不同表面处理及老化对氧化锆陶瓷抗折强度的影响

［摘要］ 目的 研究打磨、抛光、上釉及老化对氧化锆陶瓷抗折强度的影响。方法 将36片氧化锆陶瓷分成打磨组、抛光组、上釉组3组,每组试件按不同的老化时间分为0 h组（对照组）和10 h组（n=6）。将10 h组瓷块置于134 ℃,0.2 MPa 的水热环境下,进行10 h的老化试验。每组各取一个试件,用 X 线衍射 ( X-ray diffraction,XRD ) 仪测定单斜相含量,万能力学试验机测试所有试件抗折强度。结果 XRD分析显示老化前的所有试件均未显示单斜相。老化后所有组均出现单斜相,打磨组单斜相含量最高,上釉组最低。抗折强度所有组均无统计学意义（P>0.05）。结论 老化后所有试件单斜相含量均有所增加,但打磨、抛光、上釉及老化处理对氧化锆陶瓷抗折强度未产生影响。     

牙科氧化锆陶瓷的低温时效性能研究

目的 研究时效对5种牙科氧化锆陶瓷结构稳定性的影响.方法 5种氧化锆预烧结块(A组:TZ-3YS;B组:Vita In-Ceram YZ;C组:Ivoclar;D组:Cercon Smart;E组:Kavo)各切取15 mm×15 mm×1.5 mm氧化锆试件18片,常压致密烧结.时效处理如下:置于高温高压消毒炉中进行循环热处理,条件是134℃,0.2 MPa压力,维持时间为0h、1h、2h、3h、4 h、5h.X射线衍射分析(X-ray diffraction,XRD)试件的晶相结构,计算试件表面单斜相(m相)的相对含量.原子力显微镜观察A组和D组时效1、4 h的抛光试件.A组氧化锆再制备25 mm×4 mm×1.2 mm的试件30根,均分为未退火组(时效前)、退火组(时效前)和时效组(时效后),测试试件的三点弯曲强度.结果 除D组试件外,A、B、C、E组试件的m相含量均随时效时间的延长而增加,A组试件的m相含量最高,E组次之,B组和C组相近.XRD未检测到D组试件表面有m相,但使用原子力显微镜可观察到D组试件有m相晶核的成核和生长.时效前后A组试件的三点弯曲强度未衰减,未退火组试件三点弯曲强度[(1301±169)MPa]显著高于退火组[(1120±185)MPa]和时效组[(1158±111)MPa],差异有统计学意义(P＜0.05);而退火组与时效组间差异无统计学意义(P＞0.05).结论 牙科氧化锆陶瓷的低温时效效应具有时间依赖性,但时效效应并未使TZ-3YS的三点弯曲强度降低.     

牙科着色氧化钇稳定四方多晶氧化锆陶瓷的结构与性能

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,分析着色后材料的显微和晶相结构,并测定其理化、机械及抗低温时效性能。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,先于1 050 ℃预烧结2 h,然后在1 500 ℃终烧结2 h,烧制5种具有一定颜色的氧化锆材料,测量烧结体的密度、收缩率、热膨胀系数、维氏硬度、三点弯曲强度、断裂韧性和化学稳定性;通过扫描电镜和X线衍射观察着色后材料的显微和晶相结构,并测试着色对材料抗低温时效性能的影响。结果着色后3Y-TZP陶瓷烧结密度在99.7%以上,烧结收缩率约20%,热膨胀系数为11×10-6·℃-1;晶粒大小均匀,主要断裂方式为穿晶断裂,主晶相为四方相氧化锆（t-ZrO2）;在弱酸性条件下具有较好的化学稳定性;5组着色氧化锆陶瓷的三点弯曲强度较未着色组略有降低,但均在900 MPa以上,断裂韧性略有提高,经低温时效处理后四方相到单斜相（m-ZrO2）的相变量约40%,但弯曲强度没有降低。结论3Y-TZP陶瓷经过着色后,具有优良的理化和机械性能,能够满足牙科临床应用的要求。     

低温等离子处理对氧化锆粘接强度的影响

目的:研究低温等离子处理对氧化锆与树脂水门汀粘接强度的影响.方法:将80个氧化锆试件随机分为8组,每组10个:对照组(C),无处理.前处理剂组(PR),在氧化锆试件表面涂布前处理剂.喷砂组(SB),用Al2O3颗粒对氧化锆试件表面均匀喷砂.喷砂+前处理剂组(SBPR).低温等离子处理组(PL),将氧化锆试件中心置于常压喷出式低温等离子体发生器喷嘴下5mm处理10sec.低温等离子处理+前处理剂组(PLPR).喷砂+低温等离子处理组(SBPL).喷砂+低温等离子处理+前处理剂组(SBPLPR).分组处理后观察氧化锆试件表面形态,测量表面接触角及剪切粘接强度.结果:等离子处理组氧化锆试件表面形态未见明显改变,接触角明显减小.低温等离子处理组剪切粘接强度(16.81 MPa)明显高于对照组(9.41 MPa)和前处理剂组(10.28 MPa)(P＜0.05),与喷砂组(14.82 MPa)和喷砂+前处理剂组(18.34 MPa)相比差异无统计学意义(P＞0.05).喷砂+低温等离子处理+前处理剂组剪切粘接强度最高(23.95 MPa).XPS结果显示低温等离子处理使氧化锆试件表面氧元素(O)含量增加,碳元素(C)含量减少,碳/氧比值(C/O)减小.结论:低温等离子处理能显著的增加氧化锆表面的亲水性,显著提高氧化锆与树脂水门汀的粘接强度.     

口腔修复氧化锆陶瓷低温老化的研究进展

氧化锆陶瓷兼具优异的力学性能和美学性能,在口腔医学领域应用广泛。然而,临床常用的四方相氧化锆陶瓷在口腔环境中可发生低温老化,导致修复体表面粗糙度增加、微裂纹产生、力学性能下降等。氧化锆陶瓷低温老化受晶体大小、应力、稳定剂含量和类型、表面处理、烧结条件等因素影响,本文就口腔修复学领域氧化锆陶瓷低温老化的研究进展进行综述,...     

光纤激光蚀刻对氧化锆陶瓷性能影响的研究

目的:通过比较喷砂和不同功率光纤激光蚀刻处理对氧化锆陶瓷抗弯曲强度和剪切粘结强度的影响,探讨光纤激光蚀刻氧化锆陶瓷的可行性,为光纤激光蚀刻应用于临床提供参考。方法:将结晶后的氧化锆试件随机分为5组(n=10),处理如下:A组为空白对照组,B组为氧化铝颗粒喷砂组,C-E组分别为功率为2、4、6 W光纤激光处理组。测定各组试件的三点抗弯曲强度并观察其处理面的显微形貌。再将各组试件处理面与双固化复合树脂 Multilink N粘固,37 ℃恒温水浴24 h后测试剪切粘结强度。采用方差分析和LSD多重检验进行比较(α=0.05)。结果:各组试件的抗弯强度无统计学差异。A组与E组的粘结强度无明显差异;而与其余3组间的粘结强度差异均有统计学意义(P<0.005)。喷砂组和光纤激光蚀刻组两两比较显示,B、C、D 3组间的粘结强度无明显差异,E组的粘结强度低于B、C、D 3组(P<0.05)。结论:采用合适激光功率的光纤激光蚀刻技术能增强氧化锆陶瓷与复合树脂间的粘结强度,且对氧化锆自身的抗弯曲强度无明显影响,可以作为临床上氧化锆陶瓷表面处理的一种方法。     

不同人工老化强度对氧化锆陶瓷粘结强度的影响

目的评价氧化锆陶瓷经几种表面处理后在不同强度的人工老化实验条件下的粘结耐久性。方法制备4组氧化锆陶瓷/树脂粘结试件128个,各组试件氧化锆陶瓷按照以下方式处理并使用不同种类的树脂水门汀。组A,摩擦化学法硅涂层+硅烷偶联剂;组B,氧化铝喷砂;组C,氧化铝喷砂+应用氧化锆涂底剂Z-Prime Plus;组D,氧化铝喷砂+应用氧化锆涂底剂Z-Prime Plus。组A和C使用传统Bis-GMA基光固化树脂水门汀,组B和D使用自粘结树脂水门汀。各实验组再分为4个亚组接受不同的人工老化。不接受人工老化(a),水储40 d(b);冷热循环1 200次(c);水储40 d后冷热循环12 000次(d)。测试各组剪切粘结强度值并进行统计学分析。摩擦化学法硅涂层和氧化铝喷砂的氧化锆陶瓷表面以扫描电镜观察并进行能谱分析。结果不论接受或不接受人工老化,4种表面处理间对氧化锆陶瓷的粘结强度值影响无统计学差异。各实验组单独来看,仅有人工老化方式d时粘结强度值都出现了下降,差别具有统计学意义。结论不同人工老化强度对氧化锆陶瓷粘结强度的影响不同。     

表面融附玻璃陶瓷对氧化锆与树脂粘接强度的影响

目的 评估氧化锆玻璃陶瓷表面融附处理后粘接力的变化.方法 将60个氧化锆陶瓷试件平均分为3组,分别接受以下表面处理:50 μm氧化铝喷砂(Sb组);融附玻璃陶瓷(Fu组);氧化铝喷砂后融附玻璃陶瓷(Sb-Fu组).另以20个铸瓷试件作为铸瓷对照组.所有试件应用树脂粘接材料Super bond C＆B粘接在核树脂圆柱上,其中1/2试件经过冷热循环老化(10 000次,5～55℃),测量所有试件的粘接强度.结果 未经过冷热循环处理的Sb、Fu、Sb-Fu和铸瓷对照组试件的粘接强度标准差±均值分别是24.76±2.80、29.08±5.80、28.67±7.20和31.30±2.90 MPa,Sb组的粘接强度明显低于其他3组(P＜0.05),而Fu和Sb-Fu组与铸瓷对照组相比差异无统计学意义;冷热循环后,4组的粘接强度分别是24.45±3.90、28.50±3.70、25.41±2.00和32.19±3.90 MPa,Sb和Sb-Fu组明显低于铸瓷对照组(P＜0.01).Fu和Sb-Fu组多为树脂内聚断裂和混合断裂.结论 玻璃陶瓷融附处理比单纯喷砂更能提高氧化锆的粘接强度.     

几种常用口腔材料细菌粘附性能比较

目的：探讨5种口腔常用材料的抗细菌粘附性能。方法将自凝甲基丙烯酸甲酯基托树脂、Z250复合树脂、氧化锆陶瓷、纯钛和镍铬合金5种牙科常用修复材料,分别制备成3．0cm ×2．0cm ×0．2cm的板片试件,每组各5片。各组试件表面进行抛光处理,使试件表面粗糙度( Ra)值无显著性差异。实验菌株选用变形链球菌,用细菌悬浮液置试件表面,37℃培养48h,对粘附在材料表面的细菌再进行洗脱、培养、菌落计数,使用SPSSl7．0软件对试验结果进行统计分析。结果纯钛表面变形链球菌粘附量最低,依次为氧化锆陶瓷、Z250复合树脂、镍铬合金、自凝甲基丙烯酸甲酯基托树脂。结论不同口腔材料在同样粗糙度的条件下,抗细菌粘附性能存在差异,钛具有较好的抗细菌粘附性能。     

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.     

The effect of low temperature aging on the mechanical property & phase stability of Y-TZP ceramics

STATEMENT OF PROBLEM

Recently Yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) has been introduced due to superior flexural strength and fracture toughness compared to other dental ceramic systems. Although zirconia has outstanding mechanical properties, the phenomenon of decrease in the life-time of zirconia resulted from degradation in flexural strength after low temperature aging has been reported.

PURPOSE

The objective of this study was to investigate degradation of flexural strength of Y-TZP ceramics after various low temperature aging treatments and to evaluate the phase stability and micro-structural change after aging by using X-ray diffraction analysis and a scanning electron microscope (SEM).

MATERIAL AND METHODS

Y-TZP blocks of Vita In-Ceram YZ (Vita Zahnfabrik, Bad Säckingen, Germany) were prepared in 40 mm (length) × 4 mm (width) × 3 mm (height) samples. Specimens were artificially aged in distilled water by heat-treatment at a temperature of 75, 100, 125, 150, 175, 200, and 225℃ for 10 hours, in order to induce the phase transformation at the surface. To measure the mechanical property, the specimens were subjected to a four-point bending test using a universal testing machine (Instron model 3365; Instron, Canton, Mass, USA). In addition, X-ray diffraction analysis (DMAX 2500; Rigaku, Tokyo, Japan) and SEM (Hitachi s4700; Jeol Ltd, Tokyo, Japan) were performed to estimate the phase transformation. The statistical analysis was done using SAS 9.1.3 (SAS institute, USA). The flexural strength data of the experimental groups were analyzed by one-way analysis of variance and to detect statistically significant differences (α= .05).

RESULTS

The mean flexural strength of sintered Vita In-Ceram YZ without autoclaving was 798 MPa. When applied aging temperature at below 125℃ for 10 hours, the flexural strength of Vita In-Ceram YZ increased up to 1,161 MPa. However, at above 150℃, the flexural strength started to decrease. Although low temperature aging caused the tetragonal-to-monoclinic phase transformation related to temperature, the minimum flexural strength was above 700 MPa.

CONCLUSION

The monoclinic phase started to appear after aging treatment above 100℃. With the higher aging temperature, the fraction of monoclinic phase increased. The ratio of monoclinic/tetragonal + monoclinic phase reached a plateau value, circa 75% above 175℃. The point of monoclinic concentration at which the flexural strength begins to decrease was between 12% and 54%.     

Influence of low-temperature environmental exposure on the mechanical properties and structural stability of dental zirconia

Purpose: The effect of dental fabrication procedures of zirconia monolithic restorations and changes in properties during low‐temperature exposure in the oral environment is not completely understood. The purpose of this study was to investigate the effect of procedures for fabrication of dental restorations by low‐temperature simulation and relative changes of flexural strength, nanoindentation hardness, Young's modulus, surface roughness, and structural stability of yttria‐stabilized zirconia. Materials and Methods: A total of 64 zirconia specimens were prepared to simulate dental practice. The specimens were divided into the control group and the accelerated aging group. The simulated group followed the same procedure as the control group except for the aging treatment. Atomic force microscopy was used to measure surface roughness. The degree of tetragonal‐to‐monoclinic transformation was determined using X‐ray diffraction. Nanoindentation hardness and modulus measurements were carried out on the surface of the zirconia specimens using a nanoindenter XP/G200 system. The yttria levels for nonaged and aged specimens were measured using energy dispersive spectroscopy. Flexural strength was determined using the piston‐on‐three‐ball test. The t‐test was used to determine statistical significance. Results: Means and standard deviations were calculated using all observations for each condition and evaluated using a group t‐test (p < 0.05). The LTD treatment resulted in increased surface roughness (from 12.23 nm to 21.56 nm for Ra and 15.06 nm to 27.45 nm for RMS) and monoclinic phase fractions (from 2% to 21%), with a concomitant decrease in hardness (from 16.56 GPa to 15.14 GPa) and modulus (from 275.68 GPa to 256.56 GPa). Yttria content (from 4.43% to 4.46%) and flexural strength (from 586 MPa to 578 MPa) were not significantly altered, supporting longer term in vivo function without biomechanical fracture. Conclusion: The LTD treatment induced the tetragonal‐to‐monoclinic transformation with surface roughening in zirconia prepared using dental procedures.     

Influence of aging on flexural strength of translucent zirconia for monolithic restorations

Statement of problem

Concern has been raised with regard to the low-temperature degradation (LTD) of translucent yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) for monolithic zirconia restorations.

The effect of accelerated aging on crystalline structures and optical properties of different monolithic zirconia: A qualitative systematic review

ObjectiveThis study aimed to systematically review the literature related to the impact of low temperature degradation (LTD) on the crystalline structures and optical properties of different types of dental monolithic zirconia materials.MethodsThe systemic review was performed based on the PRISMA statement. In vitro studies investigating the effect of accelerated aging in autoclave (2 bar pressure 134°C – ISO standard 13356-2008) on the crystalline structure and/or optical properties of Yttria-partially stabilized zirconia (Y-PSZ) were included. Specific search terms were used for peer-reviewed articles published in PubMed, Ovid MEDLINE, and EMBASE databases.ResultsFrom 286 eligible articles, 51 articles were selected for full-text analysis, 10 failed to meet the inclusion criteria, and 41 articles were included in this review. Autoclave aging (30 min – 300 h) results in an increase in monoclinic phase (m) content up to 80% for tetragonal zirconia and reaching saturation after 35 h of autoclave aging. All included articles reported less than 1% of monoclinic phase for cubic zirconia after autoclave aging. Translucency parameter was reported between 2.34 and 19.7 after autoclave aging (4–100 h). For same aging time, contrast ratio ranged between 0.48 and 0.95.SignificanceAn increase in monoclinic phase was reported for tetragonal zirconia, while cubic zirconia demonstrates resistance to LTD. The optical properties for all zirconia materials investigated seem more compromised with increasing aging time.     

Influence of shading on zirconia's phase transformation and flexural strength after artificial aging

ObjectivesThe aim of this study was to determine the phase transformation and the influence of aging on the flexural strength of different colored zirconia. The effect of hydrothermal aging in an autoclave was compared with the effect of mechanical stress by simulating chewing.MethodsHigh-strength zirconia (3Y-TZP) was investigated in three different colors: uncolored, A3, and D3. Disc-shaped specimens (N = 3) were analyzed by X-ray diffraction (XRD), and flexural strength was determined on bar-shaped specimens (N = 15) in a 4-point bending test before and after performing two different aging protocols: aging in an autoclave (134 °C, 70 h) and aging in a chewing simulator (5 kg load, 1.2 million cycles). During autoclave aging, the fraction of monoclinic phase on the surface was determined every 5 h. Once this exceeded 25 vol%, aging of the bar specimens was stopped.ResultsWhile in the unstained group the mean value of the proportion of monoclinic phase already exceeded 25 vol% after 30 h in the autoclave, this was the case in both stained groups only after 70 h. No measurable phase transformation could be detected after chewing simulation. Only color A3 showed a statistically significant (p ≤ 0.05) decrease in flexural strength after aging in the chewing simulator.SignificanceThe colored zirconia showed a higher resistance to phase transformation through hydrothermal aging. The metal oxides in the staining solutions are assumed to hinder the phase transformation in the zirconia. Therefore, the significant reduction in the stained zirconia after chewing simulation is particularly interesting     

钛酸钾晶须的填充量对其增强牙用复合树脂抗弯强度的影响

目的：研究钛酸钾晶须填充量对于其增强牙用复合树脂抗弯强度的影响。方法：以3％硅烷偶联剂修饰钛酸钾晶须,修饰后晶须按照40％、50％、60％、70％、75％的填充量分别与树脂基质通过手工搅拌的方式进行混合,合成五组复合树脂并制作出标准试件,然后进行三点弯曲测试及断面的电镜扫描观察。结果：五组的抗弯强度分别是（109．85±15．25）MPa、（133．50±21．66）MPa、（145．30±19．63）MPa、（112．15±11．04）MPa、（112．75±8．73）MPa。当填充量为60％时复合树脂的抗弯强度达到最大。利用SAS统计软件对五组结果进行均数间的Tukey检验可知,60％组与40％、70％、75％组的抗弯强度在α=0．01水平上具有显著性差异,40％、50％、70％、75％四组间抗弯强度在α=0．05水平上差异不显著。断面的电镜扫描可见40％、50％、60％组中晶须均匀分散于树脂基质中,并且结合良好。结论：钛酸钾晶须可以提高复合材料的强度,但过多或过少都不能达到最佳的效果。     

氧化锆对二硅酸锂玻璃陶瓷力学性能的影响

目的:测定牙科氧化锆-二硅酸锂玻璃陶瓷复合材料(ZTCLDC)的力学性能,探讨氧化锆质量分数变化对ZTCLDC力学性能的影响及机制。方法:向制备好的二硅酸锂基础玻璃粉体中分别添加不同质量分数的ZrO(21%,2%,3%,4%),静压成型晶化热处理,每组中的半数试件进行牙科热压铸处理,分别测试热压铸前后的三点弯曲强度及断裂韧性;扫描电镜观察晶体微观结构;X射线衍射分析其晶相组成。结果:热压铸前,ZTCLDC抗弯强度和断裂韧性随ZrO2含量的增加而升高;热压铸后,ZTCLDC抗弯强度随ZrO2含量的增加而降低,ZrO2加入量为4%时,压铸后的断裂韧性最高为4.3 MPa.m1/2。结论:ZrO2对实验二硅酸锂玻璃陶瓷存在增韧效果,能够提高复合材料的断裂韧性。