【作者】 邹承蓉；

【导师】 何惠明； 王宝成；

【作者基本信息】 第四军医大学 ， 口腔临床医学， 2008， 硕士

【摘要】 纯钛具有良好的生物相容性、耐腐蚀性、比强度高、质量轻、价格低廉等优点等,成为目前理想的牙科材料之一。然而,由于纯钛的机械强度、硬度等方面尚不能完全满足义齿支架的要求,寻求理想的义齿支架用钛合金十分必要。第一代钛合金以Ti-6Al-4V为代表,含有毒元素矾,引起了许多争议。20世纪80年代中期,瑞士开发了第二代无矾的医用Ti-6Al-7Nb合金,该合金为ISO标准化的医用钛合金,其机械性能与Ti-6Al-4V相当,耐腐蚀性与纯钛相当。近年来,尽管很多学者开发研究了第三代医用钛合金,但将其用于齿科临床还有待于进一步研究。本文选取Ti-6Al-7Nb合金,分别采用氧化镁、磷酸盐及氧化锆系钛用包埋材料,与临床常用TA2型纯钛铸造效果作比较,对比分析了铸造试件表面反应层的结构、化学成分、铸流率及适合性等指标,为临床合理选择Ti-6Al-7Nb合金的包埋材料提供实验依据。研究内容与方法:1.研究不同体系包埋材料对Ti-6Al-7Nb合金表面反应层结构的影响。肉眼观察氧化镁、磷酸盐及氧化锆系钛用包埋材料包埋铸造Ti-6Al-7Nb合金和纯钛铸件表面光滑度和粘砂情况,并且通过扫描电镜、能谱分析仪、金相显微镜和显微硬度仪对Ti-6Al-7Nb合金和纯钛铸件表面反应层的微观结构、元素组成、晶相结构和维氏显微硬度进行观察和检测。2.研究不同体系包埋材料对Ti-6Al-7Nb合金铸流率的影响。采用20 mm×20 mm×0.85 mm且具有7×7格栅网的网状试样,研究Ti-6Al-7Nb合金、纯钛分别在氧化镁、磷酸盐及氧化锆系钛用包埋材料下的铸流率,并进行评价比较。3.研究不同体系包埋材料对Ti-6Al-7Nb合金全冠适合性的影响。根据王惠芸恒牙测量统计表的数据,设计制作模拟下颌第一磨牙预备体的不锈钢代型,在此基础上分别采用不同包埋材料包埋制作Ti-6Al-7Nb合金和纯钛基底冠,并采用金相显微镜测量全冠粘固剂厚度及边缘间隙值,对其适合性进行评价。研究结果:1.氧化镁系包埋材料包埋铸造的试件表面光滑,基本无粘砂;氧化锆系包埋材料包埋铸造的试件表面粘砂较多。通过显微硬度、金相分析、扫描电镜及能谱分析(EDS)的方法研究结果显示:氧化镁系包埋料组试件表面反应最轻微,未见明显反应层,表面O元素及其它元素含量极少,表面显微硬度值最低;磷酸盐和氧化锆系包埋料组试件表面反应层由外向内的方向可见四层结构,为烧结层、氧化层、包埋料元素浸入层及金属基体层,并且表面烧结层和氧化层内富含O元素及包埋料中的Al、Zr、Si等元素,随深度增加,包埋料浸入层内O元素含量逐渐减少,仍有少量来自包埋料中的元素成分,直至金属基体层内这些元素才完全消失,其表面显微硬度值均较氧化镁系包埋料组试件高,且Ti-6Al-7Nb合金组与纯钛组之间变化规律基本一致。2.铸流率结果经方差分析显示,各组试件铸流率均达到90%以上;三种包埋料包埋铸造的试件铸流率无明显差异(P>0.05);纯钛组和Ti-6Al-7Nb组间无明显差异(P>0.05)。3.三种包埋料包埋铸造Ti-6Al-7Nb合金和纯钛基底冠,各点间隙均小于120μm,不论是Ti-6Al-7Nb合金还是纯钛,氧化镁和磷酸盐系包埋材料铸出试件的各测量点间隙无显著性差异(P>0.05),氧化镁和磷酸盐系包埋料组与氧化锆系组之间冠边缘间隙存在显著性差异(P<0.05)。结论:1.在对铸件表面反应层的影响方面,氧化镁系包埋材料比氧化锆系和磷酸盐系包埋材料更适合于Ti-6Al-7Nb合金。2. Ti-6Al-7Nb合金与纯钛一样具有较高的铸流率,受三种不同体系包埋料的影响均较小。3.在铸造全冠的适合性方面,Ti-6Al-7Nb合金应用氧化镁系包埋材料进行包埋铸造时,其精度最佳。更多还原

【Abstract】 Pure titanium has widely used in dentistry currently, because of its good biocompatibility, corrosion resistance, specific strength, light weight, cheap price and so on. However, the mechanical strength and hardness can not meet the requirement of denture framework, it is necessary to develop titanium alloys for denture framework. The first generation of titanium alloy represented by Ti-6Al-4V has caused much dispute, because of poisonous element V. In the mid 1980s, a new titanium alloy Ti-6Al-7Nb, which was up to the ISO standard, was developed by Switzerland. The mechanical properties of Ti-6Al-7Nb and Ti-6Al-4V were not significantly different,and the corrosion resistance properties of Ti-6Al-7Nb and TA2 were not significantly different yet. In recent years, although the third generation of titanium alloys has been developed, further research should been made before the application in the dental clinic. In this study, the castings of Ti-6Al-7Nb alloy were invested with the different investments based by ZrO₂, MgO, Phosphate, and TA2 was used as control group. The structure and chemical composition of reaction layer was investigated. The influence of different investmens on the castability and adaptation of Ti-6Al-7Nb alloy castings were analyzed. It can provide theoretical basis for choosing the suitable investment materials for Ti-6Al-7Nb alloy in clinic.Contents and methods:1. To investigate the influence of different investments on the reaction layer of Ti-6Al-7Nb alloy castings. The roughness and the status of sticky powder were macroscopically observed. The structure of reaction layer was observed with scanning electron microscopy （SEM） and metallurgical microscope. The element composition was analyzed with energy dispersive spectrum （EDS）. The hardness and thickness of reaction layer were observed with microhardness apparatus.2. To evaluate the influence of three investments on the castability value of Ti-6Al-7Nb alloy. Net patterns were applied in this study. TA2 and Ti-6Al-7Nb alloy were invested in three investments respectively. The castability values of TA2 and Ti-6Al-7Nb were compared.3. To investigate the influence on adaptation of casting full crowns of Ti-6Al-7Nb alloy with different investments. According to the data of Hui-yun Wang permanent teeth statistical chart, stainless steel dies of mandibular first molars preparation were made. Then the casting full crowns were made and cemented on the dies. The thickness of cement and marginal gaps of all castings were examined with a metallurgical microscope.Results:1. The reaction layer of castings invested with MgO-based investment was the thinnest and had the lowest microhardness and the castings had little sand adherence. The castings invested with ZrO2-based investment had the most sand adherence. The reaction layer of castings invested with Phosphate and ZrO2-based investment was consisted of sintering, oxide, immersion and alloy layer. The content of O, Al, Zr, P, Si was high and reduced with the depth. The microhardness of these two groups was higher than that of MgO-based group. The regularity of Ti-6Al-7Nb and TA2 was not significantly different.2. Three investments had no significant influence on the castability value of Ti-6Al-7Nb and TA2. And also, there had no significant difference between TA2 and Ti-6Al-7Nb （p>0.05） in their castability value, both were over 90%.3. The experimental data of gaps were less than 120μm. The adaptation of the castings invested with MgO and Phosphate-based investment had no significant difference （p>0.05）. The castings invested with MgO and Phosphate-based investment had significant lower marginal gap than the castings invested with ZrO2-based investment at the magins of crowns （p<0.05）. The adaptation of TA2 and Ti-6Al-7Nb invested with MgO investment had no significant difference （p>0.05）.Conclusions:1. The MgO-based investment material may be the best choice for casting Ti-6Al-7Nb alloy on the influence of reaction layer.2. TA2 and Ti-6Al-7Nb alloy had excellent castability. The three investments had no significant effect on the castability value of Ti-6Al-7Nb and TA2.3. The castings of Ti-6Al-7Nb invested with MgO-based investment had better adapatation.更多还原