市售螢光染劑對於釔安定正方晶相二氧化鋯陶瓷顏色、螢光及表面微結構之影響

Abstract

背景 釔安定正方晶相二氧化鋯(3％ mol yttrium-stabilized tetragonal zirconia poly-crystal, 3Y-TZP)陶瓷為近年來廣泛應用之牙科贋復材料。其與自然牙相近之象牙色外觀，視為極具應用於美觀區贋復材料之潛力。欲使釔安定正方晶相二氧化鋯(3Y-TZP)陶瓷達到最佳化擬真效果，多家廠商推出市售螢光染劑，能使二氧化鋯陶瓷(3Y-TZP)和自然牙具有相同螢光反應，使其更亮白。然而對於如何使用市售螢光染劑調控二氧化鋯陶瓷(3Y-TZP)螢光表現，及其對二氧化鋯陶瓷(3Y-TZP)顏色及微結構之影響，目前並無具體的文獻報告。 目的 本實驗欲檢測市售螢光劑是否可調控二氧化鋯陶瓷(3％ mol yttrium-stabilized tetragonal zirconia poly-crystal, 3Y-TZP)之螢光強度及其螢光表現與自然牙螢光表現之差異。同時觀察市售螢光劑之使用是否會伴隨二氧化鋯陶瓷(3Y-TZP)顏色改變。此外，觀察使用市售螢光劑是否會改變二氧化鋯陶瓷(3Y-TZP)微結構:晶體結構、表面型態與平均粒徑尺寸。 材料與方法 本實驗將未燒結ZirkonzahnR PRETTAU ZIRKON二氧化鋯陶瓷(3％ mol yttrium-stabilized tetragonal zirconia poly-crystal, 3Y-TZP)切削，再燒結成大小為直徑10 mm與厚 2 mm 之圓錠樣本。二氧化鋯陶瓷(3Y-TZP)樣本分為未染色C與以市售螢光染劑做為螢光來源之染色樣本F，先將需染色樣本進行染色後，再將所有樣本進行最終燒結。螢光染色之二氧化鋯陶瓷(3Y-TZP)樣本F又依染色方法分為浸泡或塗抹染色兩組。浸泡染色組依浸泡時間分為5秒、1分鐘與10分鐘，依序為F(5)、F(60)、F(600)三小組; 塗抹染色組依塗抹次數分為1與4次兩小組，依序為F1、F4。實驗分為三個部分進行: (1)以螢光光譜儀及紫外燈觀察浸泡染色時間及塗抹染色次數對螢光強度的影響，並與自然牙比較螢光光譜之差異;(2)以數位比色機紀錄市售螢光劑浸泡時間及塗抹次數所導致二氧化鋯陶瓷(3Y-TZP)之CIE L*a*b*值之變化，以了解螢光劑是否會導致可辨識顏色之變化(ΔE>3.7)，其顏色是否與自然牙顏色有所差異，並與淺色系A1及中間色系A3染劑染色後二氧化鋯陶瓷(3Y-TZP)之顏色做比較。以單因子變異數分析比較各組L*、a*、b*與∆E平均值是否有差異，定義P value = 0.05為顯著水平，若P value ≦0.05，進行事後多重比較，分析各組之差異。利用student t test分析各組樣本之∆E值與數值∆E = 3.7是否有統計上顯著差異，若P value ≦0.05則具統計上顯著意義;(3)以粉末X射線繞射儀觀察未染色與以不同方法染色之二氧化鋯陶瓷(3Y-TZP)之晶相結構，分析染色及染色方法是否會導致晶相改變。以掃描式電子顯微鏡觀察未染色與以不同方法染色之二氧化鋯陶瓷(3Y-TZP)的表面微結構差異，利用截距法計算平均粒徑及以能量分散光譜儀分析表面元素組成。結果以單因子變異數分析(one-way ANOVA) 比較各組平均數是否有差異， P value ≦ 0.05代表具統計顯著意義。 結果 一、以市售螢光染劑作為螢光來源之二氧化鋯陶瓷(3Y-TZP)與自然牙有不同的螢光表現。螢光染色二氧化鋯陶瓷(3Y-TZP)之激發與放射光譜波形相較於自然牙較為狹窄集中，往低波長偏移。二、市售螢光染劑染色二氧化鋯陶瓷(3Y-TZP)之螢光於CIE色度座標上，光譜相較於自然牙明顯往藍光位移。三、以市售螢光染劑作為二氧化鋯陶瓷(3Y-TZP)之螢光來源，可藉由浸泡時間調控螢光強度，隨浸泡時間增加，螢光強度增加。然而5秒、1分鐘與10分鐘之浸泡時間所造成螢光強度之差異無法以肉眼區分。四、以市售螢光染劑作為二氧化鋯陶瓷(3Y-TZP)之螢光來源，亦可藉由塗抹染色次數調控螢光強度，隨塗抹次數增加，螢光強度增加。塗抹一次及四次所造成螢光強度之差異，能以肉眼區分。五、市售螢光染劑改變二氧化鋯陶瓷(3Y-TZP)螢光之同時，伴隨顏色之改變，導致二氧化鋯陶瓷(3Y-TZP)之CIE L*值下降，a*值及b*值增加。使用最短的浸泡時間或最少的塗抹次數仍會造成肉眼可辨識顏色之改變(ΔE>3.7)，達到統計上顯著，p < 0.05。六、市售螢光染劑造成顏色之改變(ΔE)遠大於淺色系之染劑A1，p < 0.05。七、以浸泡與塗抹方法使用螢光染劑染色，達到相同的螢光強度時，塗抹方法對二氧化鋯陶瓷(3Y-TZP)之顏色的改變較少。此外，浸泡螢光染劑10分鐘會導致二氧化鋯陶瓷(3Y-TZP)顏色超出自然牙顏色區間外。八、未染色及使用市售螢光劑染色後的二氧化鋯陶瓷(3Y-TZP)均以正方晶相二氧化鋯(tetragonal phase ZrO2, t-ZrO2)為主體，含有少量的單斜晶相二氧化鋯(monoclinic phase ZrO2, m-ZrO2)。九、使用市售螢光劑以不同方法染色之二氧化鋯陶瓷(3Y-TZP)於電子顯微鏡下具有不同微結構之特徵，包含染劑物質分布、顆粒之均質性及平均粒徑尺寸。使用浸泡法染色之二氧化鋯陶瓷(3Y-TZP)F(600)其平均粒徑大於未染色C與使用塗抹法染色之二氧化鋯陶瓷(3Y-TZP) F4，達到統計上顯著，p < 0.05。 結論 使用市售螢光染劑(ZirkonzahnR Colour Liquid Fluoreszenz for Prettau)作為二氧化鋯陶瓷(3Y-TZP)之螢光來源，可藉由浸泡時間及塗抹染色次數調控二氧化鋯陶瓷(3Y-TZP)之螢光強度，同時伴隨肉眼可辨識之顏色變化。並且由於顏色變化比淺色染劑明顯，不適用於淺色區。塗抹染色之方法於增加螢光強度同時有較少的顏色變化，符合臨床上之需求，且染色後能維持均勻且適當粒徑尺寸，可避免二氧化鋯陶瓷(3Y-TZP)抗低溫衰變能力之下降。

Background 3％ mol yttrium-stabilized tetragonal zirconia poly-crystal (3Y-TZP) is becoming one of the most promising restorative materials. To mimic the photoluminescence of natural teeth, manufactories provide a fluorescent liquid applied on the 3Y-TZP. However, there is no document about the capacity of the fluorescent agent to regulate the photoluminescence intensity of 3Y-TZP, the photoluminescence expression, and the effect on the color and microstructure of 3Y-TZP. Purpose The purpose of this study was to explore if using a commercial fluorescent agent was able to regulate the photoluminescence intensity of 3Y-TZP, and to analyze the difference of photoluminescence expression between dyed 3Y-TZP and natural teeth. The color, crystallographic forms, surface morphology, and mean grain size of dyed 3Y-TZP were recorded and the results were compared to undyed 3Y-TZP. Materials and methods Zirconia sample was milled to disc form. Shading process was prior to sintering and the commercial fluorescent agent was applied by dipping and brushing methods. The discs were divided into 3 groups: the undyed control group; the dipping groups; the brushing groups. The dipping groups- F(5)、F(60)、F(600) were immersed in the commercial fluorescent agent for 5 sec., 1 and 10 min., respectively. The brushing groups- F1、F4 were tinted with the commercial fluorescent agent by 1 or 4 strokes respectively. This study was divided into 3 parts: (1) The photoluminescence excitation was observed by naked eyes under UV lamp and measured by photoluminescence spectrophotometer. (2) CIE L*, a*, b* values of various group were measured by digital colorimeter. Color change (∆E) of various groups was compared to ∆E=3.7. Student t test was performed to detect the difference (at a significance difference of p ≦ 0.05). One-way ANOVA tests (at a significance difference of p ≦ 0.05) were used to evaluate the difference of mean L*, a*, b*, ∆E values among various groups. (3) The crystallographic shapes of C、F(600)、F4 were measured by X-ray powder diffractometer (XRD). Surface structural and chemical differences among C、F(600)、F4 were evaluated using scanning electron microscopy (SEM) and energy dispersive analysis (EDS). The mean grain size was calculated. One-way ANOVA were used to detect the difference (at a significance difference of p ≦ 0.05). Results The results were listed below: (1) The photoluminescence excitation of dyed 3Y-TZP differed from a natural tooth. Their spectra were more concentrated than a natural tooth’s spectra, and the peaks were left-shifted. (2) The color of the photoluminescence of dyed 3Y-TZP was blue-shifted. (3) The commercial fluorescent agent could regulate the photoluminescence intensity of dyed 3Y-TZP by immersion time, and the intensity increased as immersion time increased. The difference of the photoluminescence intensity among F(5), F(60) and F(600) was not detected by naked eyes. (4) The commercial fluorescent agent could regulate the photoluminescence intensity of dyed 3Y-TZP by the number of strokes applied, and the intensity increased as strokes increased. The difference of the photoluminescence intensity between F1 and F4 could be detected by naked eyes. (5) The commercial fluorescent agent changed the color. The commercial fluorescent agent made L* value decreased, and a* and b* values increased. Even these samples with the shortest immersion time or the least applied stroke produced color change detectable by naked eyes, ΔE >3.7 ( p < 0.05). (6) The commercial fluorescence agent led to more color change than light-colored A1 agent (p<0.05). (7) The dipping groups caused more notable color change than the brushing groups as the photoluminescence intensity achieved the same level. (8) Undyed C and F4, F(600) samples were composed mainly of t-ZrO2, and a small quantity of m-ZrO2 content. (9) Different shading methods made microstructure distinct, such as the distribution of coloring pigment, homogeneity of grain size, and mean grain size. The dipping group F(600) had a significantly larger grain size than the control group C and the brushing group F4 ( p < 0.05). Conclusion The commercial fluorescent agent can regulate the photoluminescence intensity by immersion time and the number of the strokes applied. However, the increase of the photoluminescence intensity accompanies with color change. The color change is detectable by naked eyes and even more obvious than light-colored dye agent’s. The brushing method cause less color change than the dipping method as the photoluminescence intensity at the same level. Besides, the brushing method compared to the dipping method can maintain even and adequate grain size, which is thought as a key factor to avoid the low temperature degradation. These results show the brushing method more practical clinically than the dipping method.