Heffernan Michael J, Aquilino Steven A, Diaz-Arnold Ana M, Haselton Debra R, Stanford Clark M, Vargas Marcos A
School of Dentistry and Dows Institute for Dental Research, University of Iowa, Iowa City, Iowa, USA.
J Prosthet Dent. 2002 Jul;88(1):4-9.
All-ceramic restorations have been advocated for superior esthetics. Various materials have been used to improve ceramic core strength, but it is unclear whether they affect the opacity of all-ceramic systems.
This study compared the translucency of 6 all-ceramic system core materials at clinically appropriate thicknesses.
Disc specimens 13 mm in diameter and 0.49 +/- 0.01 mm in thickness were fabricated from the following materials (n = 5 per group): IPS Empress dentin, IPS Empress 2 dentin, In-Ceram Alumina core, In-Ceram Spinell core, In-Ceram Zirconia core, and Procera AllCeram core. Empress and Empress 2 dentin specimens also were fabricated and tested at a thickness of 0.77 +/- 0.02 mm (the manufacturer's recommended core thickness is 0.8 mm). A high-noble metal-ceramic alloy (Porc. 52 SF) served as the control, and Vitadur Alpha opaque dentin was used as a standard. Sample reflectance (ratio of the intensity of reflected light to that of the incident light) was measured with an integrating sphere attached to a spectrophotometer across the visible spectrum (380 to 700 nm); 0-degree illumination and diffuse viewing geometry were used. Contrast ratios were calculated from the luminous reflectance (Y) of the specimens with a black (Yb) and a white (Yw) backing to give Yb/Yw with CIE illuminant D65 and a 2-degree observer function (0.0 = transparent, 1.0 = opaque). One-way analysis of variance and Tukey's multiple-comparison test were used to analyze the data (P<.05).
Contrast ratios in order of most translucent to most opaque were as follows: Vitadur Alpha 0.60 +/- 0.03, Empress (0.5 mm) 0.64 +/- 0.01, In-Ceram Spinell 0.67 +/- 0.02, Empress 2 (0.5 mm) 0.68 +/- 0.02, Empress (0.8 mm) 0.72 +/- 0.01, Procera 0.72 +/- 0.01, Empress 2 (0.8 mm) 0.74 +/- 0.01, In-Ceram Alumina 0.87 +/- 0.01, In-Ceram Zirconia 1.00 +/- 0.01, and 52 SF alloy 1.00 +/- 0.00.
Within the limitations of this study, there was a range of ceramic core translucency at clinically relevant core thicknesses. In order of decreasing translucency, the ranges were Vitadur Alpha dentin (standard) > In-Ceram Spinell > Empress, Procera, Empress 2 > In-Ceram Alumina > In-Ceram Zirconia, 52 SF alloy.
全瓷修复体因其卓越的美学效果而备受推崇。人们使用了各种材料来提高陶瓷核的强度，但这些材料是否会影响全瓷系统的不透明度尚不清楚。
本研究比较了6种全瓷系统核材料在临床适宜厚度下的半透明度。
用以下材料制作直径13mm、厚度0.49±0.01mm的圆盘状试件（每组n = 5）：IPS Empress牙本质、IPS Empress 2牙本质、In-Ceram氧化铝核、In-Ceram尖晶石核、In-Ceram氧化锆核和Procera AllCeram核。还制作并测试了厚度为0.77±0.02mm的Empress和Empress 2牙本质试件（制造商推荐的核厚度为0.8mm）。一种高贵金属烤瓷合金（Porc. 52 SF）用作对照，Vitadur Alpha不透明牙本质用作标准。使用连接到分光光度计的积分球在可见光谱（380至700nm）范围内测量样品反射率（反射光强度与入射光强度之比）；采用0度照明和漫反射观察几何条件。根据试件在黑色（Yb）和白色（Yw）背景下的发光反射率（Y）计算对比度，以CIE照明体D65和2度观察者函数得出Yb/Yw（0.0 = 透明，1.0 = 不透明）。采用单因素方差分析和Tukey多重比较检验分析数据（P<0.05）。
从最半透明到最不透明的对比度顺序如下：Vitadur Alpha 0.60±0.03、Empress（0.5mm）0.64±0.01、In-Ceram尖晶石0.67±0.02、Empress 2（0.5mm）0.68±0.02、Empress（0.8mm）0.72±0.01、Procera 0.72±0.01、Empress 2（0.8mm）0.74±0.01、In-Ceram氧化铝0.87±0.01、In-Ceram氧化锆1.00±0.01和52 SF合金1.00±0.00。
在本研究的局限性范围内，在临床相关的核厚度下，陶瓷核的半透明度存在一定范围。按照半透明度降低的顺序，范围为Vitadur Alpha牙本质（标准）> In-Ceram尖晶石> Empress、Procera、Empress 2> In-Ceram氧化铝> In-Ceram氧化锆、52 SF合金。
