title: Internal fit of pressed and computer-aided design/computer-aided manufacturing ceramic crowns made from digital and conventional impressions.
abstract: BACKGROUND
  No studies have evaluated the internal adaptation of pressed and milled ceramic crowns made from digital impressions.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to evaluate the internal fit of pressed and milled ceramic crowns made from digital and conventional impressions.
  
  
  METHODS
  Thirty polyvinyl siloxane (PVS) impressions and 30 Lava COS impressions made of a prepared dentoform tooth (master die) were fabricated. Thirty crowns were pressed in lithium disilicate (IPS e.max Press), and 30 crowns were milled from lithium disilicate blocks (IPS e.max CAD) (15/impression technique) with the E4D scanner and milling engine. The master die and the intaglio of the crowns were digitized with a 3-dimensional laser coordinate measurement machine. The digital master die and intaglio of each crown were merged. The distance between the die and the intaglio surface of the crown was measured at 3 standardized points. One-way ANOVA was used for statistical analysis (α=.05).
  
  
  RESULTS
  One-way ANOVA revealed that the internal gap obtained from the Lava/press group (0.211 mm, ±SD 0.041) was significantly greater than that obtained from the other groups (P<.001), while no significant differences were found among PVS/press (0.111 mm ±SD 0.047), PVS/CAD/CAM (0.116 mm ±SD 0.02), and Lava/CAD/CAM (0.145 mm ±SD 0.024).
  
  
  CONCLUSIONS
  The combination of the digital impression and pressed crown produced the least accurate internal fit.
authors.affiliation: Clinical Assistant Professor, Department of General Dentistry, Goldman School of Dental Medicine, Boston University, Boston, MA. Electronic address: vanadioti@gmail.com.
authors.forename: Evanthia
authors.initials: E
authors.lastname: Anadioti
authors.affiliation: Professor, Department of Prosthodontics, The University of Iowa College of Dentistry, Iowa City, Iowa.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Aquilino
authors.affiliation: Associate Professor, Department of Prosthodontics, The University of Iowa College of Dentistry, Iowa City, Iowa.
authors.forename: David G
authors.initials: DG
authors.lastname: Gratton
authors.affiliation: Professor, Department of Prosthodontics, The University of Iowa College of Dentistry, Iowa City, Iowa.
authors.forename: Julie A
authors.initials: JA
authors.lastname: Holloway
authors.affiliation: Professor, Department of Prosthodontics, The University of Iowa College of Dentistry, Iowa City, Iowa.
authors.forename: Isabelle L
authors.initials: IL
authors.lastname: Denry
authors.affiliation: Associate Professor, Mechanical and Industrial Engineering, The University of Iowa College of Engineering, Iowa City, Iowa.
authors.forename: Geb W
authors.initials: GW
authors.lastname: Thomas
authors.affiliation: Associate Research Scientist, Department of Preventive and Community Dentistry, The University of Iowa College of Dentistry, Iowa City, Iowa.
authors.forename: Fang
authors.initials: F
authors.lastname: Qian
mesh_terms: D017076:Computer-Aided Design; D003442:Crowns; D003760:Dental Impression Materials / Q000737:chemistry; D003761:Dental Impression Technique; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007834:Lasers; D018613:Microscopy, Confocal / Q000379:methods; D011145:Polyvinyls / Q000737:chemistry; D012833:Siloxanes / Q000737:chemistry; D013499:Surface Properties; D041623:Tomography, Optical Coherence / Q000379:methods
chemical_list: D003760:Dental Impression Materials; C520133:IPS e.max CAD LT; C508050:IPS e.max Press; D011145:Polyvinyls; D012833:Siloxanes; C493120:lithia disilicate; C034183:vinyl polysiloxane; D003776:Dental Porcelain