Tear Strength of Low-viscosity Elastomeric Impression Materials

Marginal tearing of an elastomer reduces the accuracy of the impression. Objectives: The purpose of this study was to determine the tear strength of various low viscosity elastomers. Methods: Ten materials were tested: Aquasil Ultra XLV and Aquasil Ultra LV (Caulk), Affinity Light Body HF (Clinician’s Choice), Splash Extra Lite (Discus), Take 1 Wash and Extrude Wash (Kerr), Flextime Correct Flow (Kulzer), Examix NDS Injection (GC), and Impregum Penta Soft Light Body and Imprint II Low (3M/ESPE). Five axial notch specimens, measuring 4" x 0.75" x 0.020", were made in a proprietary Plexiglas mold. The mold was filled with impression material, sealed, and immediately placed in a water bath at 35⁰C.  At the manufacturer’s recommended mouth removal time, the mold was retrieved from the water bath. The specimens were gripped over the first inch from either end leaving 2 inches of gage length and continuously loaded on an Instron testing machine at a crosshead speed of 10 inch/minute until failure occurred. The data was analyzed by using ANOVA and Tukey’s least significant difference test (p<0.05). Letters (a-e) denote statistically significant differences in tear strength between the groups. Results:

Conclusions: Resistance to marginal tearing may be affected due to significant differences in the tear strength of low viscosity elastomeric impression materials. This research was supported in part by Dentsply Caulk.