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.     

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,往复幅度(D)500μm,往复频率(F)2 Hz,循环次数(N)10000次.通过白光干涉三维形貌仪获得磨损深度,通过扫描电子显微镜观察磨斑形貌和损伤特征,分析磨损机制及耐磨损性.结果 4种玻璃陶瓷的平均摩擦系数在酸性环境下最低,在中性环境下和碱性环境下差异无统计学意义.不同pH环境下4种玻璃陶瓷的最大磨损深度VM最大,其次是EC,VS和EX.结论 在不同pH环境下,EX最耐磨,VM最不耐磨,该研究可为临床选择修复材料提供参考.     

氧化磷含量对新型牙科玻璃陶瓷微观结构和强度的影响

目的：分析不同氧化磷含量对新型牙科二硅酸锂玻璃陶瓷微观结构和强度的影响。方法：通过调控Li2O、SiO2、K2O、Al2O3、ZrO2-P2O5玻璃系统中氧化磷（P2O5）的含量（0.5%,1.0%,1.5%和2.0%）,并进行相应的热处理,应用X射线衍射技术（XRD）,电子扫描显微术（SEM）分析制备的各组玻璃陶瓷的微观形貌,根据ISO6872标准测试玻璃陶瓷的弯曲强度,进行统计学分析。结果：各组玻璃陶瓷样本的主晶相均为二硅酸锂（Li2Si2O5）,随着P2O5含量的改变,析出晶体的形貌和分布有显著不同。1.0%组玻璃陶瓷具有最高的弯曲强度值。结论：通过调控P2O5含量,可制备具有高强度和适宜微观形貌的二硅酸锂玻璃陶瓷。     

三种二硅酸锂玻璃陶瓷冠抗折强度研究

目的    通过抗折破坏实验分析3种牙科二硅酸锂玻璃陶瓷抗折强度的差异,为国产二硅酸锂玻璃陶瓷临床应用提供依据。方法    将30个下颌第一磨牙标准预备体代型随机分为3组,每组10个,分别制作国产二硅酸锂玻璃陶瓷冠试件（DID组）、IPS e.max CAD冠试件（IPC组）和IPS e.max Press冠试件（IPP组）。3组全瓷冠试件粘接后,分别放置于电子万能试验机上,用直径6 mm圆形加载头,以0.5 mm/min速度垂直加载于全瓷冠面中央至瓷层碎裂,记录最大载荷,即二硅酸锂玻璃陶瓷冠抗折强度。用扫描电镜（SEM）观察表面形态。采用SPSS21.0 统计软件对3组全瓷冠试件抗折强度值进行单因素方差分析和组间两两比较的q检验,检验水准取双侧α = 0.05。结果    3组全瓷冠试件抗折强度结果：DID组为（949.7 ± 119. 4）N,IPC组为（1746.9 ± 244.8）N,IPP组为（2161.8 ± 239.0）N 。3组间总的比较,差异有统计学意义（F = 86.685,P < 0.05）;各组间两两比较,差异亦均有统计学意义（均P < 0.05）。3组全瓷冠试件的断裂模式无显著差异,大部分试件断裂类型均为Ⅰ型。SEM观察,DID组可见晶体在样本中分布不均匀,大小不一,表面有细小裂隙;IPC组可见析出晶体在样本中分布较均匀,晶体较为长大;IPP组可见析出的棒状二硅酸锂晶体均匀分布于玻璃相中,互相嵌合,并形成一种互锁微结构。结论    研究条件下,不同二硅酸锂玻璃陶瓷对抗折强度及断裂类型均有影响,国产二硅酸锂玻璃陶瓷可以满足临床要求,对于其在临床应用有一定指导意义。     

一种新型牙科二硅酸锂玻璃陶瓷的微观结构分析

目的:分析牙科二硅酸锂玻璃陶瓷的微观结构,探讨其可能的自增韧机制。方法:使用X射线衍射仪分析一种新型二硅酸锂玻璃陶瓷及IPS e.max Press LT和MO瓷块的物相组成,并使用扫描电镜观察其表面特征和裂纹扩展方式。结果:3种玻璃陶瓷的主晶相均为Li2Si2O5,次晶相均为Li2SiO3和Li3PO4。Li2Si2O5晶体均呈棒状,交错排列,形成互锁微结构。新型玻璃陶瓷的晶体尺寸大于LT和MO瓷块,其表面孔隙缺陷较后两者少而深。裂纹在这3种玻璃陶瓷中主要沿着晶体间较薄弱的玻璃相扩展。结论:新型玻璃陶瓷与IPS e.max Press LT和MO瓷块的微观结构相似,长棒状的Li2Si2O5晶体所形成的互锁微结构,以及内部的残余应力可对其起到增强增韧的作用。     

IPS Empress 2研究新进展

IPS Empress 2是最近推出的一种新型二硅酸锂增强热压铸入玻璃陶瓷。与白榴石增强玻璃陶瓷IPS Empress相比,机械强度提高了3倍,同时具有透光性好、耐磨性与牙釉质相近、边缘适合性好等优点,临床上可进行各类嵌体、贴面、冠以及三单位固定桥的修复,是一种很有应用前景的陶瓷材料。     

氢氟酸处理对二硅酸锂玻璃陶瓷表面形貌及粗糙度的影响

目的 探讨氢氟酸处理时间对二硅酸锂玻璃陶瓷表面形貌及粗糙度的影响,拟为与之相关的玻璃陶瓷机械强度和树脂粘接强度做出初步解释.方法 采用失蜡铸造法制作直径10 mm、厚1 mm的玻璃陶瓷片状试件15个,打磨抛光之后随机分为5组,每组3个.陶瓷表面分别接受9.5％的氢氟酸凝胶酸蚀处理0、20、40、60和120 s.使用原子力显微镜(AFM)测量表面粗糙度参数和酸蚀深度,观测其表面三维形貌,并结合使用场发射扫描电子显微镜(FE-SEM)对陶瓷表面微观结构进行观察分析.结果 FE-SEM观察显示,陶瓷表面的玻璃基质首先被氢氟酸侵蚀溶解,随着酸蚀时间的延长,玻璃基质进一步被侵蚀,部分晶体结构也从陶瓷表面脱落、消失.AFM测量酸蚀表面得出,对照组、20、40、60和120 s氢氟酸处理组陶瓷片表面粗糙度Ra[分别为(17.2±1.6)、(241.8±23.6)、(290.6±38.2)、(322.6±19.6)和(371.3 ± 43.0) nm]随氢氟酸酸蚀时间的延长而显著增加(P＜0.05),且与酸蚀时间成正相关.结论 氢氟酸处理可显著增加二硅酸锂陶瓷表面粗糙度.结合使用FE-SEM和AFM能够更好地对玻璃陶瓷的酸蚀表面微观形貌结构进行分析评价.     

酸蚀对可切削陶瓷表面及内部微观结构影响的研究

目的探讨酸蚀是否对可切削陶瓷的表面形貌、内部微观结构产生影响。方法制备大小为4 mm×4 mm×2 mm的树脂渗透陶瓷、二硅酸锂玻璃陶瓷试件各32个,经打磨、清洗后,随机分为4组(n=8):①4%氢氟酸;②9.5%氢氟酸;③MBEP;对照组。原子力显微镜测量试件的表面粗糙度及三维形貌,X射线能谱仪对树脂渗透陶瓷的元素Si/C、二硅酸锂玻璃陶瓷的元素Si/K比率进行检测。结果两种材料的氢氟酸处理组表面粗糙度参数值均高于对照组。树脂渗透陶瓷的氢氟酸处理组元素Si/C比率均低于对照组。SEM显示两种材料9.5%氢氟酸处理组均有更具侵蚀性的表面酸蚀图案,MBEP组产生与对照组相似的表面蚀刻图案。结论酸蚀对两种可切削陶瓷的表面形貌、内部微观结构产生影响。MBEP有较为温和的酸蚀能力。     

一种通用粘接剂对不同CAD/CAM可切削材料的短期粘接成绩

[摘要] 目的 评估一种通用粘接剂对于三种不同类型的CAD/CAM可切削材料的短期粘接成绩。方法 制作氧化钇稳定四方相氧化锆陶瓷,纳米复合陶瓷和二硅酸锂玻璃陶瓷试件各20枚,其中前两者进行喷砂处理,后者进行HF酸蚀处理。各组陶瓷再分为2亚组,分别使用（SBU）或不使用（Ctr）通用粘接剂Single Bond Universal。以上表面处理瓷片与复合树脂柱通过树脂水门汀粘接,制作粘接试件,37℃水储24ｈ后测试剪切粘接强度并记录断裂模式。喷砂处理的氧化锆陶瓷和纳米复合陶瓷,以及酸蚀处理的二硅酸锂玻璃陶瓷通过扫描电镜（SEM）观察表面微观形态。结果SEM观察显示酸蚀处理的二硅酸锂玻璃陶瓷,喷砂处理的氧化锆陶瓷和纳米复合陶瓷相对于粗化处理前呈现出粗糙的表面形态。三种经粗化处理的材料使用通用粘接剂表面处理后,剪切强度较未使用者显著增强。结论 通用粘接剂Single Bond Universal能够增强氧化钇稳定四方相氧化锆陶瓷,纳米复合陶瓷和二硅酸锂玻璃陶瓷三种类型CAD/CAM可切削材料的短期粘接强度。     

氟磷灰石玻璃陶瓷、长石质饰瓷与天然牙摩擦磨损性能的研究

目的：研究牙科氟磷灰石玻璃陶瓷、长石质饰瓷与天然牙在干摩擦和唾液润滑条件下的摩擦磨损学性能。方法：制备涂覆IPS-emaxcream和Vita vm9 2种饰面瓷的氧化锆-饰面瓷双层材料试样,尺寸为20 mm×20 mm×4.5 mm,各20个。利用MMV-1摩擦磨损试验机,通过设置不同大小的垂直载荷和转速,分别在干摩擦和唾液润滑条件下,对2种氧化锆-饰面瓷试样进行摩擦磨损试验。采用SPSS 17.0软件包进行单因素方差分析和t检验,确定各组间摩擦系数和磨损量是否存在差异。结果：氟磷灰石玻璃陶瓷在唾液润滑条件下的动态摩擦系数和磨损量显著大于干摩擦条件下的数值;与氟磷灰石玻璃陶瓷相反,长石质饰瓷在干摩擦时的动态摩擦系数和磨损量显著大于在唾液润滑条件下的数值。在干摩擦和唾液润滑条件下,氟磷灰石玻璃陶瓷的磨损量均小于长石质饰瓷。扫描电镜显示,在唾液润滑条件下,氟磷灰石玻璃陶瓷及对应天然牙表现出比干摩擦更为严重的磨损表面。在干摩擦条件下,长石质饰瓷及对应天然牙较氟磷灰石玻璃陶瓷磨损更为严重,在唾液润滑条件下差异较小。结论：与长石质饰瓷相比,氟磷灰石玻璃陶瓷与天然牙在干摩擦条件下表现出更优越的耐磨损性能。加入唾液后,能减少2种饰瓷摩擦磨损性能之间的差异。     

The cast glass-ceramic restoration

The use of Dicor cast glass-ceramic material for fixed prosthodontic complete crowns has been described. The advantages of this material are chemical and physical uniformity, marginal accuracy, uncomplicated fabrication from wax-up to casting, ceramming, and coloring, ease of adjustment, excellent esthetics resulting from natural translucency, light absorption, light refraction, and natural color for the crown, and its inherent resistance to bacterial plaque.     

Fracture resistance of pressable glass-ceramic fixed partial dentures

The aim of the present study was to evaluate the mechanical strength of the Empress2 system, which is based on the use of a high-strength glass--ceramic core of lithium disilicate, and the fracture resistance of fixed partial dentures fabricated with this material. To evaluate mechanical strength, four types of ceramic materials were tested for four-point flexural strength and diametral tensile strength: Empress2 core material, Empress2 layering porcelain, conventional Empress material and Dicor. Then, using Empress2, conventional Empress and Dicor, actual clinical type anterior fixed partial dentures were fabricated for fracture testing. The results showed that the Empress2 core material, at 329 MPa, has more than twice the flexural strength of conventional materials and at 271 MPa, more than four times the diametral tensile strength of conventional materials. Furthermore, fixed partial dentures fabricated with Empress2 had a fracture resistance of 1424 N. That is, they were more than twice as fracture resistant as fixed partial dentures made with conventional materials.     

超韧牙科氟金云母玻璃陶瓷的可加工性能初探

目的 分析不同晶化温度和晶化时间对一种氟金云母玻璃陶瓷加工性能的影响,探讨其延性切削行为的机制.方法 使用SiO2-B2O3-R:O-Al2O3-ZnO-MgO-F(R为碱金属)玻璃陶瓷粉制备晶化温度和晶化时间分别为650 ℃(60 min)、680 ℃(60 min)、710 ℃(60 min)、740 ℃(60 min)、680 ℃(30 min)、680 ℃(120 min)、680 ℃(240 min)的试件,分为A、B、C、D、E、F、G组,每组6个;长石质可切削陶瓷试件作为对照组.测定8组试件钻孔30 s后的钻孔深度,并进行车床切削实验定性分析.扫描电镜和X射线衍射分析观察试件的微观结构.结果 A组钻孔深度最大,为(7.1±0.8)mm;D组最小,为(0.5±0.1)mm.除D组外,其余组钻孔深度均大于对照组[(0.8±0.1)mm],差异均有统计学意义(P＜0.05).A组试件可在普通车床高速车削条件下形成连续带状切屑,其晶体相含量约为40%.结论 这种云母玻璃陶瓷具有良好的可加工性,其机制可能与云母晶体的互锁结构和玻璃相黏滞流动作用相关.     

A novel bioactive glass-ceramic for treating dentin hypersensitivity

Dentin hypersensitivity (DH) is a painful response to stimulus applied to the open dentinal tubules of a vital tooth. It's a common oral condition, however, without an ideal treatment available yet. This work evaluated in vitro the effect of micron-sized particles from a novel bioactive glass-ceramic (Biosilicate) in occluding open dentinal tubules. A dentin disc model was employed to observe comparatively, using scanning electron microscopy (SEM), dentinal tubule occlusion by different products and deposition of hydroxyl carbonate apatite (HCA) on dentin surface by Biosilicate, after a single application: G1 - Dentifrice with potassium nitrate and fluoride; G2 - Two-step calcium phosphate precipitation treatment; G3 - Water-free gel containing Biosilicate particles (1%); G4 - Biosilicate particles mixed with distilled water in a 1:10 ratio; all of them after 1, 12 and 24 hours of immersion in artificial saliva. Fourier transform infrared spectroscopy (FTIR) was performed to detect HCA formation on dentin discs filled with Biosilicate after 2 minutes, 30 minutes and 12 hours of immersion in artificial saliva. SEM showed a layer of HCA formed on dentin surface after 24 hours by G4. G1, G2 and G3 promoted not total occlusion of open dentinal tubules after 24 hours. FTIR showed HCA precipitation on the dentin surface induced by Biosilicate after 30 minutes. The micron-sized particles from the bioactive glass-ceramic thus were able to induce HCA deposition in open dentinal tubules in vitro. This finding suggests that Biosilicate may provide a new option for treating DH.     

两种多孔生物玻璃支架材料的体外细胞相容性研究

目的 对比研究采用同样原料但以不同方法制备的两种多孔生物玻璃支架材料的体外细胞相容性。方法 溶胶－凝胶法制备A/W生物活性微晶玻璃（4006材料）,熔融法制备多孔生物活性玻璃（45S5材料）。体外诱导分离培养及鉴定兔骨髓基质细胞（BMSCs）,通过材料浸提液细胞毒性实验（MTT法）、细胞黏附实验、倒置相差显微镜、扫描电镜和环境扫描电镜比较4006材料和45S5材料对BMSCs细胞黏附和生长的影响,并探索与材料复合的最佳BMSCs细胞悬液浓度。结果 4006材料浸提液培养1 d时,其细胞活力与纯培养液间无统计学差异（P>0.05）;但培养3 d后,其细胞活力低于纯培养液（P<0.01）。45S5材料浸提液培养的细胞活力明显低于纯培养液（P<0.01）。细胞与材料复合培养后,镜下见BMSCs在4006材料孔隙内贴壁生长良好,分泌基质活跃;而在45S5材料上细胞黏附生长较差。BMSCs与4006材料的黏附量随接种细胞浓度升高而升高,细胞悬液浓度为2×10⁷个•mL^-1时的细胞黏附量最高。结论 溶胶－凝胶法制备的A/W生物活性微晶玻璃具有良好的生物活性和细胞相容性,具有作为骨组织工程支架材料的潜能。与其复合的细胞悬液浓度需要2×107 个•mL-1或以上。     

Long-term clinical results of galvano-ceramic and glass-ceramic individual crowns

STATEMENT OF PROBLEM: Alternatives to metal-ceramic restorations should possess clinical durability before being recommended to the dentist. Longitudinal clinical studies are required for evaluation so innovative types of restorations can meet the expectations of dentists and patients. PURPOSE: This study compared the performance of galvano-ceramic restorations (Auvo Galvano Crown [ACG]) and glass-ceramic individual crowns (Dicor) based on longitudinal clinical trials. MATERIAL AND METHODS: A total of 769 galvano-ceramic single crowns (AGC) in 322 patients and 173 glass-ceramic individual crowns (Dicor) in 88 patients were reviewed for 8 years and a maximum of 11 years, respectively, after cementation. Risk of fracture was determined with use of a survival analysis (Kaplan and Meier). RESULTS: Partial ceramic cracking was observed at the time of the last recording of data in 11 galvano-ceramic crowns, 8 of the units remained in place. Two crowns became dislodged and 1 tooth exhibited a fractured root, despite an intact crown. One restoration was removed because of hypersensitivity and 1 with partial ceramic fracture. Forty-two of the glass-ceramic crowns were completely fractured. After a comparable 7 years under risk, 96.5% (+/-3.4; 95% confidence interval) of the galvano-ceramic premolar and molar crowns and 92% (+/- 8.5) of crowns placed on incisors and canines crowns were intact. The corresponding data for the glass-ceramic restorations were only 70% (+/- 10.6) in posterior and 82.7% (+/- 8. 1) in anterior quadrants. CONCLUSION: Long-term results of electroformed individual crown restorations were superior to glass-ceramic restorations.     

Microleakage of resin composite restorations with glass-ceramic inserts.

OBJECTIVE: The purpose of this study was to evaluate the effects of glass-ceramic inserts and different application techniques of resin composites on marginal leakage. METHOD AND MATERIALS: Three groups of 10 standardized, round, Class V cavities were prepared on the buccal surface of 30 extracted human molar teeth. Group 1 received resin composite restorations, placed in one increment (bulk). Group 2 received resin composite restorations that were placed in two increments, and group 3 received resin composite restorations with beta-quartz ceramic inserts. After the teeth were thermocycled and placed in 0.5% basic fuchsin for 24 hours, they were sectioned and examined for microleakage. RESULTS: On the occlusal margins, there was no statistically significant difference between the restorations placed with the incremental technique and the restorations with beta-quartz inserts. The restorations placed with the bulk technique had significantly more microleakage than did the others. On the gingival margins, the restorations with beta-quartz inserts exhibited significantly less microleakage than did the other groups. The restorations placed with the bulk technique showed significantly more dye penetration than did the others. CONCLUSION: The use of a glass-ceramic insert reduced the marginal leakage of Class V resin composite restorations.     

Evaluation of the Accuracy of Solid Implant Casts

Purpose Materials used to fabricate the most dimensionally accurate implant casts have not been identified experimentally. The purpose of this investigation was to examine the dimensional accuracy of implant casts fabricated with different materials. Measurements of linear horizontal dimensional change and strain produced on a master framework were evaluated and correlated. Materials and Methods A master framework was fabricated to fit an aluminum five-implant model. Forty polyether implant impressions of the aluminum model were randomly grouped and poured in either Vel-mix, Die Keen, Resin Rock, or Low Fusing Alloy. A digital veneer caliper was used to measure linear distance between the most distal abutments on each of the experimental implant casts and the master model. In addition, strain values were recorded from strain gauges bonded in the mesiodistal axis of the framework, which was secured by prosthetic retaining screws torqued to 10 Ncm. Results A one-way ANOVA showed a significant difference among the four die materials in dimensional change of the experimental casts (p= .0001). A post-hoc Duncan's multiple-range test (p < .05) showed that casts fabricated with Low Fusing Alloy had the least linear dimensional change from the master cast, but the material exhibited the greatest dimensional variability. A MANOVA (Wilks' Lambda) showed significant differences in strain on the framework based upon die material (p= .015). A post-hoc Duncan's multiple-range test (p < .05) showed that Resin Rock casts induced significantly less strain on the framework than the other materials. Negligible correlation was found between the linear horizontal dimensional change and the total absolute strain on the framework. Conclusion Experimental implant casts made of Resin Rock minimized strain on the master framework and decreased the amount of framework distortion on casts of this material. Low Fusing Alloy yielded accurate casts, but highly variable linear dimensional changes in the horizontal dimension may preclude its clinical benefit.