title: Clinical marginal and internal adaptation of CAD/CAM milling, laser sintering, and cast metal ceramic crowns.
abstract: BACKGROUND
  Metal ceramic crowns are widely used in clinical practice, but comparisons of the clinical adaptation of restorations made with different processing techniques are lacking.
  
  
  OBJECTIVE
  The purpose of this study was to compare the clinical marginal and internal adaptation of metal ceramic crowns fabricated with 3 different techniques: computer-aided design and computer-aided manufacturing (CAD/CAM) milling (CCM), direct metal laser sintering (DMLS), and traditional casting (TC).
  
  
  METHODS
  Twenty CCM, 20 DMLS, and 20 TC metal ceramic crowns were fabricated for 42 patients. Before luting the crowns, silicone replicas were obtained to measure marginal gap and internal adaptation that was evaluated at 3 regions: axial wall, axio-occlusal angle, and occlusal surface. Measurements were made with a reflected light binocular stereomicroscope at 20× magnification and analyzed with 1-way analysis of variance (ANOVA) and the Bonferroni post hoc test (α=.05).
  
  
  RESULTS
  The mean marginal gap values were 86.64 μm for CCM, 96.23 μm for DMLS, and 75.92 μm for TC. The means at the axial wall region were 117.5 μm for the CCM group, 139.02 μm for the DMLS group, and 121.38 μm for the TC group. One-way ANOVA revealed no statistically significant differences among the groups for measurements at the marginal gap (P=.082) and the axial wall region (P=.114). The means at the axio-occlusal region were 142.1 μm for CCM, 188.12 μm for DMLS, and 140.63 μm for TC, and those at the occlusal surface region were 265.73 μm for CCM, 290.39 μm for DMLS, and 201.09 μm for TC. The mean values of group DMLS were significantly higher at the axio-occlusal region and the occlusal surface region than those of other groups (P<.05).
  
  
  CONCLUSIONS
  CCM, DMLS and TC metal ceramic crowns performed similarly in terms of clinical marginal and axial wall adaptation. The cement film thickness at the occlusal region and axio-occlusal region were higher for DMLS crowns.
authors.affiliation: Research Assistant, Department of Prosthetic Dentistry, School of Dentistry, Ege University, Izmir, Turkey.
authors.forename: Ece
authors.initials: E
authors.lastname: Tamac
authors.affiliation: Professor, Department of Prosthetic Dentistry, School of Dentistry, Ege University, Izmir, Turkey.
authors.forename: Suna
authors.initials: S
authors.lastname: Toksavul
authors.affiliation: Associate Professor, Department of Prosthetic Dentistry, School of Dentistry, Ege University, Izmir, Turkey. Electronic address: tomantr@yahoo.com.
authors.forename: Muhittin
authors.initials: M
authors.lastname: Toman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002858:Chromium Alloys / Q000737:chemistry; D017076:Computer-Aided Design; D003442:Crowns; D003735:Dental Casting Technique; D018772:Dental Marginal Adaptation; D017267:Dental Prosthesis Design; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007834:Lasers; D008297:Male; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D008875:Middle Aged; D010781:Photography / Q000379:methods; D011076:Polycarboxylate Cement / Q000737:chemistry; D013499:Surface Properties; D055815:Young Adult
chemical_list: D002858:Chromium Alloys; D016876:Metal Ceramic Alloys; D011076:Polycarboxylate Cement