Tear Strengths of Dental Impression Elastomers

Marginal tearing of an elastomer reduces the accuracy of the impression.  Objective: The purpose of this study was to determine the tear strength of commonly used elastomeric impression materials.  Methods: Seven materials were tested, Affinis Precious Light Body  (Coltene/Whaledent),  Aquasil Ultra XLV Fast Set (Caulk), Exafast NDS Injection Fast Set, Exa'lence Extra Light Body Fast Set (GC),  Imprint 3 Quick Step Light Body, Impregum Soft Quick Step Light Body (3M ESPE), and Take 1 Advanced LB Wash Super Fast Set (Kerr).  For each material, five axial notch specimens, measuring 4” x 0.75” x 0.0090”, were made in a proprietary stainless steel injection mold.  The mold was filled with impression material, sealed, and immediately placed in a water bath at 35°C.  At the recommended mouth removal time, the specimens were demolded.  The specimens were gripped providing 2” of gage length and then continuously loaded in tension in an Instron testing machine at a crosshead speed of 10”/min until failure.  Tear stress data were statistically analyzed using one-way ANOVA and the Tukey-Kramer HSD tests (p ≤ 0.001). Results:  Tear stress values are given in the following table.  Letters (a-e) denote significant statistical differences between the materials.

Conclusions: Highest tear strengths were found for Affinis Precious Light, Aquasil Ultra XLV Fast Set and Imprint 3 Quick Step Light.  Clinical Relevance: Resistance to marginal tearing may be affected by tear strength of elastomeric impression materials.  This research was supported in part by Reality Publishing Company.