IPS-Empress全瓷冠临床观察

目的 :探讨IPS -Empress可铸玻璃陶瓷的修复效果 ,为临床应用提供参考。 方法 :对 68例 179个全瓷冠修复 3年观察 ,对前牙和后牙全瓷冠单冠修复的临床效果进行评价。结果 :68例 79个修复体具有良好的边缘密合性 ,色泽稳定 ,强度高 ,成功率达 86.0 8%。前牙成功率 97.68% ,后牙成功率 70 .0 0 %。结论 :IPS -Empress是一种修复效果较好的全瓷修复材料     

不同材料嵌体修复后牙体组织应力分析

目的:研究3种材料嵌体在垂直载荷下牙体组织的应力分布。方法:建立下颌第一磨牙嵌体修复后颊舌向模式图。分别对3种材料及其不同厚度嵌体底部最大主应力进行计算。结果:在同样载荷下,镍铬合金的应力最大、烤瓷次之、复合树脂最小,且应力均与嵌体的厚度成正比。结论:适当减小镍铬合金和烤瓷嵌体的厚度对预防牙体折裂有一定的作用。     

Behaviour of bone marrow osteoblast-like cells on mineral trioxide aggregate: morphology and expression of type I collagen and bone-related protein mRNAs

AIM: To investigate the in vitro behaviour of rat bone marrow cells (RBM) on mineral trioxide aggregate (MTA) (ProRoot, MTA Root Canal Repair Material; Dentsply Tulsa, Tulsa, OK, USA) compared with intermediate restorative materials (IRM) (Dentsply Caulk, Milford, DE, USA). METHODOLOGY: RBM were obtained from rat femur and were primary cultured and then subcultured. Cells were then seeded on three dishes of each material, and cultured for 3 days, after which they were evaluated morphologically using scanning (SEM) and transmission (TEM) electron microscopy. Furthermore, the calcium released from hydrated material, the cell proliferation ratio and alkaline phosphatase (ALP) activity were analysed, and the expression of type I collagen and bone-related protein mRNAs were evaluated. The data were averaged and analysed via one-way analysis of variance (anova) and were then compared by the Scheffe's test. RESULTS: SEM showed that RBM attached to MTA and had a flattened appearance without nuclear protrusions and microspikes. TEM showed that the cells attached in the same manner as the control group, but gaps larger than 2 microm were frequently seen. The calcium released from hydrated MTA was about 130 ppm after 3 days of immersion in saline. The ALP activity was similar to the control group. Cell proliferation and expression of type I collagen mRNA was significantly lower, while the expression of osteopontin mRNA was significantly higher than the control group at the third day of culture. In IRM groups, a few rounded cells were observed on the material but no living cells were seen. CONCLUSIONS: MTA is a material of low toxicity which does not inhibit cell growth, but does suppress the differentiation of osteoblast-like cells.     

瓷层厚度影响金瓷界面抗断裂能力的初步研究

目的：采用云纹干涉法结合界面断裂力学研究瓷厚度对金瓷界面抗断裂能力的影响。方法：比较瓷厚度分别为0．5mm,1.5mm,2.5mm的试件（金属均为0．5mm)界面断裂韧性Jc并观测裂纹扩展。结果：0．5mm组试件的Jc值及承受最大载荷均值（2．813N/m,9.979N)低于1．5mm及2．5mm组（5．395N／m,19.134N与5．429N/m,19.256N).1.5mm与0．5mm组试件，裂纹易沿界面扩展。结论：（1）瓷厚度为1．5mm与2．5mm组的金瓷界面抗断裂能力相当，厚度为0．5mm时减弱，（2）瓷厚度为1．5mm与0．5mm组的界面裂纹易沿界面扩展，厚度为2．5mm组易向瓷层内扩展。     

新型义齿软衬材料的Ames试验研究

本文报道用Ａｍｅｓ法检测了１种新型义齿软衬材料的致突变性，结果表明，经ＴＡ９７、ＴＡ９８、ＴＡ１００和ＴＡ１０２株测试的材料在平皿掺入试验中未诱发阳性反应，但是４个菌株所对应的突变剂均诱发了阳性突变，因此所测试的义齿软衬材料在本实验条件下无诱发突变作用。     

矿物三氧化物凝聚体用于犬牙直接盖髓的实验研究

目的：观察矿物三氧化物凝聚体(MTA)直接盖髓后牙髓炎症反应和修复性牙本质的形成。方法：人工机械暴露犬牙髓，用MTA或氢氧化钙直接盖髓。结果：实验2周和8周，MTA诱导修复性牙本质形成的效果优于氢氧化钙，炎症反应较轻。结论：MTA是一种效果较好的盖髓剂。     

Physical properties and compatibility with dental stones of current alginate impression materials

This study examined physical properties and compatibility with dental stones of two types of alginate impression materials. Five powder-type alginate impression materials (Alginoplast EM, Aroma Fine, Algiace Z, Coe Alginate, Jeltrate Plus) and a paste-type alginate impression material (Tokuso AP-1) were used. The dynamic viscosity immediately after mixing was measured by means of a controlled-stress rheometer. The gelation times were determined according to Japanese Industrial Standards (JIS) T6505, and recovery from deformation, strain in compression and compressive strength were determined according to the International Organization for Standardization (ISO) specification 1563. Detail reproduction and surface roughness of type III dental stones (New Plastone, New Sunstone) and a type IV dental stone (Die Stone) were evaluated using a ruled test block as specified in the ISO specification 1563 and a profilometer, respectively. The alginate impression materials evaluated in this study were all in compliance with the ISO specification 1563 and JIS T6505. The alginate impression materials had similar mechanical properties after gelation, whilst a wide range of dynamic viscosity immediately after being mixed, gelation times and compatibility with dental stones were found among the materials. The paste-type material had a higher dynamic viscosity and a shorter gelation time than the powder-type materials. The best surface quality was obtained with the paste-type material/type III dental stone cast combinations. The materials should be selected in consideration of initial flow, setting characteristics and compatibility with dental stones. The results suggested that a paste-type material would better meet the requirements of an alginate impression material.     

无机活性元素组织工程支架材料重建修复山羊颌骨缺损的扫描电镜观察

目的:用扫描电镜观察无机活性元素组织工程支架材料构建的组织工程骨及其修复羊大面积颌骨缺损的体内成骨状况.方法:实验组对15只山羊下颌角缺损(30 mm×25 mm×10 mm大小)以支架材料修复,左侧为实验组,右侧为空白对照组,术后分别于1、3、6个月处死5只动物行扫描电镜及生物化学检查,观察无机活性元素组织工程支架材料体内成骨情况.结果:实验组骨缺损新生骨在1、3、6个月显著优于对照组,空白对照组6个月骨缺损区均无明显骨修复现象.结论:应用扫描电镜观察到无机活性元素组织工程支架材料具有优良的成骨效果.     

牙槽突裂植骨术研究进展

本文阐述了牙槽突裂植入骨的来源,认为自体骨如髂骨仍是最佳材料。有研究应用重组人骨形成蛋白、小牛骨粉及生物胶原膜、组织工程成骨材料修复牙槽突裂取得一定效果。术前适当的正畸治疗对于部分牙槽突裂患者相当重要,术后正畸也必不可少。影响牙槽突裂移植骨成活率的原因较多,包括适应证的选择、手术时机及手术技巧等。应用三维CT评价牙槽突裂植骨较以往的牙片可以获得更全面的信息。     

Probabilistic analysis of peri-implant strain predictions as influenced by uncertainties in bone properties and occlusal forces

OBJECTIVES: The purpose of this study was to examine the influence of variability in bone properties and loading on peri-implant crestal and cancellous bone strains using a probabilistic approach, in combination with finite element (FE) analysis. MATERIAL AND METHODS: Oblique occlusal loading was applied to a single endosseous implant embedded in a two-dimensional (2-D) FE model of a premolar section of a mandible. Perfect bonding was assumed at all interfaces. Five independent parameters (cortical bone thickness (T), cortical (ECORT) and cancellous (ECANC) bone Young's moduli, and vertical (FVERT) and horizontal (FHOR) occlusal forces) were assigned statistical distributions based on data in the literature. Two cancellous bone distribution models were examined, one with a lower mean and range (LM) and the second with a higher mean and range (HM) of cancellous bone Young's modulus values. Sets of randomly chosen values for the five parameters were selected from the distributions and FE analyses were performed for all randomly selected sets. RESULTS: In the LM model, 50% of the cases experienced hyper-physiologic peri-implant crestal strains in the region of commonly reported saucerization, compared with about 25% of the cases in the HM model. Relative probabilistic sensitivities (%) of bone strains to the independent input parameters (T, ECORT, ECANC, FVERT and FHOR) were as follows: 29, 11, 30, 13, and 17 for the LM model, and 17, 11, 35, 21, and 15 for the HM model, respectively. CONCLUSION: Probabilistic analyses of FE models suggest that up to twice as many cases in the LM distribution may be at risk of saucerization as compared with the HM distribution model. Although based on hypothetical distribution values and the limitations inherent to a 2-D analysis, this probabilistic study demonstrated that FE models are very sensitive to the often arbitrarily assigned values for cancellous bone Young's modulus, and also to values used for cortical bone thickness, when the cancellous bone modulus is low.