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Scientific article
English

Photopolymerization of highly filled dimethacrylate-based composites using Type I or Type II photoinitiators and varying co-monomer ratios

Published inDental materials, vol. 32, no. 2, p. 136-148
Publication date2016-02
First online date2015-12-21
Abstract

Objectives: The use of a Type I photoinitiator (monoacylphosphine oxide, MAPO) was described as advantageous in a model formulation, as compared to the conventional Type II photoinitiator (Camphorquinone, CQ). The aim of the present work was to study the kinetics of polymerization of various composite mixtures (20-40-60-80 mol%) of bisphenol A glycidyl dimethacrylate/triethylene glycol dimethacrylate (BisGMA/TegDMA) containing either CQ or MAPO, based on real-time measurements and on the characterization of various post-cure characteristics.

Methods: Polymerization kinetics were monitored by Fourier-transform near-infrared spectroscopy (FT-NIRS) and dielectric analysis (DEA). A range of postcure properties was also investigated.

Results: FT-NIRS and DEA proved complementary to follow the fast kinetics observed with both systems. Autodecceleration occurred after ≈1 s irradiation for MAPO-composites and ≈5-10 s for CQ-composites. Conversion decreased with increasing initial viscosity for both photoinitiating systems. However despite shorter light exposure (3s for MAPO vs 20s for CQ-composites), MAPO-composites yielded higher conversions for all co-monomer mixtures, except at 20 mol% BisGMA, the less viscous material. MAPO systems were associated with increased amounts of trapped free radicals, improved flexural strength and modulus, and reduced free monomer release for all co-monomer ratios, except at 20 mol% BisGMA.

Significance: This work confirms the major influence of the initiation system both on the conversion and network cross-linking of highly-filled composites, and further highlights the advantages of using MAPO photoinitiating systems in highly-filled dimethacrylate-based composites provided that sufficient BisGMA content (>40 mol%) and adapted light spectrum are used.

eng
Keywords
  • Camphorquinone
  • Dielectric analysis
  • Dimethacrylate
  • Elution
  • Kinetics
  • MAPO
  • Photoinitiator
  • Photopolymerization
  • Resin composite
  • Trapped radicals
  • Bisphenol A-Glycidyl Methacrylate / chemistry
  • Camphor / analogs & derivatives
  • Camphor / chemistry
  • Composite Resins / chemistry
  • Curing Lights, Dental
  • Elastic Modulus
  • Hardness
  • Materials Testing
  • Methacrylates / chemistry
  • Oxides / chemistry
  • Phosphines / chemistry
  • Polyethylene Glycols / chemistry
  • Polymerization
  • Polymethacrylic Acids / chemistry
  • Spectroscopy, Fourier Transform Infrared
  • Viscosity
Affiliation Not a UNIGE publication
Citation (ISO format)
RANDOLPH, Luc D et al. Photopolymerization of highly filled dimethacrylate-based composites using Type I or Type II photoinitiators and varying co-monomer ratios. In: Dental materials, 2016, vol. 32, n° 2, p. 136–148. doi: 10.1016/j.dental.2015.11.032
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Article (Published version)
accessLevelRestricted
Identifiers
ISSN of the journal0109-5641
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