Synthesis, formulation and evaluation of novel zinc-calcium phosphate-based adhesive resin composite cement

Preparation of a low viscosity urethane-based composite for improved dental restoratives

Several new urethane-based dimethacrylates were synthesized, characterized and used to formulate the resin composites. Compressive strength (CS) was used as a screen tool to evaluate the mechanical property of the formed composites. Flexural strength, diametral tensile strength, water sorption, degree of conversion and shrinkage of the composites were also evaluated. The results show that most of the synthesized urethane-based dimethacrylates were solid, which are not suitable to dental filling restorations. However, it was found that liquid urethane-based dimethacrylates could be derivatized using asymmetrical methacrylate synthesis. Not only the newly synthesized urethane-based dimethacrylates showed lower viscosity values but also their constructed composites exhibited higher mechanical strengths. Without triethyleneglycol dimethacrylate (TEGDMA) addition, the new urethane-constructed composites showed significantly lower water sorption and shrinkage.

Preparation of new low viscosity urethane dimethacrylates for dental composites

Urethane-based polymers are very biocompatible in many biomedical applications. This study reports the synthesis of new low viscosity urethane dimethacrylates and evaluation of the formed composites. New urethane dimethacrylates were synthesized and formulated to form the composites. Compressive strength was used as a primary tool to evaluate the mechanical property. Water sorption, solubility, degree of conversion, flexural strengths and shrinkage were also investigated. It was found that liquid urethane dimethacrylates could be synthesized by derivatizing isocyanates with asymmetrical methacrylates. By eliminating diluent triethylene glycol dimethacrylate, the new urethane dimethacrylate-composed composites showed significantly higher modulus, lower water sorption, lower solubility and lower shrinkage, as compared to commercial BisGMA- and UDMA-based ones.

Novel Injectable and In situ Curable Glycolide/Lactide Based Biodegradable Polymer Resins and Composites

Novel in situ polymerizable liquid three-arm biodegradable oligomeric polyesters based upon glycolic acid (GA), L-lactic acid (LLA), and their copolymers are synthesized and characterized. Injectable and in situ curable polymer neat resins and their composites formulated with bioabsorbable beta-tricalcium phosphate are prepared at room temperature using photo- and redox-initiation systems, respectively. The cured neat resins show the initial compressive yield strength (YCS, MPa), modulus (M, MPa), ultimate compressive strength (UCS, MPa), and toughness (T, kN mm), ranging from 4.0 to 20.1, 201.5 to 730.2, 82.7 to 310.5, and 1.02 to 3.93. The cured composites show the initial YCS, M, UCS and T, ranging from 27.7 to 56.4, 1440 to 4870, 81.6 to 158.9, and 0.94 to 1.97. Increasing GA/LLA ratio increases all the initial compressive strengths of both neat resins and composites. Increasing filler content increases YCS and M but decreases UCS and T. A diametral tensile strength test shows the same trend as a compressive strength test. There seems to be an optimal flexural strength for the composite at the filler content around 43%. An increasing molar ratio increases curing time but decreases the degree of conversion (DC). An increasing filler content increases curing time but decreases exotherm and DC. During the course of degradation, all the materials show a burst degradation behavior within 24 h, followed by an increase in CS. The poly(glycolic acid) neat resin completely loses its strength at around Day 45. The composites completely lose their strengths at different time intervals, depending on their molar ratio and filler content. The degradation rate is found to be molar ratio and filler-content dependent.

Synthesis, characterization, and antibacterial activities of a novel nanohydroxyapatite/zinc oxide complex

Nanohydroxyapatite (n-HA)/zinc oxide (ZnO) complex was synthesized by a direct precipitation method, and the antibacterial capability and antibacterial mechanism of this complex were investigated in this article. Transmission electron microscope (TEM), Fourier transform infrared, X-ray photoelectronic spectroscopy (XPS), and X-ray diffraction (XRD) were used to analyze the materials. In addition, the antibacterial capacity of n-HA/ZnO complex was examined by bacteriolytic plate, inhibition effect, and antibacterial rate assays under light or without light. Furthermore, agarose gel electrophoresis of plasmid DNA (pUC18) was used to study biocidal action of this complex. The results of TEM observation revealed that the complex's rods had a single crystalline obelisk-like hexagonal wurtzite structure and the crystal retained the nanometer size. XRD analysis indicated that the phase of ZnO appeared and the lattice parameters of n-HA and ZnO changed. XPS spectra showed that the bonding energy of Ca, P, and O atoms changed in the complex. The analyses also showed that the two phases of ZnO and n-HA combined closely. Further, the results of the antibacterial test revealed that this complex possessed strong antibacterial capability; the antibacterial rate was 99.45% to S. aureus and 95.65% to E. coli under light, respectively. The antibacterial activity of this complex under light was better than without light, which was attributed to the generation of .OH under light. From the agarose gel electrophoresis, the dissolving solution of this complex could catalyze the cleavage of pUC18.