Surface hardness and pressing accuracy of reused IPS empress 2

Son, Oe Soo; Kim, Yu Lee; Lee, Kyung Ja; Jin, Tai Ho

Abstract

STATEMENT OF PROBLEM: IPS Empress2 system was developed and used in prosthodontic treatment, but the cost of ingot is expensive for wide application. PURPOSE: This study was to investigate the possibility on recycling of IPS Empress 2 ceramic for wide application of IPS Empress 2 ceramic in prosthodontic treatment. MATERIAL AND METHOD: 1st, 2nd and 3rd pressed disc-shaped(10x1.5mm) IPS Empress 2 specimens were made with IPS Empress ingot(200, Ivoclar, Liechtenstein) and pressing furnace(IPS Empress EP 500, Ivoclar, Liechtenstein). Vicker's surface hardness and fracture toughness, acid resistance, and pressing accuracy of IPS Empress 2 ceramic were measured and analyzed. Surface hardness was measured by microhardness tester(MTX 70, Matsuzawa, Japan). before and after surface treatment with 0.5% hydrofluoric acid and carbonic acid(Coca cola) for evaluation of acid resistance. RESULTS: The surface hardness of 1st pressed specimen was the higher(5.11 GPa) than those of 2nd pressed( 4.89 GPa) and 3rd pressed specimen(4.86 GPa). and the fracture toughness of 1st pressed (1.58 MPam1/2)and 2nd pressed specimen(1.51 MPam1/2) were higher than that of 3rd pressed specimen(1.39 MPam1/2). The changes of surface hardness of 1st, 2nd, and 3rd pressed specimens after treatment with fluoric acid were 0.17, 0.06, 0.05(GPa) respectively, and those of 1st, 2nd, and 3rd pressed specimens after treatment with carbonic acid were 0.07, 0.00, 0.05(MPa) respectively. The pressing accuracy of 1st, 2nd and 3rd specimen were 77.22%, 85.681%, and 75.05%. The pressing accuracy of 2nd pressed specimen was higher than that of the 3rd specimen. CONCLUSION: The changes of physical properties according to recycling of IPS Empress 2 from this study were insignificant. Therefore the possibility of recycling of IPS Empress 2 can be suggested from the results.