title: [Evaluation of marginal adaptation of three different copings of metal-ceramic crowns].
abstract: OBJECTIVE
  To evaluate the marginal adaptation of three different copings of metal ceramic crowns cast in high golden, cobalt-chrome and nickel-chrome alloy.
  
  
  METHODS
  Thirty working dies were created from a single master die and used to fabricate thirty copings in each as the following groups: A(high golden alloy, n=10), B(cobalt-chrome alloy, n=10) and C(nickel-chrome alloy, n=10). All the metal copings were fabricated using the conventional lost wax casting technique. The restorations were seated on the master die, and high-resolution digital photographs were made of the marginal area on all four sides. The vertical marginal gap was then measured using a calibrated digital software program. One-way ANOVA and LSD tests were used to determine the differences using SPSS11.5 software package.
  
  
  RESULTS
  The mean marginal gaps were group A:(72.9±29.3)μm; group B(85.9±33.0)μm and group C(94.1±44.9)μm. There was significant difference among three groups(P(AB)<0.01,P(AC)<0.001,P(BC)<0.05).
  
  
  CONCLUSIONS
  The marginal gaps of three different metal copings are all clinical acceptable. The high golden copings resulted in smaller marginal gaps than either cobalt-chrome or nickel-chrome copings.
authors.affiliation: Department of VIP, Zhejiang Chinese Medical University. Hangzhou, Zhejiang Province, China. lilyxumei@qq.com
authors.forename: Mei
authors.initials: M
authors.lastname: Xu
authors.forename: Fan
authors.initials: F
authors.lastname: Yang
authors.forename: Ren-fei
authors.initials: RF
authors.lastname: Wang
mesh_terms: D002516:Ceramics; D002858:Chromium Alloys; D003442:Crowns; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D006801:Humans; D016876:Metal Ceramic Alloys; D009532:Nickel
chemical_list: D002858:Chromium Alloys; D016876:Metal Ceramic Alloys; D003776:Dental Porcelain; D009532:Nickel