【作者】 周琳；

【导师】 赵铱民；

【作者基本信息】 第四军医大学 ， 口腔临床医学， 2010， 博士

【摘要】 硅橡胶材料由于其优异的生物相容性、化学稳定性及良好的物理机械性能,被国际上公认为颌面缺损软组织修复的首选材料。目前国内外赝复硅橡胶的种类繁多,多数性能已接近或达到了理想值水平,但由于硅橡胶表面疏松多孔,极易被细菌粘附,从而导致患者白色念珠菌性口炎和其他细菌感染的发生。同时,赝复硅橡胶材料也具有表面润湿性差的缺点,与患者敏感脆弱的伤后粘膜接触时会产生摩擦,造成患者不适。这些不足,都是赝复硅橡胶研究中亟待解决的问题。Parylene具有极好的防潮性、防霉、抗细菌性、并有极佳的生物惰性和生物相容性、无毒无刺激,可用于金属、玻璃、树脂、塑料、橡胶、陶瓷、纸张等多种材料,已被广泛应用于航空、航天、军工、微电子、半导体、医疗、文物保护等领域。被称为电子器件、医疗元件、橡胶制品和金属零件保护涂层的最高标准。本研究首次将Parylene涂敷技术用于口腔生物材料改性方面。并通过多方面性能测试评价了该项技术应用于赝复硅橡胶表面改性的可行性,为口腔生物材料表面改性提出了新的方法和思路,为今后的研究提供参考和依据。所进行的研究及结果如下:第一部分用于赝复硅橡胶表面改性的Parylene类型筛选本实验通过扫描电镜观察三种类型的Parylene涂敷后的试件断面,发现Parylene N涂层与硅橡胶的结合优于Parylene C和Parylene D。Parylene涂敷前,硅橡胶表面疏松多孔,Parylene涂敷后,硅橡胶表面致密,有散在球状突起,无孔隙。通过测试Parylene涂敷前后硅橡胶试件的表面粗糙度,结果表明,Parylene涂敷后的硅橡胶表面粗糙度明显低于涂敷前。第二部分Parylene涂敷技术对赝复硅橡胶的抗细菌粘附性能的影响本部分以白色念珠菌和变性链球菌为研究对象,分别采用了多种方法测试Parylene涂敷前后白色念珠菌和变性链球菌对硅橡胶和基托树脂的粘附性。计数法结果显示Parylene涂敷可显著降低白色念珠菌和变性链球菌在硅橡胶和基托树脂表面的粘附。XTT减量法用来检测活菌数,结果显示Parylene涂敷后XTT值明显降低。扫描电镜结果显示Parylene涂敷后硅橡胶表面未见明显丝状型白色念珠菌的形成,硅橡胶A-2186和基托树脂L199经Parylene涂敷后,变形链球菌疏松粘附于其表面,有较少的胞外基质形成,细菌菌体量也明显减少。说明Parylene具有一定的抗细菌生物膜形成的能力。激光共聚焦显微镜结果显示Parylene可以减少细菌的粘附,但不具有杀菌性。第三部分Parylene涂敷对增强赝复硅橡胶色彩稳定性的研究本部分采用常见的三种清洁剂:75%酒精、0.0125%NaClO、蒸馏水和四种日常生活中常接触的四种外源性染色剂:红酒、咖啡、茶水、可乐,通过测试各试件的色度值和对实验前后色差值的对比分析,探讨在它们的作用下Parylene涂敷对两种赝复硅橡胶色彩稳定性的影响。实验结果显示:Parylene涂敷可显著降低清洁剂和外源性染色剂对硅橡胶A-2186和ZY-1造成的颜色改变,可增强其色彩稳定性。第四部分Parylene涂敷对改善赝复硅橡胶表面润湿性的研究本部分采用极性不同的四种液体(水、甘油、甲酰胺、二碘甲烷),分别测试其在两种硅橡胶表面的接触角,并根据接触角测值计算出材料表面自由能和其极性分量、非极性分量。结果显示:Parylene涂敷可显著降低四种液体在硅橡胶表面的接触角,Parylene涂敷后材料的表面自由能显著升高,且其极性分量和非极性分量均有显著升高。第五部分Parylene涂敷对赝复硅橡胶机械性能的影响本部分通过测试Parylene涂敷前后两种硅橡胶的撕裂强度、拉伸强度、扯断伸长率、永久变形率和邵氏硬度,评价Parylene涂敷对赝复硅橡胶机械性能的影响。结果显示:Parylene涂敷后两种硅橡胶的撕裂强度、拉伸强度、扯断伸长率及邵氏硬度高于涂敷前,但数值仍在理想值范围内。两种硅橡胶在Parylene涂敷前后的永久变形率无显著性差异。第六部分Parylene涂敷对赝复硅橡胶吸水率、溶解率的影响本部分通过采用称重法测试Parylene涂敷对赝复硅橡胶吸水率、溶解率的影响,结果显示:Parylene涂敷前,两种硅橡胶的吸水率随着时间增长显著增加,Parylene涂敷后,两种硅橡胶的吸水率于4周以后无显著增长。Parylene涂敷前,两种硅橡胶的溶解率随着时间增长显著增加,Parylene涂敷后,两种硅橡胶的溶解率于2周以后无显著增长。通过上述六个部分的实验可知,Parylene涂敷技术用于赝复硅橡胶的表面改性是可行的,可解决赝复硅橡胶易粘附细菌、色彩稳定性差、表面润湿性差、吸水率大等问题,可满足改性要求,改性后可显著提高赝复硅橡胶的整体性能,可提高赝复体的远期修复效果,具有重要的临床意义。更多还原

【Abstract】 Silicone elastomer has been internationally recognized to be the first choice of material to repair oral and maxillofacial defects due to its excellent biocompatibility, chemical stability and good mechanical properties. There are many types of silicone elastomers at present, and the most performances close to or reach the ideal value. Bacterials stick to silicone elastomer easily because the surface of silicone elastomer is porous and it will cause denture stomatitis and other infects of patients. Silicone elastomer also has poor surface wettability, which will cause friction of mucosa and make patient discomfort. These deficiencies are all problems of silicone elastomer should be solved.Parylene has excellent moisture resistance, anti-mildew, anti-bacterial, bioinert, biocompatible, and without toxicity or irritant. It can be used on the surface of mental, glass, resin, plastic, rubber, ceramic, paper and many kinds of materials. It has been widely used in aviation, aerospace, defense, microelectronics, semiconductor, medical, heritage conservation and other fields. It has been considered to be the the highest standard of protective coating on electronic components, medical components, rubber products and metal parts.This is the first time that Parylene coating is used in surface modification of oral biomaterials. Its feasibility is evalued by various performance tests. This research provides new method to surface modification of oral biomaterial, and also provides basis to futher researchs.1. Type choice of Parylene which used in surface modification of silicone elastomer.We observe the cross-section of specimens after three types Parylene coating by SEM. It is found that the combination between Parylene N and silicone elastomer is better than Parylene C or Parylene D. Befor Parylene coating, the surface of silicone elastomer is porous. After Parylene coating, it is dense, and there are scattered globular protuberance on the surface but without any holes. We also test the roughness of silicone elastomer. Results show that the roughness of silicone elastomer after Parylene coating is lower than before Parylene coating.2. Research on bacterial adhesion to silicone elastomer before and after Parylene coating.This part is mainly about Candida albicans and Streptococcus mutans. We use several methods to test the adhesion of Candida albicans and Streptococcus mutans to silicone elastomer and resin before and after Parylene coating. Cells count assay shows that Parylene can reduce Candida albicans and Streptococcus mutans adhesion to silicone elastomer and resin. XTT reduction assay is used to quantify the viable cells in biofilm. We found that XTT absorbance readings ofsilicone elastomer and resin after Parylene coating decreased significantly compared before Parylene coating. SEM results show that hyphal forms of Candida albicans were scarcely observed on the surface of silicone elastomer after Parylene coating. Streptococcus mutans are loosely attached to the surfaces of silicone elastomers A2186 and lucitone 199 resin, with significantly decreased biomass and fewer extracellular matrixes visualized. It means that Parylene has the ability of anti-bacterial biofilm formation. CLSM results show that Parylene can reduce bacterial adhesion to the suface of material, but it is not bactericidal.3. Research on color stability of silicone elastomer before and after Parylene coating.We use three types of common cleaning: 75% alcohol, 0.0125%NaClO, distilled water and four types of exogenous dyes which is daily frequently contacted: red wine, coffee, tea, and cola. By testing and analysising the color values of specimens before and after the experiment, the color stability of silicone elastomer before and after Parylene coating with the influence of the seven liquids above is got. Results show that with the effect of three cleaing and four exogenous dyes Parylene can increase the color stability of silicone elastomer A-2186 and ZY-1.4. Research on suface wettability of silicone elastomer before and after Parylene coating.We use four liquids (water, glycerol, formamide and diiodomethane) with dfferent polar, and test their contact angles on the surface of silicone elastomer. After that the surface free energies of the specimens and their polar and disperse components were calculated from contact angle measurements. Results show that Parylene can reduce the contact angle between the four liquids and silicone elastomer. The surface free energy of silicone elastomer and their polar and disperse components all increase after Parylene coating.5. Research on mechanical property of silicone elastomer before and after Parylene coating.We test the tear strength, tensile strength, elongation, permanent deformation rate and Shore hardness of silicone elastomer before and after Parylene coating to evaluate the influence of Parylene on the mechanical property of silicone elastomer. Results show that the tear strength, tensile strength, elongation and Shore hardness of silicone elastomer increase in ideal value range after Parylene coating. The permanent deformation rate of silicone elastomer doesn’t change much after Parylene coating.6. Research on water absorption and solution of silicone elastomer before and after Parylene coating.We test the water absorption and solution of silicone elastomer before and after Parylene coating by weight method. Results show that before Parylene coating, the water absorption of silicone elastomer increases with the time passing by. After Parylene coating, the water absorption of silicone elastomer doesn’t increase much after 4 weeks. Before Parylene coating, the solution of silicone elastomer increases with the time passing by. After Parylene coating, the solution of silicone elastomer doesn’t increase much after 4 weeks.Through the six parts above, we can conclude that Parylene coating technique can be used in the surface modification of silicone elastomer. It can reduce bacterial adhesion to silicone elastomer and its water absorbtion. It also improves the color stability and wettability of silicone elastomer. In a word, Parylene coating can significantly improve the performance of silicone elastomer.更多还原