羟磷灰石加阿霉素瘤内注射治疗小鼠肝癌的实验研究

作者通过动物实验研究了羟磷灰石(HA)的抑癌效果及其机理。将80只移植有H_(22)肝癌的BALB/c小鼠分为4组:Ⅰ组HA加阿霉素(ADM)瘤内注射;Ⅱ组HA瘤内注射;Ⅲ组ADM瘤内注射;Ⅳ组未给药。结果Ⅰ～Ⅲ组的肿瘤生长抑制率分别为65.9％、41.9％及51.1％。Ⅰ～Ⅳ组的生存时间分别为32、22、26及18天。作者认为HA抑癌作用的机理可能是:①直接界面作用;②诱导组织纤维化;③免疫激活作用;④药物载体和缓释作用。结果显示HA加ADM瘤内注射可能成为一种治疗恶性肿瘤的新方法。     

生物陶瓷微颗粒引发的细胞和组织损害

为论证生物陶瓷烧结不完全形成的微颗粒（〈5μm）引发细胞和组织损害的假设，对该类颗粒在体内和体外的细胞和组织损害进行了研究：（1）对4种双相生物陶瓷（BCP）进行细胞毒性试验。试验发现所有的浸出液出现细胞毒性，但是浸出液经离心后，毒性消失；（2）对羟基磷灰石（HA）、p磷酸三钙（pTCP）和40％pTCP／60％HA混合物微颗粒进行细胞抑制实验。结果显示随着微颗粒的浓度增加，成纤维细胞活力下降；而当微颗粒浓度达到一万个／细胞时，细胞活力和增殖能力完全消失；（3）HA，pTCP和BCP陶瓷颗粒（500-1500um）被植入到兔子股骨远端，种植12周后β-TCP的降解率为40％，BCP为5％，但是HA接近不降解。新骨形成在β-TCP（21％）和HA（18％）比BCP（12％）更为明显。同时BCP颗粒的周围有很多的微颗粒形成，可见吞噬细胞吞噬微颗粒，形成吞噬体。以上结果提示，微颗粒可能是局部炎症和细胞损害的首要原因，而且有可能影响骨形成。因此，我们必须注意生物陶瓷烧结的重要性，它们的烧结不良就可形成微颗粒，引发细胞和组织的损害。特别是BCP陶瓷含有两种需要不同烧结温度的粉体，它的烧结难度较高，很易形成微颗粒。     

两种生物陶瓷材料用于乳磨牙牙髓切断术的随机对照研究

目的:通过比较新型生物陶瓷材料iRoot BP Plus和三氧化矿物凝聚体（mineral trioxide aggregate,MTA）作为盖髓剂在乳磨牙牙髓切断术应用中的成功率,探讨iRoot BP Plus的临床应用价值。方法:按照纳入和排除标准收集2018年8至12月于北京大学口腔医学院·口腔医院儿童口腔科行全...     

Synthesis methods for nanosized hydroxyapatite with diverse structures

Hydroxyapatite (HAp) is the major mineral constituent of vertebrate bones and teeth. It has been well documented that HAp nanoparticles can significantly increase the biocompatibility and bioactivity of man-made biomaterials. Over the past decade, HAp nanoparticles have therefore increasingly been in demand, and extensive efforts have been devoted to develop many synthetic routes, involving both scientifically and economically new features. Several investigations have also been made to determine how critical properties of HAp can be effectively controlled by varying the processing parameters. With such a wide variety of methods for the preparation of HAp nanoparticles, choosing a specific procedure to synthesize a well-defined powder can be laborious; accordingly, in the present review, we have summarized all the available information on the preparation methodologies of HAp, and highlighted the inherent advantages and disadvantages involved in each method. This article is focused on nanosized HAp, although recent articles on microsized particles, especially those assembled from nanoparticles and/or nanocrystals, have also been reviewed for comparison. We have also provided several scientific figures and discussed a number of critical issues and challenges which require further research and development.     

Bioceramic materials in endodontics

During the past two decades, a number of major advances have been made in the field of bioactive ceramics used for endodontic treatment. This article reviews the physico-chemical and biological properties of bioceramic materials and the application of bioceramic technology to endodontics. Bioceramic materials, with their biocompatible nature and excellent physico-chemical properties, are widely used in endodontic applications. They can function as cements, root repair materials, root canal sealers and filling materials, which have the advantages of enhanced biocompatibility, potential increased root strength following obturation, antibacterial properties and sealing ability. New bioceramic materials have demonstrated the ability to overcome some of the significant limitations of earlier generations of endodontic materials. Most bioceramic materials have been shown to be biocompatible and have good physico-chemical characteristics, therefore having a potential use in clinical endodontics. Although in vitro studies on the use of bioceramic materials in endodontics have given encouraging results, randomized and double-blind clinical studies of sufficient length with these materials are needed to confirm long-term success following their use.     

新型生物陶瓷材料在儿童牙髓治疗中的临床研究进展

当代的儿童口腔医学，对乳牙和年轻恒牙的牙髓治疗理念越来越趋于"保守"，即在尽可能保存活髓组织或根部活髓组织的前提下达到治愈患牙的目的。这一理念的改变得益于口腔材料的发展，如MTA等由于其良好的性能及临床效果，已在儿童牙髓治疗中广泛应用，但其在操作性，美观性等方面依然存在一些不可避免的缺点。新型生物陶瓷材料，如iRoot BP、Biodentine等具有理想的理化性能和生物相容性，并且较好的解决了原有生物陶瓷材料的一些缺点，广泛应用于乳牙及年轻恒牙的间接牙髓治疗、直接盖髓术、牙髓切断术和牙髓血运重建术等治疗中。本文就新型生物陶瓷材料的特点及其在儿童牙髓治疗中的应用作一综述。     

骨髓间质干细胞复合多孔磷酸钙陶瓷修复兔颅骨缺损的研究

目的探讨以骨髓间质干细胞(MSCs)作为种子细胞、β-磷酸三钙(β-TCP)多孔生物陶瓷作为支架材料构建组织工程化人工骨，修复兔实验性颅骨标准缺损的可行性。方法选择5月龄新西兰大白兔34只，制作颅骨标准缺损后分成3组。A组(n=20)：分离培养兔同胎异体MSCs。体外扩增后接种到预制的β-TCP多孔生物陶瓷材料上，细胞-材料复合体经体外孵育后，无菌条件下植入颅骨缺损；B组(n=10)：采用单纯β-TCP材料修复兔颅骨缺损；C组(n=4)：兔实验性颅骨标准缺损区未做骨修复。术后6周和12周分别处死动物、取材，进行缺损区大体、组织学、组织化学和免疫组织化学分析。结果颅骨缺损处A组术后6周表面肉眼可见骨样组织形成，组织学提示材料部分降解，未降解吸收的材料孔洞内广泛分布着新生骨组织，成骨细胞外基质丰富，I型胶原染色阳性；术后12周，支架材料几乎完全降解，缺损区被新生骨组织所取代。B组术后6周，可见从缺损区边缘有新生骨组织向支架材料内长入，支架材料部分吸收；术后12周，可见从缺损区边缘长入到支架材料内的新生骨组织逐渐增多，但材料的中心部位未发现新生骨形成。C组术后12周，仅见少量骨组织从缺损区边缘向缺损区内长入，缺损中央大部分区域未得到修复。结论体外培养扩增的兔MSCs在不添加外源性生长因子的情况下，与pTCP复合植入后可以在体内诱导、分化为成骨细胞，并能够对标准的颅骨缺损进行有效的修复，可进一步推广应用。     

Furthering the understanding of silicate-substitution in α-tricalcium phosphate: An X-ray diffraction,X-ray fluorescence and solid-state nuclear magnetic resonance study

High-purity (SupT) and reagent-grade (ST), stoichiometric and silicate-containing α-tricalcium phosphate (α-TCP: ST0/SupT0 and Si-TCP x = 0.10: ST10/SupT10) were prepared by solid-state reaction based on the substitution mechanism Ca₃(PO₄)_(2-x)(SiO₄)_x. Samples were determined to be phase pure by X-ray diffraction (XRD), and Rietveld analysis performed on the XRD data confirmed inclusion of Si in the α-TCP structure as determined by increases in unit cell parameters; particularly marked increases in the b-axis and β-angle were observed. X-ray fluorescence (XRF) confirmed the presence of expected levels of Si in Si-TCP compositions as well as significant levels of impurities (Mg, Al and Fe) present in all ST samples; SupT samples showed both expected levels of Si and a high degree of purity. Phosphorus (³¹P) magic-angle-spinning solid-state nuclear magnetic resonance (MAS NMR) measurements revealed that the high-purity reagents used in the synthesis of SupT0 can resolve the 12 expected peaks in the ³¹P spectrum of α-TCP compared to the low-purity ST0 that showed significant spectral line broadening; line broadening was also observed with the inclusion of Si which is indicative of induced structural disorder. Silicon (²⁹Si) MAS NMR was also performed on both Si-TCP samples which revealed Q⁰ species of Si with additional Si Q¹/Q² species that may indicate a potential charge-balancing mechanism involving the inclusion of disilicate groups; additional Q⁴ Si species were also observed, but only for ST10. Heating and cooling rates were briefly investigated by ³¹P MAS NMR which showed no significant line broadening other than that associated with the emergence of β-TCP which was only realised with the reagent-grade sample ST0. This study provides an insight into the structural effects of Si-substitution in α-TCP and could provide a basis for understanding how substitution affects the physicochemical properties of the material.     

Bioinspired structure of bioceramics for bone regeneration in load-bearing sites

The major problem with the use of porous bioceramics as bone regeneration grafts is their weak mechanical strength, which has not been overcome to date. Here we described a novel way to solve this problem. Beta-tricalcium phosphate (β-TCP) bioceramics with a bioinspired structure were designed and prepared with a porous cancellous core (porosity: 70–90%) inside and a dense compact shell (porosity: 5–10%) outside that mimics the characteristics of natural bone. They showed excellent mechanical properties, with a compressive strength of 10–80 MPa and an elastic modulus of 180 MPa–1.0 GPa, which could be tailored by the dense/porous cross-sectional area ratio obeying the rule of exponential growth. The in vitro degradation of the bioinspired bioceramics was faster than that of dense bioceramics but slower than that of porous counterparts. The changes in mechanical properties of the bioinspired ceramics during in vitro degradation were also investigated. A concept of the bioinspired macrostructure design of natural bone was proposed which provided a simple but effective way to increase the mechanical properties of porous bioceramics for load-bearing bone regeneration applications. It should be readily applicable to other porous materials.