Monomers used in resin composites: degree of conversion, mechanical properties and water sorption/solubility

Abstract

The organic phase of resin composites is constituted by dimethacrylate resins, the most common monomers being the bisphenol A diglycidildimethacrylate (BisGMA), its ethoxylated version (BisEMA), triethylene glycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA). This study compared the homopolymers formed from the monomers used in restorative dental composites in terms of their degree of conversion (DC) and reaction kinetics (by near infra-red spectroscopy, n=3), mechanical properties (flexural modulus and strength in three point-bending, FM and FS, respectively, n=15), water sorption and solubility (WS and SL, respectively -ISO 4049, n=5). Materials were made photopolymerizable by the addition of camphoroquinone/dimethylamine ethyl methacrylate. TEGDMA showed the highest DC, followed by BisEMA, UDMA and BisGMA, both at 10 min and at 24h (p<0.001). UDMA showed the highest rate of polymerization, followed by TEGDMA, BisEMA and BisGMA (H 0 =13.254, p<0.001). UDMA and TEGDMA presented similar FM, significantly higher (p<0.001) than BisEMA and BisGMA, which in turn present statistically similar values (p>0.001). For FS, UDMA presented the highest value (p<0.001), followed by TEGDMA, then by BisEMA and BisGMA, which were statistically similar (p>0.001). BisGMA showed the highest WS, and TEGDMA and BisEMA the lowest. UDMA was statistically similar to all (H 0 =16.074, p<0.001). TEGDMA presented the highest SL, followed by UDMA, BisGMA and BisEMA (p<0.001). The tested homopolymers presented different behaviors in terms of polymerization kinetics, flexural properties, water sorption and solubility. Therefore, the use of copolymers is justified in order to obtain high DC and mechanical properties, as well as good resistance to water degradation.

Diametral Tensile Strength, Flexural Strength, and Surface Microhardness of Bioactive Bulk Fill Restorative

“…2 The physicochemical and mechanical properties of such polymers depend on the degree of conversion (DC) and definitive network structure. 3 In addition, the type of monomer has a significant influence on the polymerization reaction, mechanical properties, and water sorption of RBCs. 4 The durability and performance of bulk-fill RBCs can be evaluated by characterization of their mechanical properties.…”

Evaluation in vivo of biocompatibility of differents resin-modified cements for bonding orthodontic bands

“…The authors suggest that substances released by this cement had induced intense inflammatory response in the initial periods and because of this, the tissue had not been able to achieve adequate remodeling even after 30 days of follow-up. The RMO ® contains BisGMA, a monomer with a low degree of conversion values due to the presence of strong hydrogen bond and π -π interactions provided by bisphenol-A (Gajewski et al 2012). Normally, the monomers present in these materials are converted into polymers during the polymerization process, however, inadequate conversion would result in a larger quantity of residual monomers capable of causing a significant cytotoxic effect and affecting the compatibility of the material with the oral tissues (Lacerda-Santos et al 2014, 2016a, Santos et al 2012 compatibility.…”

Water sorption, solubility and surface roughness of resin surface sealants

“…The incorporation of TEGDMA monomers to this blend increases the conversion degree due to its high mobility. Also, the higher amount of TEGDMA monomers proportional to Bis-GMA increases the extent and the degree of reticulation of the resulting polymer, reducing its susceptibility to water penetration and solubilization 11,19 . This may explain the lower water sorption and solubility of Natural Glaze when compared to Permaseal, as the former is constituted by Bis-GMA and TEGDMA and most likely formed a denser polymer by the presence of this monomer [16][17] .…”