| Abstract: | 金屬燒附陶瓷復形體已使用多年，其生物相容性與美觀仍有無法改進之處。為改善其缺點而發展之全陶瓷復形體，其透光度與抗彎曲強度能力已成為臨床上選擇全陶瓷系統之重要依據。
本研究之目的為評估不同的全陶瓷系統冠心體之透光性質及抗彎曲強度，並觀察其顯微結構的差異。選擇三種全陶瓷系統冠心體材料：IPS Empress(R) 2，VITA In-Ceram(R) Alumina 與 VITA In-Ceram(R) Zirconia。IPS Empress(R) 2使用壓鑄法製做試片，命名為Em2組；VITA In-Ceram(R) Alumina 與 VITA In-Ceram(R) Zirconia 使用DCS(R)電腦輔助系統製作試片，分別命名為InA與InZ組，每種陶瓷各做出厚度為0.5 mm與0.8 mm，直徑為14 mm之試片，經研磨拋光及模擬烤瓷而成所需試片。
使用色度計（Color meter）進行試片之透光度測試，所得數值0為全透光，1為全不透光，而後依照國際標準組織第 6872號（ISO 6872）規範，進行陶瓷試片之雙軸抗彎曲測試。透光度、荷重（N）與彎曲強度值（MPa）；結果均採用單向變異數分析法（One-way ANOVA）以及Tukeys事後檢定檢測組間差異性，並使用韋伯統計（Weibull statistics）計算各材料彎曲強度之m值以分析穩定度。另使用電子顯微鏡（SEM）觀察比較破裂陶瓷試片內部顯微結構之差異。
透光度由高至低依序為Em2 0.5mm（0.78）、Em2 0.8 mm（0.85）、InA 0.5 mm（0.94）、InA 0.8 mm（0.98）、InZ 0.5mm（1.00）、InZ 0.8 mm（1.00）。荷重值由高至低依序為InZ 0.8mm、InA 0.8 mm、Em2 0.8 mm、InZ 0.5 mm、InA 0.5 mm、Em2 0.5 mm。雙軸彎曲強度值InZ最高，InA次之，Em2最低，三種材料彼此之間於統計上有顯著差異(P < 0.05)。韋伯分析結果m值由高至低依序為Em2 0.8mm、Em2 0.5 mm、InZ 0.8 mm、InA 0.5 mm、InA 0.8mm、InZ 0.5 mm。掃描式電子顯微鏡影像中，Em2材料結構以針狀矽酸鋰結晶為主，斷裂模式主要為玻璃質斷裂與矽酸鋰之貫穿晶格斷裂，InA與InZ可觀察到氧化鋁框架以及浸潤之玻璃材，斷裂模式主為氧化鋁之貫穿晶格斷裂，此外InZ亦觀察到氧化鋯晶體的存在。IPS Empress(R) 2透光度高彎曲強度較低宜用於美觀高度要求之前牙區，而美觀需求不高之後牙區，宜用彎曲強度高透光度較低之 VITA In-Ceram(R) Alumina或VITA In-Ceram(R) Zirconia。
Porcelain fused to metal prostheses had been used for many years, while the biocompatibility and esthetic properties were still insufficiently. The all ceramic prostheses were developed for improving those disadvantages. The translucency and flexural strength are most important properties when choosing all ceramic materials.
The purpose of this study is to evaluate the translucency and biaxial flexural strength of all ceramic core materials, as well as the microstructure in different ceramic systems.
Three kinds of all ceramic core materials were chosen: IPS Empress(R) 2, VITA In-Ceram(R) Alumina and VITA In-Ceram(R) Zirconia. The specimens of IPS Empress(R) 2 were fabricated by heat-pressed method, named Em2 group, and the specimens of VITA In-Ceram(R) Alumina and VITA In-Ceram(R) Zirconia were fabricated by DCS(R) system, named InA group and InZ group. All disc specimens were prepared 0.5+0.05 mm and 0.8+0.05 mm in thickness and 14 mm in diameter ( n = 5 per group ). After grinding and polishing with sandpaper, simulate firing procedures (according to the manufacturer''s recommend) were applied to all specimens.
The color meter was used to measure the translucency of specimens (0 = transparent, 1 = opaque), then the biaxial flexural test was used to measure the flexural strength of the specimens. The data of translucency, load (N) and flexural strength (MPa) were analyzed by one-way ANOVA followed by Tukey multiple comparison test for significant findings ( α = 0.05 ). Weibull statistics were also applied to all data for calculating the Weibull modulus (m). The fracture surface of these core materials were observed under scanning electron microscope ( SEM ).
The translucency values in order of most translucent to most opaque were as follows: Em2 0.5mm, Em2 0.8 mm, InA 0.5 mm, InA 0.8 mm, InZ 0.5mm, InZ 0.8 mm. The load (N) data in order of high to low were as follows: InZ 0.8mm, InA 0.8 mm, Em2 0.8 mm, InZ 0.5 mm, InA 0.5 mm, Em2 0.5 mm. The flexural strength of InZ were highest, follow by InA, and Em2, and there was a statistically significant difference among these 3 kinds of core materials. Weibull modulus in order of high to low were as follows: Em2 0.8mm, Em2 0.5 mm, InZ 0.8 mm, InA 0.5 mm, InA 0.8mm, InZ 0.5 mm. The SEM analysis of the fractured surfaces indicated that Em2 was mostly of transgranular fracture of lithium disilicate crystalls, InA and InZ was mostly of transgranular fracture of alumina platelets, the zirconia particles of InZ were also observed. IPS Empress(R) 2 can be used for anterior region because of higher translucency and lower flexural strength. VITA In-Ceram(R) Alumina and VITA In-Ceram(R) Zirconia can be used for posterior region because of lower translucency and higher flexural strength. |
