title: Marginal fit of leucite-glass pressable ceramic restorations and ceramic-pressed-to-metal restorations.
abstract: BACKGROUND
  Fabricating a feldspathic porcelain margin on a metal-ceramic restoration with a clinically acceptable marginal fit has proven to be a technique-sensitive procedure. Pressable ceramics are advocated to solve this problem.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to compare the marginal adaptation of a pressable ceramic system when used with both all-ceramic and metal-ceramic crowns, with a traditional metal-ceramic restoration.
  
  
  METHODS
  A 1.5-mm, 360-degree chamfer margin was prepared on a typodont maxillary central incisor. Polyether impressions were made and poured in a Type IV dental stone, and the following crowns were fabricated on individual dies: 15 metal ceramic restorations (MCR) (Ceramco II, Ceramco, and Argelite 60), 15 pressed-to-metal restorations (PTM) (CPC-MK, and Argelite 60), and 15 pressed ceramic restorations (PCR) (CPC-MK). The marginal fit of the crowns was evaluated every 90 degrees around the crown margin circumference under a microscope at original magnification x 45. A 1-way analysis of variance (ANOVA) was used to compare data (alpha=.05).
  
  
  RESULTS
  The mean marginal discrepancy for MCRs was 94 +/- 41 microm, for PTMs, 88 +/- 29 microm, and for PCRs, 81 +/- 25 microm. The 1-way ANOVA showed no significant difference between groups ( P =.568).
  
  
  CONCLUSIONS
  The marginal fit of pressed-to-metal (PTMs) and pressed all-ceramic crowns (PCRs) was similar to that of traditional metal-ceramic crowns (MCRs).
authors.affiliation: New York University College of Dentistry, New York, NY, USA. edg0790@nyu.edu
authors.forename: Edward B
authors.initials: EB
authors.lastname: Goldin
authors.forename: Norman W
authors.initials: NW
authors.lastname: Boyd
authors.forename: Gary R
authors.initials: GR
authors.lastname: Goldstein
authors.forename: Eugene L
authors.initials: EL
authors.lastname: Hittelman
authors.forename: Van P
authors.initials: VP
authors.lastname: Thompson
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry; D003442:Crowns; D018772:Dental Marginal Adaptation / Q000592:standards*; D017267:Dental Prosthesis Design; D006801:Humans; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D016876:Metal Ceramic Alloys; C078519:leucite