Abstract
Mechanical properties of recently developed resin-modified glass ionomer cements(RMGI)were compared with those of conventional acid-base glass ionomer(ABGI)cement.We studied three commercial RMGI cements and one ABGI cement as a control.Specimens for compressive, direct tensile, diametral, bending, fracture toughness measurement, and hardness measurement tests were prepared using the specific molds and stored in deionized water at 37℃ for 1 hour, 1 day, and 1 week prior to testing.ABGI was very brittle and fractured with little plastic deformation in each test.However, RMGI fractured after plastic deformation.Tensile, diametral tensile, and bending strengths of RMGI were significantly higher than those of ABGI.In addition, fracture toughness and critical energy release rate of RMGI were significantly higher than of ABGI.Hardness of RMGI increased with the increases in the duration of light exposure.These results indicated RMGI had a higher resistance to fracture than ABGI in the early stage after setting and that use of RMGI would be beneficial in applications involving restorative materials.
