铸钛表面多结构层对钛瓷结合的影响

目的研究铸钛表面多结构层对钛瓷结合产生的影响。方法采用电子探针界面分析及剪切强度测试的方法，考察了钛瓷界面的结合状况及结合强度。结果铸钛表面多结构层组（Ｒ１）的钛瓷界面出现裂隙，界面区元素扩散带宽度为２９０３μｍ，剪切强度为２９４５ＭＰａ；去除多结构层铸钛组（Ｒ２）及锻钛组（Ｒ３）的钛瓷界面结合紧密、无裂隙，界面区元素扩散带宽度分别为６９０μｍ和７．０１μｍ，剪切强度分别为５２７５ＭＰａ和４８３２ＭＰａ。统计学结果表明，Ｒ１组剪切强度和元素扩散带宽度与Ｒ２、Ｒ３组比较，差异均有非常显著性（Ｐ＜０．０１）。结论铸钛件表面烤瓷前，应先去除其表面多结构层。     

桩影响前牙烤瓷冠修复后牙本质应力分布的三维有限元分析

采用三维有限元法分析桩对上颌中切牙金属烤瓷冠修复后牙本质应力分布的影响。选择一标准的上颌中切牙，经包埋、螺旋ＣＴ扫描、图形数字化，采用ＳｕｐｅｒＳＡＰ有限元分析软件在微机上建立三维有限元模型，模拟了牙槽骨、牙周膜、牙本质、桩、金属烤瓷冠的金属帽状冠及烤瓷层等结构，与临床实际结构类似。分别分析ＳＤＡ－Ⅱ型中熔合金桩修复前后，牙本质应力分布情况。结果表明：金属桩可改变牙本质原有的应力分布模式，使桩与牙本质交界区应力值增大；但与此同时又降低了牙本质应力峰值，Ｖｏｎｍｉｓｅｓ应力降低１３．９８％，最大主应力降低７．０５％。即从力学角度提示：合理桩修复可防止牙体断裂。     

种植金瓷固定桥的瓷层厚度对瓷裂影响的试验研究

作者研究了烤瓷厚度对松风一镍铬合金系列的种植金瓷固定义齿瓷裂的影响、结果表明：当瓷粉厚度达到3.5mm时，开始出现瓷裂；达到4mm时，全部样本产生瓷裂；连接体是产生裂纹的主要部位；用体视镜观察裂纹优于肉眼观察。提示应保证涂塑的体瓷粉厚度小于3．5mm，为了更好地满足此要求，可在种植体基桩与支架固位体之间做内冠。同时要求支架连接体外形和连接体处的瓷表面外形为平缓曲面，以避免连接体外的形状突然变化而引起的瓷裂     

钛表面烤瓷的预氧化处理工艺研究

目的：考察预氧化处理工艺是否适合钛－瓷修复。方法：采用剪切实验法测试在未预氧化处理（Ｒ１），３００℃（Ｒ２）、５００℃（Ｒ３）及７００℃（Ｒ４）预氧化处理时钛－氧化处理时钛－瓷结合强度，并用金、相显微镜及电子探针分析各组的钛－瓷界面状况。结果：Ｒ１、Ｒ２、Ｒ３及Ｒ４各组剪切强度值分别为５０．２５±６．５２ＭＰａ、４４．６７±７．０８ＭＰａ、２７．６９±５．２７ＭＰａ和２２．５１±４．９０Ｍｐａ。界面分析表明，各组钛与瓷界面结合紧密、无裂隙，并存在元素扩散带，不同的是各组元素扩散带宽度不一，其规律是Ｒ１＜Ｒ２＜Ｒ３＜Ｒ４。结论：预氧化处理工艺不适合钛－瓷修复。     

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目的观察采用金属烤瓷全冠修复早期隐裂牙以保存活髓的临床疗效。方法对2007年7月至2010年1月泰州市口腔病防治院门诊收治的26例患者的30颗未治疗早期活髓隐裂牙,随机分为两组,Ⅰ组15颗患牙采用综合治疗,Ⅱ组15颗患牙直接行金属烤瓷全冠修复。对两组牙随访观察2年并对临床疗效进行比较分析。结果Ⅰ组的治疗成功率为73.3%,Ⅱ组的治疗成功率为93.3%,两组比较,差异有统计学意义(P<0.05)。结论对早期隐裂牙应进行仔细检查,明确诊断及分类,保存活髓的直接金属烤瓷全冠修复是有效的治疗方法之一。     

Flexural strength of fluorapatite-leucite and fluorapatite porcelains exposed to erosive agents in cyclic immersion

Objective

The aim of this study was to evaluate the flexural strength of two porcelain materials (IPS d.SIGN and IPS e.max Ceram) exposed to erosive agents

Material and Methods

One hundred and twenty bar-shaped specimens were made from each of fluorapatite-leucite porcelain (IPS d.SIGN) and fluorapatite porcelain (IPS e.max Ceram) and divided into 8 groups of 15 specimens each. Six groups were alternately immersed in the following storage agents for 30 min: deionized water (control), citrate buffer solution, pineapple juice, green mango juice, cola soft drink and 4% acetic acid. Then, they were immersed for 5 min in deionized water at 37°C. Seven cycles were completed, totalizing 245 min. A 7^th group was continuously immersed in 4% acetic acid at 80°C for 16 h. The final, 8^th, group was stored dry at 37°C for 245 min. Three-point bending tests were performed in a universal testing machine. The data were analyzed statistically by 2-way ANOVA, Tukey’s HSD test and t-test at significance level of 0.05.

Results

The flexural strengths of all groups of each porcelain after exposure to erosive agents in cyclic immersion did not differ significantly (p>0.05). For both types of porcelain, dry storage at 37°C yielded the highest flexural strength, though without significant difference from the other groups (p>0.05). The flexural strengths of all groups of fluorapatite porcelains were significantly higher (p<0.05) than those of the fluorapatite-leucite porcelains.

Conclusions

This study demonstrated that the erosive agents evaluated did not affect the flexural strength of the tested dental porcelains.     

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。     

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。     

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.