title: Trueness of four different milling procedures used in dental CAD/CAM systems.
abstract: OBJECTIVE
  Milling is a crucial step in producing restorations using computer-aided design and computer-aided manufacturing (CAD/CAM) systems. In this study the trueness of currently available milling devices was evaluated.
  
  
  METHODS
  Thirty clinical cases (ten inlays, ten crowns, ten onlays) were milled from ceramic blocks using four different milling approaches: five axis with IMES CORiTEC 450i, four axis with CEREC MCXL, four axis with CEREC MCXL-EF and five axis with inLab MCX5. The milled restorations were scanned and the occlusal and inner surfaces compared to the originally calculated 3D surface using difference analysis software. The (90-10 %) / 2 percentile of the distances were calculated and analysed using one-way ANOVA with the post hoc Scheffé test (α = 0.05). Chipping of marginal areas were visually examined and analysed using one-way ANOVA with a post hoc Tamhane test (α = 0.05).
  
  
  RESULTS
  At inner surfaces, the milling trueness of IMES (33.9 ± 16.3 μm), X5 (32.3 ± 9.7 μm) and MCXL-EF (34.4 ± 7.5 μm) was significantly better (p < 0.001) than that of MCXL (62.1 ± 17.1 μm). At occlusal surfaces, MCXL-EF (25.7 ± 9.3 μm) showed significant higher accuracy (p < 0.001) than MCXL (48.7 ± 23.3 μm) and X5 (40.9 ± 20.4 μm). IMES produced the most chipping (p < 0.001).
  
  
  CONCLUSIONS
  Five-axis milling devices yield high trueness. MCXL-EF is competitive and may allow chairside fabrication with good milling results.
  
  
  CONCLUSIONS
  Accurate milling is required for well-fitting restorations and thereby requires fewer manual finishing steps, yields smaller marginal gaps, resistance to secondary caries and longevity of restorations.
authors.affiliation: Division for Computerized Restorative Dentistry, Clinic for Preventive Dentistry, Periodontology and Cariology, Center of Dental Medicine, University of Zurich, 11 Plattenstrasse, 8032, Zurich, Switzerland. corinna.kirsch@zzm.uzh.ch.
authors.forename: Corinna
authors.initials: C
authors.lastname: Kirsch
authors.affiliation: Division for Computerized Restorative Dentistry, Clinic for Preventive Dentistry, Periodontology and Cariology, Center of Dental Medicine, University of Zurich, 11 Plattenstrasse, 8032, Zurich, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Ender
authors.affiliation: Clinic for Preventive Dentistry, Periodontology and Cariology, Center of Dental Medicine, University of Zurich, 11 Plattenstrasse, 8032, Zurich, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Attin
authors.affiliation: Division for Computerized Restorative Dentistry, Clinic for Preventive Dentistry, Periodontology and Cariology, Center of Dental Medicine, University of Zurich, 11 Plattenstrasse, 8032, Zurich, Switzerland.
authors.forename: Albert
authors.initials: A
authors.lastname: Mehl
mesh_terms: D002516:Ceramics; D017076:Computer-Aided Design / Q000295:instrumentation*; D003442:Crowns; D017267:Dental Prosthesis Design / Q000295:instrumentation*; D006801:Humans; D007284:Inlays; D012984:Software; D013499:Surface Properties
keywords: Accuracy; Computer-aided design/computer-aided manufacturing (CAD/CAM); Fit; Milling; Trueness