Synthesis and Properties of PGS-Li Scaffold

Lithium ion-doped polyglycerol sebacate scaffold(PGS)-Li was synthesized by adding lithium ions to polyglycerol sebacate(PGS) during its crosslinking process due to the specific effects of lithium ions on periodontal ligament cells, cementoblasts and the eminent performance of PGS. The molecular mass, composition, structure, porosity, thermal properties, and hydrophilicity of the composite were characterized by gel permeation chromatography(GPC), Fourier transform infrared spectroscopy(FTIR), inductively coupled plasma optical emission spectrometer(ICP-OES), scanning electron microscopy(SEM), X-ray photoelectron spectroscopy(XPS), thermogravimetric analyzer(TGA) and contact angle measurments, and the degradation of the material was evaluated by in vitro degradation experiments. The biological activity of PGS-Li scaffold was detected by calcein-AM staining and cytotoxicity test. The results indicate that PGS-Li scaffold has been successfully synthesized, which has similar composition and structure to PGS, but slightly larger molecular weight. In addition, the porosity and pore size of PGS-Li scaffold ba-sically meet the requirements of engineering scaffold materials and the seaffold shows better performance in terms of hydrophilicity and thermal stability than PGS. In vitro degradation experimental results show that the degradation rate of PGS-Li scaffold is higher than that of PGS. What's more, the results of cytotoxicity test and cell staining show that there is no significant difference in the proliferation and cell morphology of cementoblasts.     

Characterization of Nanostructures in Acellular Cementum of Human Tooth Roots

Determining the microstructure in human cementum might help us design new kinds of replacement materials for the treatment of teeth injury and disease. The authors characterized the nanostructures in the cementum of health human teeth via scanning electronic microscopy(SEM). It was found that the acellular cementum is mainly composed of two kinds of nanostructures―inorganic nanoparticles and organic nanofibers. And the inorganic nanoparticles show a tendency to arrange along the organic nanofibers. Based on the micro-molding in capillary strategy, the distribution of organic component in acellular cementum was copied with UV curable resin. After removing the inorganic nanoparticles by acid etching, many isolated spindle shape nanopores were left in polymer, which su- ggested that the inorganic nanoparticles should have been isolated by the organic component in cementum, and should be oval or nanosheet in shape. We hope the present work could provide reference for the biomimetic preparation of tissue engineering materials, and help us design new types of tooth implant.     

Early results of transcutaneous injection laryngoplasty with micronized acellular dermis versus type-I thyroplasty for glottic incompetence dysphonia due to unilateral vocal fold paralysis

Medialization thyroplasty (type I) has become the gold standard to improve glottic closure due to unilateral vocal fold paralysis. A newer injection method utilizing homologous collagen from cadaveric human tissue has been described as an attractive alternative as no donor site is required, there is a very low risk of hypersensitivity, and the intact, acellular collagen fibers may suffer a reduced long-term reabsorption rate. Preliminary results on eight patients comparing presurgical and postsurgical parameters (perceptual, stroboscopic, acoustic, and aerodynamic) revealed comparable results when compared with a control group of individuals, age- and sex-matched, that had undergone standard medialization thyroplasty (type I). Further study is needed to assess the long-term results with this minimally invasive method of vocal fold medialization.     

Synchrotron radiation analysis of possible correlations between metal status in human cementum and periodontal disease

Periodontitis is a serious disease that affects up to 50% of an adult population. It is a chronic condition involving inflammation of the periodontal ligament and associated tissues leading to eventual tooth loss. Some evidence suggests that trace metals, especially zinc and copper, may be involved in the onset and severity of periodontitis. Thus we have used synchrotron X‐ray fluorescence imaging on cross sections of diseased and healthy teeth using a microbeam to explore the distribution of trace metals in cementum and adhering plaque. The comparison between diseased and healthy teeth indicates that there are elevated levels of zinc, copper and nickel in diseased teeth as opposed to healthy teeth. This preliminary correlation between elevated levels of trace metals in the cementum and plaque of diseased teeth suggests that metals may play a role in the progress of periodontitis.     

Elastic modulus of human cementum

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3D porous acellular cartilage matrix scaffold with surface mediated sustainable release of TGF-β3 for cartilage engineering

Acellular tissue matrix scaffolds are much closer to tissue’s complex natural structure and biological characteristics, thus assess great advantages in cartilage engineering. We used rabbit costal cartilage to prepare acellular microfilaments and further 3D porous acellular cartilage scaffold via crosslinking. Poly(l-lysine)/hyaluronic acid (PLL/HA) multilayer film was then built up onto the surface of the resulting porous scaffold. Furthermore, TGF-β3 was loaded into the PLL/HA multilayer film coated scaffold to obtain a 3D porous acellular cartilage scaffold with sustained releasing of TGF-β3 up to 60 days. The success of this project will provide a new way for the treatment of articular cartilage defects. Meanwhile, the anchoring and on-site sustained releasing of growth factors mediated by polyelectrolyte multilayered film can also provide a new method for improving the biocompatibility and the biofunctionality for other implanted biomaterials.     

Evaluation of Laser Ablation Inductively Coupled Plasma Mass Spectrometry for the Quantitative Determination of Lead in Different Parts of Archeological Human Teeth

ABSTRACT

The lead content of teeth or tooth-parts has been used a biomarker of cumulative lead exposure in clinical, epidemiological, environmental, and archaeological studies. Through the application of laser ablation inductively coupled plasma mass spectrometry, a pilot study of the micrometer-scale distribution and quantification of lead was conducted for two human teeth obtained from an archaeological burial site in Manhattan, New York, USA. Lead was highly localized within each tooth, with accumulation in circumpulpal dentine and cementum. The maximum localized lead content in circumpulpal dentine was remarkably high, almost 2000 µg g^?1, compared to the mean enamel and dentine content of about 5 µg g^?1. The maximum lead content in cementum was approximately 700 µg g^?1. The large quantity of cementum found in the teeth suggested that the subjects had hypercementosis (excess cementum formation) of the root, a condition reported to have been prevalent among African-American slave populations. The distribution of lead in these human teeth was remarkably similar to the distribution that we previously reported in the teeth of present-day lead-dosed goats. The data shown demonstrate the feasibility of using laser ablation inductively coupled plasma mass spectrometry to examine lead exposure in archaeological studies.     

人牙骨质的弹性模量

报道了人牙骨质弹性模量的测定,测得100个试件的弹性模量的平均值为E=2398±0.455GPa.制作试件的人牙包括切牙、尖牙、双尖牙和磨牙.在AG₁0TA型电子万能材料试验机上完成测试.用数理统计方法论证了测试数据服从正态分布.根据牙本质与牙骨质的弹性模量差异很大,阐述了:1对根尖牙骨质分布较多作了力学分析;2牙的应力分析必须考虑牙骨质的性质.