title: Effect of occlusal loading and mechanical properties of resin composite on stress generated in posterior restorations.
abstract: OBJECTIVE
  To investigate the effect of the occlusal load condition in association with the mechanical properties of resin composite, expressed by elastic modulus and post-gel shrinkage, on stresses in a premolar restored with various composites.
  
  
  METHODS
  Five resin composites (4 Seasons, Beautifil II, Filtek LS, Filtek Z250, and Z100) indicated for restoring posterior teeth were tested. Elastic modulus was measured using Knoop indentation tests (n=5). Post-gel shrinkage was measured with strain gauges (n = 10). Finite element analysis was used to calculate the stresses in a two-dimensional pre-molar model under four conditions: (We, without occlusal contact, representing stresses due to composite shrinkage only; Ct: contact generated between enamel of restored tooth and antagonist tooth; Cm: contact on tooth/composite restoration margin; Cc: stable centric contact on the composite restoration).
  
  
  RESULTS
  Elastic modulus varied between 12.6 (Filtek LS) and 21.5 (Z100) GPa; post-gel shrinkage varied between 0.11 (Filtek LS) and 0.96 (Z100) vol%. Composites with higher elastic modulus and post-gel shrinkage increased stress in the restored tooth. Occlusal contact on the tooth/composite restoration margin increased the stresses around the margin of the restoration. Stable centric contact on the restoration resulted in better stress distribution.
authors.forename: Aline A
authors.initials: AA
authors.lastname: Bicalho
authors.forename: Daranee
authors.initials: D
authors.lastname: Tantbirojn
authors.forename: Antheunis
authors.initials: A
authors.lastname: Versluis
authors.forename: Carlos J
authors.initials: CJ
authors.lastname: Soares
mesh_terms: D001641:Bicuspid / Q000503:physiopathology; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D001732:Bite Force; D003188:Composite Resins / Q000737:chemistry*; D003743:Dental Enamel / Q000503:physiopathology; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006244:Hardness; D006801:Humans; D008422:Materials Testing; D055595:Mechanical Phenomena; D058105:Polymerization; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D015040:Zirconium / Q000737:chemistry
chemical_list: C470433:Beautifil composite resin; D003188:Composite Resins; D003764:Dental Materials; C543062:Filtek LS Low Shrink resin; C444701:Filtek Z250; C083568:Z100 composite resin; C111840:flowable hybrid composite; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide; D015040:Zirconium