title: In vitro evaluation of the internal and marginal misfit of CAD/CAM zirconia copings.
abstract: BACKGROUND
  The constant updating of computer-aided design/computer-aided manufacture (CAD/CAM) systems and the introduction of new systems confirm the need for scientific evidence on internal and marginal adaptation.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to measure and compare the degree of internal and marginal misfits of zirconia single-unit copings made by using 3 different CAD/CAM systems (Ceramill, Lava 3M, and Neoshape).
  
  
  METHODS
  Twenty-four anatomic prefabricated abutments (Neodent) were used to fabricate zirconia copings in Ceramill (n=8), Lava (n=8), and Neoshape (n=8). All copings were cemented and cut with a precision cutting machine to obtain 5 surfaces (mesial, distal, buccal, palatal, and incisal) and angle regions (internal axiogingival and axioincisal angles). Measurements were obtained from images at a magnification of ×100 and ×200 made with a digital camera attached to an optical microscope and adapted with a measuring device. The data were statistically analyzed with the 2-way ANOVA and Tukey honestly significant difference tests (α=.05).
  
  
  RESULTS
  In the internal misfit evaluation, the mean values observed for Ceramill, Lava, and Neoshape were palatal surface 76.5, 65.5, and 77.7 μm (P=.003); angle regions 69.4, 68.6, and 74.5 μm (P=.010); incisal surface 127.7, 97.2, and 182.2 μm (P<.001); and overall mean 72.1, 69.4, and 76.4 μm (P=.003). Significant differences were not found for mesial, distal, or buccal surfaces (P>.05). In the evaluation of marginal misfit (marginal discrepancy and absolute marginal discrepancy), the mean values found were 40.9 and 65.8 μm for Ceramill, 34.2 and 70.0 μm for Lava, and 39.3 and 74.5 μm for Neoshape. No significant differences were found among the 3 systems (P>.05).
  
  
  CONCLUSIONS
  Although the Lava system showed a significantly lower value of internal misfit than the Neoshape system, all systems showed clinically acceptable marginal misfit values.
authors.affiliation: Graduate student, Department of Oral Rehabilitation, Veiga de Almeida University, Rio de Janeiro, Brazil.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Lins
authors.affiliation: Postdoctoral student, Department of Material Science, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Vinícius
authors.initials: V
authors.lastname: Bemfica
authors.affiliation: Full Professor, Department of Oral Rehabilitation, Veiga de Almeida University, Rio de Janeiro, Brazil.
authors.forename: Celso
authors.initials: C
authors.lastname: Queiroz
authors.affiliation: Full Professor, Department of Oral Rehabilitation, Veiga de Almeida University, Rio de Janeiro, Brazil. Electronic address: andradejr13@gmail.com.
authors.forename: Antonio
authors.initials: A
authors.lastname: Canabarro
mesh_terms: D002484:Cementation / Q000379:methods; D002516:Ceramics / Q000737:chemistry*; D017076:Computer-Aided Design; D003442:Crowns; D000044:Dental Abutments; D018772:Dental Marginal Adaptation; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008422:Materials Testing; D008853:Microscopy / Q000295:instrumentation; D010781:Photography / Q000379:methods; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry; D015019:Yttrium / Q000737:chemistry*; D015036:Zinc Phosphate Cement / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry*
chemical_list: D003764:Dental Materials; C499362:yttria stabilized tetragonal zirconia; D015019:Yttrium; D015036:Zinc Phosphate Cement; D015040:Zirconium; D014025:Titanium