Chlorine Dioxide Spray Disinfection Of Alginate Impression Accuracy Of The Model

Objective: To study the effect on dimension stability of impression which was sprayed by different concentrations of chlorine dioxide. The purpose of this study is to provide a feasible basis to clinical procedure.Methods: This study includes two parts. PartⅠTo Testify Reliability of Measurement System: 20 impressions were made from the master model(59mmx16mmx16mm) with irreversible hydrocolloid impression material. And then poured with die stone. Numbering the samples. The length, width and height of gypsum model were measured by a 3D coordinate measuring machine and the vernier caliper , respectively. And remeasured by the same examiner 10 days after. Data obtained were compared among the groups using statistical software package(SPSS11.0) PartⅡThe Effect of Sprayed Disinfection of Chlorine Dioxide with Different Concentrations on Dimension Stability of Alginate Impression:(1)Impressions made of irreversible hydrocolloid material after a master model(59mmx16mmx16mm)were divided into 5 treatment groups and one control group. The samples in treatment groups were disinfected by soaking them for 20 minutes in 20000mg/L glutaraldehyde, or in 1000mg/L sodium hypochlorite, or by 30-minute storage in a close unit after 550mg/L chlorine dioxide disinfectant spray, or by 20-minute storage in a close unit after 700mg/L chlorine dioxide disinfectant spray, or by 10-minute storage in a close unit after 900mg/L chlorine dioxide disinfectant spray, respectively. A 3D coordinate measuring machine was used to measure the three—dimensions of the stone casts-poured against the treated impressions. The device was capable of producing 0. 001mm reading precision. (2)Impressions were made from the standard maxillary teeth models with irreversible hydrocolloid impression material. The grouping methods, disinfection treatment and model poured as same as methods(1). The vernier caliper was used to measure the three—dimensions of plaster castings of these treated impressions at 0.02mm precision. Data obtained were compared among the groups using statistical software package (SPSS11.0)Results: 1. A statistical significance was not found comparing the differences between the means of the measurements performed ; No significant difference was observed at two different times on the models which measured by the coordinate measuring machine.2. Dimensional evaluation of casts showed significant differences(P<0. 05)in both horizontal vertical linear sizes of the 20000mg/L glutaraldehyde and 1 000mg/L sodium hypochlorite group as compared with the controls. Spray of chlorine dioxide did not appear to cause a dimensional change (P> 0. 05).Conclutions: 1. The coordinate measuring machine provides many advantages such as in precision , simplicity , high efficiency , and wide range of measurement contents with complete direct view, can be used to measure the three—dimensions of the stone casts-poured. 2. As chlorine dioxide concentration risen, the disinfecting time became shorten. The different concentrations of chlorine dioxide spray were not shown to compromise the accuracy of prosthesis. 3. Compared with 20000mg/L glutaraldehyde and 1000mg/L sodium hypochlorite, the different concentrations of chlorine dioxide spray produced modest impact on model precision, and have lowest working concentration, no stimulating smell and no adverse reaction to preferential use.