目的:研究由3%摩尔钇掺杂的四方氧化锆多晶(3Y-TZP)制成的第二代整体式假体的5年口腔内演变和低温降解(LTD)动力学以及咀嚼机械应力和釉层对这种演变的影响。
方法:这项前瞻性临床研究共包括101个后牙元素,其中包括离体LTD监测(在基线时,6个月,1年,2年,3年,和5年)使用拉曼光谱(每个评估时间n=2640个单斜晶相测量点)和扫描电子显微镜(SEM)。四种类型的区域(1-2mm2表面,六个磨牙,在每个元素表面上分析了四个前磨牙):咬合,轴向,釉面,或未上釉。拉曼映射,高分辨率SEM,并对选定的样品进行了聚焦离子束-SEM。
结果:在口腔环境中六个月后,假牙在材料的极端表面发生了四方到单斜的转变,这个过程随着时间的推移而显著增加。在五年的监测中,在单斜晶粒局部簇的存在下,转化发展不均匀。摩擦学应力从这些团簇中产生谷物拉出,这可能会引起有关3Y-TZP纳米粒子释放到体内的问题。5年后假体骨折率为4.5%。
结论:LTD在3Y-TZP假牙的表面上体内开发,随着时间的推移进展缓慢但显著,长达5年的调查。然而,老化对记录的失效率和释放到体内的氧化锆纳米颗粒的影响需要进一步研究。
OBJECTIVE: To investigate the 5-year intraoral evolution and kinetics of low-temperature degradation (LTD) of second-generation monolithic prostheses made of 3% molar
yttrium-doped tetragonal zirconia polycrystal (3Y-TZP) and the influence of masticatory mechanical stresses and glaze layer on this evolution.
METHODS: A total of 101 posterior tooth elements were included in this prospective clinical
study, which comprised ex vivo LTD monitoring (at baseline, 6 months, 1 year, 2 years, 3 years, and 5 years) using Raman spectroscopy (n = 2640 monoclinic phase measurement points per evaluation time) and scanning electron microscopy (SEM). Four types of areas (1-2 mm2 surface, six on molars, and four on premolars) were analysed on each element surface: occlusal, axial, glazed, or unglazed. Raman mapping, high-resolution SEM, and focused ion beam-SEM were performed on selected samples.
RESULTS: The dental prostheses developed a tetragonal-to-monoclinic transformation at the extreme surface of the material after six months in a buccal environment, and this process increased significantly over time. Over the five years of monitoring, the transformation developed nonuniformly with the presence of localised clusters of monoclinic grains. Tribological stresses generate grain pull-out from these clusters, which may raise questions regarding the release of 3Y-TZP nanoparticles into the body. The prosthesis fracture rate was 4.5% after 5 years.
CONCLUSIONS: LTD developed in vivo on the surfaces of 3Y-TZP dental prostheses and progressed slowly but significantly over time, up to 5 years investigation. However, the effects of aging on the failure rate recorded and of zirconia nanoparticles released into the body require further investigation.