Effects of water on the long‐term properties of Bis‐GMA and silylated‐(Bis‐GMA) polymers

Abstract

Bis-GMA (2,2-bis-[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane) is a viscous hygroscopic monomer which is used with triethyleneglycol-dimethacrylate (TEGDMA) for dental restorations. Bis-GMA was silylated with dimethyl-isopropyl-siloxane and further polymerized in order to increase water resistance and viscosity. The viscosity of the silylated monomer, SilÁBis-GMA, was 50 times lower than that of the parent monomer. After 1 month in water, poly(Bis-GMA/TEGDMA) absorbed 2.6% water and the silylated polymer, poly(SilÁBis-GMA), only 0.56%. During this process water extracted residual monomer from each polymer. The behavior of water sorption and desorption as a function of time in poly(SilÁBis-GMA) was completely different from that shown by poly(Bis-GMA/TEGDMA). The difference is discussed in terms of diffusion coefficients. Initially, water advancing contact angles (y ADV ) were 758 and 958, respectively. After 1 month in water both polymers showed a reduction of about 208 in y ADV . In poly(Bis-GMA/TEGDMA), the reduction in y ADV obey to water absorption and bulk plasticization; it showed a reduction of 158C in glass transition temperature, T g . In contrast, the reduction in y ADV in poly (SilÁBis-GMA) obeyed to water adsorption and reorientation of the molecules at the surface in contact with the water phase; it only showed a change of 28C in T g . Contact angle hysteresis provided further evidence about plasticization. According to our results poly(SilÁBis-GMA) is more stable in water than poly(Bis-GMA/TEGDMA).

A Review of Dental Composites: Methods of Characterizations

“…The Wilhelmy balance technique is a tensiometric method for the analysis of dynamic measurement of CA, which is an alternative to previously described goniometric methods. 71 Rivera-Torres et al 79 utilized this method to study the dynamic wettability of modified BisGMA-based resin composite. According to the method, CA is calculated according to the force measurement of a sample being dipped in the wetting liquid at a constant velocity (Figure 1c).…”

Photopolymerization experiments and properties of some urethane/urea methacrylates tested in dental composites

“…The motivation behind the synthesis of inorganic-organic hybrid monomers was the hydrophobic nature of silyl fragment used in our formulations, known being that such structures have potential to improve the properties of restorative composites. 8 Thus, reacting IEMA with 3-aminopropyl(diethoxy)methylsilane in the presence of dibutyltin dilaurate used as the catalyst, a silyl methacrylate, N-(methacryloyloxyethyl-N'-diethoxymethylsilylpropyl)-urea containing urea group was obtained (UHM-1).…”

“…In spite of several practically validated advantages, the main deficiencies of current resin composites are polymerization shrinkage which occurs when the material is cured, the relatively high percentage of unpolymerized (meth)acrylate functions and the susceptibility to water sorption, 3,4 all leading to a deterioration of the physical/mechanical properties of the materials, for instance, marginal leakage, insufficient abrasion and inadequate resistance to wear, degradation and fatigue, toxicity. 5,6 To surmount these critical aspects, one of the approached strategies proposed the use of novel basic monomer systems such as, modified BisGMA, 7,8 fluorinated and spiro-orthoesters, 9,10 liquid crystalline or hyperbranched monomers. 1,11 Other research tasks aimed at developing urethane di(meth)acrylates (UDMA) for use as organic matrix in polymeric composites with substantially enhanced mechanical properties and minimized polymerization shrinkage, resulting from the effective binding ability of the urethane structures.…”

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

“…Indeed, the viscosity issue of BisGMA necessitates material development; thus, Bis-GMA structural modification including the replacement of its OH groups with low hydrophilic substituents may be one solution. In this context, various derivatives of BisGMA have been synthesized by different researchers, in which the OH functional groups were partially or fully replaced with targeted substituents, including alkyls, aryls, ethers, and esters with small or bulky groups [3,[5][6][7][8][9][10][11][12]. Regardless of the type of substituent used, the viscosity of BisGMA was greatly reduced after modification, confirming that H-bonding is the major cause of its high viscosity character [2,6,10,12,13].…”