Viscosity, Degree of Polymerization, Water Uptake, and Water Solubility Studies on Experimental Dichloro-BisGMA-Based Dental Composites

The objective of this work was to investigate the advantages of using dichloro bisphenol A-glycidyl methacrylate (dCl-BisGMA) as a potential matrix for dental resin composites. A series of model composites containing 65 wt% resin (urethane dimethacrylate/triethylene glycol dimethacrylate/BisGMA as 1:3:1) and 35 wt% silanated silica were prepared. Thus, BisGMA was replaced by dCl-BisGMA as 0, 25, 50, and 100 wt% to obtain UTBC0, UTBC25, UTBC50, and UTBC100, respectively. The composites’ rheological properties, degree of double-bond conversion (DC), water sorption (WSP), and water solubility (WSL) were examined. The data revealed a statistically significant reduction in the complex viscosity of composites containing dCl-BisGMA, compared with UTBC0. No significant differences between DCs were detected (p < 0.05). A significant enhancement in the reduction of the dCl-BisGMA composite WSP was also detected, and conversely, WSL was increased. Although the viscosity, DC, and WSP characters were enhanced, a WSL increase is an undesirable development. However, WSL is supposedly caused by cyclization of small flexible chains, which is more likely to occur in the presence of hydrophobic monomers such as dCl-BisGMA and more prone to leaching than are crosslinked networks. We concluded that dCl-BisGMA is a monomer that could potentially be used as an alternative or in combination with traditional monomers, including BisGMA, in resin-based dental composites, and it deserves further investigation.