4种修复金属材料对炎性牙周组织炎症因子表达的影响

目的：评估4种口腔修复金属材料对牙周炎症状态下牙龈组织炎症因子表达的影响。方法收集牙周炎患者的炎症牙龈组织10份，原代培养人牙龈成纤维细胞，以DMEM培养的细胞作为空白对照（空白对照组），实验组采用钴铬合金（钴铬合金组）、钛合金（钛合金组）、纯钛（钝钛组）及金钯合金（金钯合金组）4种金属浸提液加入培养基。ELISA和RT?PCR法检测相关炎症因子的蛋白和mRNA表达情况。结果 ELISA和RT?PCR结果显示，与空白对照组相比，钴铬合金组和钛合金组白细胞介素?6、白细胞介素?1β、肿瘤坏死因子?α的蛋白和mRNA表达水平均较高（P<0.01），而纯钛组和金钯合金组与空白对照组相比差异无统计学意义（P>0.05）。结论对炎症牙龈成纤维细胞，纯钛和金钯合金比钴铬合金和钛合金具有更好的生物相容性。     

五种烤瓷合金金瓷结合强度的比较

目的：比较镍铬合金、含钛的镍铬合金、钴铬合金、钯银合金和纯钛的金瓷结合强度。方法：执行ISO9693标准,采用三点弯曲试验分别测定镍铬合金、含钛的镍铬合金、钻铬合金、钯银合金、纯钛在常规热处理条件下的金瓷结合强度。结果：金瓷结合强度分别为：镍铬合金（37．82±2．72）Mpa;含钛的镍铬合金（39．23±2．45）Mpa;钴铬合金（39．06±3．41）Npa;钯银合金（47．98±3．74）Npa;纯钛（32．61±5．62）Mpa。镍铬合金、含钛的镍铬合金、钻铬合金组间差异无统计学意义（P〉0．05）,这3种合金与纯钛、钯银合金组间差异都有统计学意义（P〈0．05）,纯钛与钯银合金组间差异也有统计学意义（P〈0．05）。结论：①镍铬合金、含钛的镍铬合金、钴铬合金金瓷结合强度相近,都大于纯钛且小于钯银合金的金瓷结合强度。②镍铬合金、含钛的镍铬合金、钻铬合金、钯银合金和纯钛的金瓷结合强度都大于25Mpa,按ISO9693标准均可应用于临床。     

3种烤瓷冠基底合金对HGF体外培养模型中IL-1β释出的影响

目的：通过测定人牙龈成纤维细胞（HGF）在体外培养过程中炎症因子白细胞介素-1β（IL-1β）释出量,对不同烤瓷冠基底金属合金进行对比,判断其对牙龈的作用。方法：以镍铬合金、含钛镍铬合金和纯钛为实验材料,在人牙龈成纤维细胞体外培养系统中引入不同金属浸提液,通过酶联免疫吸附试验（ELISA）测定细胞暴露于浸提液1、3、7、24h细胞分泌IL-1β的量。结果：镍铬合金和含钛镍铬合金浸提液使HGF分泌IL-1β量明显增加（P〈0.01）,纯钛组浸提液不影响HGF分泌IL-1β的量,与空白对照组无显著差异。结论：镍铬合金和含钛镍铬合金可促进HGF分泌IL-1β,纯钛材料不影响HGF对IL-1β的分泌、提示其良好的细胞相容性。     

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目的比较镍铬、钴铬、纯钛、钯基、金铂等5种常用烤瓷合金的细胞毒性。方法本研究于2011年7—10月在福建医科大学附属口腔医院中心实验室进行。按照ISO10993标准,采用CCK-8法测定第1、3、5、7天时烤瓷合金浸提液培养的小鼠肺成纤维细胞(L929细胞)的OD值,同时观察L929细胞形态,并且计算细胞相对增殖率(RGR),评价5种烤瓷合金对L929的细胞毒性。结果第7天时,除金铂合金外,其他4组烤瓷合金的OD值与阴性对照组的差别均有统计学意义(P<0.05);L929细胞的RGR由高到低分别为金铂合金(98.4%)、钯基合金(95.2%)、纯钛合金(83.0%)、镍铬合金(74.0%)、钴铬合金(72.6%)。细胞形态学观察发现:金铂合金组、钯基合金组以及纯钛合金组的细胞形态与阴性对照组相比无明显差别;而钴铬合金组和镍铬合金组的细胞排列稀疏,少量细胞皱缩变圆。结论金铂合金、钯基合金以及纯钛合金的细胞毒性为1级,具有较好的生物相容性;钴铬合金、镍铬合金的细胞毒性为2级,结合细胞形态观察认为生物相容性仍然合格。     

3种烤瓷基底合金对人牙周膜干细胞增殖和骨相分化的影响

目的：通过测定人牙周膜干细胞（hPDLSCs）在3种不同金属基底提取液培养过程中的增殖和骨相分化能力,比较3种金属基底冠对牙周组织的影响。方法：在人牙周膜干细胞体外培养系统中分别加入镍铬合金、钴铬合金、纯钛浸泡后提取液,常规进行培养及成骨分化诱导,分别测定并比较各组干细胞增殖能力及成骨分化能力。结果：纯钛提取液组人牙周膜干细胞增殖能力和成骨分化能力明显高于镍铬合金组和钴铬合金组（P〈O．05）,差异有统计学意义,与空白对照组相比无明显差异。镍铬合金组与钴铬合金组相比无明显差别,差异无统计学意义。结论：镍铬合金和钴铬合金非贵金属组可降低人牙周膜干细胞增殖和成骨分化能力,而纯钛材料对其影响不大,提示纯钛合金的良好生物相容性。     

镍铬合金、钴铬合金和纯钛金瓷结合强度的比较

目的比较镍铬合金、钴铬合金和纯钛的金瓷结合强度和金瓷界面特征。方法执行ISO9693[1]标准,采用三点弯曲试验分别测定在常规热处理条件下的镍铬合金、钴铬合金和纯钛的金瓷结合强度。运用扫描电镜和X射线衍射进行金瓷界面分析。结果金瓷结合强度分别为:镍铬合金:(37.56±2.92)Mpa,钴铬合金:(39.06±2.79)Mpa,纯钛:(32.61±5.62)Mpa,前两者组间差异无统计学意义(P>0.05),后者与前两者组间差异有统计学意义(P<0.05)。扫描电镜和X线衍射:镍铬合金和钴铬合金与瓷之间紧密接触,无裂纹,界面过渡层15～20μm。纯钛与瓷过渡层80μm,可见孔洞。纯钛基体表面可见约2μm黑色带。结论①钴铬合金与镍铬合金的金瓷结合强度接近,都大于纯钛的金瓷结合强度。②钴铬合金、镍铬合金、纯钛的金瓷结合强度都大于25Mpa,按ISO9693标准均可应用于临床。③金瓷之间存在结合介质,形成过渡层。     

异种金属间激光焊接的初步研究

目的:通过对焊件机械强度的测定及熔合区微观结构的分析,探讨口腔常用合金异种金属间激光焊接的可行性。方法:采用钴铬合金、镍铬合金、纯钛进行异种金属间的激光焊接,测定焊件的最大抗拉、抗弯强度,并进行拉伸断口的扫描电镜观察和熔合区的金相分析,探讨激光焊接异种金属的焊接质量及临床应用的可行性。结果:钴铬和镍铬合金异种金属间的激光焊件机械性能较好,钴铬焊丝组和镍铬焊丝组在最大抗拉、抗弯强度上无显著差异(P>0.05)。纯钛与钴铬或者镍铬合金激光熔接接头脆性大,断面可见严重的裂纹和气孔。结论:钴铬合金与镍铬合金异种合金间的激光焊接,不管采用钴铬焊丝或者镍铬焊丝,都可获得良好的焊接接头。纯钛与钴铬合金或者镍铬合金都不能采用激光直接进行熔接     

4种常用口腔金属材料MRI伪影对比研究

目的:比较4种不同口腔金属材料在MRI检查中伪影大小。方法:在标准备牙模型上制作钴铬合金、纯钛、银钯、金钯金属全冠实验组以及二氧化锆全瓷冠对照组,并用25 cm×13 cm×10 cm(长×宽×高)塑料容器蒸馏水包埋后放置于1.5T自旋回波序列T2加权像比较伪影大小。结果:不同金属在同一自旋回波序列中产生伪影大小不同,钴铬合金、纯钛、银钯金属冠的伪影分别为(450±665)、(343±322)、(141±186) mm²,3组间两两比较均存在差异(P＜0.05),金钯金属冠与对照组二氧化锆相比伪影大小未见明显差异。结论:4种金属MRI检查中伪影的大小钴铬合金＞纯钛＞银钯合金＞金钯合金。     

4种牙科金属材料对成纤维细胞L929凋亡相关基因及蛋白表达的影响

目的 研究4种不同牙科金属材料（金合金、银钯合金、钴铬合金、镍铬合金）浸提液对小鼠成纤维细胞L929凋亡相关基因及蛋白表达的影响。方法 以金合金（A组）、银钯合金（B组）、钴铬合金（C组）、镍铬合金（D组）的浸提液体外培养小鼠成纤维细胞L929,并以含10%胎牛血清的RPMI1640培养基作为阴性对照（E组）。采用逆转录聚合酶链反应（RT-PCR）方法检测了4种牙科金属材料浸提液对L929细胞凋亡相关基因caspase-3、8、9 mRNA和蛋白表达的影响。结果 4种牙科金属材料浸提液培养小鼠L929细胞48 h后,除A组与E组间差异无统计学意义外,各组间caspase-3 mRNA及caspase-9 mRNA表达差异有统计学意义（P<0.05）。各组间caspase-8 mRNA差异无统计学意义。除A组与C组、B组与D组间差异无统计学意义外,caspase-3及caspase-9蛋白表达差异有统计学意义,各组间caspase-8蛋白差异无统计学意义。结论 4种牙科金属材料,除金合金外,均诱导小鼠成纤维细胞L929凋亡相关基因表达增加,金属离子可能通过线粒体通路诱导细胞凋亡。     

五种全冠合金铸造后的腐蚀性研究

目的 测定五种制作全冠的合金铸造后在体外细胞培养液中析出金属离子的种类及不同时间段析出的各种金属离子的量。方法 本实验用电感藕荷等离子质谱仪（ICP－MS）定量测定金属离子测试。结果 镍铬合金和钴铬合金析出离子最多银钯合金和钯合金有一定的金属离子析出，纯钛只析出微量钛离子。结论 纯钛、钯合金的耐腐蚀性最好，银钯合金次之，镍铬合金和钴铬合金的耐腐蚀性较差。     

Occlusion (Part 2 of 2)

In the previous Journal of Esthetic and Restorative Dentistry's Talking with Patients, we defined occlusion and malocclusion and discussed when and why malocclusion is a concern. In this issue we will discuss the diagnosis and treatment of malocclusions.     

Characterisation of a Bioactive SiO2-CaO-CaF2-Na2O Glass Used in Composites

ObjectivesTo characterise the ion release, pH changes and apatite formation of a phosphate free bioactive glass.MethodsA SiO₂-CaO-CaF₂-Na₂O glass was synthesized by a melt route with a composition close to the reactive glass in the commercial Cention N® composite. The glass was characterized after immersion in three media: Artificial Saliva pH4 (AS4) Artificial Saliva pH7 (AS7) and in a high phosphate artificial saliva at pH6.5 (AS6.5). The pH and fluoride release were measured using a pH meter and an ion selective electrode. The concentration of Ca, P, Na and Si were measured by ICP-OES. The glass powders after immersion were characterized by FTIR, X-ray powder diffraction and ¹⁹F MAS-NMR.ResultsThe glass increased the pH in all three media. Fluoride was detected in all three media but was much higher in AS 6.5. Calcium fluoride formed in AS4 with a small amount of fluorapatite at long immersion times. Fluorapatite and calcium fluoride formed in AS7, whilst in AS6.5 fluorapatite formed.The ion concentrations in solution after immersion reflected the glass composition and the immersion media with fluorapatite being favoured by higher pHs and phosphate contents in the media.SignificanceThe results demonstrated the ability of the glass to increase the pH and to form fluorapatite in phosphate containing media. This may explain the low incidence of secondary caries found in the commercial composite. Unlike the commercial composite evidence was found for the precipitation of fluorite, which will act to reduce the release of fluoride for preventing secondary caries.     

2-Hydroxyethyl methacrylate as an inhibitor of matrix metalloproteinase-2

This study evaluated the effect of different concentrations of 2-hydroxyethyl methacrylate (HEMA) on the inhibition of matrix metalloproteinase-2 (MMP-2) in vitro . Mouse gingival explants were cultured overnight in Dulbecco's modified Eagle's minimal essential medium, following which the expression of secreted enzymes was analyzed by gelatin zymography and the effects of different amounts of HEMA on enzyme activity were investigated. The gelatinolytic proteinases present in the conditioned media were characterized as being matrix metalloproteinases (MMPs) by means of specific chemical inhibition. The MMPs present in the conditioned media were identified, using immunoprecipitation, as MMP-2. Three major bands were detected in the zymographic assays and were characterized, according to their respective molecular weights, into the following forms of MMP-2: zymogene (72 kDa), intermediate (66 kDa), and active (62 kDa). All forms of MMP-2 were inhibited by HEMA in a dose-dependent manner, implying that MMP-2 may be inhibited by HEMA in vivo .     

ESR investigation of ROS generated by H2O2 bleaching with TiO2 coated HAp

It is well known that clinical bleaching can be achieved with a solution of 30% hydrogen peroxide (H2O2) or H2O2/titanium dioxide (TiO2) combination. This study examined the hypothesis that TiO2 coated with hydroxyapatite (HAp-TiO2) can generate reactive oxygen species (ROS). ROS are generated via photocatalysis using electron spin resonance (ESR). The bleaching properties of HAp-TiO2 in the presence of H2O2 can be measured using hematoporphyrin litmus paper and extracted teeth. We demonstrate that superoxides (O2(?-)) and hydroxyl radicals (HO(?)) can be generated through excitation of anatase TiO2, rutile TiO2, anatase HAp-TiO2, and rutile HAp-TiO2 in the presence of H2O2. The combination of R HAp-TiO2 with H2O2 produced the highest level of HO(?) generation and the most marked bleaching effects of all the samples. The superior bleaching effects exhibited by R HAp-TiO2 with H2O2 suggest that this combination may lead to novel methods for the clinical application of bleaching treatments.     

K2O-Na2O-Al2O3-SiO2系统牙科微晶玻璃匹配氧化铝陶瓷的初步研究

目的:研究 K₂O-Na₂O-Al₂O₃-SiO₂系统牙科微晶玻璃匹配氧化铝陶瓷的热处理温度制度。方法:根据氧化铝陶瓷的热膨胀系数调整K₂O-Na₂O-Al₂O₃-SiO₂系统牙科微晶玻璃的原材料配比,利用K₂O-Na₂O-Al₂O₃-SiO₂系统牙科微晶玻璃的热处理温度制度形成微晶玻璃-氧化铝陶瓷复合材料;利用偏振光显微镜和X射线衍射分析仪观察样品的形态及显微结构特性,利用材料试验机测试材料的抗压强度。结果:经过原材料组份的调整,白榴石晶粒约1.0 μm、在玻璃基质中分布均匀;微晶玻璃-氧化铝陶瓷复合材料的抗压强度为500 MPa。结论:K₂O-Na₂O-Al₂O₃-SiO₂系统牙科微晶玻璃的热处理温度制度适合匹配氧化铝陶瓷。     

Smad2基因MH2结构域表达载体的构建和其在大肠杆菌中的表达

目的：构建Ｓｍａｄ２基因ＭＨ２结构域原核融合表达载体,在大肠杆菌中表达ＭＨ２结构域,为制备抗ＭＨ２抗体,研究Ｓｍａｄ２基因和ＭＨ２结构域的功能奠定基础。方法：用ｐＧＥＸ－４Ｔ－２表达载体构建ｐＧＥＸ－４Ｔ－２／Ｓ２ＭＨ２原核融合表达载体,转化大肠杆菌ＤＨ５α,ＩＰＴＧ诱导表达ＧＳＴ－ＭＨ２融合蛋白,１００ｇ／ＬＳＤＳ－ＰＡＧＥ检测表达产物。结果：重组载体转化ＤＨ５α,经ＩＰＴＧ诱导４ｈ后,在１００ｇ／ＬＳＤＳ－ＰＡＧＥ上出现一条新的蛋白条带,相对分子质量（Ｍｒ）约为４９×１０３。结论：构建成功ｐＧＥＸ－４Ｔ－２／Ｓ２ＭＨ２融合表达载体,在大肠杆菌ＤＨ５α内表达获得ＧＳＴ－ＭＨ２融合蛋白。     

真核表达载体pIRES2-EGFP-hBMP2的构建和鉴定

目的:构建并鉴定人hBMP2基因的真核表达载体pIRES2-EGFP-hBMP2。方法:采用RT-PCR方法从人成骨肉瘤细胞中克隆hBMP2基因,连接T载体并测序正确后与真核表达载体pIRES2-EGFP连接,并进行酶切鉴定,最后将pIRES2-EGFP-hBMP2转染入HEK293细胞中,利用荧光显微镜和Western blot进行表达鉴定。结果:成功克隆了人BMP2基因,酶切鉴定和测序均正确,构建的真核表达载体pIRES2-EGFP-hBMP2能够正确表达hBMP2蛋白。结论:构建了hBMP2基因的真核表达载体pIRES2-EGFP-hBMP2,为研究该基因的功能奠定了基础。