Effect of different impression materials on the marginal fit of frameworks: An in-vitro study

Abstract

Objectives: The objective of this study was to compare the accuracy of three different impression materials with evaluating the marginal fits of metal frameworks using replica technique.Materials and Methods: A phantom premolar tooth was prepared with a 1 mm circumferential chamfer preparation. Four impression materials: two vinyl polysiloxane (VPS) (Affinis Precious, (Group A); Elite HD, (Group E)), one polyether (Impregum Penta Soft, (Group P)) and one vinyl siloxanether (Identium, (Group I)) were used for producing stone casts of this master model. Twelve measurements per replica were carried out using a light microscope X40 magnification by Leica software, to assess the vertical marginal gap (VMG). Data were analyzed using the analysis of variance followed by Tukey’s test (p=0.05).Results: Specimens of the Group A and I showed significantly lower VMG values than those of Group E and Group P (p<0.001). Differences were not significant between groups A and I, and E and P either (p>0.05).Conclusions: All impression materials were clinically acceptable. As well as composition of the impression materials, size of filler particles and fluid mechanics of flow into very small spaces can be effective on accuracy of the materials.

Keywords

• impression materials
• marginal fit; replica technique