铝瓷核烧结长石质瓷前后贴面颜色的变化

目的：考察Procera铝瓷核表面烧结长石质饰面瓷形成双层瓷贴面前后的颜色变化。方法：应用自凝树脂和着色材料制作模仿变色牙灰色的底质，15个氧化铝圆盘随机分为3个组，每组5个标本，分别 烧A1、A2、B43种颜色的长石质陶瓷，应用美能达CR－321色度仪测量底质上氧化铝圆盘烧结长石质饰面前后 的颜色变化，并以白色背景作为对照。结果：烧结长石质饰面瓷后颜色变化差异存在显著性（P＜0．01），加入A1、A2、B4饰面陶瓷后，△E从A1（2．311）、A2（4．313）到B4（8．778）逐渐增加；△L^*从A1（－1．530）、A2（－3．369）到B4（－3．358）逐渐减小；△b从A1（－1．440）、A2（2．198）到B4（7．955）逐渐增加，颜色变化方向与已往报道一致并受背景颜色的影响。结论：可通过在氧化铝核表面烧结长石质饰面瓷来调整瓷 贴面颜色。     

Masking Ability of Zirconia with and without Veneering Porcelain

Purpose : The present study compared changes in CIE L*a*b* color coordinates of substrates of different colors when covered with zirconium oxide discs (Procera) and with such discs if veneered with two shades of porcelain. Material and Methods : Forty background substrates were fabricated and divided into four groups depending on the color of the substrates: white, black, gray, and tooth‐colored (Vita shade A3). The initial color of the substrates was measured using a colorimeter. The color of the substrates covered with plain zirconium oxide discs and with zirconium oxide discs veneered with porcelains of two shades (Vita shade A1 and B4) was measured. The color difference between the substrates, the substrates covered with plain discs, and the substrates covered with veneered discs was calculated, and the data were statistically analyzed with one‐way ANOVA and multiple paired t‐test. Results : For each group of substrates, the resulting colors were significantly different when the substrates were covered by either plain zirconium oxide discs or zirconium oxide discs veneered with Vita shade A1 or B4 porcelain. Conclusion : While zirconium oxide coping material alone has a degree of masking ability, the resulting color of a restoration can be further modified with the veneering porcelain.     

In vitro color stability of double-layer veneers after accelerated aging

STATEMENT OF PROBLEM: Porcelain laminates made from thin alumina shells veneered with feldspathic porcelain could be a promising alternative to conventional veneers. Long-term shade stability is critical for esthetics. PURPOSE: This study compared changes in CIE L*a*b* color coordinates of simulated veneers made from aluminum oxide core material veneered with feldspathic porcelain after 300 hours of accelerated photothermal aging (weathering). MATERIAL AND METHODS: Fifteen aluminum oxide disks (Procera) were divided into 3 groups. Each of the 5 disks was veneered with All-Ceram porcelain of the Vita shades A1 and B4, respectively. Five disks remained unfinished as controls. The disks were bonded to composite substrates simulating stained teeth. The color of the specimens was measured with a colorimeter. All specimens were subjected to 300 hours of accelerated aging under light exposure and thermocycling. Color measurements were repeated, and the data were statistically evaluated with multiple paired t tests. RESULTS: Color changes in the test groups involved an increase in lightness and a decrease in chroma. The calculated total color differences were not statistically significant compared with a level of 3 DeltaE units. CONCLUSION: This simulation of double-layer veneers appears to demonstrate acceptable color stability for this type of restoration. Clinical research is necessary to substantiate these in vitro findings.     

The effect of repeated firings on the color of an all-ceramic system with two different veneering porcelain shades

STATEMENT OF PROBLEM: Color matching between a restoration and natural teeth is a common clinical problem. Despite careful shade selection, color of the restoration may be affected by fabrication procedures. PURPOSE: The purpose of this study was to determine the color changes of an all-ceramic restoration with 2 different veneering porcelain shades after repeated firings. MATERIAL AND METHODS: Twenty disc-shaped ceramic specimens, 4 mm in diameter with a 1-mm core thickness and 2 different veneering porcelain shades (A1, A3), were fabricated from a zirconia-based porcelain (DC-Zirkon) (n=10). Repeated firings (3, 5, 7, or 9 firings) were performed for the specimens, and color differences (DeltaE) were determined using a spectrophotometer. Repeated measures ANOVA was used to analyze the data (number of firings, veneering porcelain color). The Tukey HSD test and paired 2-tailed tests were performed for multiple comparisons (alpha=.05). RESULTS: The L*a*b* values of the ceramic system were affected by the number of firings (3, 5, 7, or 9) (P<.001) and the veneering porcelain shade (P<.001). Significant interactions were present between the number of firings and veneering porcelain shade for L* (P=.003) and b* (P=.042) values, but not for the a* value (P=.82). An increase in the number of firings of the specimens with both A1 and A3 veneering porcelain shades produced an increase in the L* value, resulting in lighter specimens (P<.001). For both A1 and A3 veneering porcelain shades, the a* value decreased after repeated firings, which resulted in more green specimens (P=.002). The b* value did not change after repeated firings (P=.09) for the A1 veneering porcelain shade; however, it increased for the A3 veneering porcelain shade, which resulted in more yellow specimens (P=.001). CONCLUSIONS: The color of the all-ceramic specimens with different veneering porcelain shades is influenced by repeated firings. However, color changes that occurred are clinically acceptable.     

Differences in color between fired porcelain and shade guides.

The inaccuracy of premixed porcelain shades may cause errors when color matching porcelain crowns. Most brands of porcelain are labeled to match shades of the Vita shade guide, but produce slightly different colors from this guide upon firing. The purpose of this study was to quantify in CIE delta E* units the color differences between the Vita shade guide colors and four commercial porcelains for metal ceramic crowns. Two operators prepared shade-guide teeth from six shades of four brands of porcelain. Opaque, body, and incisal layers were fired in the form of shade-guide teeth on Vita ceramic carriers used for making custom shade-guide teeth. The colors of these teeth were measured with a Beckman spectrophotometer with an integrating sphere. The average delta E* values for the differences between the colors of the Vita shade guide and the fired porcelains for each of the brands were 3.1, 2.9, 4.1, and 2.0, respectively, for the first operator and 4.1, 2.6, 2.8, and 1.6, respectively, for the second operator. The color difference between the custom shade-guide teeth and the Vita master shade guide were significantly affected by both brands and shades. The overall average error resulting from the differences in colors between the Vita shade guide and fired porcelains was 3.0 for the first operator and 2.8 for the second operator. The mean delta E* between the teeth prepared by the two operators was 3.6. The color difference between the teeth made by the two operators was not significantly affected by brands or shades.     

Variation in color between intended matched shade and fabricated shade of dental porcelain

STATEMENT OF PROBLEM: The total quantifiable color difference between shade matching and shade duplication has not been investigated formally. PURPOSE: The purpose of this in vitro study was to evaluate and compare the color difference of the total color replication process and the direction of the individual color parameters for 3 dental porcelain shade-matching systems. MATERIAL AND METHODS: The shade of 11 porcelain master disks was determined visually and instrumentally using 3 porcelain shade-matching systems: (1) Vita Lumin/Vita VMK 68, (2) Vitapan 3D-Master/Vita Omega 900, and (3) Shofu ShadeEye-EX/Vintage Halo. Corresponding porcelain disks made of 4.5 mm opaque and 1 mm dentin porcelain were fabricated with each of the porcelain systems. The colors of the master disks and fabricated disks (CIE L* a* b* coordinates) were measured with a spectroradiometer with a 45 degrees /0 degrees configuration. Repeated-measures analysis of variance was used to evaluate within-group differences among the porcelain systems for the total color difference (Delta E) and direction of the color parameters (Delta L, Delta a, and Delta b). The Ryan-Einot-Gabriel-Welsch multiple range test was used for post-hoc analysis (alpha=.05). RESULTS: The largest mean Delta E was recorded for the Vitapan 3D-Master system, which was significantly different from the other systems (P=.0024). A significant difference was found between the interaction of the different systems and the direction of color (P=.0024). The amount of change within each color parameter was dependent on the porcelain system, as well as the amount of change among the color parameters. CONCLUSION: Within the limitations of this study, the results suggest that reliable delivery of a properly matched restoration to existing porcelain restorations cannot be ensured regardless of the shade assessment method used (visual or computer-generated).     

The marginal fit of porcelain veneers on titanium copings: an in vitro study.

OBJECTIVES: To compare the cervical microleakage of titanium copings veneered with 3 porcelain-based materials with that of titanium copings veneered with 2 indirect polymeric materials. METHOD AND MATERIALS: Commercially pure, grade 2 titanium was veneered with 3 porcelain systems specially designed for fusing on titanium: Ti22 (Noritake), Triceram (Esprident), and Vitatitankeramik (Vita). Additionally, 2 polymeric materials were used for veneering titanium: Chromasit and Targis (Ivoclar). Four veneer crowns for each titanium-veneer combination were obtained. After storing the specimens in basic fuchsin, the microleakage between titanium and veneer in the cervical area was assessed by measuring the extent of dye penetration within the interface. ANOVA and post hoc statistics were used to analyze the data. RESULTS: Chromasit exhibited the highest mean microleakage score (3 +/- 0.816). The least mean microleakage at the interface was recorded for Ti22 porcelain (0 +/- 0.0), followed by Triceram (0.25 +/- 0.50), Vitatitankeramik (0.75 +/- 0.957), and Targis (1.5 +/- 1.732). Only the differences between each porcelain system and Chromasit were significant (P <.05). CONCLUSION: Within the limitations of this in vitro study, there was no significant microleakage between titanium copings and the porcelain veneers, regardless of the porcelain system. The microleakage between titanium and the polymeric materials depended on the veneering material. Leakage was significantly higher when Chromasit was used.     

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。     

厚度与颜色影响IPS e.max和In-Ceram全瓷修复体色彩再现效果的实验研究

目的：研究IPS e.max和VITA In-Ceram氧化铝2种全瓷材料不同瓷层厚度与颜色对修复体色彩再现的影响,探索全瓷修复体的混色规律,为全瓷修复的临床比色、配色等提供实验依据。方法：2种全瓷材料各以A1、A2、A3为目标颜色制作不同厚度的圆形试件：IPS e.max铸瓷（0.6mm、0.9mm、1.2mm、1.5mm）;VITA In-Ce-ram切削氧化铝（核冠/饰瓷：0.5/1.2mm、0.7/1.0mm、0.9/0.8mm）,同一厚度同一颜色各制作直径为15mm的圆盘形试件7个,共计147个。使用Crystaleye分光光度比色仪对试件的颜色进行测量,测量结果以CIE＊a＊b＊格式表示。结果：2种全瓷材料黑白背景下的色差值（△E和△L）均受到厚度和颜色的影响,其差别有统计学意义（P〈0.05）。结论：在有限的临床修复空间中,全瓷材料的颜色改变、厚度的微小差别以及体瓷和饰瓷之间的厚度变化将影响修复体最终的颜色和透明性。     

Gingival health associated with porcelain veneers on maxillary incisors.

The possible detrimental effect of acid-etched resin-bonded prostheses and porcelain veneers on plaque accumulation and gingival health is currently disputed. Some workers recommend no tooth preparation prior to veneering whilst others recommend tooth preparation to prevent adverse gingival soft tissue reactions. In order to test the possible gingival effects of veneers placed without tooth preparation, this study was set up to compare gingival health on veneered and non-veneered maxillary incisors within the same individual during periods of normal tooth cleaning and of no tooth cleaning. No significant differences were noted in plaque or gingival indices, or in gingival crevicular fluid volume, between the 72 veneered and non-veneered sites during either study period. The results of this study suggest that placing porcelain veneers on unprepared teeth does not increase the risk of gingivitis.     

Spectrophotometric analysis of color differences between porcelain systems

Spectrophotometric measuring techniques were used to determine the color of four corresponding shades of three brands of metal-fusing porcelain systems. The color was expressed in terms of CIE L*a*b* color coordinates. The relationship of these values to the more commonly used attributes of Hue, lightness (Value), and saturation (Chroma) respectively were discussed. The location of the porcelain shades in the color space and the direction of the color differences found between the different brands of porcelain were evaluated. Color differences for each paired comparison within each shade group were determined from the color data. These values represent the magnitude of color differences found between brands and have a direct relationship to visual perceptibility. For the brands and shades measured, the following conclusions can be made: The CIELAB color system provides an objective technique for evaluating the color of dental porcelains. Corresponding shades of different brands of porcelain can produce perceivably different colors. The perceived color differences between the brands were mostly a result of differences in all three color directions. Greater color differences were found to exist between the corresponding opaque porcelains than between the corresponding layered samples. The addition of 1 mm of body porcelain to the opaque compensated to a large extent for the greater color differences found between the corresponding opaques. The results of this study have significant clinical ramifications. Variations in optical characteristics of porcelains produced by different manufacturers add to the problem of color control in ceramic crown fabrication.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Human-eye versus computerized color matching

This project compared the difference in color matching between human-eye assessment and computerized colorimetry. Fifty dental personnel were asked to color match Vita Lumin shade tabs to seven different randomly arranged test tabs from the Z100 shade guide. All evaluators were blinded to the shades of the test tabs and were asked to match only body shade of the Vita Lumin tab to the middle third or body of each test tab. The results obtained were subsequently computed into L*a*b* values and compared with results obtained by computerized colorimetry. Results indicate that the difference in color matching between human-eye assessment and computerized colorimetry is shade dependent. Discrepancy was significant for b* coordinates for shades A1 and B2 and L* and b* coordinates for shade C4. For all shades evaluated, color difference between human-eye and computerized color matching is perceivable under clinical settings, as delta E values are greater than 3. There is a need for correction factors in the formal specification of the color-matching software due to the discrepancy between human-eye and computerized colorimetric color matching.     

MarkⅡ型机加工陶瓷与VitaVM9饰面瓷结合界面的研究

目的研究MarkⅡ型机加工陶瓷基底层与Vita VM9饰面瓷之间的界面结合情况及匹配性。方法制作30 mm×15 mm×1 mm MarkⅡ瓷块样本1个,在底面中份预制0.5 mm深的刻痕与样本长轴垂直,表面涂布烧结0.3 mm厚的VM9不透明牙本质瓷。将样本从刻痕部位折断,在扫描电镜下观察结合界面的形貌和构象,采用电子探针对基底瓷、饰面瓷内部及结合界面进行元素定量分析,观测元素质量分数的变化。另外制作MarkⅡ瓷块样本10个,做热冲击试验,计算平均耐热冲击温度。结果扫描电镜观察显示2种材料在界面区镶嵌融合,结合紧密无间隙。电子探针分析表明界面区Al和Ca元素质量分数呈梯度变化,由基底瓷向饰面瓷Al的质量分数下降,Ca则上升;提示基底瓷中Al和饰面瓷中Ca有越过界面相互渗透的现象。10个样本的平均耐热冲击温度为（194.0±10.3）℃,裂纹均出现于饰面瓷。结论MarkⅡ型机加工陶瓷基底层与VM9饰面瓷之间有良好的结合性及热匹配性。     

应用分光光度仪比较深度变色基牙表面4种全瓷冠色度学特征

目的:采用分光光度比色仪评估深度变色ND8基底表面4种全瓷冠各部分色度学参数CIE L^*a^*b^*值及与目标色片色差。方法:制作ND8色基牙预备体,分别戴入Procera氧化铝、Procera氧化锆、Lava氧化锆、IPS E.max高度不透明压铸陶瓷底冠,分光光度仪对颈部、体部、切端测色。4组底冠经烧结A2体瓷后戴入基底(总瓷层厚度控制1.5 mm),分光光度仪同法测色,以Vitapan比色板A2体瓷色片为对照,对数据进行单因素方差分析、均数比较Bonferroni检验,计算P值。结果:4组底冠均提高基牙的L^*值,降低彩度a^*、b^*值,多数组间各部位L^*、a^*、b^*有统计学差异。烧结体瓷后,各组L^*略下降,a^*、b^*明显上升。各部分与A2色差显著减小(1.45∽3.70)。结论:4组全瓷底冠对变色基底都有较好遮色性,但各组底冠明度、彩度不一致。烧结体瓷后颜色有差异的组别减少,各组与目标色片差别在临床可接受范围。     

Effect of Veneering Techniques on Color and Translucency of Y‐TZP

Purpose: This study compared the color parameters and total luminous transmittance of disc specimens by different veneering techniques in order to examine the effect of veneering technique on esthetics of yttria‐stabilized tetragonal zirconia polycrystalline (Y‐TZP) all‐ceramic restorations. Materials and Methods: Thirty disc specimens (10‐mm diameter, 0.50 ± 0.01 mm thick) were fabricated of IPS e.max ZirCAD core material, and ZL1 IPS e.max ZirLiner (0.10‐mm thick) was layered. The specimens were randomly divided into three groups (n = 10/group). Group ZP (fully anatomical technique) was veneered 0.60 mm by heat‐pressing IPS e.max ZirPress fluorapatite glass‐ceramic ingots; Group ZC (traditional layering technique) was veneered 0.60 mm by condensing and sintering IPS e.max Ceram low‐fusing nano‐fluorapatite veneering porcelain; Group ZPC (cutback technique) was veneered by partially pressed ingots and subsequently layered 0.30 mm with veneering porcelain. Color parameters (L*, a*, b*) and total luminous transmittance (τ) of zirconia core discs and core and veneer specimens were measured with ShadeEye NCC dental colorimeter and spectrophotometer, respectively. Color saturation (C*ab) and color difference (ΔE) were calculated using color difference formula. One‐way analysis of variance (ANOVA) combined with a Tukey multiple‐range test were used to analyze the data (α= 0.05). Results: As to ZP, ZPC, and ZC groups, the value of a* increased (?1.35 ± 0.07, ?0.64 ± 0.06, ?0.36 ± 0.05, respectively) (p < 0.05); b* decreased (27.01 ± 0.07, 25.48 ± 0.11, 23.28 ± 0.25, respectively) (p < 0.05); and C*ab decreased (27.04 ± 0.08, 25.49 ± 0.11, 23.28 ± 0.25, respectively) (p < 0.05). L* value and total luminous transmittance were highest in ZP group (87.53 ± 0.48, 1.64 ± 0.03, respectively), and lowest in ZPC group (82.14 ± 0.18, 1.47 ± 0.01, respectively) (p < 0.05). Conclusions: Y‐TZP all‐ceramic restoration veneered by fully anatomical technique was the most transparent and lightest, while restorations veneered by cutback technique were the least translucent and the darkest.     

The effect of surface treatment of the interfacial surface on fatigue-related microtensile bond strength of milled zirconia to veneering porcelain

Purpose: The success of zirconia‐reinforced all‐ceramic crowns depends on the formation of a stable bond between the zirconia core and the veneering porcelain. The purpose of this study was to test the effects of liner application and airborne particle abrasion of a postsintered Y‐TZP core on the bond strength between the zirconia core and veneering porcelain with or without cyclic loading. Materials and Methods: Kavo Everest® Y‐TZP blank disks were sintered and divided into three treatment groups: airborne particle abrasion, IPS e.max® Ceram Zirliner application, or no surface treatment. The disks were then veneered with IPS e.max® ZirPress veneering porcelain. Half the veneered disks from each group were cyclically loaded. This created six experimental groups: three surface treatment groups cyclically loaded and three not loaded. The disks were then sectioned into microbars for microtensile bond strength (MTBS) testing (40 specimens per group). Specimens were luted to a fixture mount and loaded to failure using a universal testing machine (MTS Insight). The maximum force was measured and bond strength computed. Data were analyzed with a two‐way ANOVA and Tukey's HSD test (α= 0.05). Results: Airborne particle abrasion significantly decreased MTBS values (p= 0.043), and ZirLiner application did not have a significant effect on MTBS values compared to control. Cyclic loading did not have a significant effect on MTBS values. The predominant failure mode in all groups was mixed. Conclusions: Airborne particle abrasion of the interfacial surface of the Everest® Y‐TZP core significantly decreased the MTBS to ZirPress veneering porcelain when compared to no interfacial surface treatment. Application of ZirLiner to the interfacial surface of the Everest® Y‐TZP core did not significantly increase or decrease the MTBS to ZirPress veneering porcelain, compared to the other surface treatments. Cyclic loading did not affect bond strengths in any of the groups, regardless of surface treatment. Neither cyclic loading nor surface treatment affected the failure mode of the specimens.     

The effects of manipulative variables on the color of ceramic metal restorations

Certain variables were tested for their influence on the color of ceramic metal restorations. The variables included firing temperature, condensation technique, modeling liquid, and brand of porcelain. In addition, the color of different nominal shades was compared. The color was measured with a Minolta CR-121 small-area colorimeter. The small (7 mm2) measuring area enabled readings to be made on actual crown specimens rather than disks. The results were expressed in the CIELAB color system enabling comparisons to be made related to visual perception. The following conclusions can be drawn from the study. 1. The small-area colorimeter is able to detect statistically significant and perceivable color differences between shades of porcelain. The variation in color parameters associated with making replications of a restoration is significantly greater than the error associated with making repeated color measurements of the same restoration. 2. Restorations made with the different brands of porcelain studied have noticeably different colors despite having the same nominal shade. 3. Color changes caused by the choice of modeling liquid were not statistically significant in this study. If the mean color differences are truly representative, using Rainbow or Carv-eze modeling liquids with Vita VMK porcelain may produce color changes that are just barely detectable. 4. The manipulative variables of firing temperature and condensation have little influence on the color of the restorations.     

渗透对CAD/CAM氧化铝陶瓷颜色和结构的影响

目的:考察渗透过程对计算机辅助设计和制造(CAD/CAM)切削氧化铝陶瓷颜色和结构变化的影响。方法:将氧化铝瓷块样本薄片10个,随机分为A、B组,每组5个,其中A组用ALMC玻璃料渗透,B组用VitaIn-CeramAL3色玻璃料渗透,进行颜色测量和电子扫描镜观察。结果:渗透前后A组和B组颜色(L,a,b)均有显著差异(P<0.01);扫描电镜显示,玻璃颗粒渗透入氧化铝结构中。结论:氧化铝陶瓷渗透后玻璃料与氧化铝嵌合,形成致密组织,增加强度,并产生初始颜色。     

Visual and instrumental discrimination steps between two adjacent porcelain shades

Two different porcelain systems were compared over the B1 to B2 shade ranges visually and spectrophotometrically. Six samples of each porcelain were made by blending weighed increments of opaque and body porcelain and firing the blended compositions onto Option metal disks according to manufacturer's instructions. Compositional blends varied incrementally by 20% in steps. Selective blending of porcelain shades was shown to have an effect in improving the range of choices within the shade guide system. The human eye was capable of detecting small-step changes between two steps of the Vita shade guide. Systematic color changes occurred with compositional changes between B1 and B2. It appears from the overall results observed that a desired blending of porcelains at smaller intervals than full shade guide steps could be done more easily with Jelenko than with Vita porcelain. The visual rankings agreed more closely with the manufacturer's expectations than did the instrumental measurements.