Increased rates of photopolymerisation by ternary type II photoinitiator systems in dental resins. (October 2019)

• Record Type: Journal Article
• Authors: Lima, Adriano Fonseca; Salvador, Marcos Vinicius Oliveira; Dressano, Diogo; Saraceni, Cintia Helena Coury; Gonçalves, Luciano Souza; Hadis, Mohammed; Palin, William M.
• Is Part Of: Journal of the mechanical behavior of biomedical materials. Volume 98(2019)
• Page Start: 71
• Page End: 78
• Publication Date: 2019-10
• Subjects: Mechanical properties -- Dental resins -- Initiators -- Dental materials; Biomedical materials -- Periodicals; Biomedical materials -- Mechanical properties -- Periodicals; Biomedical materials; Biomedical materials -- Mechanical properties; Periodicals; Electronic journals; 610.28
• DOI: 10.1016/j.jmbbm.2019.06.005
• Languages: English
• ISSNs: 1751-6161

Abstract

Abstract: 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 ( E abs ) 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. Highlights: CQ has lower total absorbed energy than MAPO/BAPO with similar DC in ternary system. The use of DPI promote higher rate of curing despite low molar absorptivity of CQ. Ternary systems are a viable way to increase the reactivity of dental resins.