反复熔铸对金铂烤瓷合金力学性能影响的研究

目的 探讨反复熔铸对金铂烤瓷合金力学性能的影响。方法 金铂烤瓷合金经过单纯反复熔铸3次后,用拉伸实验对各代试件的拉伸强度、0.2%屈服强度、延伸率进行比较;用弯曲实验对各代试件的弯曲强度、弯曲模量进行比较;用硬度实验对各代试件的维氏硬度值进行比较。结果 经过不同熔铸次数的金铂烤瓷合金的拉伸强度、0.2%屈服强度、延伸率、弯曲强度及维氏硬度值差异均无统计学意义。Ⅱ代、Ⅲ代试件的弯曲模量与Ⅰ代相比,显著升高（P<0.05）。结论 金铂烤瓷合金至少可以反复熔铸3次而不引起力学性能的下降。     

反复熔铸对钴铬烤瓷合金力学性能影响的研究

目的 探讨反复熔铸对钴铬烤瓷合金力学性能的影响.方法 钴铬烤瓷合金经过单纯反复熔铸3次后,用拉伸实验对各代试件的拉伸强度、0.2%屈服强度、延伸率进行比较;用弯曲实验对各代试件的弯曲强度、弯曲模量进行比较;用硬度实验对各代试件的维氏硬度值进行比较.结果 经过不同熔铸次数的钴铬烤瓷合金的拉伸强度、0.2%屈服强度、延伸率...     

反复熔铸对纯钛烤瓷合金力学性能的影响

目的： 探讨反复熔铸对纯钛烤瓷合金力学性能的影响。方法：纯钛经过1~3次单纯反复熔铸后,采用拉伸实验、弯曲实验、硬度实验对各代试件的力学性能进行测试。采用SPSS13.0软件包对数据进行统计学分析。结果：经不同次数熔铸的纯钛烤瓷合金试件,其弯曲强度无显著差异。经过2次、3次熔铸的纯钛烤瓷合金试件,其弯曲模量较1次熔铸的纯钛烤瓷合金显著升高(P<0.05)。拉伸强度、0.2%屈服强度随着熔铸次数的增加而升高(P<0.05)。经过3次熔铸的纯钛烤瓷合金试件,其延伸率较经过1次、2次熔铸的纯钛烤瓷合金显著降低(P<0.05)。经过3次熔铸的纯钛烤瓷合金试件,其显微硬度较经过1次、2次熔铸的纯钛烤瓷合金显著升高(P<0.05)。结论：纯钛烤瓷合金经1~3次单纯反复熔铸后,弯曲性能、显微硬度未下降,但拉伸性能下降。     

反复熔铸对烤瓷合金热膨胀系数的影响

目的 研究反复熔铸对口腔常用烤瓷合金热膨胀系数的影响。方法 运用离心铸造方法,将常用的贵金属、钴铬、镍铬烤瓷合金分别经过1次、2次、3次熔铸后,将合金制成金属棒试件测试热膨胀系数。对测试结果进行统计学分析。结果 每种烤瓷合金经过1~3次熔铸后,每代之间的热膨胀系数值无统计学差异。结论 3种常用烤瓷合金在空气环境下经过1~3次熔铸后热膨胀系数值仍符合临床要求。     

反复熔铸对牙科烤瓷合金显微结构的影响

目的: 探讨反复熔铸对钴铬、纯钛、钯铜镓、金铂烤瓷合金显微结构的影响。方法: 在真空加氩气保护环境下,将4种烤瓷合金单纯反复熔铸1~3次。每次再熔铸前,烤瓷合金均经过课题组前期研究所得“烤瓷合金再熔铸前最佳处理方法”处理,根据金属显微组织检验方法（GB/T13298-2015）,分别对熔铸前、熔铸1~3次后的烤瓷合金进行研磨、抛光、浸蚀,采用金相显微镜或扫描电镜检测金相显微结构。结果: 随着熔铸次数增加,钴铬烤瓷合金晶粒粗化、晶粒间基质和晶界间化合物增多。纯钛烤瓷合金随熔铸次数增加,晶粒粗化明显。2次熔铸后,晶粒有等轴化倾向,3次熔铸则出现针刺状β相。钯铜镓烤瓷合金在2、3次熔铸后,晶粒结构略有长大。金铂烤瓷合金晶粒结构未随熔铸次数发生明显改变。结论: 反复熔铸显著改变钴铬、纯钛、钯铜镓烤瓷合金的显微结构,建议由厂家回收再利用烤瓷合金废旧料。     

反复熔铸对Ni-Cr烤瓷合金机械性能的影响

目的 :比较反复熔铸对Ni Cr烤瓷合金机械性能的影响。方法 :Ni Cr烤瓷合金经过熔铸 4次后 ,用拉伸实验对各代铸件的抗拉强度、屈服强度、延伸率等机械性能指标进行比较 ,并作金相和断口电镜观察。结果 :Ni Cr烤瓷合金反复熔铸 4次的抗拉强度、0 .2 %屈服强度无显著性差异 (P >0 .0 5 ) ,延伸率之间有显著性差异(P <0 .0 5 ) ;结构观察显示 ,随着熔铸次数的增加 ,铸件的树枝状晶粒明显减小 ,缩孔缩松数分布增多增广 ,有夹杂物产生 ,并且出现一些杂质富积区。结论 :Ni Cr烤瓷合金反复熔铸 4次后 ,在其机械性能方面能够满足烤瓷合金的基本要求     

真空充氩反复熔铸对烤瓷合金化学成分的影响

目的 研究真空加氩气环境中反复熔铸对4种常用非镍基烤瓷合金（钴铬、纯钛、钯基和金铂烤瓷合金）化学成分的影响。方法 真空加氩气保护环境下反复熔铸钴铬、纯钛、钯基和金铂烤瓷合金1~3次,每次再熔铸前对废旧合金均经过相应的再熔铸前处理,打磨抛光后,采用能谱仪检测4种烤瓷合金1~3次熔铸后的化学成分。结果 4种合金反复熔铸1~3次的化学成分含量变化均无统计学差异（P>0.05）。结论 真空加氩气环境中反复熔铸对钴铬、纯钛、钯基和金铂烤瓷合金的化学成分无明显影响。     

反复熔铸对镍铬烤瓷合金电化学腐蚀性能影响的研究

目的探讨反复熔铸对镍铬烤瓷合金在人工唾液中电化学腐蚀行为的影响。方法试样由镍铬烤瓷合金分别经过1、2、3、4及5次熔铸（即Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ代试样）后,再经铜导线焊接、聚甲基丙烯酸甲酯包埋、测试面氧化铝砂纸磨光和布轮抛光而成。试样浸泡于人工唾液中[温度为（37．0±1．0）℃,pH为7．4±0．1]24h后,参考ISO10271（2001）标准,采用动电位极化曲线法测试其抗腐蚀性能,并用扫描电镜观察合金腐蚀前后表面形貌的变化。结果各代试样间Ecorr、Ep、Rp、Icorr等电化学参数间差异无统计学意义（P〉0．05）;两两比较表明,Ⅱ代Ep大于Ⅰ代（P=0．023）,余差异无统计学意义;扫描电镜观察,极化扫描后试样表面产生腐蚀．但各代之间没有明显区别。结论镍铬烤瓷合金经反复熔铸5次后电化学腐蚀没有明显改变。     

贵金属烤瓷合金反复多次熔铸后金相学比较观察

目的：观察比较反复多次铸造 对贵金属烤瓷合金金相结构的影响。方法：应用倒置式金相显微镜观察Bio Herador N金烤瓷合金熔铸前、后及再反复熔铸3次后，各代铸件金相组织；侧重观察组织致密程度及铸造缺陷产生情况。结果：厂商产品之金相明显不同于铸态组织金相；从Ⅰ-Ⅳ代，随着反复熔铸次数增加，铸件铸态组织呈松散化趋势，表现在缩孔松数量分布逐代增多增广，至Ⅲ、Ⅳ代晶界逐渐模糊、消失，晶粒形态不清。结论：对BioHerador N合金而言，反复多次熔铸会使铸件铸态组织产生明显改变；提示废旧合金单纯重熔利用会导致铸件在性能方面将发生变化。     

反复熔铸对非贵金属烤瓷合金弯曲性能的影响

目的:探讨反复熔铸对非贵金属烤瓷合金弯曲性能的影响。方法:弯曲试件由非贵金属烤瓷合金分别经过1次、2次、3次、4次以及5次熔铸后,再经万能工具磨床研磨而成。根据ISO7438标准,对所有试件进行三点弯曲加载直至试件断裂,测试所有非贵金属烤瓷合金试件的弯曲强度及弯曲模量。结果:经过不同铸造次数的非贵金属烤瓷合金,在弯曲强度和弯曲模量上有显著差异(P<0.05)。经过2次、4次铸造的合金与经过1次铸造的合金之间的弯曲强度无显著差异,而经过3次、5次铸造的合金在弯曲强度上显著高于经过1次铸造的合金(P<0.05);经过2次、5次铸造的合金与经过1次铸造的合金之间的弯曲模量无显著差异,而经过3次、4次铸造的合金在弯曲模量上则显著高于经过1次铸造的合金(P<0.05)。结论:非贵金属烤瓷合金至少可以重复铸造5次而不引起弯曲性能的下降。     

反复熔铸钴铬烤瓷合金对人牙龈成纤维细胞的体外细胞毒性实验

目的:评价反复熔铸后钴铬合金的细胞毒性。方法:原代培养人牙龈成纤维细胞(HGFs),按照ISO10993标准,制备经1～3次熔铸钴铬烤瓷合金浸提液,CCK-8法测定其对HGFs增殖的影响,倒置相差显微镜观察HGFs生长情况,初步评价经1～3次熔铸后钴铬烤瓷合金的生物相容性。结果:经1～3次熔铸后的钴铬烤瓷合金细胞毒性级为1～2级,各实验组细胞形态良好,经2、3次熔铸的钴铬烤瓷合金A值与经1次熔铸的钴铬烤瓷合金差异无统计学意义。结论:初步认为经1～3次后熔铸的钴铬烤瓷合金具有较好的生物相容性。     

Plat铸造陶瓷材料的物理性能研究

目的 :初步研究了全瓷修复材料Plat铸造陶瓷材料的物理性能 ,为临床应用提供理论依据。方法 :采用经典的方法对Plat铸造陶瓷的密度 ,热膨胀系数 ,热传导率进行测定。结果 :Plat铸造陶瓷的密度为2.93g/cm3 ,热膨胀系数为9.87×10-6/℃ ,热传导率为0.0035卡/秒.cm.℃。结论 :Plat铸造陶瓷的密度 ,热膨胀系数 ,热传导率均与牙釉质相似 ,是一种有发展前景的口腔修复材料     

Effect of Recasting of Nickel: Chromium Alloy on its Castability

Castability plays an important role in selection of an alloy for cast dental restorations. This study was conducted to assess the effect of recasting of nickel-chromium alloy on its castability. Different percentage combinations of new and once casted alloy were used to produce a total of twentyfive cast samples using modified Whitlock's method and castings obtained from new alloy were used as control group. Castability value was obtained by using Whitlock's formula. Results were analyzed using student 't' test. There is no statistical difference between the castability value of the new alloy and the recasted alloy (confidence level 95%). Within the limitations of the study it is concluded that the castability value will not be affected by recasting the nickel-chromium alloy. Complete castings of any metal restoration are mandatory and to know the completeness of castings of any alloy, castability test is of prime importance.     

真空烧结粉末冶金法制作钛合金试件的物理性能测试

研究真空烧结粉末冶金法制作钛合金试件的物理性能,方法：采用真空烧结粉末冶金法制作 钛合金试件,测试烧结收缩率、开口孔隙度。结果：在１００－３００ＭＰａ范围内,随着粉末的成形压力的增大,烧结收缩率和开口孔隙度减少;采用的３种钛粉末粒度对烧结体的物理性能没有影响。;钛粉镀铜镀锡组坯体烧结后线收缩率较其它粉末配方组大。     

MC氧化铝陶瓷可切削性分析

目的 分析MC切削陶瓷的可切削性能。方法 测量MC氧化铝块和Vita In-Ceram Alumina Block的三点弯曲强度、断裂韧性和维氏硬度,计算陶瓷可加工指数,记录用两种瓷块在CerecⅡ型CAD/CAM机上加工下颌第一双尖牙底层冠所用时间。结果 MC氧化铝陶瓷的三点弯曲强度为(100.59±2.77)MPa,低于Vita In-Ceram Alumina Block的(112.47±9.37)MPa,两者间差别无统计学意义;MC陶瓷可加工指数为1.01,高于Vita In-Ceram Alumina Block的0.79;在CerecⅡ型CAD/CAM机上加工下颌第一双尖牙底层冠,两种瓷块的磨削时间都是(465±0)s。结论 MC氧化铝瓷块与进口的氧化铝陶瓷性能相当,可以满足牙科CAD/CAM加工的需要。     

Physical Properties of an Acrylic Resin after Incorporation of an Antimicrobial Monomer

Purpose: This study evaluated the effect of the incorporation of the antimicrobial monomer methacryloyloxyundecylpyridinium bromide (MUPB) on the hardness, roughness, flexural strength, and color stability of a denture base material. Materials and Methods: Ninety‐six disk‐shaped (14‐mm diameter × 4‐mm thick) and 30 rectangular (65 × 10 × 3.3 mm³) heat‐polymerized acrylic resin specimens were divided into three groups according to the concentration of MUPB (w/w): (A) 0%, (B) 0.3%, (C) 0.6%. Hardness was assessed by a hardness tester equipped with a Vickers diamond penetrator. Flexural strength and surface roughness were tested on a universal testing machine and a surface roughness tester, respectively. Color alterations (ΔE) were measured by a portable spectrophotometer after 12 and 36 days of immersion in water, coffee, or wine. Variables were analyzed by ANOVA/Tukey HSD test (α= 0.05). Results: The following mean results (±SD) were obtained for hardness (A: 15.6 ± 0.6, B: 14.6 ± 1.7, C: 14.8 ± 0.8 VHN; ANOVA: p= 0.061), flexural strength (A: 111 ± 17, B: 105 ± 12, C: 88 ± 12 MPa; ANOVA: p= 0.008), and roughness (A: 0.20 ± 0.11, B: 0.20 ± 0.11, C: 0.24 ± 0.08 μm; ANOVA: p= 0.829). Color changes of immersed specimens were significantly influenced by solutions and time (A: 9.1 ± 3.1, B: 14.8 ± 7.5, C: 13.3 ± 6.1 ΔE; ANOVA: p < 0.05). Conclusions: The incorporation of MUPB affects the mechanical properties of a denture base acrylic resin; however, the only significant change was observed for flexural strength and may not be critical. Color changes were slightly higher when resin containing MUPB was immersed in wine for a prolonged time; however, the difference has debatable clinical relevance.     

Physical Properties of Conventional and Super Slick Elastomeric Ligatures after Intraoral Use

Objective:To investigate the change in the physical properties of conventional and Super Slick elastomeric ligatures after they have been in the mouth.Materials and Methods:Nine healthy volunteers took part. One orthodontic bracket was bonded to a premolar tooth in each of the four quadrants of the mouth. Two conventional and two Super Slick elastomeric ligatures were placed at random locations on either side of the mouth. The ligatures were collected after various time intervals and tested using an Instron Universal testing machine. The two outcome measures were failure load and the static frictional resistance.Results:The failure load for conventional ligatures was reduced to 67% of the original value after 6 weeks in situ. Super Slick elastomeric ligatures showed a comparable reduction after 6 weeks in situ (63% of original value). There were no statistical differences in the static friction between conventional and Super Slick elastomerics that had been in situ for either 24 hours (P  =  .686) or 6 weeks (P  =  .416). There was a good correlation between failure load and static friction (r  =  .49).Conclusions:There were statistically significant differences in the failure loads of elastomerics that had not be placed in the mouth and those that had been in the mouth for 6 weeks. There were no differences in the static frictional forces produced by conventional and Super Slick ligatures either before or after they had been placed in the mouth. There appears to be a direct proportional relationship between failure load and static friction of elastomeric ligatures.