Anusavice K J, Zhang N Z, Moorhead J E
Department of Dental Biomaterials, University of Florida, Gainesville 32610-0446, USA.
Dent Mater. 1994 Jul;10(4):230-5. doi: 10.1016/0109-5641(94)90066-3.
The objective of this study was to characterize the influence of various metals, metal compounds, and P2O5 as a nucleating agent on the color and translucency of a Li2O-Al2O3-CaO-SiO2 glass-ceramic.
Glass frits of Li2O-Al2O3-CaO-SiO2 (LACS), LACS with 1 mol% P2O5 (LACSP), and/or LACS with one of 16 colorants were melted, poured into a cylindrical graphite mold, cut into disks, annealed, nucleated, crystallized, and annealed again. Ten translucency measurements of each of five disks were made using a tristimulus colorimeter and a D65 standard CIE illuminant. The color of each disk was analyzed using the CIE Lab* color space system (1976) as a function of colorant, colorant concentration, and P2O5.
Mean L* values of glass-ceramic disks ranged from 63.5 for LACS containing 6.2 mmol% FeCl3 (LACSP-6.2Fe) to 84.1 for LACS. No significant difference (p > 0.05) was found between the mean L* values for LACS, LACSP, and LACS with 0.19 mmol% AgNO3 (LACS-0.19Ag). The mean contrast ratio of glass-ceramic specimens ranged from 0.42 (LACS and LACS-1.0Fe) to 0.98 (LACS-0.78Ag). Mean color difference values varied from 5.8 (LACSP-1.0Fe vs. LACS) to 36.3 (LACSP-0.78Ag vs. LACSP).
The results of this study indicate that, because certain colorants in glass-ceramics affect opacity as well as hue and chroma, the development of glass-ceramics should be simplified by: 1) employing a nucleating agent that does not affect hue or chroma significantly, 2) controlling fixed levels of translucency consistent with mechanical and physical property requirements, and 3) varying the hue and chroma by means of colorants that do not affect the crystallization process. This implies that the volume fraction and mean size of crystals must be controlled, since the translucency or opacity of glass-ceramics is associated with scattering of light at the interfaces between adjacent crystals, and between crystals and the glass phase because of differences in refractive indices (McMillan, 1979a).
本研究的目的是表征各种金属、金属化合物以及作为成核剂的P2O5对Li2O-Al2O3-CaO-SiO2微晶玻璃颜色和透明度的影响。
将Li2O-Al2O3-CaO-SiO2（LACS）、含1 mol% P2O5的LACS（LACSP）和/或含16种着色剂之一的LACS玻璃料熔化，倒入圆柱形石墨模具中，切成圆盘，进行退火、成核、晶化，然后再次退火。使用三刺激色度计和D65标准CIE光源对五个圆盘中的每一个进行十次透明度测量。使用CIE Lab*颜色空间系统（1976）分析每个圆盘的颜色，作为着色剂、着色剂浓度和P2O5的函数。
微晶玻璃圆盘的平均L值范围从含6.2 mmol% FeCl3的LACS（LACSP-6.2Fe）的63.5到LACS的84.1。LACS、LACSP和含0.19 mmol% AgNO3的LACS（LACS-0.19Ag）的平均L值之间未发现显著差异（p > 0.05）。微晶玻璃试样的平均对比度范围从0.42（LACS和LACS-1.0Fe）到0.98（LACS-0.78Ag）。平均色差从5.8（LACSP-1.0Fe与LACS相比）到36.3（LACSP-0.78Ag与LACSP相比）不等。
本研究结果表明，由于微晶玻璃中的某些着色剂会影响不透明度以及色调和彩度，因此微晶玻璃的开发应通过以下方式简化：1）采用对色调或彩度影响不大的成核剂；2）根据机械和物理性能要求控制固定的透明度水平；3）通过不影响结晶过程的着色剂来改变色调和彩度。这意味着必须控制晶体的体积分数和平均尺寸，因为微晶玻璃的透明度或不透明度与相邻晶体之间以及晶体与玻璃相之间由于折射率差异导致的光散射有关（麦克米伦，1979a）。
