Evaluation of Relative Accuracy of Three Commercially Available Removable Die Systems of Different Configurations: An in vitro Study

Abstract

Introduction:The positional shift observed in removable die systems before and after sectioning the master cast may result in a cast restoration with improper occlusal and proximal contacts and marginal fit, thereby requiring time-consuming chairside adjustments.Aim: This study was done to evaluate the relative accuracy of three commercially available removable die systems with different configurations by measuring the average die displacement before and after sectioning of the cast. Materials and methods:A total of 60 impressions were made of the standardized brass master model using polyvinylsiloxane. Impressions were divided into three groups. For each group, a different removable die system was used. Group I: cross pin; group II: M R pin; and group III: conventional brass dowel pin. The presectioning measurement both in the horizontal and vertical directions of all the 60 casts obtained were made using profile projector. The casts were then sectioned and removed and replaced 30 times, and the postsectioning measurements were made using the same references. The differences between the presectioning and the postsectioning measurements were calculated Statistical analysis used: The data were analyzed using analysis of variance (ANOVA) and Tukey's multiple comparison test.Results: All the three die systems exhibited displacement both in the horizontal and vertical directions before and after sectioning the casts. Brass dowel pin exhibited the greatest amount of displacement both in the horizontal and vertical directions. Conclusion:The use of more than one pin and the presence of metallic or plastic sleeves can result in improved accuracy and stability of the die system.