%, you can get the most accurate impression; soaked in water storage impression swelling deformation. Hydrophilic silicone rubber the EX impression soaked in water, the highest accuracy. (2) two types of polyether rubber PO and IM is stored in the temperature in the environment of 23 ° C, the stamper of the highest precision, the polyether rubber impression stored in the environment of 40 ° C, maximum contraction deformation. The silicone rubber EX stored at a temperature of 4 ℃, shrinkage deformation largest. (3) 70% humidity, a temperature of 23 ° C environment, polyether rubber PO, IM, processing the silicone rubber EX system to take an impression of storage 1h, 6h irrigation mode, the smallest model size change; store 72h, 168h irrigation mode , model size changes.
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