| The purpose of this thesis is to develop several filling biomaterials that exhibit good properties and have the potential to be applied to dental or bone restorative or replacement materials. It will have a great significance to improve the current biomaterials and develop new biomaterials. Glass-ceramic reinforced dental resin composite and four inorganic biocements were studied, including:Magnesium oxychloride cement, MOC; Calcium silicate cement, CSC; Calcium aluminate cement, CAC; Calcium silicate/calcium aluminate cement, CSC/CAC. The properties of these materials were studied by specific surface analysis, X-ray diffraction (XRD), scanning electron microscope/energy dispersive analysis (SEM/EDAX), environment scanning electron microscope (ESEM), differential scanning calorimeter/thermogravimetric analysis (DSC/TGA), and Fourier transform infrared spectroscopy (FTIR) and so on. The porous fluorapatite glass-ceramic powders were used as the fillers of dental resin composites at the first time. The influence of fillers'composition and structure on the mechanical property and wear behavior of dental resin composite was discussed. The pure?-Ca2SiO4 powder was synthesized successfully. The hydration process and mechanical properties of CSC were researched. The pure CaAl2O4 powder was synthesized successfully and the influence of liquid to powder (L/P) ratio the properties of CAC was discussed. A series of new CS/CA cements were developed and the influence of CS to CA ratio on the properties of CS/CA cement was discussed. The influence of addition of phosphoric acid on the properties of MOC was discussed, including: hydration, mechanical property, and cell attachment. The conclusions are as follows:(1) Porous fluorapatite/mica glass-ceramic porous particles were prepared and used as the fillers of dental composites. Two groups (A2 and A5) that have different compositions were studied. For A2 fillers that contain lower content of fluorapatite, using porous particles as the fillers could improve the bending strength and wear resistance. However, for A5 fillers that contain more fluorapatite, the result is reverse. It can be deduced that the mechanical properties and wear behavior of dental resin composites are not monotonically influenced by the porosity of the fillers, but also influenced by the composition and structure or morphology of the fillers.(2) Three different methods have been used to synthesize the pure?-Ca2SiO4 powder:solid-state reaction, sol-gel method and Pechini technique. Pechini technique is the best way to synthesis pure (3-Ca2SiO4 powder, since it needs lower calcinations temperature (800?) and shorter time (3h). The hydration product is C-S-H hydrates, Ca1.5SiO3.5·xH2O. After crystallization, it appears as petals-like crystals under ESEM observation. There was no mass-loss of CSC after soaking in phosphate buffer solution (PBS) for 40 days. CSC can release Si ions in simulated body fluid (SBF) solution, which can promote the osseous formation when the material is implanted into the body.(3) Pure CaAl2O4 powder was synthesized by Pechini technique at 1000?and calcinations for 3h. L/P ratios had a significant influence on the properties of CAC:when L/P?0.7, there were two kinds of calcium aluminate oxide hydrates:Ca3Al2O6·xH2O and Ca3Al2O6·Ca(OH)2·18H2O, as well as katoite (Ca3Al2(OH)12) in the hydration products, and the higher L/P ratio, the higher the intensity of the katoite XRD peaks; when L/P=0.6, the water was insufficient for completing the hydration, so there was some XRD peaks of CA but no XRD peak of katoite, and also the compressive strength was lower. Adding small amount of LiCl could significantly accelerate the hydration process and decrease the setting time. It wouldn't influence the phase composition and strength of CAC. After soaking in PBS, there was no mass-loss. And hydroxyapatite with porous microstructure was formed on the surface of CAC.(4) A series of new calcium silicate/calcium aluminate cements were prepared. The setting time of CS/CAC was shorter than that of CSC or CAC. The hydration products are:gehlenite (Ca2Al2SiO7·8H2O), calcium aluminate hydrate (Ca3Al2O6·xH2O), and katoite (Ca2Al2O6·6H2O). Plate-like crystals were observed under ESEM. L/P ratio had a significant effect on the porosity and strength of CS/CAC:the lower the L/P ratio, the lower the porosity, the higher the compressive strength. The compressive strength of 3S7A cement reached to the highest value (33MPa) when L/P=0.55. The relationship of porosity and compressive strength of 3S7A cement can be described as a polynomial formula.(5) Magnesium oxychloride cement was studied as a novel biomaterial. The phosphoric acid was added in order to improve the water resistance of MOC. Adding phosphoric acid had no influence on the crystalline phases of MOC, but can promote the formation of needle-like phase 5. Adding phosphoric acid could retard the hydration process, prolong the setting time and decrease the compressive strength of MOC, but it could improve the water resistance significantly. MOC can sustain in PBS for 70 days. The higher the concentration of phosphoric acid, the slower the degradation of MOC. And MOC degraded faster in porcine serum than in PBS. Cell culture test demonstrates that MOC is not toxic. All the results suggest that MOC can be exploited as a resorbable bone restorative filling biomaterial. |
PDF Full Text Request