title: Evaluation of mechanical and optical behavior of current esthetic dental restorative CAD/CAM composites.
abstract: OBJECTIVE
  To determine the mechanical and optical properties of CAD/CAM composites (LAVA Ultimate, Cerasmart, Shofu Block and two exp. CAD/CAM composites), a hybrid material (VITA Enamic), a leucite (IPS Empress CAD) and a lithium disilicate glass-ceramic (IPS e.max CAD).
  
  
  METHODS
  Three-point flexural strength (FS) was investigated according ISO 6872:2008 (N=240/n=30). Two-body wear (TBW) was analyzed in a chewing simulator (1,200,000 cycles, 50N, 5°/55°C) using human teeth as antagonists (N=120/n=15). Quantitative analysis of wear was carried out with a 3D-scanner and associated matching software. Discoloration rate (DR) after 14 days of storage in cress, curry, red wine, and distilled water (N=384/n=12), and translucency (T) (N=384/n=48) of CAD/CAM materials were measured in a spectrophotometer (400-700nm wavelength). Data were analyzed using two-/one-way ANOVA with Scheffé post-hoc test, Kruskal-Wallis-H test, and linear mixed models (α=0.05).
  
  
  RESULTS
  IPS e.max CAD showed the highest FS (p<0.001), followed by LAVA Ultimate; however, not different from the remaining CAD/CAM composites (exception: Shofu Block). The lowest FS showed VITA Enamic and IPS Empress CAD (p<0.001). IPS Empress CAD, VITA Enamic, exp. CAD/CAM composite 2, followed by IPS e.max presented lower material TBW than the remaining CAD/CAM materials (p<0.001). The highest antagonist wear was observed for the tested glass-ceramics and the hybrid material (p<0.001). Storage medium (red wine>curry>cress>distilled water) exerted the highest influence on DR (p<0.001), closely followed by CAD/CAM material. Glass-ceramics showed lower DR than CAD/CAM composites (p<0.001).
  
  
  CONCLUSIONS
  CAD/CAM composites presented moderate FS, high T and antagonist friendly behavior. Glass-ceramic demonstrated the most favorable DR and lowest TBW on the material side.
authors.affiliation: Department of Prosthodontics, Dental School, Ludwig-Maximilians-University Munich, Goethestrasse 70, 80336 Munich, Germany. Electronic address: bogna.stawarczyk@med.uni-muenchen.de.
authors.forename: Bogna
authors.initials: B
authors.lastname: Stawarczyk
authors.affiliation: Department of Prosthodontics, Dental School, Ludwig-Maximilians-University Munich, Goethestrasse 70, 80336 Munich, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Liebermann
authors.affiliation: Department of Prosthodontics, Dental School, Ludwig-Maximilians-University Munich, Goethestrasse 70, 80336 Munich, Germany.
authors.forename: Marlis
authors.initials: M
authors.lastname: Eichberger
authors.affiliation: Department of Prosthodontics, Dental School, Ludwig-Maximilians-University Munich, Goethestrasse 70, 80336 Munich, Germany.
authors.forename: Jan-Frederik
authors.initials: JF
authors.lastname: Güth
mesh_terms: D003776:Dental Porcelain / Q000737:chemistry; D003793:Dental Restoration, Permanent; D004955:Esthetics, Dental; D008422:Materials Testing; D055595:Mechanical Phenomena; D055620:Optical Phenomena; D011108:Polymers / Q000737:chemistry
chemical_list: D011108:Polymers; C493120:lithia disilicate; D003776:Dental Porcelain
keywords: CAD/CAM composite; Discoloration; Optical and mechanical properties; Three-point flexural strength; Two-body wear