氧化锆陶瓷由于高强度、高韧性，半透明性以及良好的生物相容性，在齿科修复领域有着广泛的应用。但是，氧化锆陶瓷颜色单一为白垩色，与自然牙齿颜色相差较远，临床应用中需要熔附一层饰瓷，熔附过程中过快的烧结和冷却增大了修复体失败的概率；氧化锆陶瓷生物活性差，限制了其在种植体等方面的应用；此外，氧化锆陶瓷弹性模量和硬度远远高于自然牙齿，对被修复的牙齿产生负面作用。这一系列缺陷制约着氧化锆陶瓷在临床应用中的进一步发展。因此本文针对这些临床上的缺陷，深入研究了氧化锆基材料的美学性能，即材料色度值的调整；评价了氧化锆基材料的生物性能，即细胞在材料表面的附着、增殖；重点研究了氧化锆基材料的力学性能，包括弯曲强度、断裂韧性、弹性模量、硬度等。研究发现通过均匀沉淀方法，引入晶型诱导剂（四方相ZrO2），制备了室温稳定四方相ZrO2纳米粉体，纳米粉体呈均匀微球状，尺寸为40~50 nm。着色剂稀土氧化物Pr6O11、Er2O3，使氧化锆陶瓷的色度值呈梯度变化的。试样的色度值基本覆盖整个标准比色板，色度差?E较小(<2.2)，在合理范围内。通过加入不同浓度造孔剂硬脂酸，制备的多孔结构增大了氧化锆陶瓷表面的粗糙度，同时随造孔剂含量的提高闭孔结构转变为通孔结构，改善了rBMSCs细胞在氧化锆陶瓷表面的活性，附着面积和增殖数量都随气孔率的增大而增大。在氧化锆陶瓷中引入BaTiO3颗粒，采用放电等离子烧结技术，在氧化锆相变增韧和压电第二相增韧机制的共同作用下，BaTiO3/ZrO2复相陶瓷的断裂韧性呈上升趋势，为6.5~10.2 MPa·m1/2。树脂渗透氧化锆基复合材料的力学性能与自然牙釉质相近。预烧结温度为1150 oC的复合材料的力学性能最佳，优于现有同类商业应用修复材料。通过掺杂Fe2O3，复合材料的颜色由本征的白垩色变为淡黄色，同时强度和韧性提高，有望在齿科修复材料领域有广泛的应用。唾液和pH会影响树脂渗透氧化锆基复合材料的微观结构和力学性能。分别在人工唾液、酸溶液和碱溶液中浸泡30天后，复合材料的粗糙度增大，弯曲强度、弹性模量和硬度有所降低。
Due to its high strength and toughness, translucence, and good biocompatibility, zirconia ceramics have been widely employed in dental applications. But the colour of zirconia ceramic is white, which is far from natural teeth. For esthetic considerations, zirconia ceramic is usually covered with a layer of veneering porcelain in clinical practices. However, the restoration with porcelain veneering is characterized by high failure rate, due to too fast firing and cooling. Moreover, the poor biological activity of zirconia ceramic restricts its application in dental implant. What’s more, the excess high elastic modulus and hardness of zircomia ceramic have negative effects on the restored teeth. All of the drawbacks restrict the further development of zirconia ceramics in clinical application. Therefore, we have investigated the esthetic behavior (chromatic value), biological properties (cell attachment and proliferation), and mechanical performances, including flexural strength, fracture toughness, elastic modulus and hardness, in this paper.In this study, zirconia nanopowders of tetragonal phase stabilized at room temperature have been prepared by a homogeneous precipitation method with crystal inducing agent-tetragonal zirconia. Zirconia powders are uniform spheres and the grain size is 40~50 nm. Adding combined oxides, Pr6O11 and Er2O3, can reproduce the gradient tooth-like color of zirconia ceramics. The majority of the shade space of samples can overlap with the Vita 3D master system and the ?E between the samples of every group is below 2.2.Zirconia ceramics with porous structure have been prepared by solid-state reaction using yttria-stabilized zirconia and stearic acid powders as pore-forming agent. The porous structure is effective for the increase of surface roughness. And, the closed pores turn into interconnected ones with the increasing of the content of the stearic acid. The porous structure results in higher cell attachment areas and cell proliferation values.Composite ceramics BaTiO3/ZrO2 have been prepared by spark-plasma sintering. The fracture toughness trends to increase with the content of BaTiO3, due to the phase transformation toughenting mechanism and the piezoelectric second phase toughing mechanism. The fracture toughness of BaTiO3/ZrO2 ranges from 6.5 to 10.2 MPa·m1/2.The mechanical properties of polymer-infiltrated zirconia ceramics are close to those of natural enamel. Specimen pre-sintered at 1150 oC has optimal mechanical behaviors, which are superior to the commercial polymer-infiltrated feldspar ceramics. With increasing content of Fe2O3, the white color of composites turns into yellow. Moreover, the flexural strength and fracture toughness of polymer-infiltrated zirconia ceramics are greatly enhanced, suggesting promising restorative materials in dental clinic. However, saliva and pH have some effects on the microstructure and mechanical properties of polymer infiltrated zirconia ceramics. The composites have been immersed in artificial saliva, acid and alkali for 30 days, respectively, after which the roughnesses of specimens increase and the mechanical performances of specimens decrease.
