title: Clinical evaluations of cast gold alloy, machinable zirconia, and semiprecious alloy crowns: A multicenter study.
abstract: BACKGROUND
  Few studies have compared the marginal and internal fits of crowns fabricated from machinable palladium-silver-indium (Pd-Ag-In) semiprecious metal alloy.
  
  
  OBJECTIVE
  The purpose of this clinical study was to evaluate and compare the marginal and internal fits of machined Pd-Ag-In alloy, zirconia, and cast gold crowns.
  
  
  METHODS
  A prospective clinical trial was performed on 35 participants and 52 abutment teeth at 2 centers. Individuals requiring prosthetic restorations were treated with gold alloy or zirconia crowns (2 control groups) or Pd-Ag-In alloy crowns (experimental group). A replica technique was used to evaluate the marginal and internal fits. The buccolingual and mesiodistal cross-sections were measured, and a noninferiority comparison was conducted.
  
  
  RESULTS
  The mean marginal gaps were 68.2 μm for the gold crowns, 75.4 μm for the zirconia crowns, and 76.9 μm for the Pd-Ag-In alloy crowns. In the 5 cross-sections other than the distal cross-section, the 2-sided 95% confidence limits for the differences between the Pd-Ag-In alloy crowns and the 2 control groups were not larger than the 25-μm noninferiority margin. The control groups displayed smaller internal gaps in the line angle and occlusal spaces compared with the Pd-Ag-In crown group.
  
  
  CONCLUSIONS
  The marginal gaps of machinable Pd-Ag-In alloy crowns did not meet the noninferiority criterion in the distal margin compared with zirconia and gold alloy crowns. Nonetheless, all 3 crowns had clinically applicable precision.
authors.affiliation: Clinical Associate Professor, Department of Prosthodontics and Dental Research Institute, Seoul National University Gwanak Dental Hospital, Seoul, Korea.
authors.forename: Ji-Man
authors.initials: JM
authors.lastname: Park
authors.affiliation: Former resident, Department of Prosthodontics, School of Medicine, Ewha Womans University, Seoul, Korea.
authors.forename: Yong-Shin
authors.initials: YS
authors.lastname: Hong
authors.affiliation: Professor, Department of Prosthodontics, School of Medicine, Ewha Womans University, Seoul, Korea.
authors.forename: Eun-Jin
authors.initials: EJ
authors.lastname: Park
authors.affiliation: Professor, Department of Prosthodontics and Dental Research Institute, Seoul National University, Seoul, Korea.
authors.forename: Seong-Joo
authors.initials: SJ
authors.lastname: Heo
authors.affiliation: Professor, Department of Dentistry, School of Medicine, Inha University, Incheon, Korea. Electronic address: onsdo@inha.ac.kr.
authors.forename: Namsik
authors.initials: N
authors.lastname: Oh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017076:Computer-Aided Design; D003442:Crowns; D003722:Dental Alloys / Q000627:therapeutic use*; D018772:Dental Marginal Adaptation; D017267:Dental Prosthesis Design; D005260:Female; D006047:Gold Alloys / Q000627:therapeutic use*; D006801:Humans; D007204:Indium / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010165:Palladium / Q000627:therapeutic use; D018030:Silver Compounds / Q000627:therapeutic use; D055815:Young Adult; D015040:Zirconium / Q000627:therapeutic use*
chemical_list: D003722:Dental Alloys; D006047:Gold Alloys; D018030:Silver Compounds; D007204:Indium; D010165:Palladium; D015040:Zirconium; C028541:zirconium oxide