钇/羟基磷灰石纳米微晶对口腔细菌生长繁殖的影响

目的：评价不同钇含量羟基磷灰石(HA)纳米微晶对口腔细菌生长繁殖的影响，为研制具有一定抑菌作用的种植体涂层及高强度复合树脂等口腔生物材料奠定基础。方法：采用厌氧菌连续培养技术，比较HA纳米微晶、1mol％和5mol％钇／HA纳米微晶对构成菌斑的主要细菌——变形链球菌、远缘链球菌、血链球菌、粘性放线菌及牙龈卟啉菌生长繁殖的影响，通过记录菌落计数来描述不同纳米微晶对细菌生长繁殖的作用。结果：HA纳米微晶对变形链球菌、血链球菌、粘性放线菌的生长繁殖均有抑制作用，而对远缘链球菌、牙龈卟啉单胞菌有促进生长作用；含钇1mol%，和5mol％的钇／HA纳米微晶均对变形链球菌、远缘链球菌、血链球菌、粘性放线菌有抑制作用，而对牙龈卟啉菌无抑制作用。结论：钇／HA纳米微晶能不同程度的抑制口腔细菌的生长繁殖。     

湿法合成纳米缺钙磷灰石的实验研究

目的:合成与人体骨磷灰石成分接近的纳米缺钙磷灰石。方法:将(NH4)2HPO4和Ca(NO3)2按照2∶1的比例混合、振荡合成、陈化24 h后,清洗、离心、烘干。采用X线衍射、透射电镜、红外光谱及能谱分析等实验手段,对合成的磷灰石进行观察与评价。结果:(NH4)2HPO4和Ca(NO3)2在震荡条件下进行化学湿法合成,可制备出长约40~60 nm,宽约15~22 nm左右的缺钙磷灰石颗粒。,这种颗粒结构与通常的针状羟基磷灰石结构相比,更接近于人体骨磷灰石(长约50~64 nm,宽度为24~30 nm);该颗粒具有与骨磷灰石接近的钙磷比、相似的纳米尺寸、较低的结晶度,还含有一定量的碳元素。其合成过程简便易行,原料来源普通、经济。因为与人体骨磷灰石有着诸多的相似之处,经过今后的生物学实验,将有望成为生物活性更高的体内植入材料。结论:利用湿法合成纳米缺钙磷灰石简便有效、成分稳定、晶粒形貌受环境温度影响小,在纳米尺寸和成分上与骨磷灰石高度相似。     

纳米氧化钙改性HAP晶须的工艺研究

目的:利用纳米氧化钙良好的抗菌特性以及羟基磷灰石的生物活性,制备羟基磷灰石/氧化钙纳米复合生物材料,以发挥其综合优势.方法:用溶胶-凝胶法制备了羟基磷灰石/纳米氧化钙复合材料,以X射线衍射仪(XRD)和透射电镜(TEM)对复合材料的物相和表面形貌进行了分析.结果:实现了羟基磷灰石和氧化钙以纳米级形式复合,且它们之间产生了化学键合.结论:该种无机纳米复合材料可用于口腔修复和制备新型无机/有机纳米复合生物活性材料.     

纳米羟基磷灰石-壳聚糖复合材料对细胞粘附的影响

目的：制备纳米羟基磷灰石-壳聚糖（nano hydroxyapatite-chitosan,nHA/CS）复合材料,观察其对成纤维细胞粘附行为的影响.方法：将溶胶-凝胶法制得的纳米羟基磷灰石充分混合于2%壳聚糖乙酸溶液中,冷冻干燥法制备纳米羟基磷灰石-壳聚糖复合材料,并对材料进行X射线衍射分析（XRD）、红外光谱分析（FT-IR）、扫描电镜（SEM）、透射电镜（TEM）检测.将NIH3T3细胞分别接种于复合材料和致密羟基磷灰石（dense hydroxyapatite,HA）表面,细胞计数法计算细胞粘附数量,扫描电镜下观察细胞粘附形态.结果：XRD分析结果表明溶胶-凝胶法制备的HA和nHA的晶体结构符合标准羟基磷灰石的空间6方晶体结构.TEM分析结果显示nHA/CS材料中羟基磷灰石为纳米级粉体.接种5、7、9 d后nHA/CS材料表面的细胞粘附数量高于HA组,差异有显著性（P＜0.05）.扫描电镜下,细胞以多个突起粘附于复合材料表面,并具有良好的伸展状态.结论：与HA相比,nHA/CS材料更有利于成纤维细胞的粘附,生物相容性良好.     

电纺聚己内酯/Ⅰ型胶原蛋白/纳米锆酸钙复合支架的制备及其生物相容性的研究

目的:制备聚己内酯(PCL)/Ⅰ型胶原(COLI)/纳米锆酸钙(nCZ)复合支架用于骨组织再生,评价其性能及对人牙周膜细胞(PDLCs)生物相容性及成骨分化的影响.方法:用静电纺丝法制备PCL/COLI、PCL/COLI/纳米羟基磷灰石(nHA)和PCL/COLI/nCZ复合支架,通过扫描电子显微镜表征支架形貌,能量色...     

应用IBAD方法制备纯钛表面多孔TCP／HA涂层材料的微观分析

目的:为了改善钛种植体的生物相容性,对纯钛表面沉积多孔磷酸三钙/羟基磷灰石(Tricalciumphosphate/hydroxyapatite,TCP/HA)复合涂层材料的表面结构和化学成分进行分析,并与沉积羟基磷灰石(Hydroxyapatite,HA)的钛表面进行对比。方法:用离子束辅助沉积方法(Ionbeamassisteddeposition,IBAD)在纯钛表面沉积HA和TCP/HA涂层材料,通过扫描电镜(Scanningelectronmicroscope,SEM)、原子力显微镜(Atomicforcemicroscopy,AFM)、X射线能谱分析(EnergydispersiveX-rayanalysis,EDX)以及X射线衍射(X-raydiffraction,XRD)技术,检测两种涂层材料表面的微观形态和化学成分,并进行比较。结果:SEM和AFM显示TCP/HA涂层材料表面存在多孔结构,表面化学成分分析显示TCP/HA涂层的钙磷比低于HA,XRD证实TCP/HA涂层内同时存在TCP和HA两种化合物。结论:用IBAD方法在纯钛表面成功地沉积了具有多孔结构的TCP/HA复合涂层材料,该涂层材料和基体材料的结合牢固,改善了基体材料的生物相容性,是一种有应用前景的种植体表面涂层材料。     

溶胶-凝胶法合成不同形状纳米羟基磷灰石的研究现状

溶胶-凝胶法是在较为温和的条件下合成无机材料的一种重要方法。纳米羟基磷灰石是人体硬组织的主要无机成分,多以针状或棒状存在于人的牙齿和骨骼中。采用溶胶．凝胶法则可以在不同的工艺条件下合成多种形状的纳米羟基磷灰石,且不同形状和尺寸的纳米颗粒对其使用性能影响较大。本文综述了近年来采用溶胶．凝胶法合成不同形状纳米羟基磷灰石的研究报道,探讨其合成过程中主要工艺条件对颗粒形貌的影响。     

钇-羟基磷灰石纳米微粒对人牙周膜细胞生物学行为的影响

目的:评价Y-HA纳米微晶对人牙周膜细胞的影响.方法:通过人牙周膜细胞的体外培养技术,采用MTT法、透射电镜、细胞免疫化学检测方法,评价Y-HA纳米微晶对人牙周膜细胞增殖、亚细胞结构、Ⅰ型胶原合成的影响.结果:Y-HA和HA纳米微晶对牙周膜细胞均具有促进细胞早期增殖,促进Ⅰ型胶原合成的作用,Y-HA纳米微晶对细胞的早期增殖作用比HA纳米微晶更明显;人牙周膜细胞大量吞噬纳米微晶,细胞的体积和形态无变化,但与细胞代谢有关的一些亚细胞结构发生了一定的变化.结论:Y-HA纳米微晶比HA纳米微晶具有更好的细胞相容性.     

羟基磷灰石的表面形貌对大鼠骨髓细胞向成骨细胞分化的影响

羟基磷灰石(HA)是一种生物相容性的骨替代材料,不同孔隙率的HA具有不同的表面形貌。本实验旨在研究HA的表面形貌对大鼠骨髓细胞向成骨细胞分化的影响。材料和方法通过调控HA粉的成型压力和烧结温度制备出化学成分和晶体结构相同但孔隙率不同的三种HA试件,分别为HA5(孔隙率<5%),HA15(孔隙率为15%)和HA30(孔隙率为30%)。将Wistar大鼠的骨髓细胞接种于放有HA试件的培养板内进行成骨性诱导培养。培养2h后,用血细胞计数器对贴附于试件表面的细胞进行计数;培养14d后,计数增殖细胞数,测定碱性磷酸酶活性,用改良的Lowry法计算总蛋白含量;培…     

活性纳米羟基磷灰石复合胶原材料贴附式植骨的实验研究

目的:探讨活性纳米羟基磷灰石复合胶原材料(AnHAC)在皮质骨表面贴附式植骨的成骨速度及吸收速度。方法:54只新西兰大白兔根据植入颅骨表面的植入物不同分为:纳米羟基磷灰石复合胶原材料(nHAC)组、AnHAC组、羟基磷灰石(HA)组。材料植入后4、8、12周取材,行大体标本及组织学观察、测量新骨长入高度及材料吸收率。结果:AnHAC组材料的吸收率及新骨长入的高度最大,nHAC组次之,HA组最小。结论:AnHAC材料在新骨形成及生物降解方面均较nHAC及HA明显增强,且在皮质骨表面可保持植入材料的高度,有望应用于牙槽骨加高及加宽的治疗。     

An X-ray diffraction and solubility study of equilibration of human enamel-powder suspensions in fluoride-containing buffer

Various amounts of enamel-apatite powder were suspended in an acetate buffer (pH 4.5) containing sufficient fluoride to give molar ratios of fluoride/apatite from zero to unity. The suspensions were equilibrated at 20 °C for periods between 4 h and 1 year, with continuous gentle stirring. Solubility studies showed dissolution of hydroxyapatite, formation and re-dissolution of calcium fluoride and formation of fluorapatite. The amount of mineral dissolved was low during the fluorapatite formation and increased by a factor of approx. 10 as equilibrium was approached. The fluoride content of the solid apatite, which ranged from 0.1 to 70 mol% fluorapatite, only influenced the solubility slightly, whereas the fluoride content of the bathing solution had a large effect. X-ray diffraction showed a linear correlation between the fluoride content and the a-axis of the apatite.     

Advances in surfaces and osseointegration in implantology. Biomimetic surfaces

The present work is a revision of the processes occurring in osseointegration of titanium dental implants according to different types of surfaces -namely, polished surfaces, rough surfaces obtained from subtraction methods, as well as the new hydroxyapatite biomimetic surfaces obtained from thermochemical processes. Hydroxyapatite’s high plasma-projection temperatures have proven to prevent the formation of crystalline apatite on the titanium dental implant, but lead to the formation of amorphous calcium phosphate (i.e., with no crystal structure) instead. This layer produce some osseointegration yet the calcium phosphate layer will eventually dissolve and leave a gap between the bone and the dental implant, thus leading to osseointegration failure due to bacterial colonization. A new surface -recently obtained by thermochemical processes- produces, by crystallization, a layer of apatite with the same mineral content as human bone that is chemically bonded to the titanium surface. Osseointegration speed was tested by means of minipigs, showing bone formation after 3 to 4 weeks, with the security that a dental implant can be loaded. This surface can be an excellent candidate for immediate or early loading procedures. Key words:Dental implants, implants surfaces, osseointegration, biomimetics surfaces.     

丝素蛋白/纳米羟磷灰石支架的实验研究

目的设计和构建三维丝素蛋白/羟磷灰石骨组织工程支架材料。方法联合运用丝素蛋白非编织方法和仿生矿化技术,制备并表征三维多孔丝素蛋白/纳米羟磷灰石的有机/无机组织工程支架。结果仿生矿化在非编织支架上形成的针状羟磷灰石晶体,直径20～60 nm,长100～300 nm。复合支架孔隙度为70%～78%,孔径为（163.4±42.6）μm。结论采用非编织丝素蛋白和仿生矿化的方法可制备孔隙度和孔径可控的组织工程支架。     

An optimized synthetic substrate for orthodontic bond strength testing

OBJECTIVE: The purpose of this study was to investigate the suitability of different synthetic calcium phosphate based substrates as a biomimetic enamel surface model for orthodontic bond strength testing. METHODS: Carbonated apatite, amorphous calcium phosphate and commercial hydroxyapatite specimens were prepared as substrates for orthodontic bond strength testing. Carbonated apatite specimens were prepared by pressing, sintering and treatment with NaF. The shear bond strength was measured with a universal testing machine. RESULTS: Hydroxyapatite, amorphous and cold pressed carbonated hydroxyapatite exhibited fractures within the substrate after debonding. Mean bond strength values for carbonated hydroxyapatite were 7.38 (1.75) MPa for specimens pressed at 300 degrees C and 9.55 (2.23) MPa for specimens pressed at 300 degrees C and then sintered at 600 degrees C. An additional NaF treatment after sintering resulted in lower bond strength measurements of on average 6.52 (1.03) MPa. SIGNIFICANCE: Hot pressed and sintered carbonated hydroxyapatite showed acceptable shear bond strength values and may represent a suitable biomimetic model for orthodontic bond strength testing.     

Caries and fluoride processes

OBJECTIVES: The purpose of the work was to establish the level and source of salivary fluoride, whether it could interact with tooth mineral and whether it was able to effect calcium re-acquisition and remineralisation. METHODS: Fluoride in saliva and in solution was measured by electrode, calcium by complexometric titration and phosphate colourimetrically-to measure salivary fluoride, its uptake by mineral and the effects of such low levels on calcium and phosphate levels in solution in contact with suspensions of mineral hydroxyapatite. RESULTS: Fluoride levels in saliva were low but could interact with hydroxyapatite. Such levels caused apatite crystallite growth and preferential acquisition of calcium by calcium-deficient apatite. CONCLUSIONS: Salivary fluoride contents rose with increasing water fluoride levels. It was acquired by hydroxyapatite mineral. Topical fluoride was stored on oral tissues. Even these low fluoride contents could cause mineral crystallite growth with preferential calcium uptake. On a mineral area basis these effects were caused by quite low fluoride uptakes. These findings do not support reliance upon large fluoride uptakes by tooth enamel as evidence for commensurate caries reductions.     

含碳酸盐氟羟磷灰石生物陶瓷的研制及其基本特性

用化学沉淀法研制出缺钙型含碳酸盐氟羟磷灰石,借助热失重一差热分析、X射线衍射分析、红外光谱、扫描电镜等手段对这一材料的相组成、结构和性能进行了观察和分析,并对其与纯羟磷灰石的异同进行了分析比较,还测定了其含氟量及生物学性能。结果表明这一材料的组成和性能更接近人体硬组织内的矿物质,用于人体是安全的,煅烧可以引起其物理、化学、相组成以及微观形态的变化。     

Studies on the application of apatite to dental materials. (I) --Apatite ceramics-- (author's transl)]

Apatite ceramics is composed of hydroxyapatite [Ca10(PO4)6(OH)2] sintered at high temperature. It is known that hydroxyapatite is the main component of bone and tooth minerals. There are two synthetic methods for the apatite powder. One is so called wet synthetic method: Synthesis by the reaction of Ca++ and PO4--- in the aqueous solution of approximately pH 7.0, the other is dry method: Synthesis by the solid state reaction at high temperature. The apatite powder stable below 1400 degrees C was prepared by the latter method in this work. After passing through a sieve, this powder was cold-pressed and then sintered at 1000 degrees C to 1300 degrees C in air. Biological apatite powders were also perpared as a reference. It was found that any apatite ceramics having porosity in the range of 5 to 50% could be obtained under the various sintering conditions. Compressive strength of these apatite ceramics increased with the reduction of the porosity, and those with porosity less than 20% were more than 100 kg/cm2. Vickers hardness was measured. This result showed the same tendency as that of compressibility. Hardness of the apatite ceramics with 90% relative density was almost the same or more as that of enamel. Solubility of the synthetic apatite powder in distilled water and aqueous solution of lactic acid (pH 4.0) was nearly the same as biological apatites. The dissolution rate decreased with the reduction of porosity of the ceramics. It was certified that hot pressing technique was extremely effective to obtain high density ceramics (more than 95% of density) and thus low parosity apatite ceramics. From the facts as described above, it is understood that sintered pure hydroxy-apatite is an excellent ceramics of high mechanical strength.     

Chemical and structural challenges in remineralization of dental enamel lesions

The aim of the present paper was to identify some chemical and structural factors which may prevent a full remineralization of caries lesions and to study whether it is possible to overcome such obstacles. Samples of powdered enamel apatite were equilibrated with solutions metastably supersaturated with respect to enamel hydroxyapatite and fluorapatite. After 10 min and 60 min of equilibration at 20 degrees C the suspensions were centrifuged and the calcium and phosphate concentrations and the pH were determined in the supernatant. In parallel studies, 50 75-microns-thick sections of 27 fluorotic teeth of a severity of 5-7 according to Thylstrup and Fejerskov's classification were examined by microradiography and in polarized light using distilled water, and Thoulett's media or seen dry in air. Five obstacles inhibiting remineralization were identified: 1) Although remineralizing solutions or saliva are supersaturated with respect to enamel apatite the total amount of calcium and phosphate dissolved in it is small, so that after precipitation of the dissolved mineral only 1/20,000-1/30,000 of the volume of the mineralizing solution is occupied by mineral. 2) The concentration gradients from the mineralizing solution into the enamel is small, which indicates a slow diffusion into and out of the lesion. 3) The uptake of calcium and phosphate by the enamel apatite crystals is so rapid that the aqueous phase within the pores can be presumed to be only marginally supersaturated in the deeper parts of the lesion. 4) The surface layer of the enamel lesions was found to be a serious obstacle to remineralization so that a subsurface area remains hypomineralized after exposure to salivary remineralization even for a lifetime. 5) Nucleation of new apatite crystals to substitute lost crystals is an unsolved problem.     

近生理条件下在釉质表面原位再生类釉质氟磷灰石的研究

目的:近生理条件下在釉质表面原位合成晶体排列有序的类釉质样氟磷灰石结构。方法:使用HEDTA、CaCl₂、NaH₂PO₄·2H₂O和NaF作为原料,配成所需矿化液与基板在37 ℃水浴条件下作用一段时间可获得所需结构。用XRD、FTIR、SEM、EDS、MTT实验、抑菌环实验等评价合成结构的理化生方面性能。结果:合成结构主要成分是氟磷灰石,呈典型六棱柱结构,并且排列有序且紧密。结论:在近生理条件下合成的结构能够初步模拟釉质的形貌、组成,并有一定抑菌功能。