title: Monomer conversion versus flexure strength of a novel dental composite.
abstract: OBJECTIVE
  To quantify the monomer conversion and flexural strength of an experimental oxirane-based composite material (EXL596) compared with two, commercially available, dimethacrylate based restoratives (Z250 and Z100).
  
  
  METHODS
  Fourier-transform infra-red spectroscopy (FTIR) was utilised to evaluate the degree of conversion (DC) (n=5) and biaxial flexure strength (BFS) testing (n=20) was used to analyse flexural strength and associated Weibull moduli (m) of each material following 0.1, 0.5, 1, 4, 24 and 48 h immersion in a lightproof waterbath maintained at 37+/-1 degrees C.
  
  
  RESULTS
  The DC of Z250 and Z100 following 0.1, 0.5 and 1 h post-irradiation was significantly greater than the DC of EXL596 for the same immersion periods. This was manifested as a significant decrease in BFS and associated m of EXL596 compared with Z250 and Z100 for the 0.1, 0.5 and 1 h post-irradiation periods. The DC and BFS of EXL596 were significantly greater than Z250 and Z100 following 24 h immersion.
  
  
  CONCLUSIONS
  Assessment of FTIR spectra, BFS and associated m has provided a useful method in the quantitative analysis of resin-based composite conversion. Identification of the decreased DC of EXL596 compared with Z250 and Z100 was achieved using FTIR. However, decreased conversion rates within the first hour following irradiation of EXL596 may compromise flexural strength properties (associated with a decrease in BFS and m) which may be inadequate under masticatory loading.
authors.affiliation: Biomaterials Unit, School of Dentistry, University of Birmingham, St Chad's Queensway, B4 6NN, Birmingham, UK.
authors.forename: William M
authors.initials: WM
authors.lastname: Palin
authors.forename: Garry J P
authors.initials: GJ
authors.lastname: Fleming
authors.forename: F J Trevor
authors.initials: FJ
authors.lastname: Burke
authors.forename: Peter M
authors.initials: PM
authors.lastname: Marquis
authors.forename: Ros C
authors.initials: RC
authors.lastname: Randall
mesh_terms: D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D004548:Elasticity; D005027:Ethylene Oxide / Q000737:chemistry; D006801:Humans; D007101:Immersion; D008027:Light; D008422:Materials Testing; D018583:Pliability; D012822:Silicon Dioxide / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013997:Time Factors; D014867:Water / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C479118:EXL596; C444701:Filtek Z250; C083568:Z100 composite resin; D014867:Water; D012822:Silicon Dioxide; D015040:Zirconium; D005027:Ethylene Oxide; C028541:zirconium oxide