title: The influence of simulated clinical handling on the flexural and compressive strength of posterior composite restorative materials.
abstract: OBJECTIVE
  The aim of this study was to investigate the influence of clinical handling on the flexural and compressive strengths of two commercially available posterior composites.
  
  
  METHODS
  Since the manufacturing of test specimens in a truly clinical situation presents many problems, an in vitro model was developed, consisting of a phantom-head set-up in a clinical operatory. Two composite materials, recommended for use in posterior teeth, were used: P50 APC (3M Dental Products) and Herculite XRV (Kerr, Dental Manufacturing). Beam specimens for 3-point bending tests of both materials and cylindrical specimens for compression test of P50 were made both under ideal laboratory circumstances and under simulated clinical circumstances.
  
  
  RESULTS
  The difference in mean flexural strength between laboratory prepared and the quasi-clinically prepared specimens was highly significant for both the specimens handled in a clinical manner was 15% of the flexural strength of the P50 specimens made under laboratory conditions, and the difference for Herculite XRV was 29%. No difference in compressive strength could be shown between the laboratory-fabricated and the quasi-clinically made specimens of P50.
  
  
  CONCLUSIONS
  The relative flexural strength of composite materials in a clinical situation may differ significantly from that predicted from mechanical properties measured in vitro.
authors.affiliation: TRIKON: Institute for Dental Clinical Research, Department of Cariology and Endodontology, University of Nijmegen, The Netherlands.
authors.forename: M C
authors.initials: MC
authors.lastname: Huysmans
authors.forename: P G
authors.initials: PG
authors.lastname: van der Varst
authors.forename: E P
authors.initials: EP
authors.lastname: Lautenschlager
authors.forename: P
authors.initials: P
authors.lastname: Monaghan
mesh_terms: D001641:Bicuspid; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D016009:Chi-Square Distribution; D003188:Composite Resins / Q000737:chemistry*; D019245:Compressive Strength; D018865:Dental Research / Q000379:methods; D003793:Dental Restoration, Permanent / Q000379:methods*; D008422:Materials Testing / Q000379:methods; D008963:Molar; D018583:Pliability; D015203:Reproducibility of Results; D012107:Research Design; D019279:Resin Cements; D018709:Statistics, Nonparametric
chemical_list: D003188:Composite Resins; D019279:Resin Cements; C065770:Herculite XR; C065771:P50 composite resin; D017438:Bisphenol A-Glycidyl Methacrylate