Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China.
School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China.
J Dent. 2017 Nov;66:23-31. doi: 10.1016/j.jdent.2017.09.003. Epub 2017 Sep 12.
The purpose of this study is to elucidate the effects of small-grit grinding on the mechanical behaviors and ageing resistance of a super-translucent dental zirconia and to investigate the necessity of glazing for the small-grit ground zirconia.
Small-grit grinding was performed using two kinds of silicon carbide abrasive papers. The control group received no grinding. The unground surfaces and the ground surfaces were glazed by an experienced dental technician. Finally, the zirconia materials were thermally aged in water at 134°C for 5h. After aforementioned treatments, we observed the surface topography and the microstructures, and measured the extent of monoclinic phase, the nano-hardness and nano-modulus of the possible transformed zone and the flexural strength.
Small-grit grinding changed the surface topography. The zirconia microstructure did not change obviously after surface treatments and thermal ageing; however, the glaze in contact with zirconia showed cracks after thermal ageing. Small-grit grinding did not induce a phase transformation but improved the flexural strength and ageing resistance. Glazing prevented zirconia from thermal ageing but severely diminished the flexural strength. The nano-hardness and nano-modulus of the surface layer were increased by ultrafine grinding.
The results suggest that small-grit grinding is beneficial to the strength and ageing resistance of the super-translucent dental zirconia; however, glazing is not necessary and even impairs the strength for the super-translucent dental zirconia.
This study is helpful to the researches about dental grinding tools and maybe useful for dentists to choose reasonable zirconia surface treatments.
本研究旨在阐明小粒度研磨对超透明牙科氧化锆力学性能和耐老化性能的影响，并探讨小粒度研磨氧化锆是否需要上釉。
使用两种碳化硅磨料砂纸进行小粒度研磨。对照组未进行研磨。未经研磨的表面和研磨后的表面由有经验的牙科技术人员上釉。最后，将氧化锆材料在 134°C 的水中热老化 5h。经过上述处理后，观察表面形貌和微观结构，测量可能转化区域的单斜相程度、纳米硬度和纳米模量以及弯曲强度。
小粒度研磨改变了表面形貌。表面处理和热老化后，氧化锆的微观结构没有明显变化；然而，与氧化锆接触的釉面在热老化后出现了裂纹。小粒度研磨不会引起相变，但会提高弯曲强度和耐老化性。上釉可以防止氧化锆发生热老化，但会严重降低弯曲强度。表面层的纳米硬度和纳米模量通过超微研磨得到提高。
结果表明，小粒度研磨有利于超透明牙科氧化锆的强度和耐老化性；然而，上釉并非必要，甚至会损害超透明牙科氧化锆的强度。
本研究有助于牙科研磨工具的研究，可能对牙医选择合理的氧化锆表面处理方法有用。
