الفهرس 
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Abstract
The objective of this work was to prepare and evaluate a new modified material to be used as a dental restorative material and compare it with a commercial GIC to evaluate its properties. To verify this objective, firstly, powders of different compositions of bioactive silicate glass-ceramics were prepared by hydrothermal method, as a base material to be applicable in dentistry. It is known that bioactive calcium silicate glasses with high silica content were impossible to produce using the traditional melt derive method. However, expensive precursors are needed for the synthesis of the sol-gel-derived bioactive glasses. Moreover, the mechanical properties of the materials obtained by this technique are low in most cases. Therefore, the objective of this work firstly was to prepare silica-rich bioactive glasses of good biocompatibility and highly strengthened mechanical properties (to be used in orthopedic applications) by hydrothermal method. The prepared material was dried at a temperature of 100 ºC to reduce the carbonation and nitration limits. The carbonation and nitration phenomenon in bioactive glasses is an undesirable process because it plays a role in the instability of structural phases constituting that glass matrix. Therefore, trials were done to limit carbonation and nitration through sintering the material at a certain high temperature which was determined based on the DSC analysis. Therefore, the powder was sintering to a higher temperature (950 ºC, based upon DSC analysis) to create crystalline and/or polycrystalline desired biocompatible stable species (specific phase, anorthite phase, which was recommended in dental applications.). Apatite and wollastonite crystalline phases were also formed in the network of the glasses by the effect of sintering processes. The bioactive properties of the fabricated bioactive glasses were is carried out for the heat-treated glass-ceramic sample in vitro and characterized by SEM/EDS technique. There is a good ability to form biological hydroxyapatite in the presence of SBF since the determined Ca/P ratio was found to be in the order of the values considered for the natural HA or bone. The finer powder obtained recommends to be applied as compatible, bioactive (bone implantation) and biodental (teeth filler) materials. Completely 5 concentrations of ZnO-ZrO2 NCs specimens were prepared in various percentages by using the sol-gel method. Also, a glass material was prepared as a base material using the hydrothermal method, because it is known that bioactive calcium silicate glasses with high silica content were impossible to produce using the traditional melt derive method. However, expensive precursors are needed for the synthesis of the sol-gel-derived bioactive glasses. Moreover, the mechanical properties of the materials obtained by this technique are low in most cases. Therefore, the objective of this work firstly was to prepare silica-rich bioactive glasses of good biocompatibility and highly strengthened mechanical properties (to be used in orthopedic applications) by hydrothermal method. Secondly, the mixture of ZnO-ZrO2 NCs was added to glass-ceramic powder by a (5:1) ratio, respectively then formulated by a PAA to yield a modified GIC, which will be characterized using different techniques. This addition was done to modify specific properties such as structural, biological, and mechanical properties of the base material and compared with a commercial sample as a control group to evaluate the effective modified concentration to be suitable in various dental restorative applications. The characterization techniques of the modified GIC were performed such as FTIR, XRD, MAS-NMR, Disc Diffusion test, Vickers Hardness, Profilometer surface, and compressive strength tests. Infrared spectrophotometric measurements by (FTIR) show the maintenance of characteristic vibrational bands for the glass system, pure ZnO, ZrO2, and (ZnO-ZrO2 NCs). It gives more information about the setting reaction of GIC through the appearance of the carboxylic group (-COO-). XRD pattern shows the crystalline nature of used zinc oxide NPs and the amorphous nature of ZrO2 NPs and the semi crystallinity of the prepared glass system. Obtained diffraction data suggest that the anorthite phase was successfully prepared and recommended in dentistry. SEM images show a uniform distribution of the nanoparticles after occurring the heat treatment to the base material. In conjunction with Deconvolution Fourier Transform (DFT), it was found that the addition of 10 wt.% and 90 wt.% of ZnO NPs in the nanocomposites, have nearly the same structural role in the base glass material. Thus, more additional characterizations are needed to recommend one specific concentration to be applicable in vivo tests. The data obtained from the Disc Diffusion Test showed the antibacterial activity enhanced with increasing the concentration of ZnO NPs in the nanocomposites added to the base material. But the data obtained from different techniques such as Vickers microhardness, surface roughness tester, and universal testing machine (to obtain compressive strength value) (compared with the control group), indicate that the nanoparticles of ZrO2 make a good distribution in the base material and enhanced the results. from these results, it was recommended that group (1) yielded improvements in structural, biological, and mechanical properties. But Investigation in vivo of the recommended samples was suggested for future studies.