烧结次数对牙科全瓷微结构和色差的影响

Effects of Number of Firings on the Microstructure and Color Difference of Dental All-ceramic Systems

目的:评价烧结次数对牙科全瓷微结构和色差的影响。方法:样本由3种品牌的全瓷材料制作,即:热压全瓷(IPS EmpressⅡ)、氧化铝全瓷(In-Cream alumina)和氧化锆全瓷(Cercon CAD/CAM zirconia)。通过X射线衍射仪(x-ray diffractomer,XRD)和扫描电子显微镜(scanning electron microscope,SEM)表征烧结后全瓷样本,分光光谱仪上测量和计算烧结后全瓷样本的色差(ΔE*ab)。结果:XRD和SEM结果显示5次烧结后热压全瓷基底冠和饰面瓷均发生由无定形玻璃相向晶相的转变,而氧化铝全瓷和氧化锆全瓷的转变则相反。烧结次数与全瓷品牌和ΔE*ab之间存在交互作用(P<0.05)。氧化铝全瓷5次烧结后的色差最大(1.9),已接近临床可接受色差的域值。结论:烧结次数因玻璃相与晶相之间的相互转变对色差造成影响,5次烧结后热压全瓷发生了玻璃相向晶相的转化,氧化锆全瓷几乎不受影响。但5次烧结后的3种全瓷的色差变化仍在视觉可接受范围内。

Objective： To evaluate the effects of number of firings on the microstructure and color difference of dental all-ceramic systems.Methods： Specimens were made of three kinds of all-ceramics systems i.e.heat pressed all-ceramic（IPS Empress Π）,alumina all-ceramic（In-Cream alumina） and zirconia all-ceramic（Cercon CAD/CAM zirconia）.Specimens after firings were characterised using X-ray diffractomer（XRD） and scanning electron microscope（SEM）and color difference（ΔE＊ab） of all-ceramic after firings was measured and calculated by spectrophotometer.Results： XRD and SEM revealed the transformation of core and veneering material of Empress Π from an amorphous glass to a crystalline phase and the change of alumina and zirconia in reverse after 5 firings.Significant interactions were present between the number of firings and the brand and ΔE＊ab（P〈0.05）.The color difference of alumina all-ceramic（1.9） was the largest after 5 firings which was close to acceptable range of clinic.Conclusion： The color difference of dental all-ceramic systems was influenced by the number of firings because of the interconversion between glassy phase and crystal phase effects.5 firings result in the interconversion of IPS Express II between glassy phase and crystal phase while Cercon CAD/CAM is barely affected.However,the change of color difference after 5 firings was still within perceptible and acceptable range.