title: Fit of single tooth zirconia copings: comparison between various manufacturing processes.
abstract: BACKGROUND
  Various CAD/CAM processes are commercially available to manufacture zirconia copings. Comparative data on their performance in terms of fit are needed.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to compare the internal and marginal fit of single tooth zirconia copings manufactured with a CAD/CAM process (Procera; Nobel Biocare) and a mechanized manufacturing process (Ceramill; Amann Girrbach).
  
  
  METHODS
  Abutments (n=20) prepared in vivo for ceramic crowns served as a template for manufacturing both Procera and Ceramill zirconia copings. Copings were manufactured and cemented (Clearfil Esthetic Cement; Kuraray) on epoxy replicas of stone cast abutments. Specimens were sectioned. Nine measurements were performed for each coping. Over- and under-extended margins were evaluated. Comparisons between the 2 processes were performed with a generalized linear mixed model (α=.05).
  
  
  RESULTS
  Internal gap values between Procera and Ceramill groups were not significantly different (P=.13). The mean marginal gap (SD) for Procera copings (51(50) μm) was significantly smaller than for Ceramill (81(66) μm) (P<.005). The percentages of over- and under-extended margins were 43% and 57% for Procera respectively, and 71% and 29% for Ceramill.
  
  
  CONCLUSIONS
  Within the limitations of this in vitro study, the marginal fit of Procera copings was significantly better than that of Ceramill copings. Furthermore, Procera copings showed a smaller percentage of over-extended margins than did Ceramill copings.
authors: Department of Fixed Prosthodontics, Institute of Dentistry, University of Liége Hospital (ULg CHU), Belgium. charlotte. grenade@chu.ulg.ac.be
authors: Charlotte
authors: C
authors: Grenade
authors: Amélie
authors: A
authors: Mainjot
authors: Alain
authors: A
authors: Vanheusden
mesh_terms: D017076:Computer-Aided Design; D003442:Crowns / Q000592:standards*; D000044:Dental Abutments / Q000592:standards*; D018772:Dental Marginal Adaptation; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D006801:Humans; D014093:Tooth, Artificial / Q000145:classification / Q000592:standards; D015040:Zirconium
chemical_list: D003776:Dental Porcelain; D015040:Zirconium