Comparison of dimensional accuracy of modifided two-step condensational polyvinylsiloxane putty-wash impression technique with two-step putty-wash technique with spacing

Abstract

Impression in Fixed Prosthodontics is very important. Impression techniques is one of the most important factors affecting the dimensional changes of die. Research showed the conflicting results about the impression techniques. This study was carried out with aim of comparison two impression techniques of modifided two-step putty-wash impression technique with two-step putty-wash technique with spacing. Materials and methods: this experimental study was done on a laboratory model. 10 impression of laboratory model were taken for each techniques of modifided two-step putty-wash impression technique and two-step putty-wash technique with spacing. Impression were poured after 30 minute with vel-mix plaster Type IV. DieEs height, diameter and distance between dies were measured 6 times on laboratory model and 3 times on stone models by an expert who was not aware of impression techniques with digital coulis(Guanglu Digital Caliper.china).The Size of plaster sample comparing with experimental model, and result were tested by ANOVA and hh t-test analysis (p < 0.05 was considered significant). Results: Based on the result There was no significant difference between two techniques in height and distance between two dies and modifided impression technique is more accurate and closer to the original model. But in dieEs diameter there was significant difference between two techniques. Conclusion: within the condition of this study,The accuracy of Modified impression technique is similar to two-step with spacing impression technique and in some cases modified impression technique is more accurate than with spacing impression technique. In bridges because of the more accuracy, modified impression technique can be replace instead of two-step with spacing impression technique.