长石质和氟磷灰石饰瓷在模拟咀嚼循环条件下耐磨性能的研究

目的:比较模拟咀嚼循环条件下长石质饰瓷与氟磷灰石饰瓷的耐磨性能。方法:制备2种饰瓷长条形试件各10个,用于物理性能测试和表面形貌观察;另制备圆盘形试件各6个,分别在水环境、加载力10 N、转速200 r/min的条件下进行120万次循环磨损实验;于每10万次循环节点测量各饰瓷的体积磨损量和表面粗糙度;然后分别在磨损10、70、120万次循环节点观察各饰瓷磨损面的微观形貌,分析磨损区域的基本组成及其所占比例。结果:两种饰瓷的体积磨损量、表面粗糙度曲线均呈现正相关近似线性上升趋势,在每个测量节点,氟磷灰石瓷的体积磨损量、表面粗糙度均明显高于长石质瓷(P<0.05);长石质瓷表面均匀一致,而氟磷灰石瓷表面有较多大小不一且散在分布的气孔;随着加载循环的进行,两种饰瓷的磨痕均由稀疏变为密集,磨损面上均可见磨屑粘着。结论:在模拟咀嚼循环条件下,氟磷灰石瓷的耐磨性能较长石质瓷差。     

牙科氧化锆瓷摩擦磨损性能的研究

目的研究牙科氧化锆瓷的摩擦磨损性能以及与天然牙釉质摩擦磨损性能匹配情况。方法微摩擦磨损试验机上,以滑石瓷为对磨物,人工唾液润滑下对Upcera ST和Zenostar Zr Translucent氧化锆瓷、牙釉质和饰面瓷进行摩擦磨损实验。实验前,用激光共聚焦显微镜测试件表面粗糙度Ra;实验结束后,光学显微镜下观察滑石瓷磨斑形貌、测量滑石瓷磨斑面积;激光共聚焦显微镜测量试件磨斑宽度;扫描电镜下观察试件磨斑的微观形貌。采用单因素方差分析进行统计学分析。结果饰面瓷的磨斑宽度大于其它3种材料（P〈0.01）,饰面瓷对磨物滑石瓷磨斑面积大于氧化锆瓷和牙釉质（P〈0.05）。结论与饰面瓷对比,氧化锆瓷具有更佳耐磨性及较低对磨物磨损,并且与天然牙釉质的磨擦学性能相似。     

天然牙与全瓷饰面瓷的磨损特性研究

目的通过体外模拟实验观察全瓷饰面瓷材料（Vintage AL、Vita- alpha）与天然牙釉质的摩擦学行为特点,探讨其摩擦磨损机制。方法实验前对材料进行力学性能检测。采用摩擦磨损机观察3种材料的摩擦磨损行为,记录摩擦力矩数,计算摩擦系数;测量磨斑宽度;磨损试件表面采用动态原子力显维镜（DFM）观察;采用能谱仪分析摩擦实验前后样品元素的变化。结果3种材料显微硬度值存在统计学差异（P<0.05）;两种饰面瓷的三点弯曲强度比较有统计学差异（P<0.05）,断裂韧性差别无统计学意义。3种材料摩擦系数呈现一定时间规律性,耐磨能由高到低排列为Vintage AL、Vita- alpha、天然牙釉质。磨斑宽度比较有统计学意义（P<0.05）。DFM结果显示釉质主要表现为磨粒磨损和组织结构的变形,偶可见组织断裂片;饰面瓷摩擦表面可见大量犁沟和磨粒,偶见微裂。结论本实验中3种材料呈现良好的耐磨性。天然牙的磨损机理主要是磨粒磨损和组织结构变形;全瓷饰面瓷的磨损机理主要为磨粒磨损、黏着磨损和疲劳磨损,不同磨损类型在两种饰面瓷发挥的作用不完全相同。     

不同pH环境下椅旁用玻璃陶瓷的摩擦磨损行为

目的 探究不同pH环境下椅旁修复用长石质增强型玻璃陶瓷(VM)、白榴石增强型玻璃陶瓷(EC)、二硅酸锂增强型玻璃陶瓷(EX)和氧化锆增强型二硅酸锂玻璃陶瓷(VS)的摩擦磨损行为.方法 采用微动摩擦磨损测试仪对VM、EC、EX和VS 4种玻璃陶瓷分别在酸性、中性和碱性环境下进行磨损测试,测试参数为法向载荷(Fn)50 N...     

干湿环境下循环载荷对氧化锆-饰面瓷叠层瓷结构抗弯强度的影响

目的:比较干燥和唾液浸泡环境下动态循环加载对氧化锆/饰面瓷叠层瓷结构抗弯强度的影响。方法:制作氧化锆/饰面瓷叠层瓷结构圆片试件30个,随机分为干燥和唾液浸泡两组,循环加载10000次后进行双轴弯曲测试,光学显微镜观察其表面损伤及断裂面形貌。结果:在干燥环境下,经过10000次循环疲劳实验后,表面裂纹主要为赫兹锥状裂纹,破碎模式主要为完全断裂。而在唾液环境下,经过疲劳实验后,表面裂纹除了赫兹锥状裂纹外还有环状裂纹,破碎模式主要为饰瓷脱瓷,而且在干燥环境下的样品抗弯强度比在湿润环境下平均要高70%。结论:口腔内氧化锆全瓷修复材料长期使用后出现性能下降的疲劳现象,与牙科陶瓷修复体处于充满唾液的水环境有关。     

口腔修复材料对牙本质的磨损性能的研究

目的:研究牙色材料与天然牙本质之间磨损性能的匹配情况.方法:以牙本质为研究对象,以实验组高度抛光的聚合瓷、玻璃陶瓷、氧化锆为摩擦剂,模拟口腔环境,利用微摩擦磨损实验机,研究牙本质与不同材料之间的摩擦磨损性能.采用扫描电镜观察表面形貌,粗糙度仪测粗糙度,维氏硬度仪测表面硬度,电子天平测磨损量.结果:牙本质与3种材料粗糙度近似(P＞0.05),硬度小于3种材料(P＜0.05).牙本质与3种材料分别对磨后材料的磨损量大于牙本质对照组的磨损量(P＜0.05),牙尖牙本质的磨损量与3种材料及牙本质的硬度值呈显著正相关关系(r =0.840).其中聚合瓷组的牙本质磨损量与对照组最接近.结论:不同材料对牙本质均会造成不同程度的磨损,聚合瓷具有与牙本质相近的耐磨性能.     

两种不同氧化钇含量的牙科氧化锆瓷与牙釉质的摩擦磨损性能

目的：通过体外模拟实验考察两种不同氧化钇含量的牙科氧化锆瓷与天然牙釉质的摩擦磨损性能。方法：选择两种不同氧化钇含量的牙科氧化锆瓷UpceraST（3mo1％Y2O3-ZrO2）与Upcera TT（3mo1％Y20-ZrO2＋8mo1％Y2O3-ZrO2）在微摩擦磨损试验机上,人工唾液润滑下与天然牙釉质进行摩擦磨损实验。两种氧化锆瓷表面分别采用抛光和打磨处理。用激光共聚焦显微镜测量牙釉质磨斑宽度,扫描电子显微镜观察氧化锆瓷及牙釉质磨斑微观形貌。采用配对t检验进行统计学分析。结果：牙釉质与氧化钇含量相对较低的UpceraST对磨的磨斑宽度：抛光组474．2±18．0μm,打磨组581．5±32．7Win;牙釉质与氧化钇含量相对较高的UpceraTT对磨的磨斑宽度：抛光组476．8±33．7μm,打磨组591．3±55．7μm。不同氧化钇含量的氧化锆瓷采用相同的表面处理方式对牙釉质的磨耗无统计学差异（P〉0．05）。牙釉质磨斑宽度在不同表面处理组间差异有统计学意义（P〈0．01）：牙釉质与抛光氧化锆瓷对磨的磨斑宽度值小于打磨组。结论：两种不同氧化钇含量的氧化锆瓷摩擦磨损性能相似;氧化锆瓷表面抛光可避免牙釉质过度磨损。与抛光氧化锆瓷对磨,牙釉质的磨损类型主要是疲劳磨损;与打磨氧化锆瓷对磨,牙釉质的磨损类型主要是磨粒磨损。提示临床在对充填体或修复体调磨后应进行抛光处理,以避免造成对颌天然牙的过度磨损。     

二硅酸锂玻璃陶瓷与牛牙釉质磨损性能的体外实验研究

目的:研究模拟口腔环境下牛牙釉质与二硅酸锂玻璃陶瓷的磨损特性.方法:将18个长8 mm、直径3 mm的二硅酸锂玻璃陶瓷圆柱作为上颌磨头,分别与下颌二硅酸锂玻璃陶瓷或牛牙釉质试件配副,每组9个样本,利用摩擦磨损试验机,在人工唾液、室温环境、10 N载荷、转速100 r/min、回转半径2.5 mm、匀速圆周运动的条件下进行54万次循环磨损实验.在整个磨损周期中选取10个循环节点,用三维形貌仪测量每个节点下颌试件的磨损高度损失量并绘制相应磨损曲线,扫描电镜观察相应磨损阶段对应的磨损面微观形貌.结果:各循环节点牛牙釉质的磨损量均大于二硅酸锂玻璃陶瓷的磨损量(P＜0.05);实验循环周期内,牛牙釉质的磨损曲线呈现出“跑合期”、“稳定磨损期”、“剧烈磨损期”3个磨损阶段,而二硅酸锂玻璃陶瓷的磨损曲线呈现“跑合期”和“稳定磨损期”两个磨损阶段.2组的微观形貌也呈现出与磨损曲线相对应的阶段性动态衍化规律.结论:在模拟口腔环境下,牛牙釉质和二硅酸锂玻璃陶瓷的磨损行为均呈现出阶段性动态衍化规律;牛牙釉质的磨损量显著高于二硅酸锂的磨损量,提示应注意防止二硅酸锂玻璃陶瓷修复体对对颌天然牙的过度磨损.     

二氧化锆与钴铬合金修复体精细抛光后对天然牙磨耗的影响

［摘要］ 目的 研究临床上精细抛光对二氧化锆及钴铬合金修复体材料与天然牙间磨耗的影响。方法 使用表面粗糙度仪测量修复体材料抛光前后的粗糙度值（Ra）。在摩擦磨损测试机上,模拟口腔内的力学和化学环境,进行天然牙与不同处理的修复体材料间的摩擦磨损实验,测量两者间摩擦系数（μ）。测量实验前后各磨擦对象的自身质量损失（Δm）,扫描电镜观察实验后天然牙表面。结果 各实验组中表面Ra,不烧结饰瓷抛光组（0.933±0.186）μm小于不抛光组（2.350±0.327）μm（P=0.000）;烧结饰瓷组抛光组（2.300±0.189）μm小于不抛光组（4.200±0.871）μm（P=0.000）;钴铬合金抛光组（0.250±0.083）μm小于不抛光组（1.200±0.894）μm（P=0.000）,有统计学意义。对磨天然牙自身质量损失量（Δm）,不烧结饰瓷抛光组（6.067±0.921）mg小于不抛光组（16.690±2.113）mg（P=0.001）;烧结饰瓷抛光组（5.893±0.838）mg小于不抛光组（14.016±0.063）mg（P=0.000）;钴铬合金抛光组（4.573±1.954）mg小于不抛光组（11.433±1.087）mg（P=0.008）有统计学意义。各组修复材料自身质量损失量（Δm）不烧结饰瓷抛光组（0.300±0.010）mg小于不抛光组（0.800±0.010）mg（P=0.001）;烧结饰瓷抛光组（0.456±0.055）mg小于不抛光组（0.650±0.086）mg（P=0.031）;钴铬合金抛光组（10.236±0.357）mg小于不抛光组（14.300±0.526）mg（P=0.000）有统计学意义。抛光组的摩擦系数：不烧结饰瓷氧化锆0.068,烧结饰瓷热氧化锆0.095,钴铬合金0.063明显小于不抛光组不烧结饰瓷二氧化锆0.096,烧结饰瓷二氧化锆0.119,钴铬合金0.103,差异有统计学意义。结论 修复体表面精细抛光,可以有效降低其表面粗糙度,减小其与牙釉质间的摩擦系数,避免天然牙的过度磨耗。     

钛修复体的口腔生物摩擦学特性研究

目的　探讨牙用钛金属与天然牙的生物摩擦学特性 ,供临床应用参考。方法　在改进后的高精度自控微动实验台上 ,对牙用钛金属TA2与天然牙组成的摩擦副进行人工唾液润滑工况下的摩擦磨损实验。采用计算机控制、动态跟踪实验 ,显微硬度仪、轮廓仪、光镜、激光共聚焦显微镜、扫描电镜与X线衍射能谱仪等测试手段综合分析研究。结果　天然牙的动态摩擦系数为一长“S”形曲线 ;钛对天然牙的磨损过程表现为牙体组织的微切削和组织变性 ;磨损量 :纯钛 /天然牙为 (2 0 33±2 86 ) μm ,纯钛 /纯钛为 (38 0 0± 5 88) μm ,二者间的差异有显著性 (P <0 0 5 )。 结论　天然牙摩擦学性能优良 ,与纯钛的耐磨性匹配 ;咀嚼过程中 ,应该避免较大的咬合力和口腔副功能 ;选择牙科材料时 ,应考虑到材料的耐磨性     

Wear evaluation of the human enamel opposing different Y-TZP dental ceramics and other porcelains

PurposeThis study examined the wear resistance of human enamel and feldspathic porcelain after simulated mastication against 3 zirconia ceramics, heat-pressed ceramic and conventional feldspathic porcelain.Materials and methodsHuman teeth and feldspathic porcelain cusp were tested against ceramic discs. 5 brands were tested – 3 monolithic zirconia, Prettau, Lava, and Rainbow, one lithium disilicate, IPS e.max Press, and one feldspathic porcelain, Vita-Omega 900. The surface was polished using a 600 grit and 1200 grit SiC paper. Each group was loaded for 300,000 cycles in a chewing simulator. The wear resistance was analyzed by measuring the volume of substance lost. The wear surfaces were observed by scanning electron microscopy to determine the wear characteristics.ResultsVita-Omega 900 led to the greatest amount of enamel wears followed by IPS e.max Press, Prettau, Lava and Rainbow. There was a significant difference between Vita-Omega 900 and IPS e.max Press (p < 0.05). The wear values for human enamel were significantly greater than those for feldspathic porcelain, regardless of the surface roughness of the ceramic specimens (p < 0.05).ConclusionThe wear behaviour of human enamel and feldspathic porcelain varies according to the type of substrate materials. On the other hand, 3 zirconia ceramics caused less wear in the abrader than the conventional ceramic.Clinical significanceDental professionals should be aware of the wear effect of dental restorations on the opposing teeth or restorations. The amount of enamel wear was highest in feldspathic porcelains whereas zirconia ceramics caused less wear on the opposing teeth.     

树脂牙与天然牙釉质摩擦磨损性能的研究

目的：研究两种常用树脂牙摩擦磨损性能及与牙釉质摩擦磨损性能的匹配情况。方法：采用销盘式摩擦磨损试验机,通过体外模拟口腔环境,对牙釉质、松风牙,拜耳牙进行摩擦磨损试验,记录动态摩擦系数,采用电子扫描电镜观察表面磨损形貌,电子天平得出磨损量。结果：三者摩擦系数变化趋势相似,牙釉质稳态摩擦系数为0.90～1.00,松风牙为0.38,拜耳牙为0.47。磨损体积量：牙釉质〈松风牙〈拜耳牙（P〈0.05）,而对磨物滑石瓷体积磨损量：拜耳牙〈松风牙〈牙釉质（P〈0.05）。树脂牙的磨损机制主要为磨粒磨损,牙釉质磨损机制主要为疲劳磨损。结论：两种树脂牙稳态摩擦系数显著低于牙釉质,耐磨性弱于牙釉质,松风牙耐磨性大于拜耳牙。     

In vitro wear of four ceramic materials and human enamel on enamel antagonist

The purpose of the present study was to evaluate the wear of four different ceramics and human enamel. The ceramics used were lithium disilicate glass (e.max Press), leucite‐reinforced glass (GN‐Ceram), yttria‐stabilized zirconia (Aadva Zr), and feldspathic porcelain (Porcelain AAA). Hemispherical styli were fabricated with these ceramics and with tooth enamel. Flattened enamel was used for antagonistic specimens. After 100,000 wear cycles of a two‐body wear test, the height and volume losses of the styli and enamel antagonists were determined. The mean and standard deviation for eight specimens were calculated and statistically analyzed using a non‐parametric (Steel–Dwass) test (α = 0.05). GN‐Ceram exhibited greater stylus height and volume losses than did Porcelain AAA. E.max Press, Porcelain AAA, and enamel styli showed no significant differences, and Aadva Zr exhibited the smallest stylus height and volume losses. The wear of the enamel antagonist was not significantly different among GN‐Ceram, e.max Press, Porcelain AAA, and enamel styli. Aadva Zr resulted in significantly lower wear values of the enamel antagonist than did GN‐Ceram, Porcelain AAA, and enamel styli. In conclusion, leucite‐reinforced glass, lithium disilicate glass, and feldspathic porcelain showed wear values closer to those for human enamel than did yttria‐stabilized zirconia.     

Fatigue of dental ceramics in a simulated oral environment

Fatigue in ceramics refers to the subcritical growth of cracks, aided by the combined influence of water and stress. The dynamic fatigue (constant stressing rate) method was used to obtain subcritical crack growth parameters for three dental ceramics: a feldspathic porcelain, an aluminous porcelain, and a fine-grain, polycrystalline core material. The constant stressing rate experiments were carried out at 37 degrees C for all three ceramics in distilled water, and, for the feldspathic porcelain, in artificial saliva as well. Considerable differences were found in the value of the crack growth exponent (n) among the three ceramics. The feldspathic porcelain was lowest in n-value, while the fine-grain ceramic had the highest n-value. No differences were found for the feldspathic porcelain with respect to n measured in water and in the artificial saliva. Lifetime prediction curves in 37 degrees C water, constructed from the n-values and inert strengths, showed that fatigue failure within five years is a good possibility for feldspathic porcelain specimens at stress levels which can reasonably be anticipated to occur in the oral environment. Little likelihood of failure was perceived for the fine-grain ceramic. The aluminous porcelain was intermediate between these two materials with respect to failure probability.     

超滑结扎橡皮圈和常规结扎橡皮圈对摩擦力影响的对比研究

目的：探讨和比较超滑结扎橡皮圈和常规结扎橡皮圈在干燥和自然唾液条件下对摩擦力的影响。方法：选用超滑结扎橡皮圈和常规结扎橡皮圈、2种弓丝（0．019×0．025英寸方丝,0．018英寸圆丝）、MBT^TM直丝托槽组,模拟弓丝在后牙段在干燥和自然唾液条件下滑动,测量各组合的静、动摩擦力。结果：在于燥的条件下,无论在方丝组合还是圆丝组合,2种结扎橡皮圈静动摩擦力都无显著性差异。超滑结扎橡皮圈在自然唾液1h的条件下,与常规结扎橡皮圈结扎相比,在方丝组合,静摩擦力降低31.18％,动摩擦力降低21．66％;在圆丝组合,静摩擦力降低31．98％,动摩擦力降低28．67％。结论：超滑结扎橡皮圈在干燥条件下对静动摩擦力无显著影响。在自然唾液浸润1h的条件下,无论在方丝组合还是圆丝组合,超滑结扎橡皮圈能起到降低静动摩擦力的作用。     

Creep functions of dental ceramics measured in a beam-bending viscometer.

OBJECTIVE: To characterize the high temperature viscoelastic properties of several dental ceramics by the determination of creep functions based on mid-span deflections measured in a beam-bending viscometer (BBV). METHODS: Six groups of beam specimens (58 x 5.5 x 2.5 mm) were made from the following materials: (1) IPS Empress2 body--a glass veneer ceramic (E2V); (2) an experimental glass veneer (EXV); (3) Vita VMK 68 feldspathic body porcelain--a low-expansion body porcelain (VB); (4) Will-Ceram feldspathic body porcelain--a high-expansion body porcelain (WCB); (5) Vita feldspathic opaque porcelain--a medium-expansion opaque porcelain (VO); and (6) Will-Ceram feldspathic opaque porcelain--a high-expansion opaque porcelain (WCO). Midpoint deflections for each specimen were measured in a BBV under isothermal conditions at furnace temperatures ranging from 450 to 675 degrees C. Non-linear regression and linear regression analyses were used to determine creep functions and shear viscosities, respectively, for each material at each temperature. RESULTS: The shear viscosities of each group of dental ceramics exhibited bilinear Arrhenius behavior with the slope ratios (x) ranging from 0.19 for WCB to 0.71 for EXV. At the higher temperature ranges, activation energies ranged from 363 kJ/mol for VO to 386 kJ/mol for E2V. SIGNIFICANCE: The viscoelastic properties of dental ceramics at high temperatures are important factors in understanding how residual stresses develop in all-ceramic and metal-ceramic dental restorations.     

Contrast ratio of veneering and core ceramics as a function of thickness

PURPOSE: The recent development of several dental ceramic products has raised questions concerning the relative translucency potential of these materials. The objective of this study was to test the hypothesis that the contrast ratio of dental core and veneering ceramics is a linear function of ceramic thickness. MATERIALS AND METHODS: Four groups of disk-shaped core ceramic specimens and four groups of veneering ceramic specimens (15 mm in diameter and 0.70, 1.10, 1.25, or 1.50 mm in thickness) were prepared for analysis. Five disks were randomly assigned to each of the eight groups. Four core ceramics were selected for study: (1) tetrasilicic fluormica glass ceramic, (2) quadruple-chain silicate glass ceramic, (3) barium silicate glass ceramic, and (4) sintered alumina. The four veneering ceramics included two feldspathic body porcelains, one fine-grained veneering porcelain, and one ultralow-fusing porcelain. RESULTS: There were significant differences among the mean contrast ratio values of these materials. The most translucent group of the core materials was tetrasilicic fluormica glass ceramic, and the least translucent material was sintered alumina. The most translucent group among the veneering ceramics was one of the feldspathic ceramics (Ceramco), and the least translucent material for all thicknesses was the ultralow-fusing veneering ceramic (Duceram LFC). The mean contrast ratio values were significantly different at a thickness of 1.50 mm of the four core ceramic groups and among the four veneering ceramic groups. CONCLUSION: The results of this study indicate that the tetrasilicic fluormica glass ceramic is generally the most translucent core ceramic for thicknesses of 0.70, 1.10, and 1.25 mm, and Ceramco porcelain is the most translucent veneering ceramic. However, for a thickness of 1.50 mm, the quadruple-chain silicate glass ceramic was the most translucent core ceramic. The relationship between contrast ratio and thickness was linear for all ceramics except Vita VMK 68.