Synthesis, Polymerization And Properties Of Dental Dendritic Methacrylate Monomers

2, 2-bis[p-(2’-hydroxy-3’-methacryloxypropoxy)phenyl]propane(Bis-GMA) based dental restorative materials have been used widely in dental restoration due to their good mechanical properties and aesthetics. However, a great attention has been drawn on developing novel dental restorative materials due to the drawbacks of Bis-GMA based restorative materials, like high polymerization shrinkage and potential risk in safty caused by Bisphenol A(BPA) structure in Bis-GMA. Dendritic monomers are considered as substitute for Bis-GMA because of their lower polymerization shrinkage and high reactivity. In this dissertation, based on characteristics of dendritic monomers, a series of original dendritic maromers were synthesized with the aim to overcome the drawbacks of Bis-GMA based dental restorative materials. Polymerization behavior of dendritic monomers and the relationships between their structure and properties were investigated systematically. The potential application of dendritic monomers in dental restorative materials was discussed. It not only has significant theoretical research value, but also has important guiding significance for the development of oral materials science and polymer materials science. All the results of this study were listed as below:(1) Tert-amine contained dendritic monomer G-IEMA was synthesized using pentaerythritol tetraacrylate, diethanolamine, and 2-isocyanatoethyl methacrylate as raw materials. Three generations of tert-amine contained dendritic monomers N-G1, N-G2 and N-G3 were synthesized using triethanolamine, 1-thioglycerol and 2-isocyanatoethyl methacrylate as raw materials via thiol-ene click chemistry reaction. Three generations of polyester dendritic monomers G1, G2 and G3 were also synthesized using pentaerythritol tetraacrylate, 1-thioglycerol and 2-isocyanatoethyl methacrylate as raw materials via thiol-ene click chemistry reaction. The chemical structures of these seven original methacrylate terminated dendritic monomers were confirmed by FT-IR, 1H NMR and 13 C NMR.(2) G-IEMA was used to replace dimethylaminoethyl methacrylate(DMAEM) as co-initator totally and triethylene glycol dimethacrylate(TEGDMA) as diluent gradually in 1,6-bis(methacryloxy-2-ethoxycarbonylamino)-2,4,4-trimethylhexane(UDMA)/TEGDMA dental resin system. Selecting Bis-GMA/TEGDMA dental resin system as a control. The results showed that the prepared resins had higher double bond conversion, lower water sorption and water solubility, lower flexural strength(FS) and flexural modulus(FM), higher fracture energies, and the same or lower polymerization shrinkage. Because of its optimal comprehensive performance, UDMA/G-IEMA/TEGDMA(70/10/20, wt%/wt%/wt%) resin formulation was chosen as dental resin matrix and mixed with inorganic filler Ba Al Si O2 in different mass fraction to prepare novel BPA free dental restorative materials(GMT). The commercial dental restorative materials 3M-Z250 and GC-A3 were used as BPA containing and BPA free controls, respectively. These novel GMT had higher double bond conversion and lower shrinkage. FS and FM of them were between those of 3M-Z250 and GC-A3. Water sorption of them was slightly higher than those of 3M-Z250 and GC-A3. Water solubility of them was comparable as that of 3M-Z250 and lower than that of GC-A3.(3) N-G1, N-G2 or N-G3 was used to replace TEGDMA in UDMA/TEGDMA(70/30, wt%/wt%) resin systems gradually. FM and FS of obtained resins decreased significantly, but diametral compressive strength had no change. Double bond conversions of obtained resins were between those of Bis-GMA based control and UDMA based control. Polymerization shrinkage decreased with the increasing of dendritic monomer generation and concentration of dendritic monomer in resin. Water sorption and water solubilty of the N-G1 and N-G2 contained resins were lower or comparable as those of UDMA control. However, Water sorption and water solubility of N-G3 contained resin were higher than those of Bis-GMA based control and UDMA based control, and increased with increasing of N-G3 concentration in the resins.(4) Polyester dendritic monomers G1, G2 and G3 were added into UDMA/TEGDMA(70/30 wt%/wt%) mixture with a series of weight ratio from 10% to 40%, respectively. With the increasing of dendritic monomer generation and amount of dendritic monomers in resins, polymerization shrinkage, double bond conversion, FS and FM of obtained resins decreased, but water sorption and water solubility of obtained resins increased. UDMA/TEGDMA resin systems containing 40% of G3 was mixed with different mass fraction of filler to prepare novel dental restorative materials. The commercial dental restorative materials 3M-Z250 and GC-A3 were used as controls. When the content of Ba Al Si O2 increased from 58% to 64%, double bond conversion of these novel dental restorative materials were higher than those of control restorative materials. Polymerization shrinkage of prepared restorative materials decreased from 4.65% to 1.94% with the increaseing of G3 concentration, which were significantly lower than those of 3M-Z250 and GC-A3. FS and FM of obtained restorative materials were only half of those of 3M-Z250. Water sorption and solubility of obtained restorative materials were significantly higher than those of 3M-Z250. However, FS, FM, water sorption and water solubility of obtained restorative materials were similar to those GC-A3.(5) Dendritic monomer G-IEMA with moderate molecular weight and functionality was selected to prepare novel dental restorative materials GMT-66%, and its biocompatibility was evaluated with commercial restorative materials 3M-250, GC-AP, and GC-P as control groups. The results showed that GMT-66%, less cytotoxicity and tissue reaction, revealed its better biocompatibilty and great potential to be used in clinic.