| A great number of pathogenic microorganisms, such as bacteria, virus and fungi exist on the surface of the dental impressions,which is liable to cause cross infection among dentists, patients and dental technicians. For alginate impression materials that are generally used in China, those regular methods of impression disinfection, such as Immersion and spraying will bring negative influence to the accuracy of impression and will do harm to the quality of fixed prosthesis consequently. At the same time , the disinfectants used for immersion and spraying have strong toxic effect on the human body and can also corrode the metal impression tray. By mixing the alginate impression material with disinfectants, we can make out self-disinfecting impression material which can solve the problems above and accomplish a relatively good effect of disinfection, however, whether the self-disinfecting impression will influence the accuracy,flowability and setting time is still waiting for further study.The aim of this research paper is to make self-disinfecting impression by mixing alginate impression material with chlorhoxidine solutions of different concentrations, to study its disinfecting effect ,three-dimensional accuracy ,flowability and setting time in order to find out a fast, efficent, and convenient method for impression disinfection.This paper contains four experiments: The disinfecting effect ,three-dimensional accuracy , flowability and setting time of the chlorhoxidine self-disinfecting alginate impression materialThe results of this paper are as follows :1. Every impression disk mixed with chlorhoxidine exhibited antibaterial activity except for some ones on the Pseudomonas aeruginosa plates,with the increase of chlorhoxidine concentration,the microbial inhibition zone became larger and significant difference was detected among them. On the Pseudomonas aeruginosa plates, only the impression disks mixed with 0.1% chlorhoxidine exhibited antibaterial activity and the control group had no antibaterial activity on any plate.2. The difference between the master and casts measured in the dimensions of BL and OG is positive for all the trial groups ,which means that casts are larger in these dimensions than the master;The difference in the dimensions of IP and MD is negative for all the trial groups,which means that casts are smaller in these dimensions than the master. With the increase of the chlorhoxidine's concentration,the measurements on all dimensions of the casts made from chlorhoxidine-impregnated impression material are on the rise ,however, One-Way ANOVA reveals that there's no significant difference between all the measurements of the 5 test groups.3. There's no significant difference in flowability between the self-disinfecting impression and the control group(p > 0.05). The measurements of flowability and the 95%CI are both within the normal value determined by the State.4. There's no significant difference in setting time between the self-disinfecting impression and the control group(p > 0.05). Themeasurements of setting time and the 95%CI are both within the normalvalue determined by the ADA.In sum ,we can come to the following conclusions:1. Mixing alginate impression material with chlorhoxidine is an effective disinfecting method for impression2. No significant difference in the accuracy was found between the chlorhoxidine-impregnated impression material and water-mixed impression material3. Compared with the results of those former experiments, the chlorhoxidine-impregnated impression material is clinically acceptable4. Mixing the alginate impression material with chlorhoxidine will not influence the flowability5. Mixing the alginate impression material with chlorhoxidine will not influence the setting time6. 0.1% chlorhoxidine is recommended to make the self-disinfecting impression material.7. Further study will concentrate on the seach for another disinfectant to make self-disinfecting impression that can kill virus and fungi effectively.
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