title: Effect of metal conditioner on bonding of porcelain to cobalt-chromium alloy.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the efficacy of two different metal conditioners for non-precious metal alloys for the bonding of porcelain to a cobalt-chromium (Co-Cr) alloy.
  
  
  METHODS
  Disk-shaped specimens (2.5×10.0 mm) were cast with Co-Cr alloy and used as adherend materials. The bonding surfaces were polished with a 600-grid silicon carbide paper and airborne-particle abraded using 110 µm alumina particles. Bonding specimens were fabricated by applying and firing either of the metal conditioners on the airborne-particle abraded surface, followed by firing porcelain into 5 mm in diameter and 3 mm in height. Specimens without metal conditioner were also fabricated. Shear bond strength for each group (n=8) were measured and compared (α=.05). Sectional view of bonding interface was observed by SEM. EDS analysis was performed to determine the chemical elements of metal conditioners and to determine the failure modes after shear test.
  
  
  RESULTS
  There were significant differences among three groups, and two metal conditioner-applied groups showed significantly higher values compared to the non-metal conditioner group. The SEM observation of the sectional view at bonding interface revealed loose contact at porcelain-alloy surface for non-metal conditioner group, however, close contact at both alloy-metal conditioner and metal conditioner-porcelain interfaces for both metal conditioner-applied groups. All the specimens showed mixed failures. EDS analysis showed that one metal conditioner was Si-based material, and another was Ti-based material. Si-based metal conditioner showed higher bond strengths compared to the Ti-based metal conditioner, but exhibited more porous failure surface failure.
  
  
  CONCLUSIONS
  Based on the results of this study, it can be stated that the application of metal conditioner is recommended for the bonding of porcelain to cobalt-chromium alloys.
authors.affiliation: Kagoshima University Medical and Dental Hospital, Fixed Prosthetic Clinic, Kagoshima, Japan.
authors.forename: Yoshito
authors.identifier: 0000-0002-8269-2201
authors.initials: Y
authors.lastname: Minesaki
authors.affiliation: Kagoshima University Graduate School of Medical and Dental Sciences, Department of Fixed Prosthodontics, Kagoshima, Japan.
authors.forename: Sadaaki
authors.identifier: 0000-0002-1946-7677
authors.initials: S
authors.lastname: Murahara
authors.affiliation: Kagoshima University Medical and Dental Hospital, Fixed Prosthetic Clinic, Kagoshima, Japan.
authors.forename: Yutaro
authors.initials: Y
authors.lastname: Kajihara
authors.affiliation: A Dental Lab, Private Dental Laboratory, Kagoshima, Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Takenouchi
authors.affiliation: Kagoshima University Graduate School of Medical and Dental Sciences, Department of Fixed Prosthodontics, Kagoshima, Japan.
authors.forename: Takuo
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: School of Dentistry, University of Alabama at Birmingham, Division of Biomaterials, Birmingham, Alabama, United States of America.
authors.forename: Shiro
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: Kagoshima University Graduate School of Medical and Dental Sciences, Department of Fixed Prosthodontics, Kagoshima, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Minami
keywords: Chromium alloys; Dental porcelain; Shear strength