Hydroxyapatite grafting promotes new bone formation and osseointegration of smooth titanium implants

Titanium is the ideal metal for intra-osseous dental implants. It permits the natural formation of an oxide layer on its surface and thereby it prevents the release of potentially toxic molecules. New formation of bone around implants, partially placed into the bone marrow cavity, is a gradual process that runs from the endosteum to the surface of the implant. Deposition of hydroxyapatite crystals on collagen type I fibrils is initiated by acidic proteins and leads to bone mineralization. This study analyzed the effects of hydroxyapatite upon peri-implant bone formation after insertion of smooth titanium implants. Screw-shaped smooth titanium implants of 3.75 mm thickness and 8.5 mm length were inserted into the metaphysis of rabbit tibia, either together with bovine hydroxyapatite into the right tibia or in controls without hydroxyapatite into the left tibia. Polyfluorochrome tracers (alizarin complex, calcein, tetracycline) were injected subcutaneously at different time intervals after implantation to evaluate the time frame of bone new formation over a period of 8 weeks. All samples were processed for histology and analyzed by fluorescence and polarizing microscopy. Our results showed a higher quantity of mature type I collagen fibers around implants and an acceleration of bone formation in the presence of hydroxyapatite. Mainly immature organic matrix was formed at the surface of implants in controls. The presence of hydroxyapatite seems to promote the maturation of collagen fibers surrounding the titanium implants and to support osteoconduction. Moreover, new formation of bone was faster in all samples where implants were inserted together with hydroxyapatite.     

No deleterious effect of low dose methotrexate on titanium implant osseointegration in a rabbit model

OBJECTIVE:

To evaluate the effect of low dose methotrexate alone or in combination with glucocorticoid treatment on titanium implant osseointegration.

METHODS:

Groups of 6–8 adult New Zealand White rabbits were treated for 18 weeks with saline (control), methotrexate, glucocorticoid, or methotrexate plus glucocorticoid. The animals received a titanium implant in the tibia at week 6. Lumbar spine and tibia bone mineral densities were analyzed before and after treatment. Histomorphometric analysis of bone cortical thickness, total bone area around the implant, and % of bone to implant contact was performed.

RESULTS:

After 18 weeks, the change in the bone mineral density in the lumbar spines and tibias in the methotrexate group was comparable to the control group (0.035 vs. 0.055 g/cm² and 0.021 vs. 0.041 g/cm², respectively). In contrast, both the glucocorticoid group and glucocorticoid plus methotrexate group had significant reductions at both sites. Histomorphometric analysis of the tibia in the control and methotrexate groups revealed no significant changes in cortical thickness (133 vs. 126 µm), total bone area around the implant (33 vs. 30%), or bone to implant contact (40 vs. 38%). In contrast, glucocorticoid group had significant reductions compared to controls in tibia cortical thickness (99 vs. 133 µm), total bone area around the implant (24 vs. 33%), and bone to implant contact (27 vs. 40%). Similar reductions were observed in the glucocorticoid plus methotrexate group.

CONCLUSIONS:

Our results demonstrate that low dose methotrexate treatment does not affect titanium implant osseointegration, suggesting that this therapy is safe for surgical procedures requiring a titanium implant.     

Zn/Ag micro-galvanic couples formed on titanium and osseointegration effects in the presence of S. aureus

Titanium implants possessing simultaneous osseointegration and antibacterial ability are desirable. In this work, three types of Zn/Ag micro-galvanic couples are fabricated on titanium by plasma immersion ion implantation to investigate the osseointegration and antibacterial effects as well as the involved mechanisms. The in vitro findings disclose enhanced proliferation, osteogenic differentiation, and gene expressions of the rat bone mesenchymal stem cells (rBMSCs), as well as good antibacterial ability on all three micro-galvanic couples. Excellent antimicrobial ability is also observed in vivo and the micro-CT and histological results reveal notable osseointegration in vivo despite the presence of bacteria. The Zn/Ag micro-galvanic couple formed on Zn/Ag dual-ion co-implanted titanium shows the best osseointegration as well as good antibacterial properties in vivo obtained from a rabbit tibia model. The difference among the three Zn/Ag micro-galvanic couples can be ascribed to the contact between the Ag NPs and Zn film, which affects the corrosion process. Our results indicate that the biological behavior can be controlled by the corrosion process of the Zn/Ag micro-galvanic couples.     

Mechanical verification of soft-tissue attachment on bioactive glasses and titanium implants

Soft-tissue attachment is a desired feature of many clinical biomaterials. The aim of the current study was to design a suitable experimental method for tensile testing of implant incorporation with soft-tissues. Conical implants were made of three compositions of bioactive glass (SiO(2)-P(2)O(5)-B(2)O(3)-Na(2)O-K(2)O-CaO-MgO) or titanium fiber mesh (porosity 84.7%). The implants were surgically inserted into the dorsal subcutaneous soft-tissue or back muscles in the rat. Soft-tissue attachment was evaluated by pull-out testing using a custom-made jig 8 weeks after implantation. Titanium fiber mesh implants had developed a relatively high pull-out force in subcutaneous tissue (12.33+/-5.29 N, mean+/-SD) and also measurable attachment with muscle tissue (2.46+/-1.33 N). The bioactive glass implants failed to show mechanically relevant soft-tissue bonding. The experimental set-up of mechanical testing seems to be feasible for verification studies of soft-tissue attachment. The inexpensive small animal model is beneficial for large-scale in vivo screening of new biomaterials.     

Osteogenic protein-1 enhances osseointegration of titanium implants coated with peri-apatite in rabbit femoral defect

This study evaluated the effect of osteogenic protein-1 (OP-1) carried by Peri-Apatite (PA) on bone healing in the gap surrounding implants in a rabbit model. Cylindrical titanium implants (3 x 9 mm) were uniformly coated with PA precipitated from a calcium and phosphate solution. OP-1 solution containing 60 microg OP-1 was directly loaded on the implants immediately before implantation for the experimental group, whereas buffer solution was loaded on the implants for the control. The implant was placed in the distal femur and surrounded by a 1-mm gap. The implants were retrieved and examined 6 weeks after implantation. Mechanical testing (push-out) data showed that OP-1 enhanced implant fixation by 80%. Histomorphometric measurements indicated that bone ingrowth in the initial gap expressed as a percentage of the whole gap was significantly higher in the specimens treated with OP-1 than the control group (25.4% vs. 8.9%, p < 0.05). The percentage of the surface of implants, which was covered by bone, was significantly higher in the OP-1-treated group compared to the control group (65% vs. 25%, p < 0.05). This study suggests that OP-1 can be loaded on orthopedic implants through PA to enhance the osseointegration of orthopedic implant.     

钛植入体过盈装配对下颌骨骨重建影响的数值研究

目的研究下颌骨修复手术钛钉植入后由于过盈装配而产生的下颌骨内应力以及骨密度分布变化,探讨不同过盈量对下颌骨骨重建的影响。方法采用有限元方法,建立8种不同过盈量的钛钉过盈装配模型,利用骨重建理论中的应变能密度算法计算5%、10%、15%、20%、25%、30%、35%、40%过盈量模型在36个月内下颌骨应力和骨密度的变化。结果导向孔直径大于钛钉内径时,随着过盈量的增大,骨-钉界面的固定效果逐渐增强;而过盈量超过30%之后,反而会因为过高的过盈量引起大量骨的失效,造成钛钉固定作用的减弱。结论在下颌骨修复时,建议选择直径大小等于或略小于钛钉内径大小的导向孔。     

Histological findings in titanium implants coated with calcium phosphate ceramics installed in rabbit''s tibias

Oral reconstruction using osteointegrated implants are widely indicated nowadays. The implant bone anchorage is very important for its functional stability. Thus, ceramic biomaterials are widely used as coatings of the implant surfaces to accelerate local osteogenesis. The purpose of this study is to assess the biocompatibility and the osteoconduction of two types of calcium phosphate ceramics used as titanium dental implant coatings. These implants were installed in rabbit tibia during an 8-week healing period. The light and fluorescent microscopy observations showed that the materials are biocompatible and that they have osteoconductive activities.     

医用钛合金材料表面改性对骨整合影响的研究进展

医用钛合金材料是临床应用中较为常见的骨科植入物材料之一,作为一种具备良好的生物相容性、耐腐蚀性以及机械强度的生物材料受到了学者的广泛关注.本文专注于PubMed和Web of Science数据库中的相关文献,着重论述4种不同的表面改性设计对医用钛合金材料骨整合性能的影响.在材料学结构设计不断创新和深入研究的背景下,针...     

Richards钉治疗股骨转子间骨折的效果

目的 探讨Richards钉对股骨转子间骨折的治疗作用。方法 在经仔细术前准备后，在C型臂X线监视下，转子外斜切口行Richards钉内固定。结果 作者于1997年至2001年采用此术式治疗转子间骨折86例，随诊超过一年以上，优50例，良28例，可8例，无差病例，总优良率90.8%。结论 Richards钉治疗股骨转子间骨折有设计合理。性能坚固的优点。是治疗转子间骨折理想的内固定物。     

A review on the wettability of dental implant surfaces II: Biological and clinical aspects

Dental and orthopedic implants have been under continuous advancement to improve their interactions with bone and ensure a successful outcome for patients. Surface characteristics such as surface topography and surface chemistry can serve as design tools to enhance the biological response around the implant, with in vitro, in vivo and clinical studies confirming their effects. However, the comprehensive design of implants to promote early and long-term osseointegration requires a better understanding of the role of surface wettability and the mechanisms by which it affects the surrounding biological environment. This review provides a general overview of the available information about the contact angle values of experimental and of marketed implant surfaces, some of the techniques used to modify surface wettability of implants, and results from in vitro and clinical studies. We aim to expand the current understanding on the role of wettability of metallic implants at their interface with blood and the biological milieu, as well as with bacteria, and hard and soft tissues.     

闭合复位经皮弹性髓内钉治疗儿童股骨粗隆下骨折

目的探讨闭合复位经皮钛制弹性髓内钉固定治疗儿童股骨粗隆下骨折的临床疗效。方法回顾性分析我院2010年9月~2013年1月26例患儿采用闭合复位经皮弹性髓内钉固定治疗儿童股骨粗隆下骨折的临床资料,其中男18例,女8例,年龄4~13岁,平均8岁。结果本组26例均得到随访,时间24~48个月,伤口均未发生感染,1例患儿出现皮肤激惹,骨折处均获得骨性愈合,2例发生轻度髋内翻,无一例发生股骨头坏死及骨骺早闭,无一例发生行走跛行。远期随访髋关节功能按Sanders标准:优21例,良3例,优良率92.3%;其余2例因拒绝使用外固定并过早活动导致预后稍差。结论闭合复位经皮钛制弹性髓内钉治疗儿童股骨粗隆下骨折优点突出、疗效肯定,值得推广应用。     

Osseointegration of dental implants in 3D-printed synthetic onlay grafts customized according to bone metabolic activity in recipient site

Onlay grafts made of monolithic microporous monetite bioresorbable bioceramics have the capacity to conduct bone augmentation. However, there is heterogeneity in the graft behaviour in vivo that seems to correlate with the host anatomy. In this study, we sought to investigate the metabolic activity of the regenerated bone in monolithic monetite onlays by using positron emission tomography–computed tomography (PET-CT) in rats. This information was used to optimize the design of monetite onlays with different macroporous architecture that were then fabricated using a 3D-printing technique. In vivo, bone augmentation was attempted with these customized onlays in rabbits. PET-CT findings demonstrated that bone metabolism in the calvarial bone showed higher activity in the inferior and lateral areas of the onlays. Histological observations revealed higher bone volume (up to 47%), less heterogeneity and more implant osseointegration (up to 38%) in the augmented bone with the customized monetite onlays. Our results demonstrated for the first time that it is possible to achieve osseointegration of dental implants in bone augmented with 3D-printed synthetic onlays. It was also observed that designing the macropore geometry according to the bone metabolic activity was a key parameter in increasing the volume of bone augmented within monetite onlays.     

Implant osseointegration and the role of microroughness and nanostructures: Lessons for spine implants

The use of spinal implants for spine fusion has been steadily increasing to avoid the risks of complications and donor site morbidity involved when using autologous bone. A variety of fusion cages are clinically available, with different shapes and chemical compositions. However, detailed information about their surface properties and the effects of such properties on osteogenesis is lacking in the literature. Here we evaluate the role of surface properties for spinal implant applications, covering some of the key biological processes that occur around an implant and focusing on the role of surface properties, specifically the surface structure, on osseointegration, drawing examples from other implantology fields when required. Our findings revealed that surface properties such as microroughness and nanostructures can directly affect early cell behavior and long-term osseointegration. Microroughness has been well established in the literature to have a beneficial effect on osseointegration of implants. In the case of the role of nanostructures, the number of reports is increasing and most studies reveal a positive effect from the nanostructures alone and a synergistic effect when combined with microrough surfaces. Long-term clinical results are nevertheless necessary to establish the full implications of surface nanomodifications.     

股骨骨折模型兔外固定架稳定性与股四头肌肌腱的关系

背景:在兔股骨骨折类造模实验中,关于股四头肌肌腱是否会影响固定装置稳定性的相关研究较少。目的:分析股四头肌肌腱对兔股骨骨折模型中外固定架稳定性的影响。方法:将48只新西兰大白兔随机分为2组,使用外固定架制作兔股骨骨折模型,实验组切断股四头肌肌腱,对照组保留股四头肌肌腱,2周后行X射线检查观察在骨折造模开始到成功阶段2组外固定架失效的数量。结果与结论:(1)X射线检查:造模后2周实验组1只兔外固定架螺钉游离于股骨外,对照组7只实验兔外固定架螺钉游离于股骨外,其中1只螺钉折断,螺纹部分留置于股骨内;(2)外固定架失效率:实验组1只兔外固定架失效,失效率4%,对照组12只兔外固定架失效,失效率50%,差异有显著性意义(P<0.05)。结果证明切断兔股四头肌肌腱可以有效地保证术后兔外固定架的稳定性,间接的提高了实验的成功率。     

Bone response to endosseous titanium implants surface-modified by blasting and chemical treatment: a histomorphometric study in the rabbit femur

This study evaluated the effects of the addition of oxide structure with submicron-scale porous morphology on the periimplant bone response around titanium (Ti) implants with microroughened surfaces. Hydroxyapatite-blasted Ti implants with (experimental) and without (control) a porous oxide structure produced by chemical treatment were investigated in a rabbit femur model. Surface characterizations and in vivo bone response at 4 and 8 weeks after implantation were compared. The experimental implants had submicron-scale porous surface structure consisted of anatase and rutile phase, and the original R(a) values produced by blasting were preserved. The histomorphometric evaluation demonstrated statistically significantly increased bone-to-implant contact (BIC) for experimental implants, both in the three best consecutive threads (p < 0.01) and all threads (p < 0.05) at 4 weeks. There was no remarkable difference in the BIC% or bone area percentage between the two groups at 8 weeks. The porous Ti oxide surface enhanced periimplant bone formation around the Ti implants with microroughened surfaces at the early healing stage. Based on the results of this study, the addition of crystalline Ti oxide surface with submicron-sized porous morphology produced by chemical treatment may be an effective approach for enhancing the osseointegration of Ti implants with microroughened surfaces by increasing early bone-implant contact.     

Prospects of using titanium nickelide implants with modified surface in dental implantology

Corrosion resistance and biocompatibility of 60 specimens of titanium nickelide with modified surfaces implanted into spongy bone were studied in rabbit experiments. Specimens modified by molybdenum ions exhibited high inertness and favorable tissue reaction. No accumulation of nickel and titanium ions in animal organs was detected. __________ Translated from Byulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 145, No. 6, pp. 707–713, June, 2008     

激素性股骨头缺血性坏死模型兔股骨组织中间隙连接蛋白Cx43的表达

背景：激素性股骨头缺血性坏死的发病机制至今尚未完全阐明,间隙连接蛋白Cx43作为骨组织细胞间的主要间隙连接,通过介导骨细胞间信息、能力的正常传递参与调控骨组织细胞生长、分化,代偿性的骨增加或减少,间隙连接蛋白Cx43与激素性股骨头坏死发生发展的关系国内外尚少见报道。 目的：通过建立兔激素性股骨头坏死模型,初步探讨间隙连接蛋白Cx43在激素性股骨头坏死中的表达变化。 方法：将新西兰大白兔40只随机等分为两组,模型组采用内毒素+激素方法构建激素性股骨头坏死模型,对照组于相同时间点注射等量生理盐水。 结果与结论：建模4周后,苏木精-伊红染色结果显示,模型组股骨头软骨下区骨小梁变细,结构紊乱,空骨陷窝明显增多,脂肪细胞增多,髓腔内造血细胞明显减少;对照组股骨头软骨下区骨小梁排列整齐、很少见空骨陷窝,骨髓造血细胞丰富,脂肪细胞较少;免疫组织化学检测显示：Cx43蛋白阳性表达于骨小梁边缘成骨细胞及骨小梁内骨细胞胞浆上及骨髓细胞间质。Western blot检测显示,碱性磷酸酶和Cx43蛋白的表达在模型组中低于对照组(P < 0.05)。结果证实,在激素性股骨头坏死兔模型组织中Cx43蛋白表达下降,可能是激素性股骨头坏死发生发展的重要环节。 中国组织工程研究杂志出版内容重点：肾移植;肝移植;移植;心脏移植;组织移植;皮肤移植;皮瓣移植;血管移植;器官移植;组织工程全文链接：     

A removal torque of the laser-treated titanium implants in rabbit tibia

The purpose of the present study is to evaluate the significance of different surface textures by comparison of the removal forces for laser-treated and machined titanium screw 8 weeks after the installation in rabbit tibia. A total of 14 screw shaped, commercially pure titanium implants with a length of 5 mm, a diameter of 3.75 mm were grouped as follows: Group A: seven implants left as-machined; Group B: seven implants treated with laser method (CSM implant, CSM company, Daegu, Korea) Topographic evaluation was performed with scanning electron microscope (Hitachi S-4200, Japan) to compare the surface structure of laser-treated and machined ones. Installation procedures were done according to Branemark protocol after pre-threading, machined implants were inserted in right tibia metaphysics and laser-treated surface implants were inserted in left ones. Eight weeks post surgically seven rabbits were sacrificed. The implant sites were exposed, and the bone and soft tissues that had formed on top of the implants were carefully removed. Subsequently, the force needed to unscrew the implants (n=14) was measured using a digital torque gauge (Mark-10 corporation, USA). Scanning electron micrographs of the laser-treated and machined control groups demonstrated created a deep and regular honey-comb pattern with small pore, while machined treatment created the typical microscopically grooved and relatively smooth surface characteristic. Eight weeks after implant placement, the average removal torque was 23.58+/-3.71 N cm for the machined implants, 62.57+/-10.44 N cm for the laser-treated implants. The torque measurements yielded statistically significant differences between the machined group and the laser-etched group (p=0.00055) (Wilcoxon's signed-rank test). The laser-treated group achieved higher removal torque values compared to the machined control group.     

Bioactive glass microspheres as osteopromotive inlays in macrotextured surfaces of Ti and CoCr alloy bone implants: trapezoidal surface grooves without inlay most efficient in resisting torsional forces

We have tested the efficacy of porous bioactive glass (BG) inlays in enhancement of implant osseointegration. A total of 24 sheep underwent bilateral surgical implantation of three parallel implants on the anteromedial cortical surface of each tibia. The disc-shaped implants made of Ti6Al4V or cobalt chromium (CoCr) alloys had two parallel surface grooves (trapezoidal space with bottom widening) filled with sintered 100% bioactive glass microspheres or a selected mixture of bioactive and biocompatible glass microspheres. The surface of uncoated control implants was smooth, grit-blasted or had unfilled grooves. A subgroup of control smooth CoCr implants was coated with two or three BG layers. Implant incorporation with bone was evaluated using torque testing to failure, scanning electron microscopy and morphometry at 12 and 25 weeks. A total of 144 in vivo implants and 16 ex vivo cemented control implants were analyzed. Control Ti6Al4V implants with unfilled trapezoidal grooves showed highest torsional failure loads with excellent ingrowth of new bone and remodeling of ingrown bone into lamellar bone. Implants with BG inlays and microroughened control Ti6Al4V implants showed significantly lower torsional failure loads than control Ti6Al4V implants with unfilled grooves. In conclusion, BG inlays failed to enhance biological implant fixation. Macrotextured surface was more effective than grit-blasting in promotion of mechanical incorporation.     

Knowledge-based femur detection in conventional radiographs of the pelvis

In this paper we present a knowledge-based femur detection algorithm. The algorithm uses femur corpus constraints, Canny edge detection and Hough lines. For optimal femur template placement in the local area we use cross-correlation. The segmentation itself is done with an optimized active shape modeling technique. Using the knowledge-based technique we have located 95% of the femur shapes of N=117 X-rays. From those 83% of the target femur shapes have been segmented successfully (point-to-point error: approximately 14 pixels, point-to-boundary error = approximately 9 pixels).