Three-dimensional Accuracy Of One-step Versus Two-step Putty-wash Addition Silicone Impression Technique

Experiment one:The accuracy of replication in shoulder continuity of one-step versus two-step putty-wash addition silicone impression techniqueObjective:This study compared the three-dimensional accuracy of one-step putty-wash with two-step putty-wash addition silicone impression techniques.Methods:A crystal master model containing one full ceramic crown abutment preparation (at no.21position) was used as the positive control. The impressions of the master model were made using one-step and two-step putty-wash technique, respectively. The control models were measured with magnifying glass. Rank-sum test was employed to evaluate the variance between the control model and its impressions made by two techniques.Results:The accuracy of replication in shoulder continuity of two-step impressions was higher than that of one-step impressions, and the difference was statistically significant (P<0.05).Experiment two:The percentage deviation of one-step versus two-step putty-wash addition silicone impression technique.Objective:This study compared the three-dimensional accuracy of one-step putty-wash with two-step putty-wash addition silicone impression techniques.Methods:The impressions of the master model were made using one-step and two-step putty-wash technique, respectively. Rank-sum test was employed to evaluate the variance between the control model and its impressions made by two techniques. The stones dies were poured from impressions of the master model. Vertical and horizontal dimensions between marks on the master model and stone dies were measured with magnifying glass. Data were statistically analyzed to compare the means of percentage changes.Results:The percentage deviation of one-step technique was bigger than that of two-step technique; however there was no statistical significance.Conclusions:1. Addition silicone impression has good fluidity, elasticity and dimensional stability, and is widely used in high-precision replication in terms of teeth, periodontal and implant structure.2. Three-dimensional accuracy of the two-step putty-wash addition silicone impression technique was higher than one-step impression technique.