Abstract：
OBJECTIVE: To introduce a versatile fabrication process to fabricate zirconia/PMMA composites for chairside CAD/CAM dental restorations. These zirconia composites have nacre-like lamellar microstructures, competent and tooth-matched mechanical properties, as well as crack resistance behaviours.
METHODS: Bi-directional freeze casting was used to fabricate ceramic green bodies with highly aligned lamellar structure. Pressure was then applied to control the ceramic volume fraction. PMMA was infiltrated into the ceramic scaffold. Mechanical tests including 3-point bending, Vickers hardness, and fracture toughness were performed on the composites. The machinability of the composites was also characterised.
RESULTS: Two types of nacre-like zirconia/PMMA composites, i.e., 3Y-YZP/PMMA and 5Y-PSZ/PMMA composites were fabricated. The microstructure created was similar to the \'brick and mortar\' structure of nacre. Excellent flexural strength (up to 400 MPa and 290 MPa for 3Y-TZP/PMMA and 5Y-PSZ/PMMA composite, respectively), tuneable hardness and elastic modulus within the range similar to enamel, along with improved crack-resistance behaviour were demonstrated on both zirconia composites. In addition, both zirconia/PMMA composites showed acceptable machinability, being easy to mill, as would be required to produce a dental crown.
CONCLUSIONS: Nacre-like zirconia/PMMA composites therefore exhibit the potential for use in the production of chairside CAD/CAM dental restorations.
METHODS: Bi-directional freeze casting was used to fabricate ceramic green bodies with highly aligned lamellar structure. Pressure was then applied to control the ceramic volume fraction. PMMA was infiltrated into the ceramic scaffold. Mechanical tests including 3-point bending, Vickers hardness, and fracture toughness were performed on the composites. The machinability of the composites was also characterised.
RESULTS: Two types of nacre-like zirconia/PMMA composites, i.e., 3Y-YZP/PMMA and 5Y-PSZ/PMMA composites were fabricated. The microstructure created was similar to the \'brick and mortar\' structure of nacre. Excellent flexural strength (up to 400 MPa and 290 MPa for 3Y-TZP/PMMA and 5Y-PSZ/PMMA composite, respectively), tuneable hardness and elastic modulus within the range similar to enamel, along with improved crack-resistance behaviour were demonstrated on both zirconia composites. In addition, both zirconia/PMMA composites showed acceptable machinability, being easy to mill, as would be required to produce a dental crown.
CONCLUSIONS: Nacre-like zirconia/PMMA composites therefore exhibit the potential for use in the production of chairside CAD/CAM dental restorations.
摘要：
目的：介绍一种通用的制造工艺，以制造用于椅边CAD/CAM牙科修复的氧化锆/PMMA复合材料。这些氧化锆复合材料具有类似珍珠层的层状微结构，称职和牙齿匹配的机械性能，以及抗裂性行为。
方法：双向冷冻铸造用于制造具有高度对齐的层状结构的陶瓷生坯。然后施加压力以控制陶瓷体积分数。将PMMA渗入陶瓷支架中。机械试验，包括三点弯曲，维氏硬度,并对复合材料进行了断裂韧性。还表征了复合材料的机械加工性。
结果：两种类型的珍珠母状氧化锆/PMMA复合材料，即，制备了3Y-YZP/PMMA和5Y-PSZ/PMMA复合材料。创建的微观结构类似于珍珠质的“砖和砂浆”结构。优异的抗弯强度（3Y-TZP/PMMA和5Y-PSZ/PMMA复合材料最高可达400MPa和290MPa，分别)，可调硬度和弹性模量范围类似于搪瓷，在两种氧化锆复合材料上都证明了改善的抗裂性能。此外,两种氧化锆/PMMA复合材料均显示出可接受的可加工性，容易研磨，生产牙冠所需的。
结论：珍珠母状氧化锆/PMMA复合材料因此具有用于生产椅边CAD/CAM牙科修复体的潜力。
方法：双向冷冻铸造用于制造具有高度对齐的层状结构的陶瓷生坯。然后施加压力以控制陶瓷体积分数。将PMMA渗入陶瓷支架中。机械试验，包括三点弯曲，维氏硬度,并对复合材料进行了断裂韧性。还表征了复合材料的机械加工性。
结果：两种类型的珍珠母状氧化锆/PMMA复合材料，即，制备了3Y-YZP/PMMA和5Y-PSZ/PMMA复合材料。创建的微观结构类似于珍珠质的“砖和砂浆”结构。优异的抗弯强度（3Y-TZP/PMMA和5Y-PSZ/PMMA复合材料最高可达400MPa和290MPa，分别)，可调硬度和弹性模量范围类似于搪瓷，在两种氧化锆复合材料上都证明了改善的抗裂性能。此外,两种氧化锆/PMMA复合材料均显示出可接受的可加工性，容易研磨，生产牙冠所需的。
结论：珍珠母状氧化锆/PMMA复合材料因此具有用于生产椅边CAD/CAM牙科修复体的潜力。
