Statement of problem

Monolithic ceramic restorations designed by computer-aided design and computer-aided manufacturing are increasingly being used by clinicians. With the introduction of new materials, their optical characteristics also need to be investigated.

Purpose

The purpose of this in vitro study was to compare the translucency and opalescence of lithium disilicate, zirconia-reinforced lithium silicate, presintered zirconia-reinforced lithium silicate, polymer-infiltrated ceramic-network material, and multilayer zirconia.

Material and methods

A total of 50 rectangular plates (14×12×1 mm) of 5 monolithic ceramics were prepared in this in vitro study (n=10). Each zirconia specimen was divided into 3 groups of incisal, middle, and gingival thirds. Each group was then evaluated separately. The color parameters of specimens were measured on 3 backgrounds, white, black, and #3 Ivoclar Natural Die Color material, by using a spectrophotometer. The translucency and opalescence of the specimens were determined by the relevant equations, and between-group comparisons were made. One-way ANOVA and Tamhane post hoc tests were used to compare groups (α=.05).

Results

The difference among the groups was significant in translucency (F=137.346, df=6, P<.001), contrast ratio (F=134.148, df=6, P<.001), and opalescence parameters (F=128.028, df=6, P<.001). The 3 zirconia groups (10.87 ±0.54 to 11.88 ±0.26) had a significantly lower translucency than the other groups, and the zirconia-reinforced lithium silicate group (18.14 ±0.74) showed the highest translucency. Zirconia-reinforced lithium silicate (12.36 ±0.42) had the highest opalescence, and the lowest opalescence was found for polymer-infiltrated ceramic-network (5.43 ±0.28) and the incisal third of zirconia (5.45 ±1.06).

Conclusions

The zirconia-reinforced lithium silicate and presintered zirconia-reinforced lithium silicate specimens had the highest translucency and opalescence. The studied multilayer zirconia, which had different cubic phase values from incisal to gingival blank, showed similar translucency over the entire range, and differences among different regions were related to chromatic variables.

中文翻译：

---

不同牙科整体陶瓷的半透明性和乳光性比较

问题陈述

由计算机辅助设计和计算机辅助制造设计的整体陶瓷修复体越来越多地被临床医生使用。随着新材料的引入，它们的光学特性也需要研究。

目的

这项体外研究的目的是比较二硅酸锂、氧化锆增强硅酸锂、预烧结氧化锆增强硅酸锂、聚合物渗透陶瓷网络材料和多层氧化锆的半透明性和乳白色。

材料与方法

在该体外研究 (n=10) 中，总共制备了 50 个矩形板 (14×12×1 mm) 的 5 块整体陶瓷。每个氧化锆标本分为切缘、中、牙龈三部分。然后分别对每组进行评估。通过使用分光光度计在 3 种背景（白色、黑色和 #3 Ivoclar Natural Die Color）材料上测量样品的颜色参数。标本的半透明性和乳光性由相关方程确定，并进行组间比较。使用单向方差分析和 Tamhane 事后检验来比较组 (α=.05)。

结果

各组之间的差异在半透明度 (F=137.346, df=6,  P <.001)、对比度 (F=134.148, df=6,  P <.001) 和乳光参数 (F=128.028, df =6，P <.001）。3个氧化锆组（10.87±0.54至11.88±0.26）的半透明性明显低于其他组，氧化锆增强硅酸锂组（18.14±0.74）的半透明性最高。氧化锆增强的硅酸锂 (12.36 ±0.42) 的乳光最高，聚合物渗透陶瓷网络 (5.43 ±0.28) 和氧化锆切端的三分之一 (5.45 ±1.06) 的乳光最低。

结论

氧化锆增强硅酸锂和预烧结氧化锆增强硅酸锂试样具有最高的半透明性和乳白色。所研究的多层氧化锆从切缘到牙龈空白具有不同的立方相值，在整个范围内显示出相似的半透明度，不同区域之间的差异与色度变量有关。