Elimination of methicillin‑resistant Staphylococcus aureus biofilms on titanium implants via photothermally‑triggered nitric oxide and immunotherapy for enhanced osseointegration

Background:Treatment of methicillin-resistant Staphylococcus aureus(MRSA)biofilm infections in implant placement surgery is limited by the lack of antimicrobial activity of titanium(Ti)implants.There is a need to explore more effective approaches for the treatment of MRSA biofilm infections.Methods:Herein,an interfacial functionalization strategy is proposed by the integration of mesoporous polydopamine nanoparticles(PDA),nitric oxide(NO)release donor sodium nitroprusside(SNP)and osteogenic growth peptide(OGP)onto Ti implants,denoted as Ti-PDA@SNP-OGP.The physical and chemical properties of Ti-PDA@SNP-OGP were assessed by scanning electron microscopy,X-ray photoelectron spectroscope,water contact angle,photothermal property and NO release behavior.The synergistic antibacterial effect and elimination of the MRSA biofilms were evaluated by 2′,7′-dichlorofluorescein diacetate probe,1-N-phenylnaphthylamine assay,adenosine triphosphate intensity,O-nitrophenyl-β-D-galactopyranoside hydrolysis activity,bicinchoninic acid leakage.Fluorescence staining,assays for alkaline phosphatase activity,collagen secretion and extracellular matrix mineralization,quantitative real‑time reverse transcription‑polymerase chain reaction,and enzyme-linked immunosorbent assay(ELISA)were used to evaluate the inflammatory response and osteogenic ability in bone marrow stromal cells(MSCs),RAW264.7 cells and their co-culture system.Giemsa staining,ELISA,micro-CT,hematoxylin and eosin,Masson's trichrome and immunohistochemistry staining were used to evaluate the eradication of MRSA biofilms,inhibition of inflammatory response,and promotion of osseointegration of Ti-PDA@SNP-OGP in vivo.Results:Ti-PDA@SNP-OGP displayed a synergistic photothermal and NO-dependent antibacterial effect against MRSA following near-infrared light(NIR)irradiation,and effectively eliminated the formed MRSA biofilms by inducing reactive oxygen species(ROS)-mediated oxidative stress,destroying bacterial membrane integrity and causing leakage of intracellular components(P<0.01).In vitro experiments revealed that Ti-PDA@SNP-OGP not only facilitated osteogenic differentiation of MSCs,but also promoted the polarization of pro-inflammatory M1 macrophages to the anti-inflammatory M2-phenotype(P<0.05 or P<0.01).The favorable osteo-immune microenvironment further facilitated osteogenesis of MSCs and the anti-inflammation of RAW264.7 cells via multiple paracrine signaling pathways(P<0.01).In vivo evaluation confirmed the aforementioned results and revealed that Ti-PDA@SNP-OGP induced ameliorative osseointegration in an MRSA-infected femoral defect implantation model(P<0.01).Conclusions:Ti-PDA@SNP-OGP is a promising multi-functional material for the high-efficient treatment of MRSA infections in implant replacement surgeries.

The role of exosomes in bone remodeling and osseointegration of implants

Dental implant is an effective method in the treatment of missing teeth.The process of osseointegration of implant teeth involves the coordinated operation of immune system and bone system.The interaction between cells is closely related to bone formation and repair.Exosomes are important intercellular communication molecules.They were originally found in the supernatant of sheep erythrocytes cultured in vitro.They are micro vesicles with a diameter of 40~150 nm.They exist in a variety of cells and body fluids.They enter the target cells by endocytosis and transport,affecting the expression of cell genes and changing the fate of cells.It has an important regulatory function in the microenvironment of implant bone binding.It plays a role in bone remodeling through small molecular RNA,specific proteins and other growth factors secreted by different cells.This article reviews the role of bone derived cellderived exosomes in bone remodeling and their function in implant osseointegration.

Effect of High Positive Acceleration(+Gz) Environment on Dental Implant Osseointegration:A Preliminary Animal Study

Objective To observe the effect of high positive acceleration(+Gz) environment on dental implant osseointegration in a rabbit model and to investigate its mechanism.Methods Forty-eight New Zealand white rabbits were randomly divided into 6 groups. The rabbit’s mandibular incisors were extracted and 1 implant was placed in each socket immediately. After 1 week of rest, the rabbits were exposed to a high +Gz environment, 3 times a week. The rabbits were sacrificed at 3 weeks(2 weeks +Gz exposure), 5 weeks(4 weeks +Gz exposure), and 12 weeks(4 weeks +Gz exposure and 7 weeks normal environment) after surgery, respectively. Specimens were harvested for micro-CT scanning, histological analysis, and real-time polymerase chain reaction examination.Results Compared with those in the control group, the mRNA expression levels of bone morphogenetic protein-2(BMP-2), osteopontin(OPN), and transforming growth factor-β1(TGF-β1)were significantly lower(P < 0.05), while the mRNA expression level of receptor activator of nuclear factor κB ligand(RANKL) and the RANKL/osteoprotegerin(OPG) ratio were significantly higher(P < 0.05)at 3 weeks;values of bone volume fraction, trabecular number, bone-implant contact(BIC), and TGF-β1 and OPG mRNA expression levels were significantly lower(P < 0.05), and the value of trabecular separation, RANKL mRNA expression level and RANKL/OPG ratio were significantly higher(P < 0.05) at 5 weeks;and the value of BIC was still significantly lower(P < 0.05) at 12 weeks in the experimental group.Conclusion Early exposure to the high +Gz environment after implant surgery might have an adverse effect on osseointegration, and its mechanism could be related to the inhibition of osteoblast activity and promotion of osteoclast activity.

Enhanced Biocompatibility and Osseointegration of Calcium Titanate Coating on Titanium Screws in Rabbit Femur

This study aimed to examine the biocompatibility of calcium titanate(CaTiO3) coating prepared by a simplified technique in an attempt to assess the potential of CaTiO3coating as an alternative to current implant coating materials. CaTiO3-coated titanium screws were implanted with hydroxyapatite(HA)-coated or uncoated titanium screws into medial and lateral femoral condyles of 48 New Zealand white rabbits. Imaging, histomorphometric and biomechanical analyses were employed to evaluate the osseointegration and biocompatibility 12 weeks after the implantation. Histology and scanning electron microscopy revealed that bone tissues surrounding the screws coated with CaTiO3were fully regenerated and they were also well integrated with the screws. An interfacial fibrous membrane layer, which was found in the HA coating group, was not noticeable between the bone tissues and CaTiO3-coated screws. X-ray imaging analysis showed in the CaTiO3coating group, there was a dense and tight binding between implants and the bone tissues; no radiation translucent zone was found surrounding the implants as well as no detachment of the coating and femoral condyle fracture. In contrast, uncoated screws exhibited a fibrous membrane layer, as evidenced by the detection of a radiation translucent zone between the implants and the bone tissues. Additionally, biomechanical testing revealed that the binding strength of CaTiO3coating with bone tissues was significantly higher than that of uncoated titanium screws, and was comparable to that of HA coating. The study demonstrated that CaTiO3coating in situ to titanium screws possesses great biocompatibility and osseointegration comparable to HA coating.

Adhesion-enhancing coating embedded with osteogenesis-promoting PDA/HA nanoparticles for peri-implant soft tissue sealing and osseointegration

Following dental implantation,the characteristic bacterial milieu of the oral cavity may lead to peri-implant inflammation,which can negatively impact osseointegration and cause implant failure.To improve soft tissue sealing around the implant,enhance osseointegration,and improve implant success rates,this paper proposes a composite multifunctional coating(PHG)prepared using gelatin and polydopamine/hydroxyapatite nanoparticles,investigates the effects of this novel coating on cell adhesion,proliferation,antibacterial activity,osteogenic differentiation,and evaluates its immune-related properties.The PHG coating was proved to have satisfactory hydrophilicity and wettability for cell attachment.Furthermore,it improved the expression of adhesion-related genes and proteins in human gingival fibroblasts,indicating its adhesion-promoting effect.Additionally,bone marrow mesenchymal stem cells exhibited strong osteogenic differentiation potential and mineralization on PHG-coated surfaces.Notably,the PHG coating exhibited antibacterial activity against Streptococcus mutans,as well as anti-inflammatory effects,potentially via the regulation of macrophages.Therefore,the proposed PHG coating may promote soft tissue sealing and bone bonding,providing a potential strategy for the surface modification of dental implants.

Early Osseointegration of Implants with Cortex-like TiO2 Coatings Formed by Micro-arc Oxidation:A Histomorphometric Study in Rabbits

In our previous studies, a novel cortex-like Ti O2 coating was prepared on Ti surface through micro-arc oxidation（MAO） by using sodium tetraborate as electrolyte, and the effects of the coating on cell attachment were testified. This study aimed to investigate the effects of this cortex-like MAO coating on osseointegration. A sand-blasting and acid-etching（SLA） coating that has been widely used in clinical practice served as control. Topographical and chemical characterizations were conducted by scanning electron microscopy, energy dispersive X-ray spectrometer, X-ray diffraction, contact angle meter, and step profiler. Results showed that the cortex-like coating had microslots and nanopores and it was superhydrophilic, whereas the SLA surface was hydrophobic. The roughness of MAO was similar to that of SLA. The MAO and SLA implants were implanted into the femoral condyles of New Zealand rabbits to evaluate their in-vivo performance through micro-CT, histological analysis, and fluorescent labeling at the bone-implant interface four weeks after surgery. The micro-CT showed that the bone volume ratio and mean trabecular thickness were similar between MAO and SLA groups four weeks after implantation. Histological analysis and fluorescent labeling showed no significant differences in the bone-implant contact between the MAO and SLA surfaces. It was suggested that with micro/nanostructure and superhydrophilicity, the cortex-like MAO coating causes excellent osseointegration, holding a promise of an application to implant modification.

Evaluation of the osseointegration of dental implants coated with calcium carbonate:an animal study

In an attempt to overcome the limitations of titanium in dental and orthopaedic clinical applications, a new method has been developed to prepare calcium carbonate coatings on sandblasted and acid-etched （SA） titanium implants. The purpose of this study was to investigate the effect of calcium carbonate-SA （CC-SA） implants on osseointegration in vivo. The surfaces of SA and CC-SA implants were characterised for surface morphology and surface chemistry. Subsequently, these two kinds of implants were implanted in the femoral condyles of rabbits. The implants were retrieved and prepared for histological and histomorphometric evaluation 1, 2, 4, 8 and 12 weeks after implantation. Significantly higher values of bone-to-implant contact of the entire implant except the gap area （BIC_ALL） and the bone-to-implant contact of the gap area （BIC_GAP） were found in animals with the CC-SA implants than in those with the SA implants at 4 weeks. Higher values of total gap bone were found in those with the CC-SA implants than in those with the SA implants at 1, 2 and 4 weeks. In conclusion, the current findings demonstrate that the calcium carbonate coating can improve and accelerate the early ingrowth of bone and osseointegration at the early healine phase. This may reduce clinical healinE times and thus improve implant success rates.

Effects of bone morphogenetic protein on the osseointegration of porous-surfaced implants:An experimental study in rabbits

Objective： Research on enhancing early osseointegration of cementless implants to improve early fixation and reducing of risk of loosening. Methods ： Thirty New Zealand rabbits were divided into two groups at random. BMP combined with DBM 30 mg was inserted around the prosthesis in 15 rabbits as experimental group, the remaining rabbits were served as control group. After 4, 8, and 12 weeks, five rabbits were sacrificed in each group. The humerus with the implants were retrieved. Bone ingrowth was analyzed by none-decalcification bone ground section and biomechanical test. Results： At the end of 4 and 8 weeks the osseointegration rates of BMP group were higher than those of control （P 〈 0.05）. The ultimate shear strength between BMP treated implantation and the control was the same as the results in osseointegration rates at 4, 8 weeks （P 〈 0.05）. However, there was no difference between the treated and untreated group in the osseointegration rate and ultimate shear strength at 12 weeks （P 〉 0.05）. Conclusion： BMP combination can enhance bone growth into gaps around cementless implants, especially in the early postoperative period.

Evaluation of titanium dental implants after early failure of osseointegration by means of X-ray photoelectron spectoscopy, electron microscopy and histological studies

In this work, we analysed 56 clinically failed and retrieved implants by means of scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and histological studies. The surface contamination was compared to that of unused control implants and with that of the same implants after cleaning in a basic medium. The surfaces of the unused implants presented considerable contamination. In particular, high levels of carbon were detected. The nature of this C was elucidated by XPS analysis of the lubricant used in the machining process. The same contamination was observed in the retrieved implants. Histological studies were carried out by means of light microscopy. Fibrosis and granulomatous lesions were detected in the tissues. XPS analysis indicated the presence of traces of other elements (Na, Ca, Zn, S, F, etc.) that were not related to impurities in cpTi. We examined a cleaning process in a basic medium that eliminates the organic components of the implant surfaces. The cleaned implants were implanted in the patients and the results were excellent. None of the implants failed in following 7 months.

A biomimetic gradient porous cage with a micro-structure for enhancing mechanical properties and accelerating osseointegration in spinal fusion

Objectives:Spinal fusion is a widely employed treatment of patients with degenerative disc disease,in which a cage is used to replace the disc for spinal fusion.But it often fails for insufficient mechanical strength and poor osseointegration.Here,we designed a polyether-ether-ketone(PEEK)/tantalum(Ta)composite cage with a biomimetic gradient porous micro-structure,simultaneously enhancing mechanical properties and accelerating osseointegration in spinal fusion.Materials and methods:In the study,based on the mechanical performances of PEEK and osteogenic potential of Ta,and the three-dimensional(3D)structures of cuttlebone and vertebra,the cages were respectively 3D printed by pure PEEK,PEEK with 5 wt%Ta(PEEK/Ta-5),PEEK with 10 wt%Ta(PEEK/Ta-10)and PEEK with 15 wt%Ta(PEEK/Ta-15),then verifiedin vitroand in sheep cervical fusion model systematically.Results:Vertebral Gyroid structure PEEK/Ta-15 cage exhibited superior mechanical properties than Cuttlebone-like structure PEEK/Ta-15 cage,closer to the cervical vertebra.Furthermore,PEEK/Ta-15 cage with higher Ta microparticles in PEEK provided a biomimetic gradient porous micro-structure with higher surface energy,guiding cell biological behavior,promoting new bone penetration,and accelerating osseointegrationin vivo.Conclusion:In conclusion,the study designed a biomimetic gradient porous cage with a micro-structure for enhancing mechanical properties,accelerating osseointegration and forming an anatomical lock in the fusion segment through composites,mechanical efficiency,surface extension,and pores.

Surface modification of titanium implant for repairing/improving microenvironment of bone injury and promoting osseointegration

Bone injury and implantation operation are often accompanied by microenvironment damage of bone tis-sue,which seriously affects the process of osseointegration of implants,especially for titanium(Ti)-based bioinert materials.Thus,repairing or improving the microenvironment of damaged bone tissue is of great significance for bone rescue,reconstruction,and regeneration,which is still a major medical challenge.Oxidative stress(OS)and oxygen(O_(2))deficiency are considered to be specific physiological signals of the bone-injury microenvironment.From the above background,a coating consisting of manganese dioxide(MnO_(2))nanoenzyme and strontium(Sr)ions was fabricated on the surface of the Ti implant via a one-step hydrothermal treatment.MnO_(2) nanoenzyme presented in the coating alleviated OS and O_(2) deficiency at the injury site by catalyzing the decomposition of abundant endogenous H_(2)O_(2) around the modified Ti implants into O_(2).In addition,Sr ions were released from the surface of the implant at a certain rate in a body-fluid environment,further promoting the adhesion,growth,and osteogenic differentiation of mesenchymal stem cells.More importantly,a Sprague Dawley rat femur model demonstrated that the modified Ti implant showed significant potential to accelerate bone tissue reconstruction in vivo.In sum-mary,the present system provides a new idea for the treatment of bone injury and the development of new orthopedic implants.

聚多巴胺仿生法制备的聚己内酯螺钉羟基磷灰石涂层对兔前交叉韧带重建后骨整合的影响

目的:利用聚多巴胺仿生法在聚己内酯(PCL)螺钉表面制备羟基磷灰石(HA)涂层,评价其对前交叉韧带重建后骨整合的影响。方法:通过3D打印设计制作多孔PCL螺钉,利用聚多巴胺仿生法制备HA涂层。选取20只成年雄性新西兰大白兔,于双侧后肢建立前交叉韧带重建模型,左右侧随机植入含HA涂层(实验组)及不含HA涂层的(对照组)PCL螺钉,术后6、12周分别处死10只,取膝关节,制备股骨-前交叉韧带-胫骨复合物标本,通过Masson染色、Micro-CT检测、生物力学测试评价螺钉与骨组织界面的骨整合情况。结果:Masson染色结果示术后6、12周两组螺钉周围均有较多新生骨小梁形成并向螺钉孔隙内生长,但实验组新生骨小梁的量和深度均优于对照组。Micro-CT示术后6、12周两组螺钉界面骨隧道内新生骨逐渐增加,且实验组周围新生骨量多于对照组。与术后6周相比,两组术后12周骨体积分数、骨小梁数量、骨密度均升高,骨小梁分离率降低;术后6、12周,实验组以上指标均优于对照组(P<0.05)。术后6、12周实验组最大拉力峰值均高于对照组[(39.98±5.32)N vs(27.46±6.95)N,(62.64±8.76)N vs(50.15±6.48)N](P<0.05)。结论:聚多巴胺仿生法制备的PCL螺钉的HA涂层能够促进前交叉韧带重建术后骨整合,提高界面螺钉生物力学稳定性。

3D-printed surface promoting osteogenic differentiation and angiogenetic factor expression of BMSCs on Ti6Al4V implants and early osseointegration in vivo

Three-dimensional-printed(3 D-P) titanium implants display many advantages, such as design flexibility,higher efficiency, the capability to easily construct complex or customized structures, etc., and is believed to potentially replace traditional implants. However, the biological performance of the 3 D-P titanium surface has not been investigated systematically. Herein, we analyzed the surface characteristics of 3 D-P Ti6 Al4 V implants and evaluated the biological responses of bone marrow derived mesenchymal stromal cells(BMSCs) to the 3 D-P surface in vitro. Moreover, after implantation into the rat femoral condyle for3 and 6 weeks, the osseointegration performance was evaluated. The results showed the 3 D-P Ti6 Al4 V implant presented distinct fluctuant macroscale rough surface and relatively better hydrophilicity which enhanced the adhesion, proliferation, osteogenic differentiation and angiogenetic factor expression of BMSCs. Moreover, the in vivo osseointegration performance was also better than that of the control group at the early stage. The present study suggested the 3 D-P titanium alloy is a promising candidate to be used as implant material.

Strategies for creating living, additively manufactured, open-cellular metal and alloy implants by promoting osseointegration,osteoinduction and vascularization: An overview

Additive manufacturing of porous, open-cellular metal or alloy implants, fabricated by laser or electron beam melting of a powder bed, is briefly reviewed in relation to optimizing biomechanical compatibility by assuring elastic(Young's) modulus matching of proximate bone, along with corresponding pore sizes assuring osseointegration and vasculature development and migration. In addition, associated, requisite compressive and fatigue strengths for such implants are described. Strategies for optimizing osteoblast(bone cell) development and osteoinduction as well as vascularization of tissue in 3 D scaffolds and tissue engineering constructs for bone repair are reviewed in relation to the biology of osteogenesis and neovascularization in bone, and the role of associated growth factors, bone morphogenic proteins, signaling molecules and the like. Prospects for infusing hydrogel/collagen matrices containing these cellular and protein components or surgically extracted intramedullary(bone marrow) concentrate/aspirate containing these biological and cell components into porous implants are discussed, as strategies for creating living implants, which over the long term would act as metal or alloy scaffolds.

金属有机框架与种植体表面改性及其应用

背景:近年来,金属有机框架由于其特有性质在生物医学领域应用广泛,可以将金属有机框架应用于种植体表面改性,以改善其生物学性能,提高手术成功率。目的:介绍种植体表面改性领域常用的金属有机框架以及种植体表面金属有机框架改性的制备和作用机制。方法:采用计算机检索中国知网、PubMed和Web of Science数据库中有关金属有机框架应用于种植体表面改性的研究资料,选取发表于2010-2023年的相关文献,最终纳入64篇文献进行综述分析。结果与结论:①金属有机框架具有孔隙率高、比表面积大及空间结构多样等性质,作为一种生物活性材料,金属有机框架在组织工程和再生医学中逐渐引起重视。②种植体改性领域常用的金属有机框架类型主要有3种:类沸石骨架材料最常作为载体应用,负载各种药物和生物分子,MIL系列材料适用于药物载体和纳米酶,Bio-金属有机框架因结构多样而应用广泛,突出特点是优异的生物安全性。③金属有机框架改性的种植体材料制备方法大致分为两类,第一类是将已合成的金属有机框架结合到预处理植入材料上,第二类是在预处理的材料表面原位合成金属有机框架。④种植体表面的金属有机框架通过降解释放自身组分、负载药物、催化活性反应及与其他材料联合等多种机制,赋予种植体抗菌抗炎促进骨整合的特性,但金属有机框架涂层制备方法还需要进一步完善,同时应深入探究材料后续代谢和分布问题,积极推动其在临床上的应用。

钛表面氨基杂化介孔硅基纳米形貌保护涂层的构建及成骨效果评价

目的在钛纳米管(titanium nanotube,TNT)形貌表面原位沉积可降解的氨基杂化介孔硅(amino-hy-brid mesoporous silica,AHMS),探讨其对纳米形貌的保护作用及成骨效应。方法通过阳极氧化法和油水两相法依次制备TNT、TNT@AHMS作为实验组,以酸蚀钛作为对照组(Ti);通过改变硅源用量比探索合成参数(3∶1,1∶1,1∶3);扫描电镜观察其表面形貌、水接触角测定仪测定亲水性、X射线光电子能谱仪分析元素组成;利用纳米压痕检测及超声震荡仪体外观察TNT@AHMS机械强度形貌保持效果;体外模拟浸泡实验观察其降解行为;利用MC3T3-E1细胞系观察细胞在材料表面的黏附、增殖和分化能力;利用SD大鼠股骨植入模型和Micro-CT验证AHMS对TNT形貌的保护作用及骨结合效果。结果TNT、TNT@AHMS形貌均制备成功,硅源用量比为1:3;扫描电镜可见钛纳米管间均匀覆盖AHMS涂层,介孔径约4 nm;AHMS掺入后材料表面为亲水性(12.78°),可检测到氨基基团(NH2-)存在,并在体外12 h内即可降解完全,从而重新暴露TNT活性形貌,累计硅释放量为10 ppm;纳米压痕检测表明TNT@AHMS具有更理想的表面机械强度。电镜观察可见TNT在AHMS的保护下较好地保持了自身形貌,而TNT组出现了严重剥脱。此外TNT@AHMS表面细胞的早期黏附、增殖,ALP活性以及植入4周后的骨体积分数均显著高于TNT组。结论表面沉积AHMS可以起到保护TNT纳米形貌的作用,在发挥其生物学功效的同时,还进一步增强了成骨能力。该方案为未来纳米形貌修饰钛种植体的研发提供了新的思路。

基于3D打印工艺的多孔植入物的设计制造及应用

通过有限元模拟不同类型多孔结构,进行分析并筛选出适用骨科医疗器械的多孔结构,并用3D打印技术对该多孔结构(泰森多边形结构)进行加工制造。该文对3D打印的泰森多边形多孔结构的力学性能(拉伸、压缩和弯曲)和骨长入性能进行了系统研究。力学测试结果表明,3D打印泰森多边形结构的拉伸、压缩和弯曲性能明显优于人体皮质骨,弹性模量与人体皮质骨相当。动物实验结果表明,植入比格犬后3个月,多孔结构内有明显的骨长入。该研究为多孔结构在骨植入医疗器械上的应用提供了一定的理论依据。

磁场成骨效应在口腔领域的应用及机制研究进展

磁场是一种安全、无创的物理治疗方法。大量研究证实磁场具有良好的成骨效应,在加速正畸牙移动、促进种植体骨整合、促进骨折愈合和提高牵张成骨效果等方面有一定的临床应用价值,有望成为治疗口腔疾病的一种有效辅助手段。为更好地将磁场应用于临床,本文就磁场在口腔领域的应用、对骨组织细胞的生物学效应和磁场调控骨代谢的分子机制三方面进行综述。磁场对骨组织细胞的生物学效应主要体现为促进成骨细胞和间充质干细胞的成骨,降低骨细胞的凋亡率,对破骨细胞的影响则尚无定论。在分子层面,骨组织细胞感应并响应磁刺激,磁信号经位移电流、洛伦磁力和自由基对效应等机制转变为生物可识别的电信号,进而激活下游P2嘌呤能受体、腺苷受体信号通路、转化生长因子-β受体信号通路、哺乳动物雷帕霉素靶蛋白(mammalian target of rapamycin,m TOR)和Notch通路等信号网络。此外,本文还探讨了影响磁场成骨效应的因素——磁场参数,以期为临床医生提供参考。然而,磁场成骨效应的作用机制目前尚未明确,继续深入研究磁场的作用机制可为骨组织再生和牙周组织再生提供有效策略。另外,聚焦磁场的作用靶点,将磁场与其他药物联合应用,可为口腔疾病的治疗提供新思路。

The influence of mechanical loading on osseointegration:an animal study

Osseointegration of implant provides a stable support for the prosthesis under functional loads.The timing of loading is a critical parameter that can govern the success of the osseointegration of implant.However,it is not clear whether the early loading can affect the success of osseointegration,or whether the no-loading healing period can be shortened.This paper presents an animal study conducted to investigate how external loads influence the osseointegration at the initial stage of healing.Titanium implants were inserted into the goat tibia laterally,and different axial loadings were applied to the im-plants in 4 weeks after surgery.After the 2 weeks period of early loading,animals were sacrificed and the tibia bones with the implants were cut off from the bodies.Then mechanical test was employed to find out the differences in the pull-out force,and shear strength at the bone-implant interface between the non-loaded and the loaded implants.The implant-bone interfaces were analyzed by histomor-phometric method,SEM(scanning electron micrograph) and EDS(energy density spectrum).The re-sults indicated that the bone-implant interface did not well integrate 4 weeks after surgery,and the fi-brous tissue could be found at the interfaces of the specimens without loadings.While the results of loaded specimens with 10 N axial force showed that that parts of the interface were well integrated,indicating that the early mild loading may play a positive role in the process of the osseointegration.The results support that a certain range of external loading would influence the process of osseointe-gration,and appropriate mechanical loading can be applied to shorten the osseointegration period after surgery.

Fluorescence microscopic analysis of bone osseointegration of strontium-substituted hydroxyapatite implants

The purpose of this study was to analyze the effect of strontium-substituted hydroxyapatite (Sr-HA) on bone osseointegration of the implants using fluorescence microscopy. We allocated 20 implants to two groups: Sr-HA group and HA group. Electrochemically deposited HA and Sr-HA coatings were applied onto the implants separately. All the implants were inserted into femur bone of rabbits. Oxytetracycline hydrochloride, alizarin-complexon, and calcein green were respectively administered 7, 28, and 46 d after the implantation. After eight weeks, femurs were retrieved and prepared for the fluorescence microscopy observation. We analyzed the bone mineral apposition rates (MARs), bone area ratios (BARs), and bone to implant contact (BIC) of the two groups. Fluorescence microscopic observation showed that all groups exhibited extensive early peri-implant bone formation. The MAR of the Sr-HA group was greater than that for pure HA from 7 to 28 d after implantation, but no significant difference was found at later stage. And the BIC showed difference at 7 and 28 d compared with pure HA. We concluded that Sr-HA coating can improve the bone osseointegration of the implant in the early stage compared with the HA coating.