title: [The mechanic retention of the casting post with keeper in magnetic retentor overdenture].
abstract: OBJECTIVE
  To reduce the cost of the fabrication of the magnetic retentor,and meet the clinical requirements, nonprecious alloy such as Co-Cr alloy was used to fabricate the magnetic retentor in overdenture , instead of the precious alloy.
  
  
  METHODS
  A mandibular canine was chosen for root canal preparation in vitro. Thirty two resin posts were made in the same root canal with self-curing resin. The 32 resin posts were randomly divided into 4 groups. Among them,2 groups were fabricated with soft Co-Cr alloy, gold alloy(55.6%Au) respectively in vitro. Another 2 groups were fabricated with Co-Cr alloy, and the surface of the root casting post with keeper were treated with gold deposit and gold coating technique. After that, test of dislodgment force was done and one-way ANOVA was performed with SAS 6.2 software package.
  
  
  RESULTS
  The dislodgment force of the root casting posts with keeper which were fabricated with the Co-Cr, Ni-Cr, and gold alloy had significant difference(P<0.01). While after surface treatment by gold deposit and gold coating technique on root casting posts with keeper that were fabricated with Co-Cr and Ni-Cr alloy, there was no significant difference in dislodgment force, compared with that of gold alloy.
  
  
  CONCLUSIONS
  After surface treatment of the root casting posts with keeper which were fabricated with the Co-Cr and Ni-Cr alloy, the same clinical retentive effect can be obtained as the one that was fabricated with gold alloy.
authors.affiliation: Department of Prosthodontics, School of Stomatology, Ninth People's Hospital, Shanghai Jiaotong University, China.
authors.forename: Kan
authors.initials: K
authors.lastname: Xu
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.forename: Qing-feng
authors.initials: QF
authors.lastname: Huang
authors.forename: Rong
authors.initials: R
authors.lastname: Chen
authors.forename: Jun-lian
authors.initials: JL
authors.lastname: Gu
authors.forename: Xiao-yin
authors.initials: XY
authors.lastname: Zhang
mesh_terms: D002858:Chromium Alloys / Q000627:therapeutic use*; D003828:Denture, Overlay; D006047:Gold Alloys / Q000627:therapeutic use*; D006801:Humans; D060328:Magnetic Phenomena; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods*
chemical_list: D002858:Chromium Alloys; D006047:Gold Alloys