氧化锆和金属基底饰面瓷机械性能与微观结构的比较研究

目的比较分析氧化锆和金属基底饰面瓷的机械性能及微观结构。方法选择5种氧化锆基底饰面瓷Vintage ZR(ZR),Cerabien ZR(CZR),VitaVM9(VM9),Cercon ceram KISS(KISS),IPS e.max ceram(e.max)及烤瓷熔附金属用饰面瓷Vintage MP(MP)。每种饰面瓷各制作10个试件,测定表面粗糙度﹑三点弯曲强度(ISO 6872)和维氏硬度。计算断裂韧性。微观结构通过X射线衍射和扫描电镜分析。结果与其它饰面瓷相比,氧化锆基底用KISS的弯曲强度最高(P﹤0.05),CZR的弯曲强度最低(P﹤0.05);金属基底用MP的断裂韧性明显高于所有氧化锆用饰面瓷(P﹤0.001)。结论与氧化锆基底用饰面瓷相比较,金属基底用饰面瓷不易断裂,更具有临床可靠性。     

四种饰瓷与Vitablocs MarkⅡ瓷结合强度的比较

目的:测试并比较4种饰瓷与Vitablocs MarkⅡ瓷的结合强度,为临床使用提供依据.方法:将成品Vitablocs Mark Ⅱ瓷块切割成12 min×6 mm×2 mm的试件24个,随机分为4组,分别在其表面烧结E-maxceram、Vintage ZR、Cercon ceram kiss及VM9饰瓷,剪切实验测试各组结合强度,电镜观察确定试件的断裂方式.结果:E-max ceram、Vintage ZR、Cercon ceram kiss、VM9 4组的抗剪强度值分别为(41.07±12.42)MPa、(43.44±11.32)MPa、(35.81±8.69)MPa、(37.35±9.71)MPa;试件的断裂67%以上均发生于基底瓷;经单因素方差分析得出F=0.641,P>0.05,表明4组抗剪强度无显著性差异;单样本t检验结果显示,4组饰瓷与Vitablocs Mark Ⅱ瓷的结合强度值均高于ISO9693:1999规定的强度值(25 MPa).结论:4种饰瓷与Vi-tablocs MarkⅡ瓷的结合强度均能满足临床需要,可作为Vitablocs Mark Ⅱ的个性化饰瓷使用.     

氧化锆底瓷与饰瓷结合力的实验评估

目的：通过与钴铬合金-金属烤瓷结合力进行比较,对氧化锆底瓷-饰瓷结合力进行评估。方法：制作不同材料试件共5组,每组各10个试件。每个试件由长15mm,直径8mm的圆柱形底核与厚2mm,直径8mm的饰面构成。底核/饰面材料与分组如下：组1（对照组）钴铬合金/IPS d.SIGN烤瓷粉（Ivoclar）;组2IPS e.maxZir-Cad氧化锆瓷块/IPS e.maxZirPress专业氧化锆饰瓷（Ivoclar）;组3IPS e.maxZirCad氧化锆瓷块/IPS e.maxCeram牙本质磁粉（Ivoclar）;组4Lava Frame氧化锆瓷块（3MESPE）/Lava Ceram磁粉（3MESPE）;组5Lava Frame氧化锆瓷块（3MESPE）/IPS e.maxCeram牙本质磁粉（Ivoclar）。运用万能测试机对各试件进行剪切试验,剪切速度参数设定为0.50mm/min。实验所得结果采用SPSS18.0软件进行ANOVA单因素方差分析和LSD多重检验。结果：组1：13.87MPa,组2：13.10MPa,组3：10.97MPa,组4：12.72MPa,组5：4.77MPa。结论：氧化锆底瓷-饰瓷结合力可与钴铬合金-金属烤瓷结合力相近,热压铸塑较粉浆涂塑工艺制备的饰瓷与底瓷结合力更高,底瓷与饰瓷分别来源于不同产家时结合力最弱。     

氧化锆基底和饰瓷结合强度的分析

目的分析和比较几种全瓷系统基底和饰瓷的结合强度。方法制作直径为8 mm、厚度为3 mm的Lava、 Cercon、IPS e.max ZirCAD、Procera试件各20个,分别为Lava组、Cercon组、IPS e.max ZirCAD组、Procera组。每组各选10个试件表面烤制厚度为1 mm的相应饰瓷,10个试件表面烤制厚度为2 mm的相应饰瓷。对试件进行剪切强度的测定和断裂模式的观察。结果饰瓷厚度为1 mm时,Lava、Cercon、IPS e.max ZirCAD、Procera组的剪切强度分别为：（13.82±3.71）、（13.24±2.09）、（6.37±4.15）、（5.19±5.31）MPa;饰瓷厚度为2 mm时,各组的剪切强度分别为：（38.77±1.69）、（21.67±3.34）、（12.70±4.24）、（9.94±6.67）MPa。Lava组和Cercon组的剪切强度高于IPS e.max ZirCAD组和Procera组（P<0.05）,饰瓷厚度为2 mm的试件的剪切强度高于饰瓷厚度为1 mm的试件（P<0.05）。各组试件破坏模式均以界面破坏为主。结论氧化锆基底和饰瓷的结合强度因基底材料的不同而不同,饰瓷的厚度对结合强度有明显的影响。     

饰面瓷表面粗糙度对全瓷修复体颜色及透射率的影响

目的：探讨不同饰面瓷表面粗糙度对全瓷修复体颜色及透射率的影响。方法：将Cercon氧化锆陶瓷材料和IPS e.max铸瓷材料分别制作成厚2.0 mm、直径15 mm的圆盘状试件,各分为4组,每组5个试件,试件表面分别用水砂纸打磨至400#、600#、800#、1000#,测量其表面粗糙度Ra值、L*a*b*颜色参数及透射率。结果：随着饰面瓷表面粗糙度的增加,Cercon氧化锆的明度L*值呈增大趋势,b*值呈减小趋势,IPS e.max热压铸瓷的L*、a*、b*值无明显变化趋势;可见光透射率呈上升趋势。结论：不同饰面瓷表面粗糙度对Cercon氧化锆和IPS e.max全瓷修复体的颜色及透射率有一定影响。     

Upcera氧化锆基底材料与IPS E.max Ceram饰面瓷结合性能的研究

目的:探讨Upcera氧化锆基底材料与IPS E.max Ceram饰面瓷的结合性能。方法:使用CAD/CAM系统,将氧化锆制成大小为30 mm×20 mm×2 mm的长方体瓷块。800℃-850℃下低温烧结2 mm饰瓷,加载速度l.0 mm/min,测试界面抗剪切强度,通过肉眼观察、能谱分析、热冲击试验等方法研究其烧结结合性能。结果:肉眼观察IPS E.max Ceram完全烧结后,与氧化锆基底材料结合良好。界面结合强度结果为31.12±5.15 MPa。能谱分析结果显示:在氧化锆区可检测到少量A12O3和SiO2,饰瓷区均未见ZrO2及Y2O3。抗热冲击试验中试样在60-240℃的整个过程中,均未发现层间或径向开裂或裂纹现象,试样开裂温度△T>240℃。结论:氧化锆与饰瓷间可观察到化学元素渗透的情况,提示两者间可能存在化学结合。Upcera氧化锆基底材料与IPS E.max Ceram饰面瓷与可达到良好匹配,符合临床使用要求。     

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。     

牙科着色氧化钇稳定四方多晶氧化锆陶瓷的制备及颜色性能

目的添加不同着色剂组合配制着色的牙科氧化钇稳定四方多晶氧化锆（3Y-TZP）陶瓷,并测定其颜色性能。方法将TZ-3Y-S粉体与一定组分的着色剂球磨混合后,在200 MPa压力下等静压成型,在1 500 ℃烧结2 h,烧制5种具有一定颜色的氧化锆材料,每个颜色组分别制备10 mm×10 mm×0.5 mm和10 mm×10 mm×1 mm着色氧化锆陶瓷片,在黑色背景下用柯尼卡美能达CM-2600d分光光度计进行颜色测定,并与VITA In-Ceram YZ染色液比色板颜色作比较。结果通过对粉体进行着色,配制出具有一定颜色的本体着色氧化锆陶瓷材料,颜色明度逐级降低,饱和度逐渐增大,2种厚度3Y-TZP陶瓷的颜色片色差较小,颜色空间范围是L*：67.76～77.78;a*：-2.19～3.80;b*：12.13～25.01。与VITA In-Ceram YZ染色液比色板相比,颜色空间近似,但明度的最低值仍较高。结论着色氧化锆陶瓷材料适宜用于临床上与饰面瓷颜色匹配,有必要再进一步研究低明度的着色氧化锆色片。     

改良液式冲蚀对3Y-TZP氧化锆基底与饰面瓷结合强度的影响

目的:探讨采用改良液式冲蚀方式对3Y-TZP氧化锆基底表面进行冲蚀后,对其与饰面瓷间结合强度的影响.方法:制作[8 mm×8 mm×3 mm(±0.02)]氧化锆试件块174个,根据不同尺寸的刚玉磨粒、不同的喷砂压强、不同的喷砂时间,采用传统喷砂方式进行分组处理(实验组),在氧化锆处理面上饰面瓷.表面未做处理的氧化锆试件直接上饰面瓷作为对照组,应用电子万能测力计检测各组试件与饰面瓷间的最大剪切力,计算剪切强度.分别用传统干式喷砂、改良液式冲蚀方式在相同条件下(150 μm,0.6 MPa,30 s)处理氧化锆试件块,用扫描电镜下观察处理面,再上饰面瓷,计算剪切强度,与对照组进行组间比较.采用SPSS17.0软件包对数据进行统计学分析.结果:采用传统干式喷砂方式,在0.4 MPa压强作用下,以110 μm A12O3喷砂粉喷砂20 s时,氧化锆与饰面瓷之间的剪切强度最大,显著大于对照组(P＜0.05);改良液式冲蚀组饰面瓷的结合强度显著大于传统干式喷砂处理组及对照组(P＜0.01).扫描电镜下可见,采用改良液式冲蚀的试件表面呈现均匀的粗糙面:采用传统干式喷砂处理的试件表面呈现不均匀的粗糙面,部分位置可见微裂纹.结论:对3Y-TZP氧化锆表面喷砂,能够增强其与饰面瓷间的结合强度;改良液式冲蚀比传统干式喷砂更适用于3Y-TZP氧化锆的表面处理.     

纳米硅涂层对钛瓷结合强度的影响

目的探讨纯钛表面纳米硅涂层改性对钛瓷结合强度的影响。方法将16个纯钛试件（25 mm×3 mm×0.5 mm）平均分为2组,A组用溶胶-凝胶法在表面形成钠米硅涂层,B组不作处理。在试件中份烧结Vita Titankeramik瓷粉,测试钛瓷间的三点弯曲结合强度;对钛瓷结合界面和分离界面进行扫描电子显微镜观察,对钛瓷结合界面进行X射线能谱分析;并用X射线衍射分析仪分析涂层结构。结果A组钛瓷结合界面的硅元素明显增加,钛瓷结合强度为（37.768±0.777）MPa,明显大于B组的结合强度（29.483±1.007）MPa,其差异有统计学意义（P=0.000）。扫描电子显微镜显示A组钛瓷分离界面瓷残留较多。结论纳米硅涂层可明显提高钛瓷结合强度。     

不同表面处理方法对氧化错陶瓷基底与饰面瓷结合强度的影响

目的:研究不同表面处理方法对Upcera氧化错基底材料与Cercon ceram kiss饰面瓷结合强度的影响.方法:以计算机辅助设计/计算机辅助制作(CAD/CAM)切削后未做其他处理的试样为对照组,对3个实验组试样表面分别进行120号砂纸打磨、氧化铝喷砂、硅烷化的单面处理方法,并对处理面进行扫描电镜观察.试样表面烧...     

Effects of multiple firings on the mechanical properties and microstructure of veneering ceramics for zirconia frameworks

Objectives

The purpose of this study is to evaluate the effects of multiple firings on the mechanical properties and microstructure of veneering ceramics used with zirconia frameworks.

Methods

Five different veneering ceramics for zirconia frameworks were used: Vintage ZR (ZR), Cerabien ZR (CZR), Vita VM9 (VM9), Cercon ceram KISS (KISS), IPS e.max ceram (e.max), and one veneering ceramic used for PFM frameworks: Vintage MP (MP). Twenty specimens were fabricated of each veneering ceramic. Ten specimens were fired twice and another ten specimens were fired ten times. Three-point flexural strength following the ISO 6872 and Vickers hardness were measured, and fracture toughness (K_IC) was calculated. Density and porosity were determined. Specimens were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM).

Results

For all materials, density increased and porosity decreased after 10 firings. Significant differences in density and porosity were observed between 2 and 10 firings, with the exception of VM9 (P < 0.05). There were no significant differences in flexural strength between 2 and 10 firings except for MP. The Vickers hardness of ZR, VM9, KISS and MP increased significantly after 10 firings (P < 0.001). There were no significant differences in fracture toughness for ZR, CZR, VM9 and MP between 2 and 10 firings. However, e.max underwent a significant increase in fracture toughness (P = 0.000), and there was a significant decrease in the toughness of KISS after 10 firings (P = 0.007).

Conclusion

Multiple firings could be effective for improving the densification and the hardness of veneering ceramics for zirconia restorations.

Clinical significance

By 10 firings, the density and hardness of the veneering ceramics used with zirconia frameworks were raised, and porosity was reduced. However, no significant changes occurred in flexural strength, fracture toughness or microstructure.     

Four-point flexural strength and microtensile bond strength of digitally and conventionally veneered zirconia

This study intended to evaluate the effect of digital veneering on four-point flexural strength (FS) and microtensile bond strength (μTBS) of veneered zirconia. Two different zirconia blocks, a lithium disilicate and a feldspathic ceramic block, and two different layering ceramics were used. IPS e.max Zir CAD (ZC) and Vita In-Ceram YZ (YZ) with yttria stabilized tetragonal zirconia polycrystals (3Y-TZP) were used as substructures. IPS e.max CAD (LD), Vita Mark II (VMII), IPS e.max Ceram (EC) and Vita VM9 (VM9) were used for veneering. Resin cement and fusion ceramic were placed between veneer and zirconia substructure for digital veneering. A total of one hundred and fifty specimens in five groups (n = 30) were prepared for FS and tested in universal machine at 1.0 mm/min. One hundred specimens in five groups (n = 20) were obtained for the μTBS and tested at 1.0 mm/min. Statistical analysis was made by one way ANOVA and Tukey HSD. Conventional veneering showed statistically significant FS. ZC veneered with EC had the highest mean FS and the lowest was obtained in groups veneered through resin cement. YZ layered with VM9 had the highest mean μTBS. ZC veneered through fusion ceramic and YZ veneered through resin cement showed significantly lower and similar μTBS.     

Biaxial flexural strength of bilayered zirconia using various veneering ceramics

PURPOSE

The aim of this study was to evaluate the biaxial flexural strength (BFS) of one zirconia-based ceramic used with various veneering ceramics.

MATERIALS AND METHODS

Zirconia core material (Katana) and five veneering ceramics (Cerabien ZR; CZR, Lava Ceram; LV, Cercon Ceram Kiss; CC, IPS e.max Ceram; EM and VITA VM9; VT) were selected. Using the powder/liquid layering technique, bilayered disk specimens (diameter: 12.50 mm, thickness: 1.50 mm) were prepared to follow ISO standard 6872:2008 into five groups according to veneering ceramics as follows; Katana zirconia veneering with CZR (K/CZR), Katana zirconia veneering with LV (K/LV), Katana zirconia veneering with CC (K/CC), Katana zirconia veneering with EM (K/EM) and Katana zirconia veneering with VT (K/VT). After 20,000 thermocycling, load tests were conducted using a universal testing machine (Instron). The BFS were calculated and analyzed with one-way ANOVA and Tukey HSD (α=0.05). The Weibull analysis was performed for reliability of strength. The mode of fracture and fractured surface were observed by SEM.

RESULTS

It showed that K/CC had significantly the highest BFS, followed by K/LV. BFS of K/CZR, K/EM and K/VT were not significantly different from each other, but were significantly lower than the other two groups. Weibull distribution reported the same trend of reliability as the BFS results.

CONCLUSION

From the result of this study, the BFS of the bilayered zirconia/veneer composite did not only depend on the Young''s modulus value of the materials. Further studies regarding interfacial strength and sintering factors are necessary to achieve the optimal strength.     

Microstructure,composition, and flexural strength of different layers within zirconia materials with strength gradient

ObjectivesThe aim of this study was to compare composition, microstructure, and mechanical strength of current multilayer zirconia blanks.MethodsBar shaped specimens were made from several layers of multilayer zirconia blanks (Cercon ht ML, Dentsply Sirona, US; Katana Zirconia YML, Kuraray, J;SHOFU Disk ZR Lucent Supra, Shofu, J; priti multidisc ZrO₂ Multi Translucent, Pritidenta, D; IPS e.max ZirCAD Prime, Ivoclar Vivadent, FL). Flexural strength was determined in a three-point bending test on extra-thin bars. X-ray diffraction (XRD) with Rietveld refinement was used to assess crystal structure and scanning electron microscopy (SEM) imaging to visualize the microstructure of each material and layer.ResultsMean flexural strength varied between 467.5 ± 97.5 MPa (top layer, IPS e.max ZirCAD Prime) and 898.0 ± 188.5 MPa (bottom layer, Cercon ht ML) with significant (p ≤ 0.055) differences between the individual layers. XRD indicated 5Y-TZP for enamel-layers, 3Y-TZP for dentine-layers, individual mixtures of 3Y-TZP, 4Y-TZP, or 5 Y-TZP for intermediate layers. SEM analysis showed grain sizes between approx. 0.15 and 4 µm. Grain size tended to decrease from top to bottom layers.SignificanceThe investigated blanks differ predominantly in the intermediate layers. In addition to dimensioning of restorations, the milling position in the blanks must also be taken into account when using multilayer zirconia as restorative material.     

Influence of the veneering process on the marginal fit of zirconia fixed dental prostheses

Summary Distortions in the marginal region during manufacture are detrimental to the long‐term success of fixed dental prostheses (FDPs). The aim of the present in vitro study was to evaluate changes in marginal fit because of the veneering process of four‐unit FDPs made from different zirconia materials. Two groups of FDPs with 10 specimens each were machined from white body zirconia blanks (VITA In‐Ceram YZ Cubes, KaVo Everest ZS‐Blanks) by means of computer‐aided design/computer‐aided manufacturing systems and subsequently sintered to their final density. The marginal and internal gaps of the frameworks were determined using a replica technique. Afterwards, frameworks were veneered with the recommended ceramics (VITA VM9, GC Initial Zr), and fitting accuracy was evaluated again. Statistical analyses were performed by Student’s t‐test with the level of significance chosen at 0·05. With one framework/veneering system (Everest ZS‐Blanks/Initial Zr), both marginal gap (P = 0·019) and internal gap (P = 0·001) at the premolar retainer were significantly affected by the veneering process. The resulting distortions were directed towards the lumina of the retainers and the mean values of the measured gaps decreased by about 23·8 μm (marginal gap) and 27·3 μm (internal gap). For the other system (In‐Ceram YZ Cubes/VM9), no distortions because of the veneering were found. The veneering of zirconia restorations may lead to significant changes in the marginal fit, while the combination of core and veneering material used influences the resulting distortions.     

Biaxial flexural strength of the bilayered disk composed of ceria-stabilized zirconia/alumina nanocomposite (Ce-TZP/A) and veneering porcelain

Objective

Herein we investigated the flexural strengths of bilayered ceria-stabilized zirconia/alumina nanocomposite (Ce-TZP/A) disks using different veneering porcelains.

Effect of thermal expansion mismatch on the Y-TZP/veneer interfacial adhesion determined by strain energy release rate

PurposesThe aim of this study was to assess the effect of differences in the thermal expansion behaviour of veneering ceramics on the adhesion to Y-TZP, using a fracture mechanics approach.MethodsSeven veneering ceramics (VM7, VM9, VM13, Lava Ceram, Zirox, Triceram, Allux) and one Y-TZP ceramic were investigated. Thermal expansion coefficients and glass transition temperatures were determined to calculate residual stresses (σ_R, MPa) between core and veneer. Subsequently, the veneering ceramics were fired onto rectangular shaped zirconia specimens, ground flat and notched on the veneering porcelain side. Then specimens were loaded in a four-point bending test and load-displacement curves were recorded. The critical load to induce stable crack extension at the adhesion interface was evaluated to calculate the strain energy release rate (G, J/m²) for each system.ResultsResidual stresses ranged from ?48.3 ± 1.5 MPa (VM7) to 36.1 ± 4.8 MPa (VM13) with significant differences between all groups (p < 0.05). The strain energy release rate of the Y-TZP/veneer specimens ranged from 8.2 ± 1.7 J/m² (Lava Ceram) to 17.1 ± 2.8 J/m² (VM9). Values for G could not be obtained with the VM7, Allux and VM13 specimens, due to spontaneous debonding or unstable crack growth. Except for Triceram and Zirox specimens, strain energy release rate was significantly different between all groups (p < 0.05).ConclusionThermal residual stresses and strain energy release rates were correlated. Slight compressive stresses in the region of ?20 MPa were beneficial for the Y-TZP/veneer interfacial adhesion. Stresses higher or lower than this value exhibited decreased adhesion.     

Effects of ageing on surface textures of veneering ceramics for zirconia frameworks

ObjectivesTo evaluate the effects of ageing on surface textures of veneering ceramics for zirconia frameworks.MethodsFive different veneering ceramics for zirconia frameworks, Vintage ZR (ZR), Cerabien ZR (CZR), VitaVM9 (VM9), Cercon ceram KISS (KISS), and IPS e.max ceram (e.max), and one veneering ceramic with metal frameworks, Vintage MP (MP), were evaluated. Twenty specimens were fabricated from each veneering ceramic. All specimens were divided into two groups, one of which was subjected to accelerated ageing. The other was used as the control. Accelerated ageing was performed on the distilled water for 5 h at 200 °C and 2 atm. Surface textures were examined using laser profilometry, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS).ResultsCompared to unaged specimens, surface roughness parameters (Ra, Rp, Rv) of all aged specimens except e.max were significantly greater (P = 0.000). Compared to the unaged specimens, sodium and potassium on the surfaces of all the aged specimens significantly decreased (P < 0.05). However, oxygen levels increased significantly (P < 0.05). Silicon showed a tendency to decrease in all aged specimens, and that of ZR, KISS and e.max have a significant decrease (P < 0.01). Numerous ruffled cracks were observed on the surfaces of all aged specimens, as shown by SEM. The peaks of all crystalline phases on the surfaces of all specimens changed after accelerated ageing.ConclusionSurface textures of all examined veneering ceramics were changed by the accelerated ageing test.