Kheur Mohit, Lakha Tabrez, Shaikh Saleha, Kheur Supriya, Qamri Batul, Zhen Lee Wan, Al-Haj Husain Nadin, Özcan Mutlu
Department of Prosthodontics and Implantology, M.A. Rangoonwala College of Dental Sciences & Research Centre, Pune 411001, India.
Department of Oral Pathology and Microbiology, D.Y. Patil Dental College, D.Y. Patil Vidyapeeth, Pune 411018, India.
Materials (Basel). 2022 Mar 16;15(6):2202. doi: 10.3390/ma15062202.
This study evaluated the effects of different simulated chairside grinding and polishing protocols on the physical and mechanical properties of surface roughness, hardness, and flexural strength of monolithic zirconia. Sintered monolithic zirconia specimens (15 mm × 3 mm × 3 mm) were abraded using three different burs: diamond bur, modified diamond bur (zirconia specified), and tungsten carbide bur, along with a group of unprepared specimens that served as a control group. The study was divided into two phases, Phase 1 and Phase 2. Surface roughness, surface hardness, and flexural strength were assessed before and after the grinding procedure to determine the ‘best test group’ in Phase 1. The best abrasive agent was selected for Phase 2 of the study. The specimens in Phase 2 underwent grinding with the best abrasive agent selected. Following the grinding, the specimens were then polished using commercially available diamond polishing paste, a porcelain polishing kit, and an indigenously developed low-temperature sintered zirconia slurry. The physical and mechanical properties were again assessed. Results were analyzed using one-way ANOVA test. Specimens were observed under scanning electron microscopy (SEM) and X-ray diffraction (XRD) for their microstructure and crystalline phases, respectively. Grinding with diamond burs did not weaken zirconia (p > 0.05) but produced rougher surfaces than the control group (p < 0.05). Tungsten carbide burs did not significantly roughen the zirconia surface. However, specimens ground by tungsten carbide burs had a significantly reduced mean flexural strength (p < 0.05) and SEM revealed fine surface cracks. Phase transformation was not detected by XRD. Polishing with commercially available polishing agents, however, restored the surface roughness levels to the control group. Dental monolithic zirconia ground with tungsten carbide burs had a significantly reduced flexural strength and a smooth but defective surface. However, grinding with diamond burs roughened the zirconia surface. These defects may be reduced by polishing with commercially available polishing agents. The use of tungsten carbide burs for grinding dental zirconia should not be advocated. Grinding with diamond abrasives does not weaken zirconia but requires further polishing with commercially available polishing agents.
本研究评估了不同的模拟椅旁研磨和抛光方案对整体式氧化锆表面粗糙度、硬度和抗弯强度等物理和力学性能的影响。使用三种不同的车针研磨烧结后的整体式氧化锆试件（15毫米×3毫米×3毫米）：金刚石车针、改良金刚石车针（特定氧化锆用）和碳化钨车针，同时设置一组未处理的试件作为对照组。该研究分为两个阶段，即阶段1和阶段2。在研磨程序前后评估表面粗糙度、表面硬度和抗弯强度，以确定阶段1中的“最佳测试组”。为研究的阶段2选择最佳磨料。阶段2中的试件使用选定的最佳磨料进行研磨。研磨后，然后使用市售金刚石抛光膏、瓷质抛光套件和自行研制的低温烧结氧化锆浆料对试件进行抛光。再次评估物理和力学性能。结果采用单因素方差分析进行分析。分别在扫描电子显微镜（SEM）和X射线衍射（XRD）下观察试件的微观结构和晶相。用金刚石车针研磨不会削弱氧化锆（p>0.05），但比对照组产生更粗糙的表面（p<0.05）。碳化钨车针不会使氧化锆表面显著变粗糙。然而，用碳化钨车针研磨的试件平均抗弯强度显著降低（p<0.05），SEM显示表面有细微裂纹。XRD未检测到相变。然而，用市售抛光剂抛光可将表面粗糙度恢复到对照组水平。用碳化钨车针研磨的牙科整体式氧化锆抗弯强度显著降低，表面光滑但有缺陷。然而，用金刚石车针研磨会使氧化锆表面变粗糙。使用市售抛光剂抛光可减少这些缺陷。不提倡使用碳化钨车针研磨牙科氧化锆。用金刚石磨料研磨不会削弱氧化锆，但需要用市售抛光剂进一步抛光。
