title: Comparison of the marginal fit of pressable ceramic to metal ceramic restorations.
abstract: OBJECTIVE
  The aim of this in vitro study was to compare the marginal adaptation of a pressed ceramic material, when used with and without a metal substructure, to a traditional feldspathic porcelain-fused-to-metal restoration with a porcelain butt margin.
  
  
  METHODS
  A maxillary central incisor typodont tooth was prepared with a 1.5 mm 360 degrees shoulder with rounded internal line angle, and 30 polyether impressions were made. Dies were poured in type IV dental stone, and 30 restorations were fabricated: 10 metal ceramic restorations (MCR) with porcelain butt joints, 10 pressed to metal restorations (PTM), and 10 all-ceramic restorations (PCR). All restorations were evaluated on their respective dies at 45x magnification using an Olympus SZX-12, measurements of the marginal openings were made, and ANOVA and Scheffé post hoc tests were used to evaluate the data.
  
  
  RESULTS
  The mean marginal opening was 72.2 +/- 5.9 microm for MCR, 49.0 +/- 5.9 microm for PTM, and 55.8 +/- 5.9 microm for PCR. The post hoc tests showed that there was a statistical difference between the marginal adaptation of the PTM and MCR groups (p < 0.05). There was no significant difference in marginal adaptation between the PTM and the PCR groups, or the PCR and the MCR groups.
  
  
  CONCLUSIONS
  The PTM group demonstrated a smaller mean marginal opening than the MCR group. The mean marginal openings of all three groups were within a clinically acceptable range.
authors.affiliation: Department of Prosthodontics, New York University College of Dentistry, New York, NY, USA. jh1063@nyu.edu
authors.forename: Jason E
authors.initials: JE
authors.lastname: Holden
authors.forename: Gary R
authors.initials: GR
authors.lastname: Goldstein
authors.forename: Eugene L
authors.initials: EL
authors.lastname: Hittelman
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Clark
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry*; D003442:Crowns; D018772:Dental Marginal Adaptation / Q000592:standards*; D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design; D006801:Humans; D007180:Incisor; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D003765:Models, Dental; D017680:Potassium Compounds / Q000737:chemistry; D013499:Surface Properties; D019231:Tooth Preparation, Prosthodontic
chemical_list: D000538:Aluminum Silicates; D016876:Metal Ceramic Alloys; D017680:Potassium Compounds; D003776:Dental Porcelain; C016447:feldspar