title: Comparative in vitro wear resistance of CAD/CAM composite resin and ceramic materials.
abstract: BACKGROUND
  Composite resin is a promising option in computer-aided design and computer-aided manufacturing (CAD/CAM) dentistry; however, the wear resistance of composite resin remains a primary concern.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to evaluate the wear resistance of 5 CAD/CAM materials (n=10), consisting of 4 composite resins (3M Lava Ultimate, Kerr experimental composite resin material, Vita Enamic, 3M Paradigm MZ100) and 1 ceramic (Vita Mark II) in contact with natural human enamel cusps.
  
  
  METHODS
  Specimens were loaded into a computer-controlled mastication simulator and subjected to 200000 mechanical cycles (49 N) against natural human enamel simultaneously with 500 thermal cycles (5°C to 50°C to 5°C). The wear resistance was analyzed by measuring the vertical substance loss (the maximum depth of the worn area) in the contact point area of the specimen. The worn surfaces were observed by scanning electron microscopy to determine the wear patterns.
  
  
  RESULTS
  Vita Mark II exhibited the best wear resistance among the tested materials, followed by 3M Lava Ultimate, Vita Enamic, and 3M Paradigm MZ100. The Kerr experimental material exhibited the lowest wear resistance, yet its results were not significantly different from those of the 3 other composite resin blocks (P>.05).
  
  
  CONCLUSIONS
  Within the limitations of this in vitro study, the wear resistance of composite resin blocks in contact with enamel cusps was significantly lower than that of a ceramic block.
authors.affiliation: Assistant, Department of Stomatology, Beijing University, People's Hospital, Beijing, China. Electronic address: lizhi@pkuph.edu.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Zhi
authors.affiliation: Research Section Head, Division of Cariology and Endodontology, School of Dental Medicine, University of Geneva, Geneva, Switzerland.
authors.forename: Tissiana
authors.initials: T
authors.lastname: Bortolotto
authors.affiliation: Professor, Division of Cariology and Endodontology, School of Dental Medicine, University of Geneva, Geneva, Switzerland.
authors.forename: Ivo
authors.initials: I
authors.lastname: Krejci
mesh_terms: D002516:Ceramics; D003188:Composite Resins / Q000737:chemistry*; D017076:Computer-Aided Design; D003743:Dental Enamel; D003776:Dental Porcelain / Q000737:chemistry*; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D003776:Dental Porcelain