Hardness and Elastic Modulus in Compression of Denture Base Soft Lining Materials Determined by a Modified Experimental Hardness Tester

Abstract

The hardness and the elastic modulus in the compression of six commercial denture base soft lining materials were investigated. The testing apparatus was a modification of the hardness test meter designed by Inoue et al. (1985) for oral soft tissue. The values obtained by this instrument were compared with the results from two other methods (a Dulometer and an Autograph). The hardness values of all the materials increased slightly with the time elapsed after setting. This result correlated well with the hardness values obtained by the Dulometer. The elastic modulus in compression at 37℃ of the test specimens stored in an air cabinet at 37±0.5℃ for 24 hr after setting was 87.2×10⁶ dyne/cm² for olefin polymer, 25.9×10⁶ dyne/cm² for fluoro polymer, 3.58×10⁶ & 26.4×10⁶ dyne/cm² for silicone materials and 4.96×10⁶ & 6.46×10⁶ dyne/cm² for acrylate materials. The modified instrument was considered satisfactory for examining the mechanical properties of soft lining materials, impression materials or oral soft tissue.