Longzhao KANG,Yan ZHOU,Jinle LAN,Yunhua YU,Qing CAI,Xiaoping YANG
This study intends to obtain a kind of polymer-infiltrated ceramic-network (PICN) composite with improved performance for dental restoration. Porous ceramic network was prepared via compressing feldspar powders, followed by resin infiltration using Bis-GMA/TEGDMA or UDMA/TEGDMA mixtures to obtain PICN composites after thermocuring. The sintering parameters (temperature, duration) for the formation of feldspathic network with proper porosity were investigated. The ratios of resin mixtures were adjusted to optimize the infiltration. Comprehensive characterizations were conducted on the porosity and the shrinkage of preformed ceramic-networks, the viscosity of resin mixtures and their infiltration into the ceramic networks, as well as, flexural properties, Vickers hardness and wear resistance of the final PICN composites. It turned out that the PICN composite prepared from Bis-GMA/TEGDMA (6:4) achieved the best performance among all the samples, which is expected to be a suitable material for computer-aided design/computer-aided manufacturing (CAD/CAM) dental restorative applications.
Lei Li,Dan Li,Wenwen Zhao,Qing Cai,Gang Li,Yunhua Yu,Xiaoping Yang
Objective The object is to find an easy but efficient way to illustrate the in-situ dispersion of nano-scaled one-dimensional fillers in composite resins, and to correlate their dispersion status with the properties of composite resins. Methods Fluorescent europium-doped hydroxyapatite nanowires (HANW:Eu) were synthesized via the hydrothermal method . The HANW:Eu was mixed into Bis-GMA/TEGDMA (60/40, w/w) at different contents (1–5 wt.%), and different processing methods (kneading, grinding, stirring) were tested to achieve good dispersion of HANW:Eu with the aid of fluorescent imaging system. Then, the mixtures of HANW:Eu and barium glass powder (BaGP) were kneaded into resin at a fixed content (70 wt.%) while at different mixing ratios. In addition to the 3D fluorescent imaging, characterizations were carried out on mechanical properties , fractured surface, wear resistance and polymerization shrinkage, to correlate the composite properties of with the dispersion status of the incorporated HANW:Eu. Results By doping calcium with 5 mol.% of europium , the obtained HANW:Eu displayed strong fluorescence, which made the illustration of its in-situ dispersion status within composites being possible. And this helped to judge that kneading was more efficient to homogeneously disperse HANW:Eu than grinding and stirring. However, it was illustrated vividly that HANW:Eu aggregated severely when it was co-incorporated with BaGP into composites at the total content of 70 wt.%, which had not been previously revealed by other microscope observations. In comparison with composites containing 70 wt.% of BaGP, improvements in the mechanical properties of resulting composites were identified for the cases containing 3 wt.% of HANW and 67 wt.% of BaGP, however, their wear volume loss and the polymerization shrinkage did not decrease as expected due to the HANW aggregations. Significance The fluorescent filler prepared in this study provides a feasible strategy to illustrate the in-situ dispersion status of inorganic fillers, which provides guidance for the processing of composite resins.
Song Guo,Shao-hua Luo,Xiaolong Li,Zihan Wang,Xian Zhang,Xuefei Lei,Sheng-xue Yan
This investigation focused on the contribution of various silane blends, used as coupling agents, to the ultimate performance of dental nanocomposite dimethacrylate photocurable resins . Initially, the surface of silica nanospheres was silanized with three different silane coupling agents : γ-MPS, APTES , and OTMS, with the grafting rate serving as the index. Fourier Transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) verified the modification of nanosilica . Through orthogonal test experiments on the three silane coupling agents, the optimal modifier concentration, temperature, and time were determined. Subsequently, 15 wt% organomodified SiO 2 nanospheres were incorporated into Bis-GMA/TEGDMA (70/30 by wt%) based resins via a photocuring process. Scanning electron microscopy (SEM) findings revealed a relatively vague interface between inorganic fillers and resins in the polymer composite , especially when reactive silanes like γ-MPS and their corresponding blends were used. The combination of SiO 2 and γ-MPS functional silane blend provided the highest flexural properties and the lowest solubility after storing the nanocomposite in water for 1 week at 37 °C. With these methods, composite resins containing 15 wt% MPS-SiO 2 nanospheres in a Bis-GMA/TEGDMA (70/30 by wt%) mixture exhibited the best comprehensive properties, making them a promising choice for achieving long-term durable restorations in clinical therapies.
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