| Periodontitis is an inflammatory disease that leads to a progressive destruction of periodontal tissues, thereby leading to the loss of tooth in adults. An ideal result of treating periodontal disease is to return the tissues to their original state before infection started using periodontal regenerative techniques, in order to restore their original form and function of the lost structures. In recent years, bone grafts and guided tissue regeneration technique have become the two most important methods of treating periodontal tissue defects. In this thesis, Poly(vinyl alcohol)(PVA) was used to modify chitosan(CS) membrane in order to improve its pratical use. Bingpeng San(BPS) was introduced into chitosan membrane to prevent bacteria infect during the process of guiding periodontal tissue regeneration. Bone grafts was combined with guided tissue regeneration technique to improve the bioactivity of CS membrane.(1) The preparation of CS/PVA composite membranes by solution cast methodCS/PVA composite membranes were prepared by solution cast method. Their chemical property, physical property, thermal stability, surface wettability, mechanical propertes, degradability and biocompatibility were studied comprehensively. It was found that CS had strong interaction with PVA by forming intermolecular and intramolecular hydrogen bondings. When CS was the main component in the membrane, CS and PVA were miscible. While when the content of PVA was futher increased, phase separation began to appear to some extent. Adding PVA into CS membrane could greatly improve CS membrane’s flexibility and wettability and was able to controllably change the degradation speed and surface morphology of CS membrane during degradation. All the membranes prepared were biocompatible and have potential applications in guided tissue regeneration technology.(2) The perparion of CS/BPS composite membranes by gel methodCS/BPS composite membranes were produced by gel method. This method prevented BPS from being impacted by acid and alkali introduced when CS membranes were treated, thus maintaining the drug activity. Adding BPS into CS membrane could decrease the density of intermolecular and intramolecular hydrogen bondings, increasing the amount of free amino groups and hydrogen groups. When the weight ratio of CS and BPS was high, CS and BPS were miscible, there was no phase separation. When the weight ratio of CS and BPS was low, their miscibility became worse and began to appear phase separation. CS/BPS composite membranes had excellent surface wettability and their mechanical preoperties could meet the requirement of guiding periodontal tissue regeneration. CS/BPS composite membranes could improve cell spreading, growth and proliferation.(3) Biomineralization of CS hydrogels by electrochemical approach to prepare organic/inorganic hybrid materialsCS hydrogels were used as templates to prepare CS/hydroxyapatite/calcium carbonate with asymmetrical structure which had bioactive minerials at one side by electrochemical approach. The animo groups of CS had strong interations with calcium ions and pH values had great impact on the formation of minerials. There were no minerials formed at anode side, while mineral particles with5-6μm in diameter were formed on CS hydrogel surfaces at cathode side and each mineral particle was composed of smaller paticles with only a few nanometers in diameter. Compared with the biomineralization approach which was usually conducted by incubating a material in simulated body fluid (SBF), this biomineralization approach could greatly reduce the time of biomineralization. Ca/P ratio decreased with time,but higher than1.65(ratio of hydroxyapatite). The high Ca/P ratios make sure that the organic/inorganic hybrid material has high calcium and adequate phosphate contents needed to maintain healthy levels of bone mineral density. |
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