title: Bond and fracture strength of metal-ceramic restorations formed by selective laser sintering.
abstract: OBJECTIVE
  The purpose of this study was to compare the fracture strength of the metal and the bond strength in metal-ceramic restorations produced by selective laser sintering (SLS) and by conventional casting (CAST).
  
  
  METHODS
  Non-precious alloy (StarLoy C, DeguDent, Hanau, Germany) was used in CAST group and metal powder (SP2, EOS GmbH, Munich, Germany) in SLS group. Metal specimens in the form of sheets (25.0 × 3.0 × 0.5 mm) were produced in accordance with ISO 9693:1999 standards (n=30). To measure the bond strength, ceramic was fired on a metal specimen and then three-point bending test was performed. In addition, the metal fracture strength was measured by continuing the application of the load. The values were statistically analyzed by performing independent t-tests (α=.05).
  
  
  RESULTS
  The mean bond strength of the SLS group (50.60 MPa) was higher than that of the CAST group (46.29 MPa), but there was no statistically significant difference. The metal fracture strength of the SLS group (1087.2 MPa) was lower than that of the CAST group (2399.1 MPa), and this difference was statistically significant.
  
  
  CONCLUSIONS
  In conclusion the balling phenomenon and the gap formation of the SLS process may increase the metal-ceramic bond strength.
authors.affiliation: Department of Dental Laboratory Science and Engineering, Korea University, Seoul, Republic of Korea.
authors.forename: Eun-Jeong
authors.initials: EJ
authors.lastname: Bae
authors.affiliation: Department of Dental Laboratory Science and Engineering, Korea University, Seoul, Republic of Korea.
authors.forename: Ji-Hwan
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Dental Laboratory Science and Engineering, Korea University, Seoul, Republic of Korea.
authors.forename: Woong-Chul
authors.initials: WC
authors.lastname: Kim
authors.affiliation: Department of Dental Laboratory Science and Engineering, Korea University, Seoul, Republic of Korea.
authors.forename: Hae-Young
authors.initials: HY
authors.lastname: Kim
keywords: Balling phenomenon; Bond strength; Fracture strength; Metal-ceramic restoration; Selective laser sintering