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

Research output: Contribution to journalArticlepeer-review

Authors

  • Luc D Randolph
  • Johannes Steinhaus
  • Bernhard Moginger
  • Bernard Gallez
  • Jeffrey Stansbury
  • Gaetane Leloup
  • Julian G Leprince

Colleges, School and Institutes

External organisations

  • Bonn-Rhein-Sieg University of Applied Sciences, Department of Natural Sciences,
  • University of Colorado at Boulder
  • Université Catholique de Louvain
  • Center for Research and Engineering on Biomaterials

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 (3 s for MAPO vs 20 s 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.

Details

Original languageEnglish
Pages (from-to)136-148
JournalDental Materials
Volume32
Issue number2
Early online date21 Dec 2015
Publication statusPublished - Feb 2016

Keywords

  • Photopolymerization, Dimethacrylate, Resin composite, Photoinitiator, Camphorquinone, MAPO, Kinetics, Dielectric analysis, Trapped radicals, Elution