E-max和IPS-EMPRESS Ⅱ全瓷贴面对变色牙颜色改善的研究

目的:观察对比E-max和IPS-EMPRESSS Ⅱ两种全瓷贴面对变色牙颜色改善的修复效果,为临床应用提供参考。方法:对36颗变色上前牙分别采用E-max和IPS—EMPRESS Ⅱ全瓷贴面修复。用Shade-Eye-NCC电脑比色仪分别测定修复前牙齿、贴面就位(无试色糊剂)和试粘接(分别用WOT和Tro试色糊剂)及最后粘接后两种修复体唇侧的中1/3处的L*、a*、b*值,根据色差公式△E=[(△L*)2+(△a*)2+(△b*)2]1/2,对比两种瓷贴面对变色牙的修复效果,为临床应用提供参考。结果:IPS-EMPRESSSⅡ全瓷贴面粘接后与牙体预备前的色差值为7.9960,粘接后与试戴(无试色糊剂)的色差值为2.3906,粘接后与试戴(有试色糊剂)的色差值为1.6578。E-max全瓷贴面粘接后与牙体预备前的色差值为8.2428,粘接后与试戴(无试色糊剂)的色差值为1.4638,粘接后与试戴(有试色糊剂)的色差值为1.2596。两组全瓷贴面试戴后(无试色糊剂)、试粘接(有试色糊剂)、粘接后与基牙牙体预备前△E*在统计学上差异有显著性,两组全瓷贴面修复前后的的L*、a*、b*值之间有统计学差异,修复后的L*增大,a*、b*值减少。试粘接后L*值和b*值增大,a*值减少。修复后的L*、a*、b*值与贴面自身相比存在差异,修复后的L*值偏小,a*、b*值偏大。两组瓷贴面在采用WOT糊剂粘接后L*值、b*值最大,与Trt组比,差异均有统计学意义。结论:E-max全瓷贴面比IPS-EMPRESSSⅡ全瓷贴面更有效改善变色牙的颜色,IPS-EMPRESSSⅡ全瓷贴面粘接后较试戴(无试色糊剂)明亮度降低比E-max瓷贴面明显。     

瓷贴面基底烧结饰面瓷的临床应用研究

目的探讨瓷贴面基底烧结饰面瓷的临床应用效果。方法对12例患者的54颗着色牙进行全瓷贴面修复,根据着色原因不同将其分为四环素牙组、氟斑牙组和死髓牙组。应用MarkⅡ瓷块制作贴面基底,在其上烧结饰面瓷,制作全瓷贴面。分别在牙体预备前、贴面基底在白背景和基牙上试戴时、全瓷贴面在白背景和基牙上黏固后采用Shade Eye电脑比色仪进行颜色测量,测量结果采用CIE1976L*a*b*标准色度系统表示,计算色差。全瓷贴面黏固后每3个月检查1次修复体的边缘密合度、颜色以及折裂、脱落情况。结果瓷贴面可在很大程度上改变基牙的颜色,其中四环素牙组和死髓牙组的贴面基底和瓷贴面在白背景和基牙背景下有明显的颜色差异,而氟斑牙组贴面在白背景和基牙背景下的颜色差异较小,肉眼几乎无法察觉。全瓷贴面黏固后3～12个月复诊,贴面边缘密合良好,无食物嵌塞、继发龋、牙龈炎等,也无1例发生修复体脱落或折裂。结论全瓷贴面修复着色牙具有较好的效果,氟斑牙是较理想的适应证,而中度以上的四环素牙和变色较重的死髓牙在设计全瓷贴面时应选择色度较深的基底瓷以增加贴面的遮色能力或应用不透明材料制作基底。     

三种烤瓷修复体的色度学研究

目的：研究3种烤瓷修复体之间及与Vita标准比色片之间的色差。方法：实验组为In-Ceram全瓷修复体（A组）、钛金属烤瓷修复体（B组）、镍铬合金烤瓷修复体（C组）。对照组为VitaA2标准比色片（D组）。实验组每组10个圆盘状试件，每个试件直径15mm。玻璃渗透氧化铝底层和金属底层均厚1mm。使用VitaA2瓷粉，遮色瓷厚0．2mm，体瓷厚1mm，透明瓷厚0．4mm，按操作常规烧制。使用Spectrascan PR650分光光谱测色仪测试试件和VitaA2标准比色片。颜色系统为CIE1976，L^＊a^＊^b^＊色度系统。结果：各实验组之间除A-C组的a^＊值外，其余的色度值之间均有显著差异。3组之间的色差范围为3．25-8．50ΔE。与标准比色片相比，除C-D组的L^＊值和b^＊值及A-D组的b^＊值外，其余色度值之间均有显著差异。实验组与标准比色片的色差范围为2．29-8．31ΔE。结论：实验组之间及与标准比色片之间色差过大，应进一步改进这3种烤瓷修复体的颜色匹配性能。     

瓷贴面厚度及试色糊剂对IPS e.max铸瓷贴面色彩效果的影响

目的:观察不同瓷片厚度及试色糊剂对IPS e.max瓷贴面修复体颜色的影响,从而为临床提供理论依据。方法:将不同厚度A1色IPSe.max铸瓷片覆盖ND5色树脂块模拟瓷贴面修复变色基牙。电脑比色仪在标准白背景下分别测定对照组(瓷试样和树脂试样间加用水)、试色糊剂组(瓷试样和树脂试样间使用试色糊剂剂)色度值L~*、a~*、b~*值,计算明度差△L~*值及色差△E值,应用SPSS11.5软件行统计学分析。结果:相同瓷片厚度下,各试色糊剂组与对照组间△E>1.5NBS,肉眼可辨;其中使用+3、-3试色糊剂引起的明度差△L~*较大,色差△E亦较大,而其他几种试色糊剂引起的明度和色差变化较小;随着瓷贴面厚度的增加,同一色糊剂组与对照组明度差△L~*及色差△E均逐渐减小,当瓷贴面厚度为1mm时,试件明度差及色差变化最小。试色糊剂组与对照组色差值差异受到瓷贴面厚度和试色糊剂种类的显著影响(P<0.05)。结论:瓷贴面厚度及试色糊剂种类均影响修复体最终颜色。瓷厚度增加,遮色能力增强,试色糊剂对修复体颜色影响减小;而所有试色糊剂中+3、-3号试色糊剂调节颜色的能力较强。     

带金属底冠定制比色板的制作及其颜色特征

目的：探讨带金属底冠定制比色板的制作方法对其颜色特征的影响。方法：以右侧上颌中切牙为模型,按照临床金属融附烤瓷全冠的制作要求,制作与VITAPAN比色板颜色相对应的16色带金属基底的定制比色板标本,采用PR-650型光谱扫描色度仪,对上不同瓷层后的比色片进行颜色测量。结果：上釉完成后的比色片与上遮色瓷时的比色片进行比较,发现L^＊值呈下降趋势,a^＊、b^＊值呈上升的趋势。从上遮色瓷到上体瓷的过程中,比色片的L^＊值明显下降,而a^＊、b^＊值明显增加;随着釉瓷和透明瓷厚度的增加,L^＊、a^＊和b^＊值均稍有减小;上釉可增加比色片的明亮度。结论：金瓷修复体中各瓷层对修复体颜色都会产生一定影响,并且其影响作用各不相同。     

Nd—YAG激光漂白四环素牙效果观察

目的：评价Nd-YAG激光漂白四环素牙的有效性及持续性。方法：采用Nd-YAG激光及漂白糊剂实施诊室漂白及2周家庭漂白。利用PR－560测色计CIEL^*a^*b^*表色系对漂白前术后1d，2周，3月及6月的牙齿分别测色，分析牙色的变化。结果：漂白牙齿的平均测色结果表示，术后复查各阶段L^*均高于术前，与术前比较均有显著性差异（P＜0．01）；b^*均低于术前，除6月，术后各阶段与术前比较均有显著性差异（P＜0．05）；a^*各阶段与术前比较均无显著性差异。色差△E值呈逐渐下降趋势。结论：Nd-YAG激光漂白四环素牙即刻效果卓越，短期效果明显。     

松风HALO技工比色板修饰瓷粉的颜色分析

目的：研究松风HALO技工比色板修饰瓷粉颜色分布及各组修饰色的应用。方法：采用数码摄影和计算机技术对松风HALO修饰瓷比色板进行测量,根据比色板不透明修饰色,浓缩色、配合色、牙龈色的L^*,a^*,b^*,Ca^*b^*值分别绘制L－C及a-b散点图。结果：牙龈色a^*值较高,能够表现牙龈粉色彩效果;不透明层修饰色具有高亮度和彩度分布区域广,不透明等特点,其修饰等特点,其修饰功能非常强;浓缩色具有高亮度、低彩度的特性,配合色其亮度,彩度a^*、b^*值均接近,两者与牙本质瓷粉和切端瓷粉混合时,能够加强其颜色,但是降低亮度和提高彩度负面影响较小。结论：松风HALO技工比色板修饰色的亮度1彩度分布区域以及组成色调a^*、b^*值分布范围非常广阔,足以模拟正常人牙齿颜色,但必须加强技工对修饰瓷粉颜色的理解。     

Rely XTM Veneer试色糊剂遮色性的临床评价

目的:观察Rely XTM Veneer试色糊剂的遮色性.方法:100颗变色的上前牙,其中50颗全瓷冠修复、50颗全瓷贴面修复(均为Ips-empress Ⅱ系统制作).粘接前用试色糊剂[A1、A3、Transluent(Trt)、White opaque(WOT)和B0.5 opaque(B0.5)]代替粘接剂对基牙进行遮色,遮色后用ShadeEye-NCC电脑比色仪测定修复体的L*、a*、b*值,并记录测点的瓷层厚度.数据采用SAS6.12软件处理,根据公式色AE=[(△L*)2 (△a*)2 (△b*)2]1/2、L=L*、C=[(a*)2 (b*)2]1/2、H=arctan(b*/a2)计算并分析每种糊剂试色后的△E、L、C和H.,单因素方差分析全冠和贴面组的△E、L、C和H.结果:全瓷冠采用5种试色糊剂遮色后,WOT组的色差最大,与A1、A3、Trt、B0.5组之间有统计学差异(P＜0.05);全瓷贴面采用5种试色糊剂遮色后,WOT组的色差最大,B0.5组次之,WOT组和与A1、A3、Trt组之间有统计学差异(P＜0.05);贴面组与全冠组的色差间有统计学差异(P＜0.05).结论:WOT糊剂的遮色性最强,B0.5糊剂次之,其余3种糊剂的遮色性较为接近;瓷层厚度影响粘接剂的遮色效果.     

陶瓷材料对瓷贴面颜色的影响

目的研究两类三种陶瓷材料对瓷贴面修复颜色的影响,为临床工作中瓷贴面修复体与比色板的颜色匹配性提供指导。方法制作直径10mm、厚度0.7mm的A2色瓷贴面圆盘试件,按陶瓷材料及制作工艺分为无遮色长石质烤瓷组、遮色长石质烤瓷组、IPSe.maxPress铸瓷组3组。每组10个试件,共计30个试件。选择Natural Die Material Shade Guide比色板中的ND4、ND6、ND8三种颜色,分别代表轻、中、重度变色牙底色,采用对应颜色树脂各制作1个底色圆盘。对每个瓷贴面试件分别以3种底色圆盘为基牙底色,采用Vita Easyshade电脑比色仪测量瓷贴面修复体的色度值。计算各组瓷贴面修复体与标准比色片A2的色差。结果在轻、中、重度变色牙背景条件下,两种陶瓷材料的瓷贴面修复体与标准比色片A2间色差的比较结果为,IPS e.max Press铸瓷组<无遮色长石质烤瓷组<遮色长石质烤瓷组,差异有统计学意义(P<0.05)。结论采用长石质烤瓷贴面及IPS e.max Press热压铸瓷贴面模拟修复不同程度的变色牙时,热压铸瓷贴面与标准比色片的颜色匹配性高于长石质烤瓷贴面。     

两种VITA比色板的色度学比较

目的：对两种VITA比色板的色度范围进行比较分析，并与中国人牙色度范围相比较，以便为临床选色和瓷粉的使用提供指导。方法：选用CIEl976—L^*a^*b^*色度系统，用Minolta CM—2600d分光测色计对两种VITA比色板的色度佰进行测定，对二者的色度范围做了比较分析。结果：与Vita C1assical比色板相比，Vita 3D Master比色片明度值在较低的区域也有分布，a^*增大，使颜色向黄红色调方向移动；b^*也增大，使颜色的饱和度增大。Vita 3D—Master比色板几乎全部涵盖了Vita Classical比色板的明度和饱和度范围。二者与中国人牙色度范围相比较，部缺乏明度较高的色片，Vita 3D Master比色板较Vita C1assical比色板能够更好的覆盖中国人牙色范围，二者的色度范围相加则更有代表性。结论：Vita 3D—Master比色板较Vita Classical比色板颜色分布的范围更符合中国人牙色度范围、排列更合理，为临床准确地选色、配色提供了可靠的依据。     

饰瓷工艺对氧化锆陶瓷颜色和透光性的影响

目的 测定采用不同饰瓷工艺制作的氧化锆试件的色彩参数和透射比,探讨饰瓷工艺对氧化锆全瓷修复体颜色和透光性的影响.方法 制作15片厚度为(0.50±0.01)mm、直径为10 mm的氧化锆圆盘试件,表面烧结0.10 mm结合层瓷.按随机排列表法将试件分为3组(ZP、ZC和ZPC组),每组5片.ZP组采用直接热压铸技术压铸0.60 mm厚饰瓷层;ZC组采用涂层技术涂塑烧结0.60 mm厚饰瓷层;ZPC组先压铸0.30 mm厚饰瓷层,再涂塑烧结0.30 mm厚饰瓷层.用电脑比色仪和分光光度计测定饰瓷前后试件的色彩参数L*、a*、b*值和可见光积分透射比τ,计算色饱和度C*ab和色差ΔE,进行单因素方差分析(α=0.05)和Turkey's多重检验.测定A2色标准比色片的色彩参数,计算各组与比色片的色差.结果 ZP、ZPC、ZC 3组的a*值分别为-1.35±0.07、-0.64±0.06、-0.36±0.05,差异有统计学意义(P＜0.05);b*值分别为27.01±0.07、25.48±0.11、23.28±0.25,差异有统计学意义(P＜0.05);C*ab值分别为27.04±0.08、25.49±0.11、23.28±0.25,差异有统计学意义(P＜0.05).3组中ZP组的L*值和τ值最大,分别为87.53±0.48和1.64±0.03;ZPC组的L*值和τ值最小,分别为82.14±0.18和1.47±0.01(P＜0.05).ZC组与比色片的色差最小ΔE=1.04,ZP组与比色片的色差最大AE=4.86.结论 热压铸技术饰瓷的氧化锆陶瓷明度较高、透光性较好;热压铸后涂层技术饰瓷的氧化锆陶瓷明度较低、透光性较差;涂层技术饰瓷的氧化锆陶瓷与比色片的色差最小,能准确再现比色结果.     

试色糊剂对Ips-empress Ⅱ全瓷贴面颜色的影响

目的：观察试色糊剂对全瓷贴面颜色的影响.方法：收集临床上严重变色或缺损的上前牙50颗,行全瓷贴面修复（Ips-empressⅡ全瓷系统制作）.贴面粘结前由同一实验人员用试色糊剂试色,将全瓷贴面就位后未涂试色糊剂时作为对照组,用电脑比色仪测定其及5种试色糊剂[A1、A3、Transluent（Trt）、White opaque（WOT）和B0.50paque（B0.5）]试色后的L＊、a＊、b＊值,用卡尺测量被测点的瓷层厚度,根据公式△Ea＊b＊=（△L＊2＋△a＊2＋△b＊2）1/2、Cab=（a＊2＋b＊2）1/2、Hab=arctan（b＊/a＊）计算每种糊剂试色后的色差及Cab、Hab值,采用单因素方差分析比较色差值（△Ea＊b＊）和L＊、Cab、Hab值的变化.结果：50例全瓷贴面被测点的平均瓷层厚度为1.088mm,用5种试色糊剂试色后,与对照组之间的色差大小依次为WOT、B0.5、A3、A1、Trt,WOT糊剂和B0.5糊剂引起的色差分别为2.371NBS和1.842NBS,临床上肉眼可以识别,主要表现为L＊值和Cab值增大（P＜0.05）.其余3种糊剂引起的色差不明显,其间均无统计学差异（P＞0.05）.结论：试色糊剂有遮色作用,且对黏结剂的选择具有一定指导意义.对变色严重的基牙,可以选用遮色性能较强的WOT或B0.5黏结剂,以削弱基牙颜色对贴面颜色的影响;对变色不严重或无需遮色的基牙,可以酌情选用其他3种黏结剂进行粘结.     

4种全瓷材料单层及双层结构颜色再现的差异性比较研究

目的 对4种全瓷材料单层结构及双层结构颜色再现的差异性进行比较,为全瓷材料的灵活应用提供参考。方法 选择4种全瓷材料：IPS E.max Press、 Vita In-Cream YZ 氧化锆、Cercon HT氧化锆、爱尔创Upcera ST氧化锆,分别为3例患者制作4种全瓷材料单层结构(M组)及双层结构(B组)的全冠,通过比色仪测修复体的Lab值及目测法评价修复体的美学效果,对单层及双层结构全瓷冠的颜色再现能力进行比较。 结果 全瓷材料的结构对L* 、a* 、b* 值均没有影响; 全瓷材料的种类对a* 、b* 值有显著影响( P ＜0． 001); 全瓷材料的种类和结构的交互作用对a*值有影响( P=0.040)。全瓷材料的结构和种类对目测评分均有显著性影响,且存在交互作用。目测评价的SNK结果表明Vita-M组与 Cercon-M组与其他6组间有显著性差异。结论 4种全瓷材料的双层结构修复体均能满足临床上的需要,单层结构组的Vita与Cercon HT修复体不被接受而另两种材料的可以。临床上选择修复材料时必须考虑材料的半透性、自然牙的通透性、颜色的分布、对修复体美学和强度的要求。在自然牙通透性低,颜色较单一,对强度要求高的时候可以考虑单层结构的修复体。     

应用牙科分光光度比色仪对钴铬合金基底表面4种全瓷冠色度学特征的研究

目的 采用牙科分光光度比色仪评估钴铬合金基底表面4种全瓷冠各部位的色度学参数及与目标色片的色差。方法制作钴铬合金基牙预备体（钴铬合金基底）,分别戴入Procera氧化铝（Pro-Alu）、Procera氧化锆（Pro-Zir）、Lava氧化锆（Lava-Zir）、二矽酸锂增强压铸玻璃陶瓷IPS E.max Press（E.max-HO）4种材料的底冠,并烧结与底冠相同材料的体瓷,制作成全瓷冠。采用牙科分光光度比色仪对钴铬合金基底及底冠、体瓷戴入后样本的颈1/3、体1/3、切1/3区域进行测色。以Vitapan Classical比色板A2色体瓷片为对照,比较各组样本与目标色片A2的色差。结果4种底冠均提高基牙的L*和b*值,a*值下降（除Lava-zir底冠颈部外）;4种底冠L*（除Pro-Zir与Lava-Zir切端、Lava-Zir与E.max-HO颈部外）、a*、b*值均有统计学差异。戴入体瓷后,4种全瓷冠L*值略下降（除Pro-Alu体瓷外）,a*、b*值明显上升。4种体瓷与A2体瓷色差ΔΕ均小于4。结论4种全瓷冠对金属基底都有良好遮色性,虽然明度、彩度有差别,但颜色一致性在临床可接受范围。     

牙齿漂白专用比色板的设计方法初探

目的 通过对变色牙色度值的分析,探讨通过统计学方法设计牙齿漂白专用的,可以科学、准确地评价漂白效果的比色板。方法 分析2009年2月-2014年7月就诊的Beyond冷光美白患者的136张临床照片,其中四环素牙25例,氟斑牙61例,黄牙50例,测量变色牙色度值;用系统聚类分析法确定色标L*值,根据变色牙的a*、b*均值确定色标a*、b*值,为3种变色牙分别设计漂白专用比色板,并评价其效果。结果 3种变色牙的色度值存在差异;所设计的比色板与Vitapan Classical比色板相比色标排列更有规律,对漂白效果的评价更准确、更科学,其色标与变色牙的色差值更小。结论 这种牙齿漂白专用比色板的设计方法理论上是可行的,其实际效果还有待临床检验。     

粘接剂与基牙颜色对三种CAD/CAM全瓷贴面颜色的影响

目的 评价全瓷修复体材料、基牙颜色及粘接剂对CAD/CAM椅旁系统修复体色泽的影响.方法 选择三种CAD/CAM椅旁全瓷修复材料：IPS Empress CAD、IPS E.max CAD和Cerec Blocs.每种材料各制备出厚度为（0.8±0.02）mm的试样18片,随机分为3组,以聚四氟乙烯为模板,制作15mm×13mm×2mm的3种颜色的基牙树脂试件,分别采用2种颜色（Transparent与Bleach）的粘接剂粘接瓷片与基牙树脂,每组3片,静压2min,光照20s,使用台式分光亮度仪测量三种全瓷材料的透光度,比较粘接前后修复体的L＊、a＊、b＊值,并计算粘接前后的色差△E.结果 不管基牙颜色或瓷片种类如何,透明色粘接剂组粘接前后的色差△E皆显著大于漂白色粘接剂组.Cerec Blocs组粘接前后的色差最大,E.max组的色差最小,而Empress则介于两者之间.结论 三种全瓷材料中,Empress的透光度最佳,Cerec Blocs陶瓷材料更易受基牙颜色与粘接剂的影响.透明色粘接剂对基牙树脂与瓷贴面复合体的颜色影响大于漂白色粘接剂.     

不同设计类型的IPS Empress铸瓷贴面前牙美学修复的疗效观察

目的：通过比较研究不同设计类型的IPS?Empress铸瓷贴面在前牙美学修复中的临床疗效,探讨铸瓷贴面不同设计类型对瓷贴面成功率的影响。方法分别采用唇面覆盖型（Ⅰ型）、唇切缘覆盖型（L型）和唇切邻面覆盖型（U型）3种类型的贴面修复方法,对41例患者共计124颗患牙行铸瓷贴面修复,于修复后1周、6个月,12个月复诊观察修复体保存完整度、颜色匹配和边缘适合性等评价指标,评估其临床疗效。?结果???Ⅰ型贴面在第12个月时有1例在切端出现微小间歇;L型贴面在第6个月时出现2例脱落,第12个月时又出现1例因咬硬物脱落;U型贴面在第6个月时有1例出现边缘微小缝隙。3种类型的贴面在各随访时间段的成功率比较无明显差异。结论3种类型的铸瓷贴面均能取得较好的临床修复效果。     

Contrast ratios and masking ability of three types of ceramic veneers

STATEMENT OF PROBLEM: Although ceramic veneers have been proven to be clinically successful in longevity studies, there is little information on the contrast ratios and masking ability of the available ceramic systems because dental laboratory technology and expensive experimental equipment are required for the investigation. Moreover, the complexity in understanding how to evaluate translucent ceramic materials may also explain why information in this area is limited. PURPOSE: The purpose of this study was to determine the contrast ratios and masking abilities of 3 types of all-ceramic veneers by measuring their luminance and color difference over white and black backgrounds. MATERIAL AND METHODS: Disk-shaped specimens (8-mm diameter x 0.7-mm thickness) of Shade A2 (Vita Lumin) of 3 types of all-ceramic systems: Procera (n=8), Empress 2 (n=8), and Vitadur Alpha (n=10) were fabricated. The luminance (as Y) and color (as CIE L*a*b*) of the specimens were measured with a colorimeter. The contrast ratio (CR=Yb/Yw), defined as the ratio of illuminance (Y) of the test material when it is placed on the black background (Yb) to the illuminance of the same material when it is placed over a white background (Yw), was determined. The masking ability of a specimen was evaluated by calculating the color difference (DeltaE) of the veneers over white and black backgrounds. Both CR and DeltaE* data were analyzed with 1-way ANOVA and the Tukey HSD test (alpha=.05). RESULTS: The mean contrast ratios (SD) of Procera, Empress 2, and Vitadur Alpha specimens were 0.50 (0.02), 0.46 (0.05), and 0.39 (0.02), respectively. CR values were significantly different among the 3 materials (P<.001). Procera veneers had a significantly higher CR compared to Empress 2 (P=.01) or Vitadur Alpha (P=.01), whereas the CR of Empress 2 was significantly higher than that of Vitadur Alpha (P=.046). Color difference (DeltaE*) (SD) of Procera, Empress 2, and Vitadur Alpha specimens over black and white backgrounds were 24.46 (1.03), 25.80 (1.03), and 31.08 (1.19), respectively. DeltaE* values were statistically different among the 3 materials (P<.001). Vitadur Alpha specimens had significantly higher DeltaE* when compared with Procera (P<.001) or Empress 2 (P<.001), whereas DeltaE* values between Procera and Empress 2 were not significantly different (P=.331). CONCLUSIONS: Vitadur Alpha had significantly lower contrast ratio and poorer masking ability compared to Procera or Empress 2. The clinical application of Vitadur Alpha as a veneer material over discolored teeth is cautioned. Although the contrast ratio of Procera was significantly higher than that of Empress 2, the masking abilities of these materials were not significantly different. The clinical application of these 2 ceramics as a veneer material may still be limited when applied over intense tooth discoloration because neither can fully mask the color of a black background.     

Influence of cement shade and water storage on the final color of leucite-reinforced ceramics

Leucite-reinforced ceramics have a translucent structure, which may have an advantage when fabricating esthetic restorations. However, the different shades of cement and water storage may adversely affect the final color of translucent restorations. Over time, the final color of a restoration may be significantly affected by the shade of the cement. This in vitro study evaluated the effect of two different cement shades (Vita A1 and A3) and water storage on the final color of leucite-reinforced ceramics over time. Twenty disks of standardized thickness (0.8 mm), diameter (5 mm) and color (shade 110, Chromascope) were prepared from leucite-reinforced glass-ceramic (IPS Empress). Ten freshly extracted human molars were used as the underlying structure, and both the buccal and lingual surfaces of each tooth were prepared with a diamond rotary cutting instrument and flat surfaces were created. Initially, all of the disks were bonded to the flat surfaces of the teeth with a thin layer of bonding agent (Single Bond, 3M Dental Products) to ensure immobilization of the specimens (baseline). The teeth and ceramic specimens were not etched and silanated for easy removal of the specimens. The color of the ceramic specimens was measured with a colorimeter. All disks were gently removed from the tooth surfaces, and 10 specimens (Group A1) were luted to the buccal surfaces of teeth using a dual-polymerizing resin composite cement (Vita A1, Rely X ARC), while the remaining 10 specimens (Group A3) were luted to the lingual surfaces of the teeth with a different shade (Vita A3, Rely X ARC) of the same cement. The final color of the specimens was measured immediately after cementation and at 3-, 30- and 90-day intervals after cementation. Color coordinates L*, a*, b* were recorded. The teeth were stored in 37 degrees C saline solution during measurement intervals. The Mann-Whitney U-test (post-hoc test) was performed to compare the results (alpha=0.05). The color difference of specimens luted with the two cements with different shades was not perceivable (DeltaE<3.7) for AC (after cementation), AC/3, AC/30 and AC/90 measurements. The color alteration between baseline and immediately after cementation (AC) was not perceivable for each cement group. However, after water storage, color differences between the baseline and AC/3, AC/30 and AC/90 were above this limit in bo th cement groups. The shade of the luted 0.8 mm IPS Empress porcelain specimens became darker after cementation, particularly on the third day, regardless of the cement shade tested. When the final color of ceramics luted with cements in two different shades was compared, it was observed that the final color differences were not perceivable for each measurement session.