Increased rates of photopolymerisation by ternary type II photoinitiator systems in dental resins

Research output: Contribution to journalArticlepeer-review


  • Adriano Fonseca Lima
  • Marcos Vinicius Oliveira Salvador
  • Diogo Dressano
  • Cintia Helena Coury Saraceni
  • Luciano Souza Gonçalves

Colleges, School and Institutes

External organisations

  • Paulista University
  • State University of Campinas
  • Federal University of Rio Grande do Sul
  • University of Birmingham


To evaluate the effects of Type I and Type II photoinitiator systems on curing efficiency, degree of conversion (DC) and chemico-physical properties of resin based materials. A comonomer base containing 50%wt 2.2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane (bis-GMA) and 50%wt triethyleneglycol dimethacrylate (TEGDMA) was formulated with either 0.5 or 1mol% of Type II camphoroquinone (CQ), Type I monoacylphosphine oxide (MAPO) or bis-acylphosphine oxide (BAPO) photoinitiators. The Type II system was either a binary (1: 2 CQ:amine) or ternary system (1: 2 CQ:amine + 0.5 mol% DPI). Degree and rate of polymerization was measured by Fourier Transform Infrared Spectroscopy (FTIR). Knoop micro-hardness prior to and following ethanol immersion was assessed. Flexural strength and modulus was measured under three-point bend test. Water sorption and solubility was also evaluated. The photoinitiator absorption spectra and the total absorbed energy per unit volume (Eabs) for 0.5mol% photoinitiator in each material was calculated. Despite the reduced total absorbed energy per unit volume for CQ based systems, ternary Type II system significantly improved curing efficiency (P < 0.05) compared to both Type I photoinitiators and degree of conversion compared to MAPO only, whilst exhibiting comparable mechanical and physical properties compared to both Type I based materials at equivalent molar concentrations of photoinitiator (P > 0.05). Ternary Type II systems is an efficient alternative to improve the polymerization of resin materials, promoting similar or even better properties than Type I initiators. DPI can increase the reactivity of CQ systems and promote polymerization rates superior than Type I photoinitiators.

Bibliographic note

Copyright © 2019. Published by Elsevier Ltd.


Original languageEnglish
Pages (from-to)71-78
Number of pages8
JournalJournal of the Mechanical Behavior of Biomedical Materials
Early online date6 Jun 2019
Publication statusPublished - Oct 2019


  • Mechanical properties, Dental resins, Initiators, Dental materials