种植牙周围颌骨的骨重建模拟

研究的目的是通过骨重建模拟来预测种植牙植入后周围颌骨的密度分布情况.基于两种成熟且得到广泛应用的骨重建理论,提出了一种新的模拟骨重建的算法,该算法既包含了"死区效应",同时又是基于自组织控制过程.建立了包含种植体和颌骨在内的二维有限元模型,并用文中提出的算法对种植牙周围骨骼组织的密度分布情况进行了骨重建模拟,同时讨论了...     

Fixation of bioactive calcium alkali phosphate on Ti6Al4V implant material with femtosecond laser pulses

Bone implants made of metal, often titanium or the titanium alloy Ti6Al4V, need to be surface treated to become bioactive. This enables the formation of a firm and durable connection of the prosthesis with the living bone. We present a new method to uniformly cover Ti6Al4V with a thin layer of ceramics that imitates bone material. These calcium alkali phosphates, called GB14 and Ca10, are applied to the metal by dip coating of metal plates into an aqueous slurry containing the fine ceramic powder. The dried samples are illuminated with the 790 nm radiation of a pulsed femtosecond laser. If the laser fluence is set to a value just below the ablation threshold of the ceramic (ca. 0.4 J/cm²) the 30 fs laser pulses penetrate the partly transparent ceramic layer of 20-40 μm thickness. The remaining laser fluence at the ceramic-metal interface is still high enough to generate a thin metal melt layer leading to the ceramic fixation on the metal. The laser processing step is only possible because Ti6Al4V has a lower ablation threshold (between 0.1 and 0.15 J/cm²) than the ceramic material. After laser treatment in a fluence range between 0.1 and 0.4 J/cm², only the particles in contact with the metal withstand a post-laser treatment (ultrasonic cleaning). The non-irradiated rest of the layer is washed off. In this work, we present results of a successful ceramic fixation extending over larger areas. This is fundamental for future applications of arbitrarily shaped implants.     

Comparative characterization of oligomeric precursors intended for injectable implants

The use of injectable materials is a simple approach for drug delivery and tissue repair, in, e.g. minimally invasive surgery applications. If these materials are used past their glass transition temperature and have a low viscosity, they will be able to flow while delivered in situ. Whether these materials are to be used as low viscosity drug carriers or further crosslinked for tissue repair, there is a need for a better understanding of their handling properties. In this study, oligo(trimethylene carbonate) (oTMC) and oligo[D,L‐lactide‐co‐(ε‐caprolactone)] (oDLLA‐co‐CL) of various molecular weights within a relevant injectability range were synthesized via ring‐opening polymerization. The materials were comparatively characterized by ¹H NMR spectroscopy, differential scanning calorimetry, gel permeation chromatography, and rheological measurements. After comparing the viscosities and molecular weights of the materials, it was concluded that oDLLA‐co‐CLs were, generally, better suited as an injectable in situ crosslinking network, whereas oTMCs were found to be better candidates as injectable drug carriers. This study provides useful data and guidelines on the use of these and other similar oligomers intended for injectable implants. Copyright © 2012 John Wiley & Sons, Ltd.     

3D-Printing of Drug-Eluting Implants: An Overview of the Current Developments Described in the Literature

The usage of 3D-printing for drug-eluting implants combines the advantages of a targeted local drug therapy over longer periods of time at the precise location of the disease with a manufacturing technique that easily allows modifications of the implant shape to comply with the individual needs of each patient. Research until now has been focused on several aspects of this topic such as 3D-printing with different materials or printing techniques to achieve implants with different shapes, mechanical properties or release profiles. This review is intended to provide an overview of the developments currently described in the literature. The topic is very multifaceted and several of the investigated aspects are not related to just one type of application. Consequently, this overview deals with the topic of 3D-printed drug-eluting implants in the application fields of stents and catheters, gynecological devices, devices for bone treatment and surgical screws, antitumoral devices and surgical meshes, as well as other devices with either simple or complex geometry. Overall, the current findings highlight the great potential of the manufacturing of drug-eluting implants via 3D-printing technology for advanced individualized medicine despite remaining challenges such as the regulatory approval of individualized implants.     

生物可降解镁合金骨科植入材料的临床应用及其有限元分析

在骨-器械界面建立和维持成熟骨是骨科植入材料长期成功的关键. 镁合金由于其生物可降解性、天然骨组织的力学相似性以及成骨潜力, 并且在体内不抑制间充质干细胞(hBMSCs)的成骨特性, 成为有前途的承重骨科植入物的候选材料. 但其高降解率和植入物相关感染的风险以及不佳的力学性能, 对其临床应用提出了巨大的挑战. 有限元分析方法能对复杂结构、形态、载荷和材料力学性能进行应力分析, 可有效地帮助临床医生了解镁合金植入器械的应力及生物力学性能.     

Mathematical modeling of drug delivery from cylindrical implantable devices

A mechanistic mathematical model applicable to the controlled dispersed‐drug release from cylindrical device such as implantable drug delivery system was derived. Analytical solutions based on the pseudosteady state approximation are derived taken account an exact external medium volume. The model prediction is accurate when the initial drug load is higher than the drug solubility in the polymer. The results obtained are compared with the analytical solutions available in the literature. The equations are corroborated by comparison with experimental profiles reported in the literature for sink conditions and non sink conditions. The evolution of concentration distribution profiles is compared for different volume of external medium. A reduction in the volume of the external solution leads to an increase in the concentration on the surface of the device, which determines decreases in the release of drug. One criterion for determining whether the volume of external solution should be considered for the prediction of drug release from cylindrical devices is established. This criterion is based on establishing a maximum percentage error allowed in the values of amount of drug released. The usefulness of the model is focused in the design of implant for controlled release of drug into a small volume of external medium of release. Copyright © 2014 John Wiley & Sons, Ltd.     

载银二氧化钛纳米管表面pH敏感膜构建及其抑菌特性

采用表面涂覆硅烷偶联剂KH550、两步光接枝、阳极氧化等方法,在钛表面成功制备出一种pH型敏感膜覆盖的载银二氧化钛(TiO2)纳米管阵列。利用扫描电镜(SEM)、透射电镜(TEM)、能谱分析(EDS)、原子吸收光谱(AAS)对该pH敏感膜覆盖的载银TiO2纳米管阵列理化性能进行了表征,采用抑菌环实验定性考察了样品的抗菌特性,并计算其抑菌率。结果表明,含银离子溶液在毛细管力作用下大量进入TiO2纳米管中,并在pH型敏感膜的调控下,使银离子在不同pH环境下具备不同的释放行为,从而达到良好的控释效果;载银TiO2纳米管的抑菌率与银离子负载量成正比,且抗菌性能持久。     

人工种植牙失败原因分析

目的分析人工种植牙失败原因,探讨其预防对策。方法回顾性分析240例种植牙患者,统计其失败发生率。分析失败与性别、年龄、糖尿病、吸烟、种植部位及牙周炎的关系。结果种植牙失败主要原因为年龄、糖尿病、吸烟及牙周炎,失败率为8.75%。种植牙失败者,≥60岁的患者失败率明显高于〈60岁的患者（P〈0.05）;糖尿病与吸烟因素具有显著性差异（P〈0.01）,有糖尿病与吸烟的患者种植牙失败率分别为24.1%与16.7%;牙周炎的患者失败率明显高于无牙周炎的患者。结论年龄、糖尿病、吸烟及牙周炎与种植牙成功率密切相关,临床上应针对性加以防治。     

The Use of Bone Substitutes in the Treatment of Bone Defects – the Clinical View and History

Summary: Bone has the ability to regenerate and remodel itself. In the clinic circumstances appear when bone defects do not heal spontaneously. These situations frequently result from trauma, congenital abnormities, infection or tumor resection. Hence, filling of the resulting defect by bone transplantation is a common practise with an increasing value in the re-establishment of the musculoskeletal system to promote bone healing. Since decades, efforts have been put to improve the effectiveness of bone substitutes. Conventional approaches with the use of ivory, animal and also human bone were not satisfactory. Negative effects like allergic reactions, rejection reactions, inflammations and other problems occurred. These led to implant failure, non union and amputation, to only mention a few. The introduction of bone banks and the development of standards in bone transplantation brought up the false hope to find a final solution for the treatment of bone loss. Disease transmissions (HIV) by allografts caused critical discussions. Despite all efforts, transplantation of autogenous cancellous bone is still the “gold standard” to induce bone healing. However, autografts are only limited available and are accompanied with high morbidity and mortality during the harvest. The problems associated with autologous and allogenous bone grafts promoted the development of multiple organic and inorganic bone substitutes. Well established substitutes at the present are demineralised bone matrix (DBM), composites and calcium phosphates (hydroxyl apatite and tri-calcium phosphate). These osteoconductive substances have shown to improve new bone formation. Nevertheless, clinical application of these materials is merely successful in a good bony environment but does not induce large progress in critical bone defects.