【作者】 任艳云；

【导师】 陈晖；

【作者基本信息】 浙江大学 ， 口腔临床医学， 2007， 硕士

【摘要】 背景聚甲基丙烯酸甲酯(PMMA)因其具有良好的物理、化学和生物学性能,多年来被广泛应用于口腔临床,它是目前制作活动义齿最常用的材料。但是,它也存在着不足之处,最常见的是:配戴用PMMA材料制作的活动义齿易诱发义齿接触部位龋病、口炎等并发症,一直以来,对此临床上缺乏有效的解决方法。载银纳米二氧化钛粉是一种无机抗菌剂,它是以工业偏钛酸、工业浓硫酸为原料,将银离子以水难溶性磷酸盐的形式载入制备而成的复合物。它既利用了银离子化合物的一般杀菌作用,又利用了二氧化钛在光催化作用下的强化杀菌作用。与其它载银无机抗菌剂不同的是,载银纳米二氧化钛系粒径小于50nm的纳米材料,其接触面积大,具有抗菌力强、抗菌谱广、抗菌作用持久和生物安全性良好、价格低廉等特点。文献报道,载银纳米二氧化钛粉应用于塑料中,能使塑料具有抗菌性,但国内外未见有关将载银纳米二氧化钛粉应用于口腔领域的相关报道。目的为了提高PMMA义齿的抗菌性,降低接触部位的微生物感染率,减少配戴活动义齿所引发的口腔并发症,本试验将新型载银纳米二氧化钛粉加入PMMA义齿基托中,观察其体外抗菌性能,为复合载银纳米二氧化钛PMMA义齿基托的推广应用提供理论依据。方法1应用琼脂稀释法进行新型载银纳米二氧化钛粉对变形链球菌的体外敏感性试验,测定载银纳米二氧化钛粉对变形链球菌的最低抑菌浓度(MIC)和最低杀菌浓度(MBC)。2根据载银纳米二氧化钛粉对变形链球菌的MIC和MBC,制成含不同浓度载银纳米二氧化钛的PMMA义齿基托。应用琼脂稀释法,测定其不同浓度对3种口腔临床常见致病菌——变形链球菌、粘性放线菌和白色念珠菌的抗菌率。3使用扫描电子显微镜观察变形链球菌、粘性放线菌和白色念菌在含载银纳米二氧化钛的PMMA义齿基托上的粘附生长情况。结果1载银纳米二氧化钛粉对变形链球菌的最低抑菌浓度(MIC)为0.5mg/ml,对变形链球菌的最低杀菌浓度(MBC)为2.5mg/ml,说明载银纳米二氧化钛粉对口腔临床常见致龋菌具有良好的抗菌活性。2含2.5mg/ral载银纳米二氧化钛的PMMA义齿基托对变形链球菌的抗菌率达89.9%,对粘性放线菌的抗菌率高达94.2%;对白色念珠菌的抗菌率为31.5%,能基本满足正常口腔环境下的抗菌要求。3扫描电镜发现,变形链球菌、粘性放线菌在含2.5mg/ml载银纳米二氧化钛的PMMA义齿基托上的生长粘附比不含载银纳米二氧化钛粉PMMA义齿基托上的粘附生长明显减少(P≤0.05),白色念珠菌的细菌粘附生长也有减少,但差异无显著性意义。结论载银纳米二氧化钛粉对变形链球菌、粘性放线菌和白色念珠菌的生长有明显的抑制作用,复合载银纳米二氧化钛的PMMA义齿基托具有抗菌性,可降低其接触部位的微生物感染率。复合载银纳米二氧化钛的PMMA义齿基托可进一步在口腔临床推广应用。更多还原

【Abstract】 Polymethyl methacrylate（PMMA）is the most useful material to manufacture the removable denture currently,which has been applied extensively to mouth rehabilitation in clinical dentistry for many years because of its good physical、chemical and biological character.It also exists the shortages such as dental caries and denture stomatitides usually at the abutment tooth which are induced by wearing the artificial removable denture made of PMMA.In order to solve the medical puzzle of reducing the opportunity of complications including caries with abutment tooth of removable denture and denture stomatitis,we attempt to do the preliminary test in which we put Ag-embedded nano-TiO₂ into the artificial removable denture made of PMMA,and observe the antimicrobial activity in vitro then to provide the scientific evidence for its wide-spread applicationThe materials of Ag-embedded nano-TiO₂ were invented by School of Metallurgical Science and Engineering of Central South University.The preparation of the complex Ag-embedded nano-TiO₂ is follow:precursor of nano-TiO₂ was prepared from industrial H₂TiO₃ and 98%sulfuric acid in continuous acid dissolution and pyro-hydrolysis.The precursor was embedded with silver in the form of Ag₃PO₄.The optimum parameters for the preparation was the ratio of H₂TiO₃ to H₂SO₄ in dissolving process 3、time about 150～180 min and hydrolysis time about 100～120 min.After dried with a sprayer and thermal treated at 450℃,500℃and 550℃, the TiO₂ present in the product was in anatase phase and without simple silver saline phase based on the analyses of X-ray diffraction（XRD）.The particle size of product Ag-embedded nano-TiO₂ was in the range of 20～80 nm.The minimum inhibitor concentration（MIC）of the product was 100 ppm and the efficiency of sterilization was 99.99%to bacterium coli.The Ag-embedded nano-TiO₂ posses the characteristic such as stronger antimicrobial activity,broadly antibacterial spectrum,longer duration,more safety and lowerprice etc.But there is no report of the Ag-embedded nano-TiO₂ applied in the PMMA in the literature report retrieved by Academy of Medical Sciences of Zhejiang province.This study is to observe the antimicrobial activity of denture resins substrates with the Ag-embedded nano-TiO₂ and find out whether the Ag-embedded nano-TiO₂ can help demolishing the formation of dental plaque.It can provide more experiment data for the further application of the Ag-embedded nano-TiO₂ in the prosthodontics field.The main results of the study are as followly:At first,The minimal inhibitory concentration（MIC）and minimal bactericidal concentration（MBC）of the Ag-embedded nano-TiO₂ against Streptococcus mutans（S.mutans）was 0.5mg/ml and 2.5mg/ml respectively in vitro.The denture base with Ag-embedded nano-TiO₂ has good antimicrobial activities against S.mutans,which can be used in the denture base for antimicrobial activities.Secondly,When put the Ag-embedded nano-TiO₂ at 2.5mg/ml into PMMA,the inhibition ratios of the base against to S.mutans was 89.9%,against to Actinomycetes viscosus was 94.2%and against to Candida albicans was 31.5% respectively. The artificial Ag-embedded nano-TiO₂ into removable denture made of PMMA can be able to satisfy the fundamental antimicrobial request in the normal oral environment.Thirdly,Under the same culturing environment,The bacterial adherence growth of streptococcus mutans and actinomycetes viscosus on the surface of the samples of denture resins substrates with Ag-embedded nano-TiO₂ are obviously less than that of the control（P＜0.05）by scanning electron microscope（SEM）.The adherence growth of candida albicans on the surface of the samples of denture resins substrates with Ag-embedded nano-TiO2 is also less than that of the controlbut the difference is not significant（P＞0.05）by SEM.This preliminary test shows that the artificial Ag-embedded nano-TiO₂ into removable denture made of PMMA can be able to satisfy the fundamental antimicrobial request in the normal oral environment by reducing the opportunity of complications including caries with abutment tooth of removable denture and denture stomatitis,and can help demolishing the formation of dental plaque.and can provide the scientific evidence which is valuable of further application of the Ag-embedded nano-TiO₂ in the prosthodontics field.更多还原