稀土氧化物着色钇稳定四方多晶氧化锆陶瓷与饰面瓷匹配性的研究

目的:探讨通过添加稀土氧化物着色剂而制备的钇稳定四方多晶氧化锆陶瓷与饰面瓷的匹配性。方法:以稀土氧化物(Pr6O11,CeO2,Er2O3)和过渡元素氧化物(MnO2)为着色剂,采用粉体掺杂方法,在四方多晶氧化锆陶瓷粉体中添加不同质量分数的着色剂,制备出6组钇稳定四方多晶氧化锆陶瓷,测定其与Vita VM9饰面瓷的抗热震性能及界面结合强度。采用SAS6.12软件包对数据进行单因素方差分析。结果:6组钇稳定四方多晶氧化锆陶瓷与Vita-VM9饰面瓷烧结后,各组在60℃～240℃测试过程未发现径向或层间开裂或裂纹现象,加热温度>240℃。6组钇稳定四方多晶氧化锆陶瓷与VitaVM9饰面瓷界面的抗剪切强度值为(36.03±3.82)～(37.98±4.89)MPa,均高于纯四方氧化锆陶瓷组的剪切强度值,但各组与纯四方氧化锆陶瓷的抗剪切强度值无显著差异(P>0.05)。结论:稀土氧化物着色钇稳定四方多晶氧化锆陶瓷与饰面瓷的匹配性达到临床应用水平。     

纳米非晶金刚石膜与镍铬合金及烤瓷表面结合强度的研究

目的:确认纳米非晶金刚石膜能否镀覆在镍铬合金烤瓷复合体的表面,检测膜与镍铬合金及烤瓷表面的结合强度。方法:制得镍铬合金烤瓷试件共50个,分为5组,每组10个;各组试件分别镀膜厚为20nm、40nm、60nm、80nm、100nm,用纳米划痕测试仪分别对每组10个试件的两面测试膜/合金基、膜/瓷基结合强度;用激光拉曼光谱仪对镀膜后的合金面和烤瓷面进行光谱分析。结果:镀膜后的合金面和烤瓷面均可见非晶金刚石膜的特征峰;膜与镍铬合金面结合强度为7.21-10.67N,膜厚为80nm时结合强度较高;膜与烤瓷面结合强度为20.56-24.98N,膜厚为40nm时结合强度较高。结论:镀覆在镍铬合金及烤瓷表面的是非晶金刚石膜;非晶金刚石膜可与镍铬合金及烤瓷面形成较好的结合,此膜在各种膜厚与烤瓷面的结合强度均显著高于它与镍铬合金面的结合强度;膜厚不同,膜/基结合强度不同,镀膜时应选择适宜的膜厚。     

粘结瓷对钛/瓷结合强度的影响

目的：研究粘结瓷对钛/瓷结合强度的影响。方法：根据ISO9693标准,运用三点弯曲方法对Super Porcelain TI-22钛瓷系统的粘结瓷组和无粘结瓷组的钛/瓷结合强度进行测试,并对钛/瓷结合界面进行SEM/EDS观察与分析。结果：粘结瓷组的钛/瓷结合强度（39.41±0.86MPa）明显大于无粘结瓷组的钛/瓷的结合强度（24.27±2.99MPa）（P〈0.01）。粘结瓷组断裂发生在钛/瓷反应层,断裂模式为沿晶与穿晶的混合形态,晶粒中有层状亚结构组成。无粘结瓷组断口平直,有大量锡球析出,钛/瓷界面有大量的孔隙存在。结论：粘结瓷可有效地增加了钛/瓷的结合强度。     

Survival of resin-bonded porcelain veneer crowns placed with and without metal reinforcement

OBJECTIVES: The purpose of this retrospective case study of dental records was to compare the long-term failure rates and modes for resin-bonded sintered feldspathic porcelain veneer crowns (RBPVCs) either containing or without metal substructure reinforcement. METHODS: Two prosthodontists placed 62 RBPVCs fabricated with, and 167 without, metal reinforcement in 143 older adolescent and adult patients treated in a private practice. Clinical judgement determined the type of crown design placed. Preparation margins were generally finished on enamel, and all crowns occluded with opposing teeth. Observations included the patients, operators, crown designs and failure modes. Chi-square or Fisher's exact tests and life table survival statistics were used to evaluate the findings (alpha = 0.05). RESULTS: Over five years, failures occurred in 14.5% of RBPVCs fabricated with, and in 18.6% without, metal reinforcement. Cumulative survival estimates were 74.3 +/- 8.5(Standard Error)% and 72.9 +/- 4.8(SE)%, respectively (P = 0.96). Mandibular posterior crowns comprised 27.1% of the placements, but 47.5% of the failures. Bulk fracture of porcelain occurred in 7.0% of the crowns, all without metal reinforcement. Minor porcelain fractures and debonding were less frequent in both types of crowns. Persistent pulpitis occurred in 3.5% of all teeth. CONCLUSIONS: There was a significant risk of failure for sintered porcelain RBPVCs placed as posterior restorations. Although metal reinforcement was able to reduce the risk of bulk fracture of porcelain, other causes of failure were less affected.     

Fracture strength of two oxide ceramic crown systems after cyclic pre-loading and thermocycling

The aim of the present study was to investigate the fracture resistance of zirconia crowns and to compare the results with crowns made of a material with known clinical performance (alumina) in away that reflects clinical aspects. Sixty crowns were made, 30 identical crowns of alumina and 30 of zirconia. Each group of 30 was randomly divided into three groups of 10 crowns that were to undergo different treatments: (i) water storage only, (ii) pre-loading (10 000 cycles, 30-300 N, 1 Hz), (iii) thermocycling (5-55 degrees , 5000 cycles) + pre-loading (10 000 cycles, 30-300 N, 1 Hz). Subsequently, all 60 crowns were subjected to load until fracture occurred. There were two types of fracture: total fracture and partial fracture. Fracture strengths (N) were: group 1, alumina 905/zirconia 975 (P = 0.38); group 2, alumina 904/zirconia 1108 (P < 0.007) and group 3, alumina 917/zirconia 910 (P > 0.05). Total fractures were more frequent in the alumina group (P < 0.01). Within the limitations of this in vitro study, it can be concluded that there is no difference in fracture strength between crowns made with zirconia cores compared with those made of alumina if they are subjected to load without any cyclic pre-load or thermocycling. There is, however, a significant difference (P = 0.01) in the fracture mode, suggesting that the zirconia core is stronger than the alumina core. Crowns made with zirconia cores have significantly higher fracture strengths after pre-loading.     

钛瓷反应层适宜厚度及元素构成分析

目的:检测钛瓷反应层适宜厚度及元素构成.方法:利用电子探针定点定量分析方法测量钛瓷反应层厚度及元素构成情况. 结果: 观测到钛元素摩尔百分比由87.92%到0.65%的6 μm反应层. 反应层由两层构成,一层钛、氧元素为主的钛氧固溶层,厚约3 μm;另一层为钛氧硅元素为主的富硅层,厚亦约3 μm. 结论: 3 μm的厚度可作为较适宜钛氧固溶层及富硅层厚度的参考标准. 钛瓷分界处钛、氧摩尔百分比约为1∶1,钛氧化层可能以TiO为主.     

正畸烤瓷美容在前牙龈下冠折修复治疗中的应用效果

目的 分析正畸烤瓷美容在前牙龈下冠折修复治疗中的应用效果。方法 选取2021年1月-2022年 10月于济阳区中医医院接受治疗的前牙龈下冠折患者52例,随机分为对照组和观察组,各26例。对照组给予基 础桩冠修复,观察组给予正畸烤瓷美容治疗,比较两组临床疗效、咬合度、美观度、牙周咬合功能、牙周健康 及修复满意度。结果 观察组治疗总有效率为96.15%,高于对照组的65.38%,差异有统计学意义（P＜0.05）;观 察组咬合度、美观度评分高于对照组,差异有统计学意义（P＜0.05）;观察组牙周咬合功能及牙周健康优于 对照组,差异有统计学意义（P＜0.05）;观察组修复满意度为96.15%,高于对照组69.23%,差异有统计学意 义（P＜0.05）。结论 采取正畸烤瓷美容修复治疗前牙龈下冠折可改善患者咬合度及美观度,促进牙周咬合 功能提升,维持牙周健康,疗效确切,更易被患者接受,具有较高的临床应用价值。     

Leukonychia totalis in two sibs

A sister and a brother, offspring of unaffected consanguineous Arab parents, were found to have leukonychia totalis and flat, wide nails. To our knowledge this is the first report of apparent autosomal recessive transmission of this trait. A parental somatic mutation with gonadal mosaicism may explain the unusual segregation of the trait in this family. © 1993 Wiley-Liss, Inc.     

口腔烤瓷熔附修复中基底支架制作技术应用研究进展

牙科陶瓷材料以其良好的化学稳定性、生物相容性、耐磨损、表面光洁、色泽逼真、不老化和不着色而成为牙科冠桥修复的重要材料。但陶瓷本身抗弯强度低 ,脆性大 ,烧结收缩大 ,限制了在牙科的广泛应用。为改进提高瓷修复体强度 ,简化流程及复杂的工业制作工艺 ,终于在牙科推出临床修复中可行的以低熔瓷烧烤熔附的修复方式 ,借助于烤瓷熔附基底来提高修复体强度 ,从而拓展了陶瓷材料在牙科的应用范围。对烤瓷熔附基底支架制作技术 ,数年来经过不断地研究改进 ,并与当今尖端技术相融合 ,出现了很多新的制作技术