title: Two-body wear rate of CAD/CAM resin blocks and their enamel antagonists.
abstract: BACKGROUND
  Computer-aided design and computer-aided manufacturing (CAD/CAM) resins exhibit good mechanical properties and can be used as long-term restorations. The wear rate of such resins and their enamel antagonists is unknown.
  
  
  OBJECTIVE
  The purpose of this study was to test and compare the 2-body wear rate of CAD/CAM resin blocks.
  
  
  METHODS
  Wear specimens (N=42, n=6) were made from 5 CAD/CAM resins: ZENO PMMA (ZP), artBloc Temp (AT), Telio CAD (TC), Blanc High-class (HC), CAD-Temp (CT); 1 manually polymerized resin: Integral esthetic press (negative control group, IEP); and 1 glass-ceramic: VITA Mark II (positive control group, VM2). The specimens for the wear resistance were aged in a thermomechanical loading machine (49 N, 1.67 Hz, 5/50°C) with human enamel antagonists. The material loss of all specimens before, during, and after aging was evaluated with a 3DS profilometer. The measured material loss data of all tested groups were statistically evaluated with linear mixed model analysis (a=.05).
  
  
  RESULTS
  Manually polymerized resin showed significantly higher material wear (P<.001) than all other tested groups. Glass-ceramic showed significantly lower wear values (P<.001) than CAD/CAM resins ZP, AT, HC, CT, and IES. CAD/CAM resin TC was not significantly different from the positive control group. Glass-ceramic showed the highest enamel wear values (P<.001) of all tested resins. No differences were found in the enamel wear among all resins. The glass-ceramic group showed damage in the form of cracks on the worn enamel surface in 50% of specimens.
  
  
  CONCLUSIONS
  CAD/CAM resins showed lower wear rates than those conventionally polymerized. Only one CAD/CAM resin, TC, presented material wear values comparable with glass-ceramic. The tested glass-ceramic developed cracks in the enamel antagonist and showed the highest enamel wear values of all other tested groups.
authors.affiliation: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, University of Zurich, Zurich, Switzerland. bogna.stawarczyk@med.uni-muenchen.de
authors.forename: Bogna
authors.initials: B
authors.lastname: Stawarczyk
authors.forename: Mutlu
authors.initials: M
authors.lastname: Özcan
authors.forename: Albert
authors.initials: A
authors.lastname: Trottmann
authors.forename: Felix
authors.initials: F
authors.lastname: Schmutz
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Roos
authors.forename: Christoph
authors.initials: C
authors.lastname: Hämmerle
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D001732:Bite Force; D002516:Ceramics / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D017076:Computer-Aided Design; D003743:Dental Enamel / Q000473:pathology; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry; D019554:Dental Restoration Wear; D006801:Humans; D008689:Methacrylates / Q000737:chemistry; D008768:Methylmethacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D057085:Tooth Wear / Q000473:pathology
chemical_list: D000180:Acrylic Resins; D003188:Composite Resins; D003764:Dental Materials; D008689:Methacrylates; D008768:Methylmethacrylates; D011140:Polyurethanes; C082340:Vita Mark II; D003776:Dental Porcelain; C029824:urethane dimethacrylate luting resin; D017438:Bisphenol A-Glycidyl Methacrylate; C006903:carbopol 940; C023506:Glass ceramics; D019904:Polymethyl Methacrylate