Attachoo Surawut, Juntavee Niwut
Division of Biomaterials and Prosthodontics Research, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand.
Department of Prosthodontics, Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand.
J Clin Exp Dent. 2019 Feb 1;11(2):e146-e153. doi: 10.4317/jced.55497. eCollection 2019 Feb.
Sintering process is accountable for aesthetic appearance of zirconia restoration. This study appraised the effect of different sintering procedure via sintered temperatures and sintering times on spectral translucence of monolithic zirconia.
One hundred and thirty five monolithic zirconia specimens (width, length, thickness = 10, 20, 1.5 mm) were prepared from yttrium-stabilized tetragonal zirconia polycrystalline (Y-TZP, Ceramill®) and unintentionally divided into nine groups to be sintered at different temperatures [decreasing- (SD, 1350°C), regular- (SR, 1450°C), and increasing- (SI, 1550°C) sintering temperature] and different sintering times [shortening- (HS, 60 min), regular- (HR, 120 min), and prolong- (HP, 180 min) sintering time]. Spectral translucence was determined by using spectrophotometer and calculated for translucency parameter (TP). The surface topography and grain size were evaluated by using a scanning electron microscope (SEM). Crystalline structures of monoclinic (m) and tetragonal (t) phases were determined by using the X-ray diffraction (XRD). An analysis of variance (ANOVA) was used to determine for significant differences of translucence upon different sintering processes (α=0.05).
The mean, standard deviation of TP were 3.22±0.12 for SRHP, 3.14±0.18 for SIHS, 3.04±0.17 for SRHR, 2.94±0.18 for SRHS, 2.93±0.17 for SIHR, 2.67±0.15 for SIHP, 1.91±0.17 for SDHP, 1.34±0.21 for SDHR and 0.10±0.01 for SDHS. Spectral translucence was significantly affected by altering sintering temperatures and holding times (<0.05). Enlargement of grain size and increasing t→m phase metamorphosis related with upraising sintered temperatures and extending sintered holding times were signified.
Altering sintering parameters affected spectral translucence of zirconia. Upraising sintered temperature to SR and prolonging sintering time to HP were advocated to enhance spectral translucence of nano-crystal monolithic zirconia, and advised to accomplished aesthetic appearance of restoration in clinical practice. CAD-CAM, sintering process, translucency, zirconia.
烧结过程对氧化锆修复体的美学外观至关重要。本研究评估了不同烧结程序（通过烧结温度和烧结时间）对整体式氧化锆光谱半透明度的影响。
从钇稳定四方多晶氧化锆（Y-TZP，Ceramill®）制备了135个整体式氧化锆试样（宽度、长度、厚度分别为10、20、1.5毫米），并无意分为九组，在不同温度[递减（SD，1350°C）、常规（SR，1450°C）和递增（SI，1550°C）烧结温度]和不同烧结时间[缩短（HS，60分钟））、常规（HR，120分钟）和延长（HP，180分钟）烧结时间]下进行烧结。使用分光光度计测定光谱半透明度，并计算半透明度参数（TP）。使用扫描电子显微镜（SEM）评估表面形貌和晶粒尺寸。通过X射线衍射（XRD）确定单斜（m）相和四方（t）相的晶体结构。使用方差分析（ANOVA）确定不同烧结过程中半透明度的显著差异（α = 0.05）。
SRHP组的TP平均值和标准差分别为3.22±0.12、SIHS组为3.14±0.18、SRHR组为3.04±0.17、SRHS组为2.94±0.18、SIHR组为2.93±0.17、SIHP组为2.67±0.15、SDHP组为1.91±0.17、SDHR组为1.34±0.21、SDHS组为0.10±0.01。光谱半透明度受到烧结温度和保温时间变化的显著影响（<0.05）。表明晶粒尺寸增大以及t→m相变态增加与烧结温度升高和烧结保温时间延长有关。
改变烧结参数会影响氧化锆的光谱半透明度。提倡将烧结温度提高到SR并将烧结时间延长到HP，以提高纳米晶整体式氧化锆的光谱半透明度，并建议在临床实践中实现修复体的美学外观。计算机辅助设计与制造、烧结过程、半透明度、氧化锆
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