New Silicone Impression Material With Improved Tear Strength

Objectives: When taking an impression in an oral cavity with silicone impression materials, the impression becomes thinner in the interdental part and the root canal, and the strength is lower than that in the thick part. Therefore, the impression in the thin part may be torn off, and the accurate impression may not be obtained. In order to improve this point, we have developed EXA Advanced, new silicone impression material, that is hard to tear.
The purpose of this study was to evaluate tear strength, which is an index of the resistance to tearing, and to compare it with the existing product EXAMIX.
Methods: Test materials were EXA Advanced and EXAMIX (both made by GC America). The tear strength was evaluated based on ISO34-1. An acrylic mold (length of 105 mm, width of 40 mm, thickness of 0.5 mm) was placed on a plastic film, filled with the silicone impression material, and then the plastic film was placed on top and pressured. After storing in water at 35 °C for oral retention time and curing, the plate-shaped cured product was cut into a ISO34-1 angle shape without nick. The test piece was fixed up and down on the autograph and the tear test was measured (n=5, crosshead speed of 500 mm/min).
Results: From the test results of the tear strength, EXA Advanced showed significantly higher tear strength than EXAMIX in comparison between each type (Welch's t-test).
Conclusions: The new silicone impression material EXA Advanced has high tear strength and is hard to tear, so it can be expected to take an accurate impression even in clinical practice.