title: Two-body in vitro wear study of some current dental composites and amalgams.
abstract: BACKGROUND
  Wear resistance of restorative materials is a major concern in clinical practice for restorations involving occlusion. The relatively poor wear resistance of dental composites in stress-bearing posterior situations has restricted even wider clinical application of this type of restorative material.
  
  
  OBJECTIVE
  This in vitro study compared the relative wear resistance of a selection of current dental composites and amalgams under cyclic loading to explore the wear mechanisms operating on these materials and to assess their relative potential clinical wear resistance under variable masticatory loads.
  
  
  METHODS
  A 2-body in vitro wear test was undertaken on a selection of 2 Ultrafine Compact-Filled composites, 1 microfilled composite, and 3 dental amalgams. An alternating sine curve load (0.5 to 15 N) was applied to the wear surface through a rotating countersample with a purpose-built system to simulate the variable loading pattern that occurs during mastication.
  
  
  RESULTS
  Under conditions simulating the repetitive cyclic loading pattern that may occur intraorally in high stress occlusal contact situations, the Ultrafine Compact-Filled composites exhibited a delamination wear pattern and had a significantly lower wear resistance than the amalgams. By comparison, the microfilled composite (Silux Plus) displayed an improved wear resistance that was superior to some amalgams. Dispersalloy had the best wear resistance among the materials selected.
  
  
  CONCLUSIONS
  The wear of Ultrafine Compact-Filled composite and microfilled composite differed and reflect different operative wear mechanisms. For amalgams, the size, shape, and composition of the particles had an effect on the wear resistance of the materials.
authors.affiliation: School of Dentistry, The University of Birmingham, Birmingham, United Kingdom.
authors.forename: X
authors.initials: X
authors.lastname: Hu
authors.forename: P M
authors.initials: PM
authors.lastname: Marquis
authors.forename: A C
authors.initials: AC
authors.lastname: Shortall
mesh_terms: D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D001732:Bite Force; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003188:Composite Resins / Q000737:chemistry*; D003722:Dental Alloys / Q000737:chemistry; D003723:Dental Amalgam / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D019554:Dental Restoration Wear; D003793:Dental Restoration, Permanent; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010316:Particle Size; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003722:Dental Alloys; D003764:Dental Materials; C083568:Z100 composite resin; C065771:P50 composite resin; C074741:Silux Plus; C033470:Dispersalloy; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide; D003723:Dental Amalgam; C050635:command ultrafine; D015040:Zirconium