title: Evaluation of marginal fit of CAD/CAM restorations fabricated through cone beam computerized tomography and laboratory scanner data.
abstract: BACKGROUND
  Whether cone beam computed tomography (CBCT) images can be used for the fabrication of computer-aided design/computer-aided manufacturing (CAD/CAM) restorations is unknown.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to evaluate the marginal fit of CAD/CAM restorations fabricated by using data from CBCT scans with 3 different voxels and laser scanner images.
  
  
  METHODS
  A crown preparation was made on an extracted premolar tooth according to ceramic crown preparation guidelines. The prepared tooth was scanned with a 3-dimensional (3D) extraoral laser scanner (D900; 3Shape), and CBCT scans were also made with an i-CAT cone beam 3D imaging system at 3 different voxel resolution settings: 0.125 mm, 0.20 mm, and 0.30 mm. The 3D images obtained from the laser scanner and CBCT scans were sent to CAD software, and a crown design was completed. Information was sent to CAM software to mill the crowns from poly(methyl methacrylate) (PMMA) blocks (n=9 from the laser scanner and 27 from 3 different CBCT scans). A total of 144 images (4 groups, 9 crowns per group, 4 sites per crown) were measured for vertical marginal discrepancy under a stereoscopic zoom microscope. One-way analysis of variance (ANOVA) was used to analyze the data. According to the assumption of homogeneity of variance, the post hoc Tukey multiple comparison test was performed (α=.05).
  
  
  RESULTS
  The marginal gap values of crowns fabricated with an extraoral laser scanner were significantly lower than those of crowns fabricated with 0.3-, 0.2-, and 0.125-voxel CBCT images (P<.001). The marginal gap was greater when 0.3- and 0.2-voxel CBCT images were used than when 0.125-voxel CBCT images were used (P<.001).
  
  
  CONCLUSIONS
  Crowns fabricated with the laser scanner images had lower and clinically acceptable marginal discrepancies than crowns fabricated with CBCT images in 3 different voxels. Of all the CBCT scans, only images with 0.125 voxel produced crowns with clinically acceptable marginal discrepancy.
authors.affiliation: Assistant Professor, Eskisehir Osmangazi University, Faculty of Dentistry, Department of Prosthodontics, Eskisehir, Turkey. Electronic address: eseker@ogu.edu.tr.
authors.forename: Emre
authors.initials: E
authors.lastname: Şeker
authors.affiliation: Associate Professor, Baskent University Faculty of Dentistry, Department of Prosthodontics, Adana, Turkey.
authors.forename: Tuncer Burak
authors.initials: TB
authors.lastname: Ozcelik
authors.affiliation: Private practice, Nagpur, India.
authors.forename: Nakul
authors.initials: N
authors.lastname: Rathi
authors.affiliation: Associate Professor, Division of Restorative Sciences and Prosthodontics, The Ohio State University College of Dentistry, Columbus, Ohio.
authors.forename: Burak
authors.initials: B
authors.lastname: Yilmaz
mesh_terms: D017076:Computer-Aided Design; D054893:Cone-Beam Computed Tomography; D003442:Crowns; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D013499:Surface Properties
chemical_list: D003776:Dental Porcelain