Bond strength of composite luting cement to zirconia ceramic surfaces

OBJECTIVES: To evaluate the bond strength of dental resin agent to zirconia ceramic after surface pre-treatment with different techniques. METHODS: Specimens of hot isostatic pressed yttrium-oxide-partially-stabilized zirconia blocks (ZF) were fabricated (Procera Zircon, Nobel Biocare, Sweden) and compared to glossy dense zirconia blocks (ZG). Four groups of specimens with different surface treatment were prepared. Group I: ZF (n = 5) and ZG (n = 5) without any pre-treatment, Group II: ZF-s (n = 5) and ZG-s (n = 5) treated with silane solution, Group III: ZF-P (n = 10) and ZG-P (n = 10) treated with RF plasma spraying (hexamethyldisiloxane) using a reactor (Plasma Electronic, Germany), Group IV: ZF-p (n = 10) and ZG-p (n = 10) treated with micro pearls of low fusing porcelain (720 degrees C) on the surfaces. Composite cylinders (Charisma, Hereus Kulzer, Dormagen, Germany) were luted with Variolink II (Ivoclar-Vivadent, Schaan, Liechtenstein) to the test specimens. The specimens were then stored in air for 1 h before shear loading in a universal testing machine (LRX, Lloyd Instruments, Farnham, England) until failure. RESULTS: No statistical difference was found between the untreated ZF and ZG specimens (Group I) neither between the specimens treated with silane (Group II). Plasma spraying treatment improved bond strength by a factor of three (p < 0.001). Treatment with low fusing porcelain micro pearls increased the bond strength by a factor of 10 compared to untreated surfaces (p < 0.001). No significant difference was seen between the surfaces treated ZF-p and ZG-p specimens. The thickness of the glass pearls layer did not exceed 5 microm. SEM showed dense grain borders of ZF and a flat glossy texture of ZG. SIGNIFICANCE: Treatment of zirconia ceramic surfaces with plasma spraying or a low fusing porcelain pearl layer significantly increased the bond strength of resin cement to the ceramic surface.     

GI-Ⅱ型渗透陶瓷赫兹触压循环疲劳的实验研究

目的:研究GI-Ⅱ型渗透陶瓷在赫兹触压循环加载下的疲劳模式。方法:应用半径3.18mm的碳化钨球,对GI-II型渗透陶瓷标准试件进行循环加载,测试加载后试件的残余三点弯曲强度,观测试件表面及次表面损伤,数据进行单因素方差分析。结果:当最大载荷为900N时,第一次循环后试件的强度从原始的(395.7±46.5)MPa下降至(318.6±40.3)MPa,当循环次数增加至105次时,试件的三点弯曲强度再次显著性降低至(203.6±18.7)MPa(P<0.05),此后持续下降;2×105次时,降至(170±33.9)MPa。疲劳损伤随加载周期依次表现为加载区的屈服、加载区外围即滑移区的虫蚀状磨损和片状剥落,以及随后出现大块脱落。而在最大载荷为500N时,即使当循环次数增加至105次,强度的下降仍无统计学意义。结论:GI-Ⅱ型渗透陶瓷在赫兹触压循环加载下的疲劳模式为剪切应力和张应力驱动的、以裂尖屏蔽以及晶体桥接效应机械降低过程为特征的类塑性模式。     

Ceramic dental biomaterials and CAD/CAM technology: State of the art

PurposeCeramics are widely used as indirect restorative materials in dentistry because of their high biocompatibility and pleasing aesthetics. The objective is to review the state of the arts of CAD/CAM all-ceramic biomaterials.Study selectionCAD/CAM all-ceramic biomaterials are highlighted and a subsequent literature search was conducted for the relevant subjects using PubMed followed by manual search.ResultsDevelopments in CAD/CAM technology have catalyzed researches in all-ceramic biomaterials and their applications. Feldspathic glass ceramic and glass infiltrated ceramic can be fabricated by traditional laboratory methods or CAD/CAM. The advent of polycrystalline ceramics is a direct result of CAD/CAM technology without which the fabrication would not have been possible.ConclusionsThe clinical uses of these ceramics have met with variable clinical success. Multiple options are now available to the clinicians for the fabrication of aesthetic all ceramic restorations.     

白榴石微晶化增强牙科玻璃陶瓷的热处理温度制度的研究

目的 探索白榴石微晶化的热处理温度制度。方法 根据白榴石的化学式和K20-Na2O-Al2O3-SiO2系统相图制定原材料配比，在预设的熔融、成核、析晶温度中选择最佳温度；利用偏振光显微镜和x射线衍射分析仪观察样品的形态及显微结构特性。结果 玻璃融熔温度为1600℃，成核温度为1200℃，晶化温度为1500℃；微晶化后的自榴石晶粒约0．8μm，在玻璃基质中分布均匀。结论 按照一定的热处理温度制度。白榴石可以在玻璃中微晶化。     

自锁托槽与双翼托槽滑动法关闭间隙的临床比较

目的：比较3M SmartClip自锁托槽与3M Gemini MBT双翼托槽在拔除第一前磨牙患者使用滑动法关闭间隙的速度。方法选择需拔除第一前磨牙矫治的安氏Ⅰ类错患者20例,采用自身牙弓左右对比的方法,即牙弓一侧第二前磨牙和第一磨牙粘接3M自锁托槽,另一侧粘接Gemini MBT双翼托槽。排齐整平后用0.48 mm ×0.64 mm（0.019英寸×0.025英寸）不锈钢丝及镍钛拉簧关闭间隙,计算关闭间隙的平均速度（mm/月）。结果自锁托槽侧的平均移动速度是1.03 mm/月,传统双翼托槽侧的平均移动速度是1.00 mm/月,差异无统计学意义（t=0.70,P=0.48）。结论3M SmartClip自锁托槽与Gemini MBT双翼托槽滑动法关闭间隙速度没有明显差异。     

金属修复体表面粗糙度对其磨耗性能的影响

目的：采用标准化牙釉质试件与金属材料试件对磨的方式,评价常用的几种口腔修复材料在不同表面粗糙度下的磨耗性能。方法：以镍基铸造合金、镍基合金、钴铬钼合金和钛合金4种合金材料作为对磨材料样本,牙釉质为磨耗样本,进行磨耗实验,定量检测牙釉质样本的磨耗量,采用SAS14.0软件包对数据进行统计学分析。结果：与镍基铸造合金180目组和400目组对磨的牙釉质平均磨耗量无显著差异,而与400目组与1200目组对磨的牙釉质试件平均磨耗量差异显著。与3种不同粗糙度的钴铬钼合金、镍铬合金及不同处理组钛合金对磨的牙釉质试件平均磨耗量之间均有显著差异。结论：镍铬合金、钴铬钼合金、钛合金的表面粗糙度对牙釉质的磨耗量会产生影响,粗糙程度大的金属,会显著增加牙釉质的磨耗量。     

两种酸蚀剂对Vita VMK68瓷与树脂粘结强度的影响

目的：观察用２．５％和５％氢氟酸处理ＶｉｔａＶＭＫ６８瓷不同时间对该瓷与树脂粘结强度的影响。     

两种牙科氧化锆-玻璃复相全瓷材料的比较研究

目的：观察不同配方的玻璃添加剂对牙科Y-TZP/玻璃复相全瓷材料烧结、力学性能及显著结构的影响。方法：Y-TZP中分别加入两种不同配方的玻璃添加剂,干压成型后在五种温度下烧结,观察材料的相对密度,抗弯强度,X射线衍射图及微观形貌。结果：B组氧化锆玻璃复相材料1400℃烧结,抗弯强度高,微观形态分布均匀。结论：玻璃相成分对材料烧结温度和性能有明显影响,既要有效降低烧结温度,又具有优良的力学性能才能适应牙科全瓷材料的需要,材料B有临床应用前景。     

制备高性能氧化锆陶瓷牙科修复体的初步研究

目的 :本文对以氧化钇稳定四方相氧化锆 (Y -TZP)纳米微粉为原料 ,经部分烧结 -牙科计算机辅助设计/计算机辅助制造系统 (CAD/CAM)加工 -完全烧结三步法制备高性能的牙科修复体的工艺路线进行了初步探索。方法 :先经模压成型 ,低温烧结 ,制作了可供CAD/CAM加工的部分烧结Y -TZP陶瓷块 ;然后经牙科CAD/CAM机加工 ,得到初步的牙科修复体 ;最后对此修复体进行完全烧结 ,得到高性能的氧化锆牙科修复体。结果 :部分烧结的陶瓷块的切削性能优良 ,与CAD/CAM预期时间吻合。完全烧结的陶瓷材料机械性能优良 ,弯曲强度达到710MPa,断裂韧性达到 4 .77MPa·m1/ 2 。在完全烧结过程中 ,各个方向收缩均匀一致。得到的牙冠形态逼真 ,无裂纹。结论 :部分烧结 -CAD/CAM加工 -完全烧结三步法制备高性能的牙科修复体的工艺路线为一条切实可行的路线     

Silica infiltration on translucent zirconia restorations: Effects on the antagonist wear and survivability

ObjectiveTo assess potential antagonist wear and survival probability of silica-infiltrated zirconia compared to glass-graded, glazed, and polished zirconia.MethodsTable top restorations made of 3Y-TZP (3Y), 5Y-PSZ (5Y), and lithium disilicate (LD) were bonded onto epoxy resin preparations. Each zirconia was divided into five groups according to the surface treatment: polishing; glaze; polishing-glaze; glass infiltration; and silica infiltration. The LD restorations received a glaze layer. Specimens were subjected to sliding fatigue wear using a steatite antagonist (1.25 ×10⁶ cycles, 200 N). The presence of cracks, fractures, and/or debonding was checked every one/third of the total number of cycles was completed. Roughness, microstructural, Scanning electron microscopy, wear and residual stress analyses were conducted. Kaplan–Meier, Mantel–Cox (log-rank) and ANOVA tests were performed for statistical analyses.ResultsThe survival probability was different among the groups. Silica infiltration and polishing-glaze led to lower volume loss than glaze and glass-infiltration. Difference was observed for roughness among the zirconia and surface treatment, while lithium disilicate presented similar roughness compared to both glazed zirconia. Scanning electron microscopy revealed the removal of the surface treatment after sliding fatigue wear in all groups. Compressive stress was detected on 3Y surfaces, while tensile stress was observed on 5Y.Significance3Y and 5Y zirconia behaved similarly regarding antagonist wear, presenting higher antagonist wear than the glass ceramic. Silica-infiltrated and polished-glazed zirconia produced lower antagonist volume loss than glazed and glass-infiltrated zirconia. Silica-infiltrated 3Y and lithium disilicate restorations were the only groups to show survival probabilities lower than 85%.     

Fracture strength of monolithic all-ceramic crowns made of high translucent yttrium oxide-stabilized zirconium dioxide compared to porcelain-veneered crowns and lithium disilicate crowns

Objective. The aim of the study was to provide data on the fracture strength of monolithic high translucent Y-TZP crowns and porcelain-veneered high translucent Y-TZP crown cores and to compare that data with the fracture strength of porcelain-veneered Y-TZP crown cores and monolithic lithium disilicate glass-ceramic crowns. Materials and methods. Sixty standardized crowns divided into six groups (n = 10) were fabricated: monolithic high translucent Y-TZP crowns, brand A, monolithic high translucent Y-TZP crowns, brand B, veneered high translucent Y-TZP crown cores, brand A, veneered high translucent Y-TZP crown cores, brand B, heat-pressed monolithic lithium disilicate crowns and veneered Y-TZP crown cores. All crowns were thermocycled, cemented onto dies, cyclically pre-loaded and finally loaded to fracture. Results. The monolithic Y-TZP groups showed significantly higher fracture strength (2795 N and 3038 N) compared to all other groups. The fracture strength in the veneered Y-TZP group (2229 N) was significantly higher than the monolithic lithium disilicate group (1856 N) and the veneered high translucent Y-TZP groups (1480 N and 1808 N). Conclusions. The fracture strength of monolithic high translucent Y-TZP crowns is considerably higher than that of porcelain-veneered Y-TZP crown cores, porcelain-veneered high translucent Y-TZP crown cores and monolithic lithium disilicate crowns. The fracture strength of a crown made of monolithic high translucent Y-TZP is, with a large safety margin, sufficient for clinical use for the majority of patients. Porcelain-veneered Y-TZP crown cores show higher fracture resistance than monolithic lithium disilicate crowns.     

表面处理对瓷牙材料机械强度影响的实验研究

目的 比较不同表面处理因素对瓷瓦材料机械强度的影响。方法 制备３００个表面均匀一致的实验标本,对抛光面进行表面处理,处理后的标本用万能实验机进行机械循环,然后用Ｐｉｓｔｏｎ－ｏｎ－ｔｈｒｅｅ ｂａｌｌ方法检查实验标本的挠屈强度。结果 双向卡方检验说明不同表面处理因素及不同循环次数对实验标本挠屈强度的影响都具有显著意义（（Ｐ〈０．０００１）;Ｑ－检验说明自然上釉、酸蚀、喷砂等表面自理和表面抛光相比,     

牙科着色氧化锆陶瓷饰瓷前后的力学性能及断裂模式分析

目的:本研究对牙科氧化锆陶瓷着色及构筑饰面瓷前后的力学性能及断裂模式进行分析.方法:球磨混合一定组分的着色剂(氧化铁及氧化铈)和3Y-TZP(钇稳定氧化锆)粉体制备着色氧化锆陶瓷.根据ISO6872牙科陶瓷标准,制备着色和未着色氧化锆陶瓷的三点弯曲强度样品和构筑饰面瓷后的双层瓷样品,核心瓷与饰面瓷的厚度比为1:1.对所获得样品进行三点弯曲强度、断裂韧性和维氏硬度测试.采用X射线衍射(XRD)分析物相结构,扫描电镜(SEM)观察样品的断裂模式.结果:白色氧化锆陶瓷与着色氧化锆陶瓷的三点弯曲强度分别为1301 MPa和1203:MPa,统计学结果显示二者间没有明显差异,构筑饰面瓷后的三点弯曲强度分别为817 MPa和803 MPa,统计学结果显示二者间没有明显差异,但构筑饰面瓷后比单一材料样品强度降低,二者间有显著差异.在所有的双层瓷样品中,断裂模式的应力位移曲线显示为单峰断裂模式,断裂起始于核心瓷的张应力面中心区域同时发生饰面瓷的破碎和瓷层剥脱.结论:对氧化锆粉体的适当着色并没有明显影响材料的机械性能,着色和未着色氧化锆材料与饰面瓷具有良好的物理匹配性.     

背景材料对3种牙科全瓷底层材料饰瓷后颜色的影响

目的：探讨不同桩核材料背景色对3种全瓷材料饰瓷后的颜色影响。方法：采用色差计测量各组饰瓷后试样在贵金属、镍铬合金、银汞合金和树脂背景上的色度值并计算组间色差值。结果：EmpressⅡ材料在贵金属背景色与两种非贵金属和树脂背景色之间,出现明度值和色品值的组间显著差异（P〈0．05）,渗透氧化铝陶瓷在不同背景色下,只出现了色品值的组间显著差异（P〈0．05）。4组氧化锆试样不同背景色下的色度值无组间显著性差异（P〉0．05）。结论：饰瓷后,EmpressⅡ铸瓷修复体透明度较高,受背景色的影响较大,人眼可以辨别;渗透氧化铝陶瓷受背景色影响较小,人眼不能辨别。氧化锆陶瓷不受背景色的影响。     

背景颜色对3种牙科全瓷底层材料颜色的影响

目的:探讨不同桩核材料背景色对3种全瓷底层材料的颜色影响。方法:采用色差计测量各组试样在贵 金属、镍铬合金、银汞合金和树脂背景上的色度值并计算组间色差值。结果:3种EmpressⅡ铸瓷试样在不同背景之 间的色差值均能够为人眼所识别(ΔE>1.5),而渗透氧化铝和氧化锆陶瓷的组间色差值不能为人眼所识别。结 论:AL1色系渗透氧化铝和EmpressⅡ铸瓷材料受背景色影响较大,应采用适当的遮蔽背景色的方法。AL2色系选 用树脂材料作为核桩材料时不须遮蔽背景色。而AL3、AL4色系渗透氧化铝和氧化锆材料不受背景色的影响。     

牙科纳米氧化铝陶瓷的烧结研究

目的 :探讨干压成型、低温烧结制备牙科纳米氧化铝陶瓷的工艺方法。方法 :采用Al2 O3-CaO -MgO -SiO2 系统来研制纳米氧化铝陶瓷 ,通过扫描电子显微镜 (SEM)及力学性能测试 ,比较了不同MgO含量、成型压力及烧结温度对氧化铝陶瓷的密度及力学性能的影响。结果 :1.2 9wt%MgO试样组的陶瓷晶粒均匀且发育比较完全 ;随着粉料成型压力的升高 ,烧结后瓷体的密度及维氏硬度均增大 ;在 130 0℃烧结后 ,晶体发育差且气孔较多 ,随着烧结温度的升高 ,晶粒逐渐增大 ,在 145 0℃时可见瓷体晶形发育较完全。结论 :选择适当的复合烧结助剂、成型压力及烧结温度可制得较理想的纳米氧化铝陶瓷