title: BAPO as an alternative photoinitiator for the radical polymerization of dental resins.
abstract: OBJECTIVE
  This study evaluated the performance of phenylbis (2,4,6-trimethylbenzoyl)-phosphine oxide (BAPO) as an alternative photoinitiator in the polymerization kinetics (PK), flexural strength (σ) and elastic modulus (E) of a model dental resin.
  
  
  METHODS
  A monomer mixture based on Bis-GMA and TEGDMA was used as model dental resin. Initially a screening was performed to evaluate BAPO concentrations (0.125, 0.25, 0.50, 1, 2, and 4 mol%). Photoinitiator systems were formed with the combination of camphorquinone (CQ), ethyl-dimethylamino benzoate (EDAB), diphenyliodonium hexafluorophosphate (DPIHFP), and BAPO. Groups with unitary photoinitiator systems (BAPO and CQ), binary (BAPO+EDAB, BAPO+DPIHFP and CQ+EDAB), ternary (BAPO+CQ+EDAB, BAPO+CQ+DPIHFP, BAPO+EDAB+DPIHFP and CQ+EDAB+DPIHFP) and quaternary (BAPO+CQ+EDAB+DPIHFP) were formulated for evaluation. Real-time Fourier transform infrared spectroscopy was used to investigate the PK and test mini-bending to evaluate σ and E.
  
  
  RESULTS
  When only CQ was used, a slow polymerization reaction was observed and a lower monomer conversion. When only BAPO was used as photoinitiator an increase in the polymerization rate was observed and conversion was higher than CQ+EDAB. The ternary system (BAPO+EDAB+DPIHFP) showed the highest polymerization and conversion rate, in short photo-activation time.
  
  
  CONCLUSIONS
  BAPO it is a potential photoinitiator for the photopolymerization of dental materials.
authors: Biomaterials Development and Control Center, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil.
authors: Carine T W
authors: CT
authors: Meereis
authors: Biomaterials Development and Control Center, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil.
authors: Fernanda B
authors: FB
authors: Leal
authors: Dentistry Course, University Center of Várzea Grande, Várzea Grande, MT, Brazil.
authors: Giana S
authors: GS
authors: Lima
authors: School of Dentistry, University of North of Paraná, Londrina, PR, Brazil.
authors: Rodrigo V
authors: RV
authors: de Carvalho
authors: Biomaterials Development and Control Center, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil.
authors: Evandro
authors: E
authors: Piva
authors: Biomaterials Development and Control Center, School of Dentistry, Federal University of Pelotas, Pelotas, RS, Brazil; School of Materials Engineering, Federal University of Pelotas, Pelotas, RS, Brazil. Electronic address: ogliari@gmail.com.
authors: Fabrício A
authors: FA
authors: Ogliari
mesh_terms: D003188:Composite Resins; D055117:Curing Lights, Dental; D007700:Kinetics; D008422:Materials Testing; D010720:Phosphines / Q000737:chemistry*; D058105:Polymerization; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: C520678:(2,4,6-trimethylbenzoyl) diphenylphosphine oxide; D003188:Composite Resins; D010720:Phosphines
keywords: Camphorquinone; Dental resins; Diphenyliodonium hexafluorophosphate; Elastic modulus; Flexural strength; Oxide bisacylphosphine; Phenylbis (2,4,6-trimethylbenzoyl)-phosphine oxide; Photoinitiator; Polymerization kinetics