Hafezeqoran Ali, Sabanik Pouya, Koodaryan Roodabeh, Ghalili Kambiz M
Associate Professor, Prosthodontics, Department of Prosthodontics, Faculty of Dentistry, Tabriz University of Medical Sciences, Tabriz, East Azerbaijan Province, Iran.
Private practice, Tabriz, East Azerbaijan Province, Iran.
J Prosthet Dent. 2023 Dec;130(6):917-926. doi: 10.1016/j.prosdent.2021.12.005. Epub 2022 Jan 31.
Advances in dentistry have led to more esthetic and biocompatible restorative materials such as translucent zirconia and to faster and more accurate manufacturing methods. How changes in the surface and optical properties of translucent zirconia affect the esthetics and durability of these restorations under different conditions and manufacturing processes is unclear.
The purpose of this in vitro study was to evaluate the effect of the sintering speed, aging process, and different surface treatments on the translucency and surface structure of monolithic zirconia restorations.
Prepared typodont teeth were scanned, and 40 three-unit fixed partial dentures (FPDs) and 40 disk specimens were designed and prepared from monolithic zirconia blanks. The specimens were divided into traditional or speed sintering groups (20 FPDs and 20 disks each); half of each group (10 FPDs and 10 disks) was polished with a handpiece at 10 000 rpm, and the other half was glazed. Half of the specimens were thermocycled with 3500 cycles in 5 °C and 55 °C water baths, and the remaining half were not thermocycled. Translucency was measured with a spectrophotometer. Surface free energy was calculated in mNm with a contact angle device; surface roughness was measured in nm with an atomic force microscope. Translucency data were analyzed by the Kruskal-Wallis and Mann-Whitney tests, while surface free energy and surface roughness data were analyzed by 3-way ANOVA (α=.05).
The highest transmittance was in the speed sintered, polished, nonthermocycled group, and the lowest transmittance was in the speed sintered, polished, thermocycled group (P=.029). The transmittance of the traditionally sintered, polished, nonthermocycled group was significantly higher than that in all the speed sintered, glazed groups; the traditionally sintered, glazed groups; and the traditionally sintered, polished, thermocycled group (P=.029). The transmittance of the traditionally sintered, polished, thermocycled group was significantly higher than that of all traditionally sintered, glazed groups (P=.029). The mean surface free energy in the traditionally sintered groups was higher than that in the speed sintered groups (P=.002); also, it was higher in the glazed groups than in the polished groups (P<.001). The aging process decreased surface free energy (P=.023). The mean surface roughness in the speed sintered groups was significantly lower than that in the traditionally sintered groups (P=.004). No significant difference in surface roughness was found between the polished and glazed groups and between the 2 variables of the aging process (P>.05).
Speed sintering and polishing may decrease the surface free energy and increase the translucency of the monolithic zirconia restoration. Also, speed sintering creates a smoother surface. Aging had a more significant effect on decreasing the surface free energy of the specimens and could make the least translucent restorations.
牙科领域的进展带来了更美观且生物相容性更好的修复材料，如半透明氧化锆，以及更快、更精确的制造方法。半透明氧化锆的表面和光学性能变化如何在不同条件和制造工艺下影响这些修复体的美观性和耐久性尚不清楚。
本体外研究的目的是评估烧结速度、老化过程和不同表面处理对整体式氧化锆修复体的半透明度和表面结构的影响。
对制备好的模型牙进行扫描，从整体式氧化锆坯料设计并制备40个三单位固定局部义齿（FPD）和40个圆盘试件。将试件分为传统烧结组或快速烧结组（每组20个FPD和20个圆盘）；每组的一半（10个FPD和10个圆盘）用转速为10000转/分钟的手机进行抛光，另一半进行上釉处理。一半试件在5℃和55℃水浴中进行3500次热循环，另一半不进行热循环。用分光光度计测量半透明度。用接触角装置以mNm为单位计算表面自由能；用原子力显微镜以nm为单位测量表面粗糙度。半透明度数据采用Kruskal-Wallis和Mann-Whitney检验进行分析，而表面自由能和表面粗糙度数据采用三因素方差分析（α = 0.05）。
最高透光率出现在快速烧结、抛光、未热循环组，最低透光率出现在快速烧结、抛光、热循环组（P = 0.029）。传统烧结、抛光、未热循环组的透光率显著高于所有快速烧结、上釉组；传统烧结、上釉组；以及传统烧结、抛光、热循环组（P = 0.029）。传统烧结、抛光、热循环组的透光率显著高于所有传统烧结、上釉组（P = 0.029）。传统烧结组的平均表面自由能高于快速烧结组（P = 0.002）；同样，上釉组的表面自由能高于抛光组（P < 0.001）。老化过程降低了表面自由能（P = 0.023）。快速烧结组的平均表面粗糙度显著低于传统烧结组（P = 0.004）。抛光组和上釉组之间以及老化过程的两个变量之间在表面粗糙度上没有显著差异（P > 0.05）。
快速烧结和抛光可能会降低整体式氧化锆修复体的表面自由能并提高其半透明度。此外，快速烧结可形成更光滑的表面。老化对降低试件的表面自由能有更显著的影响，并且可能使修复体的半透明度最低。
