Luz Julio Nogueira, Kaizer Marina da Rosa, Ramos Nathália de Carvalho, Anami Lilian Costa, Thompson Van P, Saavedra Guilherme de Siqueira Ferreira Anzaloni, Zhang Yu
Department of Dental Materials and Prosthodontics, Institute of Science and Technology of Sao Jose dos Campos, Sao Paulo State University (UNESP), 777 Eng. Francisco Jose Longo Avenue, Sao Jose dos Campos, SP 12245-000, Brazil.
Graduate Program in Dentistry, Positivo University, Curitiba, PR 81280-330, Brazil.
Dent Mater. 2021 May;37(5):875-881. doi: 10.1016/j.dental.2021.02.026. Epub 2021 Mar 11.
Continuous efforts have been made to hasten the zirconia densification process without compromising properties. This study evaluated the long-term structural durability of microwave speed-sintered zirconia (MWZ) relative to a conventionally sintered zirconia (CZ).
As-machined dental 3Y-TZP discs (Ø12 × 1.2 mm) were speed sintered at 1450 °C for 15 min using an industrial microwave oven, while conventional sintering was conducted in a standard dental furnace at 1530 °C for 2 h. Both were followed by natural cooling. The total sintering time was 105 min for MWZ and 600 min for CZ. Groups were compared regarding density, grain size, phase composition, and fracture resistance. Structural durability was investigated employing two fatigue protocols, step-stress and dynamic fatigue.
Compared to CZ, MWZ exhibited a slightly lower density (MWZ = 5.98 g/cm, CZ = 6.03 g/cm), but significantly smaller grain sizes (MWZ = 0.53 ± 0.09 μm, CZ = 0.89 ± 0.10 μm), lower cubic-zirconia contents (MWZ = 15.3%, CZ = 22.7%), and poorer translucency properties (TP) (MWZ = 13 ± 1, CZ = 29 ± 0.8). However, the two materials showed similar flexural strength (MWZ = 978 ± 112 MPa, CZ = 1044 ± 161 MPa). Additionally, step-stress testing failed to capture the fatigue effect in 3Y-TZP, whereas dynamic fatigue revealed structural degradation due to moisture-assisted slow-crack-growth (SCG). Finally, MWZ possessed a slightly higher Weibull modulus (MWZ = 7.9, CZ = 6.7) but similar resistance to SCG (MWZ = 27.5, CZ = 24.1) relative to CZ.
Dental 3Y-TZP with similar structural durability can be fabricated six-times faster by microwave than conventional sintering.
人们一直在不断努力，在不影响性能的前提下加速氧化锆致密化过程。本研究评估了微波快速烧结氧化锆（MWZ）相对于传统烧结氧化锆（CZ）的长期结构耐久性。
将加工好的牙科用3Y-TZP圆盘（直径12×1.2毫米）用工业微波炉在1450℃下快速烧结15分钟，而传统烧结则在标准牙科熔炉中于1530℃下进行2小时。两者均自然冷却。MWZ的总烧结时间为105分钟，CZ为600分钟。比较两组在密度、晶粒尺寸、相组成和抗断裂性方面的差异。采用阶梯应力和动态疲劳两种疲劳试验方案研究结构耐久性。
与CZ相比，MWZ的密度略低（MWZ = 5.98克/立方厘米，CZ = 6.03克/立方厘米），但晶粒尺寸明显更小（MWZ = 0.53±0.09微米，CZ = 0.89±0.10微米），立方氧化锆含量更低（MWZ = 15.3%，CZ = 22.7%），半透明性能（TP）更差（MWZ = 13±1，CZ = 29±0.8）。然而，两种材料的弯曲强度相似（MWZ = 978±112兆帕，CZ = 1044±161兆帕）。此外，阶梯应力测试未能捕捉到3Y-TZP中的疲劳效应，而动态疲劳显示由于水分辅助慢裂纹扩展（SCG）导致结构退化。最后，相对于CZ，MWZ的威布尔模量略高（MWZ = 7.9，CZ = 6.7），但对SCG的抗性相似（MWZ = 27.5，CZ = 24.1）。
具有相似结构耐久性的牙科用3Y-TZP通过微波烧结的速度比传统烧结快六倍。
