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Sample records for microtopography accelerated osseointegration

  1. The acceleration of implant osseointegration by liposomal Wnt3a.

    PubMed

    Popelut, Antoine; Rooker, Scott M; Leucht, Philipp; Medio, Marie; Brunski, John B; Helms, Jill A

    2010-12-01

    The strength of a Wnt-based strategy for tissue regeneration lies in the central role that Wnts play in healing. Tissue injury triggers local Wnt activation at the site of damage, and this Wnt signal is required for the repair and/or regeneration of almost all tissues including bone, neural tissues, myocardium, and epidermis. We developed a biologically based approach to create a transient elevation in Wnt signaling in peri-implant tissues, and in doing so, accelerated bone formation around the implant. Our subsequent molecular and cellular analyses provide mechanistic insights into the basis for this pro-osteogenic effect. Given the essential role of Wnt signaling in bone formation, this protein-based approach may have widespread application in implant osseointegration. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. The Osseointegration Group of Australia Accelerated Protocol (OGAAP-1) for two-stage osseointegrated reconstruction of amputated limbs.

    PubMed

    Muderis, M Al; Tetsworth, K; Khemka, A; Wilmot, S; Bosley, B; Lord, S J; Glatt, V

    2016-07-01

    This study describes the Osseointegration Group of Australia's Accelerated Protocol two-stage strategy (OGAAP-1) for the osseointegrated reconstruction of amputated limbs. We report clinical outcomes in 50 unilateral trans-femoral amputees with a mean age of 49.4 years (24 to 73), with a minimum one-year follow-up. Outcome measures included the Questionnaire for persons with a Trans-Femoral Amputation, the health assessment questionnaire Short-Form-36 Health Survey, the Amputation Mobility Predictor scores presented as K-levels, 6 Minute Walk Test and timed up and go tests. Adverse events included soft-tissue problems, infection, fractures and failure of the implant. Our results demonstrated statistically significant improvements in all five outcome measures. A total of 27 patients experienced adverse events but at the conclusion of the study, all 50 were walking on osseointegrated prostheses. These results demonstrate that osseointegrated prostheses are a suitable alternative to socket-fit devices for amputees experiencing socket-related discomfort and that our strategy offers more rapid progress to walking than other similar protocols. Cite this article: Bone Joint J 2016;98-B:952-60. ©2016 The British Editorial Society of Bone & Joint Surgery.

  3. Single-stage osseointegrated reconstruction and rehabilitation of lower limb amputees: the Osseointegration Group of Australia Accelerated Protocol-2 (OGAAP-2) for a prospective cohort study

    PubMed Central

    Al Muderis, Munjed; Lu, William; Tetsworth, Kevin; Bosley, Belinda; Li, Jiao Jiao

    2017-01-01

    Introduction Lower limb amputations have detrimental influences on the quality of life, function and body image of the affected patients. Following amputation, prolonged rehabilitation is required for patients to be fitted with traditional socket prostheses, and many patients experience symptomatic socket–residuum interface problems which lead to reduced prosthetic use and quality of life. Osseointegration has recently emerged as a novel approach for the reconstruction of amputated limbs, which overcomes many of the socket-related problems by directly attaching the prosthesis to the skeletal residuum. To date, the vast majority of osseointegration procedures worldwide have been performed in 2 stages, which require at least 4 months and up to 18 months for the completion of reconstruction and rehabilitation from the time of the initial surgery. The current prospective cohort study evaluates the safety and efficacy of a single-stage osseointegration procedure performed under the Osseointegration Group of Australia Accelerated Protocol-2 (OGAAP-2), which dramatically reduces the time of recovery to ∼3–6 weeks. Methods and analysis The inclusion criteria for osseointegrated reconstruction under the OGAAP-2 procedure are age over 18 years, unilateral transfemoral amputation and experiencing problems or difficulties in using socket prostheses. All patients receive osseointegrated implants which are press-fitted into the residual bone. Functional and quality-of-life outcome measures are recorded preoperatively and at defined postoperative follow-up intervals up to 2 years. Postoperative adverse events are also recorded. The preoperative and postoperative values are compared for each outcome measure, and the benefits and harms of the single-stage OGAAP-2 procedure will be compared with the results obtained using a previously employed 2-stage procedure. Ethics and dissemination This study has received ethics approval from the University of Notre Dame, Sydney

  4. PDGF-B gene therapy accelerates bone engineering and oral implant osseointegration.

    PubMed

    Chang, P-C; Seol, Y-J; Cirelli, J A; Pellegrini, G; Jin, Q; Franco, L M; Goldstein, S A; Chandler, L A; Sosnowski, B; Giannobile, W V

    2010-01-01

    Platelet-derived growth factor-BB (PDGF-BB) stimulates repair of healing-impaired chronic wounds such as diabetic ulcers and periodontal lesions. However, limitations in predictability of tissue regeneration occur due, in part, to transient growth factor bioavailability in vivo. Here, we report that gene delivery of PDGF-B stimulates repair of oral implant extraction socket defects. Alveolar ridge defects were created in rats and were treated at the time of titanium implant installation with a collagen matrix containing an adenoviral (Ad) vector encoding PDGF-B (5.5 x 10(8) or 5.5 x 10(9) pfu ml(-1)), Ad encoding luciferase (Ad-Luc; 5.5 x 10(9) pfu ml(-1); control) or recombinant human PDGF-BB protein (rhPDGF-BB, 0.3 mg ml(-1)). Bone repair and osseointegration were measured through backscattered scanning electron microscopy, histomorphometry, micro-computed tomography and biomechanical assessments. Furthermore, a panel of local and systemic safety assessments was performed. Results indicated that bone repair was accelerated by Ad-PDGF-B and rhPDGF-BB delivery compared with Ad-Luc, with the high dose of Ad-PDGF-B more effective than the low dose. No significant dissemination of the vector construct or alteration of systemic parameters was noted. In summary, gene delivery of Ad-PDGF-B shows regenerative and safety capabilities for bone tissue engineering and osseointegration in alveolar bone defects comparable with rhPDGF-BB protein delivery in vivo.

  5. Low-magnitude high-frequency loading, by whole-body vibration, accelerates early implant osseointegration in ovariectomized rats

    PubMed Central

    LIANG, YONG-QIANG; QI, MENG-CHUN; XU, JIANG; XU, JUAN; LIU, HUA-WEI; DONG, WEI; LI, JIN-YUAN; HU, MIN

    2014-01-01

    Osteoporosis deteriorates jaw bone quality and may compromise early implant osseointegration and early implant loading. The influence of low-magnitude, high-frequency (LMHF) vibration on peri-implant bone healing and implant integration in osteoporotic bones remains poorly understood. LMHF loading via whole-body vibration (WBV) for 8 weeks has previously been demonstrated to significantly enhance bone-to-implant contact, peri-implant bone fraction and implant mechanical properties in osteoporotic rats. In the present study, LMHF loading by WBV was performed in osteoporotic rats, with a loading duration of 4 weeks during the early stages of bone healing. The results indicated that 4-week LMHF loading by WBV partly reversed the negative effects of osteoporosis and accelerated early peri-implant osseointegration in ovariectomized rats. PMID:25270245

  6. Microtopography of manganese crusts

    NASA Astrophysics Data System (ADS)

    Morgan, Charles L.

    Quantitative examination of the seafloor surface roughness will be necessary for any design of equipment intended for use in collecting surface deposits such as cobalt-rich manganese crusts or nodules. Furthermore, it is an essential prerequisite to the confident interpretation of returns from high frequency side-scan and other acoustic systems. The objectives of the project were to develop the capability at the University of Hawaii of generating high resolution (less than 1 cm horizontal and vertical) topographic models of the seafloor from 35 mm stereo photographs; to produce such models from existing photographs of cobalt-rich manganese crust deposits; and to optimize the configuration of the existing Hawaii Undersea Research Laboratory (HURL) camera system for stereo photograph collection and correlation of acoustic data with the photographic ground-truth. These tasks were accomplished and have also led to the development of a follow-on project (MMTC/OBD Project 1512) dedicated to the simultaneous acquisition of both optical and side-scan acoustic data for future accurate determination of seabed microtopography.

  7. Osseointegrated implant prosthodontics.

    PubMed

    Rogoff, G S

    1992-06-01

    This review covers recent literature on prosthodontic aspects of osseointegrated implants. Long-term prognosis, diagnosis and treatment planning, and clinical impression techniques and fabrication technology are discussed.

  8. Osseointegrated finger prostheses.

    PubMed

    Doppen, P; Solomons, M; Kritzinger, S

    2009-02-01

    Amputation of a digit can lead to functional and psychological problems and patients can benefit from digital prostheses. Unfortunately, standard prostheses are often unstable, particularly when fitted over short amputation stumps. Prosthesis fixation by osseointegration is widely used in oral and extraoral applications and may help avoid the problem of instability. This paper reports the results of four patients with five finger amputations who were treated with osseointegrated implants to attach finger prostheses. One implant failed to osseointegrate and the procedure was abandoned. Three patients were successfully treated to completion of three finger prostheses and are extremely satisfied with their outcomes, both cosmetically and functionally, with osseoperception reported by all three patients.

  9. System of optical noncontact microtopography.

    PubMed

    Costa, M F; Almeida, J B

    1993-09-01

    In this paper we describe a method of noncontact optical microtopography based on discrete triangulation. We show that a light beam with an oblique incidence on a surface can be used to assess the distance of the latter to a reference plane if the bright spot produced on the surface is imaged onto an array of detectors that tracks its lateral displacement. The light beam is swept over the surface so that large areas can be scanned. The authors have used their system with success for the topographic inspection of several surfaces, e.g., thin copper and silver films, polyethylene rough films and molds, graphite, machined metallic parts, and fabrics.

  10. Genetic Networks in Osseointegration

    PubMed Central

    Nishimura, I.

    2013-01-01

    Osseointegration-based dental implants have become a well-accepted treatment modality for complete and partial edentulism. The success of this treatment largely depends on the stable integration and maintenance of implant fixtures in alveolar bone; however, the molecular and cellular mechanisms regulating this unique tissue reaction have not yet been fully uncovered. Radiographic and histologic observations suggest the sustained retention of peri-implant bone without an apparent susceptibility to catabolic bone remodeling; therefore, implant-induced bone formation continues to be intensively investigated. Increasing numbers of whole-genome transcriptome studies suggest complex molecular pathways that may play putative roles in osseointegration. This review highlights genetic networks related to bone quality, the transient chondrogenic phase, the vitamin D axis, and the peripheral circadian rhythm to elute the regulatory mechanisms underlying the establishment and maintenance of osseointegration. PMID:24158334

  11. Microtopography of the skin and scar formation.

    PubMed

    Tring, F C

    1976-11-01

    The surface microtopography of normal human skin varies from one anatomical region to another. The patterns at different sites are considered to reflect different orientations of dermal fibers. A simple technique is described that enables such orientations to be accurately delineated. Various scars resulting from lacerations, surgical incisions, and steroid-induced striae were examined in the manner described.

  12. Microtopography recreation benefits ecosystem restoration

    Treesearch

    Wei Wei; Liding Chen; Lei Yang; F. Fred Samadani; Ge Sun

    2012-01-01

    Within the context of global warming and accelerated human activities, the surrounding environments of many terrestrial ecosystems worldwide have become increasingly deteriorated, such that finding suitable methods and effective environmental technology to confront climate change and prevent land degradation is critical to the health and sustainability of the earth. In...

  13. Vertisols with Gilgai Microtopography: Classification and Parameters of Microtopography and Morphological Types of Soils (a Review)

    NASA Astrophysics Data System (ADS)

    Khitrov, N. B.

    2016-02-01

    Data on clayey swelling soils with gilgai microtopography are systematized. Classifications of gilgai microtopography representing regularly alternating microhighs and microlows are discussed, and its geometric parameters under different landscape conditions are considered. Gilgai microtopography is developed within flat or slightly inclined elements of the mesorelief composed of swelling clays of different geneses. These materials are characterized by the high swelling-shrinking capacity upon wetting-drying cycles owing to the predominance of clay minerals of smectitic group. These processes are especially pronounced under conditions of the impeded surface drainage and contrasting of the wet seasons with strong soil moistening by atmospheric precipitation or surface water and the seasons with deep soil drying under the impact of physical evaporation and transpiration. The areas with gilgai microtopography have complex soil cover patterns composed of Vertisols and vertic soils. Their formation is related to lateral movements of solid material in the soil profiles and along the curved soil surface. The morphological types of soil complexes in such area are systematized.

  14. Mechanisms regulating osteoblast response to surface microtopography and vitamin D

    NASA Astrophysics Data System (ADS)

    Bell, Bryan Frederick, Jr.

    A comprehensive understanding of the interactions between orthopaedic and dental implant surfaces with the surrounding host tissue is essential in the design of advanced biomaterials that better promote bone growth and osseointegration of implants. Dental implants with roughened surfaces and high surface energy are well known to promote osteoblast differentiation in vitro and promote increased bone-to-implant contact in vivo. In addition, increased surface roughness increases osteoblasts response to the vitamin D metabolite 1alpha,25(OH)2D3. However, the exact mechanisms mediating cell response to surface properties and 1alpha,25(OH)2D3 are still being elucidated. The central aim of the thesis is to investigate whether integrin signaling in response to rough surface microtopography enhances osteoblast differentiation and responsiveness to 1alpha,25(OH)2D3. The hypothesis is that the integrin alpha5beta1 plays a role in osteoblast response to surface microtopography and that 1alpha,25(OH) 2D3 acts through VDR-independent pathways involving caveolae to synergistically enhance osteoblast response to surface roughness and 1alpha,25(OH) 2D3. To test this hypothesis the objectives of the studies performed in this thesis were: (1) to determine if alpha5beta 1 signaling is required for osteoblast response to surface microstructure; (2) to determine if increased responsiveness to 1alpha,25(OH)2D 3 requires the vitamin D receptor, (3) to determine if rough titanium surfaces functionalized with the peptides targeting integrins (RGD) and transmembrane proteoglycans (KRSR) will enhance both osteoblast proliferation and differentiation, and (4) to determine whether caveolae, which are associated with integrin and 1alpha,25(OH)2D3 signaling, are required for enhance osteogenic response to surface microstructure and 1alpha,25(OH)2D 3. The results demonstrate that integrins, VDR, and caveolae play important roles in mediating osteoblast response to surface properties and 1alpha,25

  15. Evaluation of Functional Dynamics during Osseointegration and Regeneration Associated with Oral Implants: A Review

    PubMed Central

    Chang, Po-Chun; Lang, Niklaus P.; Giannobile, William V.

    2009-01-01

    Objectives The aim of this paper is to review current investigations on functional assessments of osseointegration and assess correlations to the peri-implant structure. Material and methods The literature was electronically searched for studies of promoting dental implant osseointegration, functional assessments of implant stability, and finite element (FE) analyses in the field of implant dentistry, and any references regarding biological events during osseointegration were also cited as background information. Results Osseointegration involves a cascade of protein and cell apposition, vascular invasion, de novo bone formation and maturation to achieve the primary and secondary dental implant stability. This process may be accelerated by alteration of the implant surface roughness, developing a biomimetric interface, or local delivery of growth-promoting factors. The current available preclinical and clinical biomechanical assessments demonstrated a variety of correlations to the peri-implant structural parameters, and functionally integrated peri-implant structure through FE optimization can offer strong correlation to the interfacial biomechanics. Conclusions The progression of osseointegration may be accelerated by alteration of the implant interface as well as growth factor applications, and functional integration of peri-implant structure may be feasible to predict the implant function during osseointegration. More research in this field is still needed. PMID:20070743

  16. Effects of capillarity and microtopography on wetland specific yield

    USGS Publications Warehouse

    Sumner, D.M.

    2007-01-01

    Hydrologic models aid in describing water flows and levels in wetlands. Frequently, these models use a specific yield conceptualization to relate water flows to water level changes. Traditionally, a simple conceptualization of specific yield is used, composed of two constant values for above- and below-surface water levels and neglecting the effects of soil capillarity and land surface microtopography. The effects of capiltarity and microtopography on specific yield were evaluated at three wetland sites in the Florida Everglades. The effect of capillarity on specific yield was incorporated based on the fillable pore space within a soil moisture profile at hydrostatic equilibrium with the water table. The effect of microtopography was based on areal averaging of topographically varying values of specific yield. The results indicate that a more physically-based conceptualization of specific yield incorporating capillary and microtopographic considerations can be substantially different from the traditional two-part conceptualization, and from simpler conceptualizations incorporating only capillarity or only microtopography. For the sites considered, traditional estimates of specific yield could under- or overestimate the more physically based estimates by a factor of two or more. The results suggest that consideration of both capillarity and microtopography is important to the formulation of specific yield in physically based hydrologic models of wetlands. ?? 2007, The Society of Wetland Scientists.

  17. Osseointegration of Plateau Root Form Implants: Unique Healing Pathway Leading to Haversian-Like Long-Term Morphology.

    PubMed

    Coelho, Paulo G; Suzuki, Marcelo; Marin, Charles; Granato, Rodrigo; Gil, Luis F; Tovar, Nick; Jimbo, Ryo; Neiva, Rodrigo; Bonfante, Estevam A

    2015-01-01

    Endosteal dental implants have been utilized as anchors for dental and orthopedic rehabilitations for decades with one of the highest treatment success rates in medicine. Such success is due to the phenomenon of osseointegration where after the implant surgical placement, bone healing results into an intimate contact between bone and implant surface. While osseointegration is an established phenomenon, the route which osseointegration occurs around endosteal implants is related to various implant design factors including surgical instrumentation and implant macro, micro, and nanometer scale geometry. In an implant system where void spaces (healing chambers) are present between the implant and bone immediately after placement, its inherent bone healing pathway results in unique opportunities to accelerate the osseointegration phenomenon at the short-term and its maintenance on the long-term through a haversian-like bone morphology and mechanical properties.

  18. SOIL MICROTOPOGRAPHY ON GRAZING GRADIENTS IN CHIHUAHUAN DESERT GRASSLANDS

    EPA Science Inventory

    We tested the hypothesis that one of the significant impacts of livestock in the creation of
    piospheres centered on water points is the loss of soil microtopography. The size, height, and spatial distribution of micromounds and surrounding depressions were measured by a modi...

  19. Engineering the microstructure of electrospun fibrous scaffolds by microtopography.

    PubMed

    Cheng, Qian; Lee, Benjamin L-P; Komvopoulos, Kyriakos; Li, Song

    2013-05-13

    Controlling the structure and organization of electrospun fibers is desirable for fabricating scaffolds and materials with defined microstructures. However, the effects of microtopography on the deposition and, in turn, the organization of the electrospun fibers are not well understood. In this study, conductive polydimethylsiloxane (PDMS) templates with different micropatterns were fabricated by combining photolithography, silicon wet etching, and PDMS molding techniques. The fiber organization was varied by fine-tuning the microtopography of the electrospinning collector. Fiber conformity and alignment were influenced by the depth and the slope of microtopography features, resulting in scaffolds comprising either an array of microdomains with different porosity and fiber alignment or an array of microwells. Microtopography affected the fiber organization for hundreds of micrometers below the scaffold surface, resulting in scaffolds with distinct surface properties on each side. In addition, the fiber diameter was also affected by the fiber conformity. The effects of the fiber arrangement in the scaffolds on the morphology, migration, and infiltration of cells were examined by in vitro and in vivo experiments. Cell morphology and organization were guided by the fibers in the microdomains, and cell migration was enhanced by the aligned fibers and the three-dimensional scaffold structure. Cell infiltration was correlated with the microdomain porosity. Microscale control of the fiber organization and the porosity at the surface and through the thickness of the fibrous scaffolds, as demonstrated by the results of this study, provides a powerful means of engineering the three-dimensional structure of electrospun fibrous scaffolds for cell and tissue engineering.

  20. SOIL MICROTOPOGRAPHY ON GRAZING GRADIENTS IN CHIHUAHUAN DESERT GRASSLANDS

    EPA Science Inventory

    We tested the hypothesis that one of the significant impacts of livestock in the creation of
    piospheres centered on water points is the loss of soil microtopography. The size, height, and spatial distribution of micromounds and surrounding depressions were measured by a modi...

  1. Evaluation of structure from motion for soil microtopography measurement

    USDA-ARS?s Scientific Manuscript database

    Recent developments in low cost structure from motion (SFM) technologies offer new opportunities for geoscientists to acquire high resolution soil microtopography data at a fraction of the cost of conventional techniques. However, these new methodologies often lack easily accessible error metrics an...

  2. Osseointegration of dental implants in Macaca fascicularis

    NASA Astrophysics Data System (ADS)

    Dewi, R. S.; Odang, R. W.; Odelia, L.

    2017-08-01

    Osseointegration is an important factor in determining the success of a dental implant. It can be assessed from the osseointegration that occurs between the implant and the bone. The implant stability is determined by the osseous support at the implant-bone interface, which is commonly evaluated by histomorphometric analysis. This study aimed to evaluate whether the osseointegration level measured by a Low Resonance Frequency Analyzer (LRFA) gave results as good as those obtained by histomorphometric examination. Six male Macaca fascicularis were used in this study. In each animal, two types of loading were performed: immediate and delayed loading. Clinical examination and LRFA measurement were performed to determine osseointegration at the first and second weeks and at the first, second, third, and fourth months. After four months, histomorphometric examination was performed. The relationship between the histomorphometric examination and LRFA measurement was compared using the Pearson correlation coefficient. There was no significant difference in the osseointegration between immediate loading and delayed loading (p > 0.05) The bone-implant contact percentage in the first group did not differ significantly from that in the second group. Statistical analysis showed that there was a strong correlation between LRFA measurement and histomorphometric examination. Osseointegration could be evaluated through LRFA measurement as well as through histomorphometric examination.

  3. Surface microtopography regulates osteointegration: the role of implant surface microtopography in osteointegration.

    PubMed

    Schwartz, Zvi; Nasazky, Erez; Boyan, Barbara D

    2005-07-01

    Increased surface roughness of dental implants enhances the process of osseointegration. It increases bone conduction and increases BIC in all types of bone, resulting in elevated removal torque values. Surface roughness elevated the CSR of implants implanted in adverse conditions as augmented ridges and sinuses and areas of poor bone, such as the posterior maxilla, and in some cases abolished the deleterious effect of smoking. A growing number of clinical studies suggest that early and immediate loading of rough-surfaced implants may lead to predictable osseointegration. However, it is important to note that these studies provide short-term results based on radiographic observation and clinical mobility only. Before we adopt new surgical and prosthetic guidelines, longer and broader studies are needed. Most recent research has examined the effect of surface roughness on bone healing around implants in vivo and the influence of surface roughness on osteoblasts in vitro. In a study just published, it was found that changing the surface chemistry by submerging an implant in an isotonic sodium chloride solution following acid etching to avoid contamination with molecules from the atmosphere significantly increased osteoblast differentiation in vitro and BIC in vivo. This finding may lead us to a new era in dental implants.

  4. Modeling of surface microtopography and its impacts on hydrologic processes

    NASA Astrophysics Data System (ADS)

    Habtezion, Noah Lebassi

    Understanding the impacts of surface microtopography on hydrologic processes is critical. The objectives of this thesis research are: (1) to evaluate the effects of DEM resolution on microtopographic characteristics, hydrologic connectivity, and modeling of hydrologic processes; and (2) to assess the influences of multiple rainfall events on surface and subsurface hydrologic processes with the use of a puddle-to-puddle (P2P) modeling system. The change in DEM resolution has a significant effect on how surface microtopography is depicted, which in turn alters the hydrologic response of a topographic surface. The smoothing of reduced DEM resolution tends to enhance hydrologic connectivity, reduce the depression storage and infiltration, and increase surface runoff. Temporal rainfall distribution results in spatio-temporal variations in soil water dynamics, depression storage, infiltration, hydrologic connectivity, and surface runoff. The reduction in ponding time and infiltration, and the enhancement of hydrologic connectivity further caused earlier and greater surface runoff generation.

  5. The epithelial interface with osseointegrated implants.

    PubMed

    Kellett, M; Smith, G A

    1991-01-01

    The development of osseointegration has generated interest in the field of intraoral and maxillofacial implantology. There is well documented evidence of a high level of success in achieving osseointegration, using titanium and alumina-ceramic implant materials. Long term retention of intraoral implants appears in part, to be dependent upon the integrity of the epithelium/implant interface. This paper presents the design features of two commercially available systems Intra-Mobile-Zylinder (IMZ) and Tubingen (Frialit), which represent titanium and alumina-ceramic implants respectively, and reviews current knowledge of the nature of the epithelial junction to implant materials and the bacterial flora associated with successful and failing implants. Implant failure may be caused by a site specific infection with a similar ecosystem and bacterial flora to that found in periodontal disease. Care in patient selection and maintenance of a healthy epithelial junction are essential for the long term function of osseointegrated implants.

  6. STUDY OF NON-UNIFORMITY COEFFICIENT CONSIDERING MICROTOPOGRAPHY FOR SEISMIC DESIGN OF WATER PIPELINE

    NASA Astrophysics Data System (ADS)

    Shichiroumaru, Kazutaka; Miyajima, Masakatsu

    This study is focusing on a non-uniformity coefficient of ground in the earthquake-resistant of a water pipeline. A lot of earthquake damage occurs at high non-uniformity ground. Therefore it is necessary to consider non-uniformity at the earthquake-resistant of the underground pipeline. By using a microtopography classification, non-uniformity coefficient in the boundary in the microtopography is studied. As a result, earthquake damage rate of underground pipeline at the boundary of the microtopography tends to be high. Therefore, the non-uniformity at the boundary can be obtained from a kind of microtopography and the boundary condition.

  7. Evaluation of skin microtopography as a measure of ultraviolet exposure.

    PubMed

    Seddon, J M; Egan, K M; Zhang, Y; Gelles, E J; Glynn, R J; Tucker, C A; Gragoudas, E S

    1992-05-01

    A pilot study was conducted to investigate the use of skin microtopography as a semiquantitative noninvasive method for estimating cumulative sun exposure in epidemiologic studies of eye disease. The subjects received a kit through the mail containing materials needed to make a replica of the skin texture of a sun-exposed area of the hand. Each subject previously had undergone a skin biopsy around the same site to evaluate elastotic degeneration, and all were interviewed about past sun exposures. A gradable skin impression was obtained from 96 of 115 (83%) participants after two mailings. The impressions were graded according to the degree of skin texture alteration using standard photographs; interobserver reliability was 0.73 using a weighted kappa statistic. The impression score was correlated most strongly with age (r = 0.53). Independent predictors of higher impression scores (more skin texture changes) were older age, cigar or pipe smoking, less education, lighter iris color, lighter skin color, male gender, and tendency to sunburn. After adjustment for age and the other predictor variables, the biopsy score was not correlated with the impression grade (r = 0.18, P = 0.13). Behaviors indexing sun exposure were not correlated with microtopography. These results suggest that skin microtopography as done in this study reflects aging from intrinsic parameters more than from actinic damage.

  8. Engineered antifouling microtopographies: surface pattern effects on cell distribution.

    PubMed

    Decker, Joseph T; Sheats, Julian T; Brennan, Anthony B

    2014-12-23

    Microtopography has been observed to lead to altered attachment behavior for marine fouling organisms; however, quantification of this phenomenon is lacking in the scientific literature. Here, we present quantitative measurement of the disruption of normal attachment behavior of the fouling algae Ulva linza by antifouling microtopographies. The distribution of the diatom Navicula incerta was shown to be unaffected by the presence of topography. The radial distribution function was calculated for both individual zoospores and cells as well as aggregates of zoospores from attachment data for a variety topographic configurations and at a number of different attachment densities. Additionally, the screening distance and maximum values were mapped according to the location of zoospore aggregates within a single unit cell. We found that engineered topographies decreased the distance between spore aggregates compared to that for a smooth control surface; however, the distributions for individual spores were unchanged. We also found that the local attachment site geometry affected the screening distance for aggregates of zoospores, with certain geometries decreasing screening distance and others having no measurable effect. The distribution mapping techniques developed and explored in this article have yielded important insight into the design parameters for antifouling microtopographies that can be implemented in the next generation of antifouling surfaces.

  9. Engineered microtopographies and surface chemistries direct cell attachment and function

    NASA Astrophysics Data System (ADS)

    Magin, Chelsea Marie

    Harrison, in 1914, first recognized that cells respond to physicochemical cues such as substratum topography when he observed that fibroblasts elongated while cultured on spider silk. Recently, techniques developed in the micro-electronics industry have been used to create molds for producing microscaled topographies with various shapes and spatial arrangements. Although these patterning techniques are well-established, very little is known about the mechanisms underlying cell sensing and response to microtopographies. In this work cellular micro-environments with varying surface topographies and chemistries were evaluated with marine organisms and mammalian cells to investigate cellular sensing and response. Biofouling---the accumulation of micro-organisms, plants, and animals on submerged surfaces---is an environmental and economic concern. Engineered topographies, replicated in polydimethylsiloxane elastomer (PDMSe) and functionalized poly(ethylene glycol)-dimethacrylate (PEGDMA) hydrogels, were evaluated for inhibition of marine fouling organism attachment. Microtopographies replicated in PDMSe inhibited attachment of the marine bacterium, Cobetia marina up to 99% versus smooth. The average normalized attachment densities of cells of C. marina and zoospores of the green algae Ulva on PDMSe topographies scaled inversely with the Engineered Roughness Index (ERIII), a representation of surface energy. Attachment densities of Ulva from four assays and C. marina from two growth phases to PDMSe surfaces scaled inversely with one equation: ERI II multiplied by the Reynolds number of the organism (Re) (R 2 = 0.77). The same microtopographies created in PDMSe reduced the initial attachment density and attachment strength of cells of the diatoms Navicula incerta and Seminavis robusta compared to smooth PDMSe. The average normalized attachment density of Navicula after exposure to shear stress (48 Pa) was correlated with the contact area between the diatom and a

  10. Nanostructured tantala as a template for enhanced osseointegration

    NASA Astrophysics Data System (ADS)

    Ruckh, Timothy; Porter, Joshua R.; Allam, Nageh K.; Feng, Xinjian; Grimes, Craig A.; Popat, Ketul C.

    2009-01-01

    The goal of current dental and orthopedic biomaterials research is to design implants that induce controlled and guided tissue growth, and rapid healing. In addition to acceleration of normal wound healing phenomena, these implants should result in the formation of a characteristic interfacial layer with adequate biomechanical properties. To achieve these goals, however, a better understanding of events at the bone-material interface is needed, as well as the development of new materials and approaches that promote osseointegration. Here we present novel nanostructured nanoarrays from tantala that can promote cell adhesion and differentiation. Our results suggest that tantala nanotube arrays enhance osteoblast cell adhesion, proliferation and differentiation. The routes of fabrication of tantala nanotube arrays are flexible and cost-effective, enabling realization of desired platform topologies on existing non-planar orthopedic implants.

  11. The genesis of vertisols with gilgai microtopography: A review

    NASA Astrophysics Data System (ADS)

    Khitrov, N. B.

    2016-05-01

    Different hypotheses about the genesis of gilgai microtopography and corresponding soil complexes with clayey swelling soils are considered in this review. Their diversity is stipulated by specificities of the objects themselves and by the history of studies of the composition, properties, regimes, and landscape conditions of the areas with Vertisols in different countries. Most of the hypotheses about the genesis of Vertisols with the gilgai microtopography suggest that strong swelling-shrinking processes take place in these soils in the course of moistening-drying cycles; the origin of shear stress in the soils, its spatial patterns, and the particular ways of translocation of the soil material are discussed. At the early stage of Vertisol studies, a hypothesis about the leading role of the process of "self-swallowing" of the soils as a result of filling of open cracks with the material from the upper soil horizons was popular. However, numerous facts suggest that the intensity of this process is relatively low, so that it cannot play the major role in the gilgai formation and cyclic changes in the thickness and properties of the soil horizons in Vertisols. Another important mechanism is the uneven moistening and drying of the whole soil volume resulting in the irregular distribution of inner tensions in the soil with the development of shear stress and plastic deformation of the soil mass. The hypotheses suggested in the recent decades are based on the models of soil mechanics. A number of hypotheses consider possible alternation and duration of evolutionary stages of the development of Vertisols with the gilgai microtopography.

  12. Microtopography enhances nitrogen cycling and removal in created mitigation wetlands

    USGS Publications Warehouse

    Wolf, K.L.; Ahn, C.; Noe, G.B.

    2011-01-01

    Natural wetlands often have a heterogeneous soil surface topography, or microtopography (MT), that creates microsites of variable hydrology, vegetation, and soil biogeochemistry. Created mitigation wetlands are designed to mimic natural wetlands in structure and function, and recent mitigation projects have incorporated MT as one way to attain this goal. Microtopography may influence nitrogen (N) cycling in wetlands by providing adjacent areas of aerobic and anaerobic conditions and by increasing carbon storage, which together facilitate N cycling and removal. This study investigated three created wetlands in the Virginia Piedmont that incorporated disking-induced MT during construction. One site had paired disked and undisked plots, allowing an evaluation of the effects of this design feature on N flux rates. Microtopography was measured using conventional survey equipment along a 1-m circular transect and was described using two indices: tortuosity (T), describing soil surface roughness and relief, and limiting elevation difference (LD), describing soil surface relief. Ammonification, nitrification, and net N mineralization were determined with in situ incubation of modified ion-exchange resin cores and denitrification potential was determined using denitrification enzyme assay (DEA). Results demonstrated that disked plots had significantly greater LD than undisked plots one year after construction. Autogenic sources of MT (e.g. tussock-forming vegetation) in concert with variable hydrology and sedimentation maintained and in some cases enhanced MT in study wetlands. Tortuosity and LD values remained the same in one wetland when compared over a two-year period, suggesting a dynamic equilibrium of MT-forming and -eroding processes at play. Microtopography values also increased when comparing the original induced MT of a one-year old wetland with MT of older created wetlands (five and eight years old) with disking-induced MT, indicating that MT can increase by

  13. Properties and regimes of vertisols with gilgai microtopography (a review)

    NASA Astrophysics Data System (ADS)

    Khitrov, N. B.

    2016-03-01

    Data on the morphology and spatial distribution of slickensides and cracks, particle-size distribution, the organic carbon content, the content and forms of carbonate concentrations, and physical and physicochemical properties of Vertisols with the gilgai microtopography are systematized. Relatively scarce information on the functioning regimes of gilgai soil complexes (their temperature and moisture conditions, redox potential, vertical and horizontal deformations, and soil density changes) is discussed. Common properties of gilgai soils are the clayey texture of their profiles and the high portion of smectitic minerals specifying the high shrink-swell capacity of the soil material. The most important specificity of soils with the gilgai microtopography is a significant horizontal differentiation of the soil profiles with alternation of bowl-shaped morphostructures with a thick dark layer without carbonates in microlows and diapiric morphostructures composed of the rising material of the lower layers with diverse carbonate concentrations on microhighs. Data on the spatial distribution of soil properties within the gilgai microcatenas can be applied in the studies of the genesis and evolution stages of the gilgai soil complexes.

  14. Longevity of treethrow microtopography: implications for mass wasting

    USGS Publications Warehouse

    Schaetzl, R.J.; Follmer, L.R.

    1990-01-01

    This study examines and compares methods of dating pit/mound microtopography formed by tree uprooting, and provides 14C evidence for the longevity of these landforms. Microtopography can often by dated by reference to known meteorological phenomena, or within certain age constraints, by dendrochronologic means. We used 14C analysis of buried wood and charcoal in treethrow mounds in Michigan and Wisconsin, U.S.A. to arrive at estimates of the geochronometric ages of treethrow mounds. Results indicate that mounds in these areas often persist for more than 1000 years, which are two to five times longer than published estimates by less reliable methods. The longevity of treethrow mounds in these regions is ascribed to (l) sandy, porous soils which minimize runoff, (2) a continuous mat of forest litter and vegetation cover, (3) surface concentrations of gravel which may act as an "armor", (4) large initial size of the features, and (5) soil freezing. Implications are that rates of mass movement due to uprooting may be substantially less than studies from other regions suggest. ?? 1990.

  15. Longevity of treethrow microtopography: implications for mass wasting

    NASA Astrophysics Data System (ADS)

    Schaetzl, Randall J.; Follmer, Leon R.

    1990-06-01

    This study examines and compares methods of dating pit/mound microtopography formed by tree uprooting, and provides 14C evidence for the longevity of these landforms. Microtopography can often by dated by reference to known meteorological phenomena, or within certain age constraints, by dendrochronologic means. We used 14C analysis of buried wood and charcoal in treethrow mounds in Michigan and Wisconsin, U.S.A. to arrive at estimates of the geochronometric ages of treethrow mounds. Results indicate that mounds in these areas often persist for more than 1000 years, which are two to five times longer than published estimates by less reliable methods. The longevity of treethrow mounds in these regions is ascribed to (l) sandy, porous soils which minimize runoff, (2) a continuous mat of forest litter and vegetation cover, (3) surface concentrations of gravel which may act as an "armor", (4) large initial size of the features, and (5) soil freezing. Implications are that rates of mass movement due to uprooting may be substantially less than studies from other regions suggest.

  16. Simulating effects of microtopography on wetland specific yield and hydroperiod

    USGS Publications Warehouse

    Summer, David M.; Wang, Xixi

    2011-01-01

    Specific yield and hydroperiod have proven to be useful parameters in hydrologic analysis of wetlands. Specific yield is a critical parameter to quantitatively relate hydrologic fluxes (e.g., rainfall, evapotranspiration, and runoff) and water level changes. Hydroperiod measures the temporal variability and frequency of land-surface inundation. Conventionally, hydrologic analyses used these concepts without considering the effects of land surface microtopography and assumed a smoothly-varying land surface. However, these microtopographic effects could result in small-scale variations in land surface inundation and water depth above or below the land surface, which in turn affect ecologic and hydrologic processes of wetlands. The objective of this chapter is to develop a physically-based approach for estimating specific yield and hydroperiod that enables the consideration of microtopographic features of wetlands, and to illustrate the approach at sites in the Florida Everglades. The results indicate that the physically-based approach can better capture the variations of specific yield with water level, in particular when the water level falls between the minimum and maximum land surface elevations. The suggested approach for hydroperiod computation predicted that the wetlands might be completely dry or completely wet much less frequently than suggested by the conventional approach neglecting microtopography. One reasonable generalization may be that the hydroperiod approaches presented in this chapter can be a more accurate prediction tool for water resources management to meet the specific hydroperiod threshold as required by a species of plant or animal of interest.

  17. Adhesion and migration of cells responding to microtopography.

    PubMed

    Estévez, Maruxa; Martínez, Elena; Yarwood, Stephen J; Dalby, Matthew J; Samitier, Josep

    2015-05-01

    It is known that cells respond strongly to microtopography. However, cellular mechanisms of response are unclear. Here, we study wild-type fibroblasts responding to 25 µm(2) posts and compare their response to that of FAK(-/-) fibroblasts and fibroblasts with PMA treatment to stimulate protein kinase C (PKC) and the small g-protein Rac. FAK knockout cells modulated adhesion number and size in a similar way to cells on topography; that is, they used more, smaller adhesions, but migration was almost completely stalled demonstrating the importance of FAK signaling in contact guidance and adhesion turnover. Little similarity, however, was observed to PKC stimulated cells and cells on the topography. Interestingly, with PKC stimulation the cell nuclei became highly deformable bringing focus on these surfaces to the study of metastasis. Surfaces that aid the study of cellular migration are important in developing understanding of mechanisms of wound healing and repair in aligned tissues such as ligament and tendon.

  18. Unusual Microtopography on an Apollo 12 Soil Grain

    NASA Technical Reports Server (NTRS)

    Thomas-Keprta, K. L.; Keprta, N. T.; Clemett, S. J.; Berger, E. L.; Rahman, Z.; McKay, D. S.; Gibson, E. K.; Wentworth, S. J.

    2014-01-01

    We have observed the presence of a previously undescribed microtopography in several regions on the surface of a lunar grain from Apollo regolith sample 12070,29. This microtopography consists of flattened triangular prisms, henceforth referred to as denticles, set in an orderly arrangement. We propose three possible processes to describe the presence of these structures: (1) radiation; (2) aqueous activity; or (3) impact. Radiation—the surface of the Earth’s moon is subject to energetic ion and photon irradiation which can produce a multitude of morphological effects on grain surfaces including erosion/sputtering, vesicle formation, and amorphization of crystalline phases. Under certain conditions surface erosion can result in the formation of well-ordered nanostructures including mounds, dots, wave-shaped, rippled or corrugated features typically <10s nm in size and organized into pattered arrays. However larger pyramid-shaped features up to approx. 300 nm at the base, similar in shape to lunar denticles, were produced on Cu substrates ex-posed to ion beam sputtering.. Aqueous alteration—recent reports of purported water on the Moon imply the possibility of brief, limited exposure of surface materials to aqueous fluids. Aqueous corrosion of silicates can result in the formation of crystallographically controlled denticulated features, up to 10s of micron at the base, arranged in a patterned formation. Impact—the surface of the moon is impacted by meteorites, particularly by micron-size particles, resulting in the formation of a variety of crater types. While it is difficult to envision a scenario in which a patterned array could be formed by impact, fracturing along planes of crystallographic structural weakness due to external stress could explain these features.

  19. Fire and Microtopography in Peatlands: Feedbacks and Carbon Dynamics

    NASA Astrophysics Data System (ADS)

    Benscoter, B.; Turetsky, M. R.

    2011-12-01

    Fire is the dominant natural disturbance in peatland ecosystems. Over the past decade, peat fires have emerged as an important issue for global climate change, human health, and economic loss, largely due to the extreme peat fire events in Indonesia and Russia that severely impacted metropolitan areas and social infrastructure. However, the impact and importance of fire in peatland ecosystems are more far-reaching. Combustion of vegetation and soil organic matter releases an average of 2.2 kg C m-2 to the atmosphere, primarily as CO2, as well as a number of potentially harmful emissions such as fine particulate matter and mercury. Additionally, while peatlands are generally considered to be net sinks of atmospheric carbon, the removal of living vegetation by combustion halts primary production following fire resulting in a net loss of ecosystem carbon to the atmosphere for several years. The recovery of carbon sink function is linked to plant community succession and development, which can vary based on combustion severity and the resulting post-fire microhabitat conditions. Microtopography has a strong influence on fire behavior and combustion severity during peatland wildfires. In boreal continental peatlands, combustion severity is typically greatest in low-lying hollows while raised hummocks are often lightly burned or unburned. The cross-scale influence of microtopography on landscape fire behavior is due to differences in plant community composition between microforms. The physiological and ecohydrological differences among plant communities result in spatial patterns in fuel availability and condition, influencing the spread, severity, and type of combustion over local to landscape scales. In addition to heterogeneous combustion loss of soil carbon, this differential fire behavior creates variability in post-fire microhabitat conditions, resulting in differences in post-fire vegetation succession and carbon exchange trajectories. These immediate and legacy

  20. The osseointegration of zirconia dental implants.

    PubMed

    Assal, Patrick A

    2013-01-01

    Zirconia is currently extensively used in medicine, especially in orthopedic surgery for various joint replacement appliances. Its outstanding mechanical and chemical properties have made it the "material of choice" for various types of prostheses. Its color in particular makes it a favored material to manufacture dental implants. A literature search through Medline enables one to see zirconia's potential but also to point out and identify its weaknesses. The search shows that zirconia is a biocompatible, osteoconductive material that has the ability to osseointegrate. Its strength of bonding to bone depends on the surface structure of the implant. Although interesting, the studies do not allow for the recommendation of the use of zirconia implants in daily practice. The lack of studies examining the chemical and structural composition of zirconia implants does not allow for a "gold standard" to be established in the implant manufacturing process. Randomized clinical trials (RCT) are urgently needed on surface treatments of zirconia implants intended to achieve the best possible osseointegration.

  1. Effect of local zoledronate on implant osseointegration in a rat model

    PubMed Central

    2012-01-01

    Background An implant coating with poly(D, L-lactide) (PDLLA) releasing incorporated Zoledronic acid (ZOL) has already proven to positively effect osteoblasts, to inhibit osteoclasts and to accelerate fracture healing. Aim of this study was to investigate the release kinetics of the chosen coating and the effect of different concentrations of ZOL locally released from this coating on the osseointegration of implants. Methods For release kinetics the release of C14-labled ZOL out of the coating was monitored over a period of six weeks in vitro. For testing the osseointegration, titanium Kirschner wires were implanted into the medullary canal of right femurs of 100 Sprague Dawley rats. The animals were divided into five groups receiving implants either uncoated or coated with PDLLA, PDLLA/ZOL low (1.2% w/w) or PDLLA/ZOL high (2% w/w). Additionally, a group with uncoated implants received ZOL intravenously (i.v.). After 56 days animals were sacrificed, femurs dissected and either strength of fixation or histological bone/implant contacts and newly formed bone around the implants were determined. Results Release kinetics revealed an initial peak in the release of C14-ZOL with a slight further progression over the following weeks. There was no significant enhancement of osseointegration for both groups who received ZOL-coated implants or ZOL i.v. compared to the controls in biomechanical or histological analyses, except for a significant raise in strength of fixation of ZOL i.v. versus PDLLA. Conclusions Even though the investigated local ZOL application did not enhance the osseointegration of the implant, the findings might support its application in fracture treatment, since fracture stabilization devices are often explanted after consolidation. PMID:22439827

  2. Posıtıve effect of platelet rich fibrin on osseointegration

    PubMed Central

    Bayram, Burak; Kantarcı, Alpdoğan; Gülsever, Serap; Alaaddinoğlu, Emine-Elif

    2016-01-01

    Background Leukocyte-platelet rich fibrin (L-PRF) is a second generation platelet concentrate clinically used to accelerate tissue healing and bone regeneration. Achieving reduced implant osseointegration time could provide immediate or early loading of implants. The aim of this study was to evaluate the L-PRF-induced osseointegration and bone-implant contact (BIC) in an experimental animal model. Material and Methods Twelve 4-month-old New Zealand white rabbits were used. Following general anesthesia, 3-5 mL of blood was obtained from the central artery in rabbit ear and L-PRF was prepared. Two implant cavities (5 mm long and 3 mm in diameter) were created in each tibia with a total of four cavities in each animal. Two of these cavities were selected and covered with PRF (test group). The remaining L-PRF was used to soak the implants placed into the L-PRF covered sockets. Other cavities were left as controls. In total, 48 implants were placed. Animals were sacrificed after two, three, or four weeks. Histological samples were obtained and peri-implant tissues were histomorphometrically evaluated for bone-to-implant contact and new bone formation. Results Histomorphometric analyses of the defects revealed that the L-PRF was detectable up to the second week. Application of L-PRF increased the rate and amount of new bone formation in the experimental group compared to the control group. Bone-to-implant contact was enhanced when the surface was pre-wetted with L-PRF (p<0.01). Conclusions The results of this study demonstrated that L-PRF application may increases amount and rate of new bone formation during the early healing period and provides a faster osseointegration around implants. Key words:Dental implants, platelet rich fibrin, osseointegration, bone regeneration, matrix for growth factors. PMID:27475686

  3. Surface Contaminants Inhibit Osseointegration in a Novel Murine Model

    PubMed Central

    Bonsignore, Lindsay A.; Colbrunn, Robb W.; Tatro, Joscelyn M.; Messerschmitt, Patrick J.; Hernandez, Christopher J.; Goldberg, Victor M.; Stewart, Matthew C.; Greenfield, Edward M.

    2011-01-01

    Surface contaminants, such as bacterial debris and manufacturing residues, may remain on orthopaedic implants after sterilization procedures and affect osseointegration. The goals of this study were to develop a murine model of osseointegration in order to determine whether removing surface contaminants enhances osseointegration. To develop the murine model, titanium alloy implants were implanted into a unicortical pilot hole in the mid-diaphysis of the femur and osseointegration was measured over a five week time course. Histology, backscatter scanning electron microscopy and x-ray energy dispersive spectroscopy showed areas of bone in intimate physical contact with the implant, confirming osseointegration. Histomorphometric quantification of bone-to-implant contact and peri-implant bone and biomechanical pullout quantification of ultimate force, stiffness and work to failure increased significantly over time, also demonstrating successful osseointegration. We also found that a rigorous cleaning procedure significantly enhances bone-to-implant contact and biomechanical pullout measures by two-fold compared with implants that were autoclaved, as recommended by the manufacturer. The most likely interpretation of these results is that surface contaminants inhibit osseointegration. The results of this study justify the need for the development of better detection and removal techniques for contaminants on orthopaedic implants and other medical devices. PMID:21801863

  4. Laminin coatings on implant surfaces promote osseointegration: Fact or fiction?

    PubMed

    Javed, Fawad; Al Amri, Mohammad D; Kellesarian, Sergio Varela; Al-Askar, Mansour; Al-Kheraif, Abdulaziz A; Romanos, Georgios E

    2016-08-01

    To our knowledge from indexed literature, the role of laminins in the expression of osteogenic biomarkers and osseointegration enhancement has not been systematically reviewed. The aim of the present systematic review was to assess the role of laminin coatings on implant surfaces in promoting osseointegration. To address the focused question, "Do laminin coatings on implant surfaces influence osseointegration?", indexed databases were searched from 1965 up to and including November 2015 using various combination of the following keywords: "Bone to implant contact"; "implant"; "laminins"; and "osseointegration". Letters to the Editor, case-reports/case-series, historic reviews, and commentaries were excluded. The pattern of the present systematic review was customized to primarily summarize the pertinent data. Nine studies were included. Six studies were prospective and were performed in animals and 5 studies were in vitro. Results from 8 studies showed that laminin coatings enhanced new bone formation around implants and/or bone-to-implant contact. One study showed that laminin coated implants surfaces did not improve osseointegration. On experimental grounds, laminin coatings seem to enhance osteogenic biomarkers expression and/or osseointegration; however, from a clinical perspective, further randomized control trials are needed to assess the role of laminin coatings in promoting osseointegration around dental implants. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  5. The influence of controlled surface nanotopography on the early biological events of osseointegration.

    PubMed

    Karazisis, Dimitrios; Petronis, Sarunas; Agheli, Hossein; Emanuelsson, Lena; Norlindh, Birgitta; Johansson, Anna; Rasmusson, Lars; Thomsen, Peter; Omar, Omar

    2017-02-21

    The early cell and tissue interactions with nanopatterned titanium implants are insufficiently described in vivo. A limitation has been to transfer a pre-determined, well-controlled nanotopography to 3D titanium implants, without affecting other surface parameters, including surface microtopography and chemistry. This in vivo study aimed to investigate the early cellular and molecular events at the bone interface with screw-shaped titanium implants superimposed with controlled nanotopography. Polished and machined titanium implants were firstly patterned with 75-nm semispherical protrusions. Polished and machined implants without nano-patterns were designated as controls. Thereafter, all nanopatterned and control implants were sputter-coated with a 30nm titanium layer to unify the surface chemistry. The implants were inserted in rat tibiae and samples were harvested after 12h, 1d and 3d. In one group, the implants were unscrewed and the implant-adherent cells were analyzed using quantitative polymerase chain reaction. In another group, implants with surrounding bone were harvested en bloc for histology and immunohistochemistry. The results showed that nanotopography downregulated the expression of monocyte chemoattractant protein-1 (MCP-1), at 1d, and triggered the expression of osteocalcin (OC) at 3d. This was in parallel with a relatively lower number of recruited CD68-positive macrophages in the tissue surrounding the nanopatterned implants. Moreover, a higher proportion of newly formed osteoid and woven bone was found at the nanopatterned implants at 3d. It is concluded that nanotopography, per se, attenuates the inflammatory process and enhances the osteogenic response during the early phase of osseointegration. This nanotopography-induced effect appeared to be independent of the underlying microscale topography.

  6. Three dimensional spatial separation of cells in response to microtopography.

    PubMed

    Leclerc, Alexandre; Tremblay, Dominique; Hadjiantoniou, Sebastian; Bukoreshtliev, Nickolay V; Rogowski, Jacob L; Godin, Michel; Pelling, Andrew E

    2013-11-01

    Cellular organization, migration and proliferation in three-dimensions play a critical role in numerous physiological and pathological processes. Nano- and micro-fabrication approaches have demonstrated that nano- and micro-scale topographies of the cellular microenvironment directly impact organization, migration and proliferation. In this study, we investigated these dynamics of two cell types (NIH3T3 fibroblast and MDCK epithelial cells) in response to microscale grooves whose dimensions exceed typical cell sizes. Our results demonstrate that fibroblasts display a clear preference for proliferating along groove ridges whereas epithelial cells preferentially proliferate in the grooves. Importantly, these cell-type dependent behaviours were also maintained when in co-culture. We show that it is possible to spatially separate a mixed suspension of two cell types by allowing them to migrate and proliferate on a substrate with engineered microtopographies. This ability may have important implications for investigating the mechanisms that facilitate cellular topographic sensing. Moreover, our results may provide insights towards the controlled development of complex three-dimensional multi-cellular constructs.

  7. Photogrammetric reconstruction of forest floor microtopography: difficulties, advantages and application

    NASA Astrophysics Data System (ADS)

    Krasnov, Dmitrii; Krasnova, Alisa; Noe, Steffen; Niinemets, Ülo

    2017-04-01

    Soil heterogeneity plays important role in many soil processes. The microtopography of forest floor is one of the key factors that influence on such processes as water and nutrients movement (vertical and lateral) and distribution, the speed of the decomposition processes, temperature, and soil fluxes. Many previous studies of soil processes have shown importance of the spatial distribution component in experiment design, data acquisition, analyses and interpretation. Digitalizing of soil surface with minimum destruction and maximum speed is an issue for many studies especially for heterogeneous sites. The work is based on the Structure-from-Motion (SfM) photogrammetric method. To quantify the mirotophographical features, high-resolution 3D models of sample plots were reconstructed from imagery acquired with high resolution camera. Using such models it is possible to determine the location of trees, collars for soil respiration measurements, position of moisture and temperature sensors, to calculate depression (pits) and elevation (mound) areas, trees stem diameter. Obtained digital surface models can be used for modeling of soil processes and mapping, data interpretation, monitoring, and quantification, geostatistical analysis.

  8. AFM analysis of bleaching effects on dental enamel microtopography

    NASA Astrophysics Data System (ADS)

    Pedreira de Freitas, Ana Carolina; Espejo, Luciana Cardoso; Botta, Sergio Brossi; Teixeira, Fernanda de Sa; Luz, Maria Aparecida A. Cerqueira; Garone-Netto, Narciso; Matos, Adriana Bona; Salvadori, Maria Cecilia Barbosa da Silveira

    2010-02-01

    The purpose of this in vitro study was to test a new methodology to evaluate the effects of 35% hydrogen peroxide agent on the microtopography of sound enamel using an atomic force microscope (AFM). The buccal sound surfaces of three extracted human lower incisors were used, without polishing the surfaces to maintain them with natural morphology. These unpolished surfaces were subjected to bleaching procedure with 35% hydrogen peroxide that consisted of 4 applications of the bleaching agent on enamel surfaces for 10 min each application. Surface images were obtained in a 15 μm × 15 μm area using an AFM. The roughness (Ra and RMS) and the power spectral density (PSD) were obtained before and after the bleaching treatment. As results we could inquire that the PSD analyses were very suitable to identifying the morphological changes on the surfaces, while the Ra and RMS parameters were insufficient to represent the morphological alterations promoted by bleaching procedure on enamel. The morphological wavelength in the range of visible light spectrum (380-750 nm) was analyzed, showing a considerable increase of the PSD with the bleaching treatment.

  9. Incorporating Information on (micro)Topography when Modelling Soil Erosion at the Watershed Scale

    NASA Astrophysics Data System (ADS)

    Cerdan, O.

    2015-12-01

    In the context of shallow flows, the spatial distribution of the flow is highly influenced by the micro-topography. For instance, local oriented depressions may exist in which the flow depth and velocity may exceed the threshold for soil erosion initiation. If a mean uniform flow shear stress is used to characterize the area, it would be smaller and therefore may not initiate erosion. However, management of water and sediment fluxes requires analysis and modeling at the watershed scale in order to integrate the relations between upstream and downstream areas. At this scale, high resolution information on the microtopography is usually not always available and would anyway require too extensive computation resources to be explicitly integrated in modelling attempt. Moreover, in agricultural context, this information is likely to change during the year depending on the agricultural practices. In this context, the objective of this study is to propose a parameterisation of the influence of microtopography on erosion into the framework of the shallow water equation. For each cell, the proportion of wetted area is used as a microtopography indicator. For the case of erosion, the system is coupled to the sediment transport equations. In such context, an additional equation describing the micro-topography evolution caused by erosion is introduced. Different case study will be presented to investigate the potential of the approach.

  10. Microtopography of hillslopes and initiation of channels by horton overland flow

    NASA Astrophysics Data System (ADS)

    Dunne, Thomas; Whipple, Kelin X.; Aubry, Brian F.

    On long hillsides one can examine systematic downslope changes in the ground surface as Horton overland flow gathers into depressions and eventually incises the surface to form channels. Microtopography plays an important role in this process. We have sampled the microtopography of two long hillslopes in a savanna region of southern Kenya, and defined the spectral characteristics of its roughness at various distances from the drainage divide. The microtopography is fractal with a dimension that decreases systematically downslope, and the overall roughness varies between and along hillslopes in response to: (i) the weathering characteristics of the underlying bedrock; (ii) the type and density of patchy vegetation, and (iii) the tendency for wash to incise the surface with increasing intensity as runoff discharge increases downslope. The downslope decrease in fractal dimension reflects the progressive development of low-frequency roughness, here referred to as "swaley" microtopography, which the wash develops even far upslope of the channel head. The statistical analysis of surface roughness motivates a discussion of the role of microtopography in the interaction between wash and diffusive sediment transport processes that ultimately determines the critical distance from the divide at which channels begin.

  11. Bone and metal: an orthopaedic perspective on osseointegration of metals.

    PubMed

    Goriainov, Vitali; Cook, Richard; M Latham, Jeremy; G Dunlop, Douglas; Oreffo, Richard O C

    2014-10-01

    The area of implant osseointegration is of major importance, given the predicted significant rise in the number of orthopaedic procedures and an increasingly ageing population. Osseointegration is a complex process involving a number of distinct mechanisms affected by the implant bulk properties and surface characteristics. Our understanding and ability to modify these mechanisms through alterations in implant design is continuously expanding. The following review considers the main aspects of material and surface alterations in metal implants, and the extent of their subsequent influence on osseointegration. Clinically, osseointegration results in asymptomatic stable durable fixation of orthopaedic implants. The complexity of achieving this outcome through incorporation and balance of contributory factors is highlighted through a clinical case report.

  12. Arkansas BAHA experience: transcalvarial fixture placement using osseointegration surgical hardware.

    PubMed

    Lee, Christopher E; Christensen, Lisa; Richter, Gresham T; Dornhoffer, John L

    2011-04-01

    To determine what factors increase the likelihood of osseointegration failure and implant extrusion with the use of osseointegration surgical hardware, for bone-anchored hearing aids (BAHAs), in children and adults. A total of 60 patients (42 pediatric [≤19 yr] and 18 adult patients [34-69 yr]) who received osseointegration surgical hardware for a BAHA at Arkansas Children's Hospital from October 2003 to May 2009 or at the University of Arkansas for Medical Sciences from November 2005 to May 2009, respectively. BAHA placement using 3- and 4-mm fixtures. Osseointegration failure with implant extrusion. Fifty-seven loaded fixtures in the pediatric population, and 20 were placed in the adults. We had a 21% pediatric and 0% adult osseointegration failure rate. Young age, syndromic status, and failure to penetrate the inner table of the cranium increased the risk of osseointegration failures in children. In some cases, skull thickness provides an inadequate amount of bone for 4-mm fixture placement requiring placement of a 3-mm fixture instead. In these cases, transcalvarial placement of the implanted fixture may decrease the extrusion rate as 3-mm fixtures have been associated with increased rates of implant extrusion. The 3-mm fixtures that were placed in a transcalvarial fashion had a decreased extrusion rate compared with 3-mm fixtures that were surrounded by bone and did not penetrate the inner table of the cranium. Individual patient factors out of the surgeon's control likely play a large role in osseointegration failures as well. This clinical case report encourages transcalvarial fixture insertion when using 3-mm fixtures during placement of osseointegration surgical hardware for BAHAs. © 2011, Otology & Neurotology, Inc.

  13. A pre-clinical murine model of oral implant osseointegration.

    PubMed

    Mouraret, S; Hunter, D J; Bardet, C; Brunski, J B; Bouchard, P; Helms, J A

    2014-01-01

    Many of our assumptions concerning oral implant osseointegration are extrapolated from experimental models studying skeletal tissue repair in long bones. This disconnect between clinical practice and experimental research hampers our understanding of bone formation around oral implants and how this process can be improved. We postulated that oral implant osseointegration would be fundamentally equivalent to implant osseointegration elsewhere in the body. Mice underwent implant placement in the edentulous ridge anterior to the first molar and peri-implant tissues were evaluated at various timepoints after surgery. Our hypothesis was disproven; oral implant osseointegration is substantially different from osseointegration in long bones. For example, in the maxilla peri-implant pre-osteoblasts are derived from cranial neural crest whereas in the tibia peri-implant osteoblasts are derived from mesoderm. In the maxilla, new osteoid arises from periostea of the maxillary bone but in the tibia the new osteoid arises from the marrow space. Cellular and molecular analyses indicate that osteoblast activity and mineralization proceeds from the surfaces of the native bone and osteoclastic activity is responsible for extensive remodeling of the new peri-implant bone. In addition to histologic features of implant osseointegration, molecular and cellular assays conducted in a murine model provide new insights into the sequelae of implant placement and the process by which bone is generated around implants. © 2013.

  14. A pre-clinical murine model of oral implant osseointegration

    PubMed Central

    Mouraret, S.; Hunter, D.J.; Bardet, C.; Brunski, J.B.; Bouchard, P.; Helms, J.A.

    2015-01-01

    Many of our assumptions concerning oral implant osseointegration are extrapolated from experimental models studying skeletal tissue repair in long bones. This disconnect between clinical practice and experimental research hampers our understanding of bone formation around oral implants and how this process can be improved. We postulated that oral implant osseointegration would be fundamentally equivalent to implant osseointegration elsewhere in the body. Mice underwent implant placement in the edentulous ridge anterior to the first molar and peri-implant tissues were evaluated at various timepoints after surgery. Our hypothesis was disproven; oral implant osseointegration is substantially different from osseointegration in long bones. For example, in the maxilla peri-implant pre-osteoblasts are derived from cranial neural crest whereas in the tibia peri-implant osteoblasts are derived from mesoderm. In the maxilla, new osteoid arises from periostea of the maxillary bone but in the tibia the new osteoid arises from the marrow space. Cellular and molecular analyses indicate that osteoblast activity and mineralization proceeds from the surfaces of the native bone and osteoclastic activity is responsible for extensive remodeling of the new peri-implant bone. In addition to histologic features of implant osseointegration, molecular and cellular assays conducted in a murine model provide new insights into the sequelae of implant placement and the process by which bone is generated around implants. PMID:23886841

  15. Predicting the roughness length of turbulent flows over landscapes with multi-scale microtopography

    NASA Astrophysics Data System (ADS)

    Pelletier, J. D.; Field, J. P.

    2015-10-01

    The fully rough form of the law of the wall is commonly used to quantify velocity profiles and associated bed shear stresses in fluvial, aeolian, and coastal environments. A key parameter in this law is the roughness length, z0. Here we propose a predictive formula for z0 that uses the amplitude and slope of each wavelength of microtopography within a discrete-Fourier-transform-based approach. Computational fluid dynamics (CFD) modeling is used to quantify the effective z0 value of sinusoidal microtopography as a function of the amplitude and slope. The effective z0 value of landscapes with multi-scale roughness is then given by the sum of contributions from each Fourier mode of the microtopography. Predictions of the equation are tested against z0 values measured in ~105 wind velocity profiles from southwestern US playa surfaces. Our equation is capable of predicting z0 values to 50 % accuracy, on average, across a four order-of-magnitude range.

  16. Small is beautiful: why microtopography should be included in bog hydrology

    NASA Astrophysics Data System (ADS)

    Appels, Willemijn; van der Ploeg, Martine; Oosterwoud, Marieke; Cirkel, Gijsbert; van der Zee, Sjoerd; Witte, Jan-Philip

    2014-05-01

    Microtopography can have a large effect on flow processes at the soil surface and the composition of soil water. In peat areas, microtopography is shaped by differences in species, the growth rate and transpiration of the vegetation, and the amount of water flowing from higher areas. Microtopography is often represented by a roughness parameter in hillslope hydrological models. In areas without a strong topographical gradient however, microtopography may be underestimated when accumulated in a single parameter, especially in the presence of shallow groundwater systems. In this study, we review the intricate relationships between microtopography, surface runoff, and ecohydrology in systems featuring shallow water tables. In an analogy to surface runoff, the hydrology of a raised bog can be described as a combination of open water flow on a saturated medium, instead of the traditional acrotelm-catotelm concept that only acknowledges the saturated medium. We explored water flow through the microtopography of a raised bog with a simple conceptual model that accounts explicitly for microtopographic features and the changing flow directions these may cause. With this approach we were able to investigate the activation of fast flow paths on different areas of the bog as a function of their wetness level and bog-specific morphological features, such as hummocks and hollows. Our type of approach could be used to improve the understanding of the spatial and temporal variability of rainfall-runoff responses on raised bogs. In addition, similar approaches could be used to investigate how various runoff regimes affect the mixing of water with different chemical signatures, another driver of variations of the occurrence of plant species.

  17. How sedge meadow soils, microtopography, and vegetation respond to sedimentation

    USGS Publications Warehouse

    Werner, K.J.; Zedler, Joy B.

    2002-01-01

    The expansion of urban and agricultural activities in watersheds of the Midwestern USA facilitates the conversion of species-rich sedge meadows to stands of Phalaris arundinacea and Typha spp. We document the role of sediment accumulation in this process based on field surveys of three sedge meadows dominated by Carex stricta, their adjacent Phalaris or Typha stands, and transitions from Carex to these invasive species. The complex microtopography of Carex tussocks facilitates the occurrence of other native species. Tussock surface area and species richness were positively correlated in two marshes (r2 = 0.57 and 0.41); on average, a 33-cm-tall tussock supported 7.6 species. Phalaris also grew in tussock form in wetter areas but did not support native species. We found an average of 10.5 Carex tussocks per 10-m transect, but only 3.5 Phalaris tussocks. Microtopographic relief, determined with a high-precision GPS, measured 11% greater in Carex meadows than Phalaris stands. Inflowing sediments reduced microtopographic variation and surface area for native species. We calculated a loss of one species per 1000 cm2 of lost tussock surface area, and loss of 1.2 species for every 10-cm addition of sediment over the sedge meadow surface. Alluvium overlying the sedge meadow soil had a smaller proportion of organic matter content and higher dry bulk density than the buried histic materials. We conclude that sedimentation contributes to the loss of native species in remnant wetlands. ?? 2002, The Society of Wetland Scientists.

  18. Aspects of goethite surface microtopography, structure, chemistry, and reactivity

    SciTech Connect

    Rakovan, J.; Becker, U.; Hochella, M.F. Jr.

    1999-05-01

    Goethite (010), (110), and (111) growth faces and (010) cleavage surfaces of large, natural single crystals, as well as a high surface area synthetic sample were characterized using various surface sensitive microscopies and spectroscopies. Differential interference contrast and atomic force microscopy characterization of the natural single crystal faces showed microtopography indicative of growth, dissolution, and cleavage. Low energy electron diffraction patterns of the goethite (010) surface exhibit sharp, intense diffraction spots, indicating long-range order on this important surface. Ultra-high vacuum scanning tunneling microscopy was performed on (010) cleavage faces, although the tunneling properties of the surface were very heterogeneous. Atomic resolution was not obtained; however, microtopographic images are identical to those collected with AFM. XPS spectra from the (010) faces of two natural samples as well as the synthetic powder all have peak maxima for Fe(2p{sub 3/2}) at 711.5 {+-} 0.1 eV. The O(1s) line originating from the goethite can be fit with two peaks with a chemical shift of 1.3 eV. The peak at higher binding energy represents the protonated oxygen in the structure, and the peak at lower binding energy represents the proton-free oxygen in the structure. Ab initio and semi-empirical models of the (010) surface suggest that cleavage occurs through the hydroxide plane at 1/4 b in the structure. This is contrary to cleavage through the oxide plane at 1/2 b, which has been assumed in several previous studies.

  19. Microtopography and flow modulate the direction of endothelial cell migration.

    PubMed

    Uttayarat, P; Chen, M; Li, M; Allen, F D; Composto, R J; Lelkes, P I

    2008-02-01

    The migration of vascular endothelial cells under flow can be modulated by the addition of chemical or mechanical stimuli. The aim of this study was to investigate how topographic cues derived from a substrate containing three-dimensional microtopography interact with fluid shear stress in directing endothelial cell migration. Subconfluent bovine aortic endothelial cells were seeded on fibronectin-coated poly(dimethylsiloxane) substrates patterned with a combinatorial array of parallel and orthogonal microgrooves ranging from 2 to 5 microm in width at a constant depth of 1 microm. During a 4-h time-lapse observation in the absence of flow, the majority of the prealigned cells migrated parallel to the grooves with the distribution of their focal adhesions (FAs) depending on the groove width. No change in this migratory pattern was observed after the cells were exposed to moderate shear stress (13.5 dyn/cm(2)), irrespective of groove direction with respect to flow. After 4-h exposure to high shear stress (58 dyn/cm(2)) parallel to the grooves, the cells continued to migrate in the direction of both grooves and flow. By contrast, when microgrooves were oriented perpendicular to flow, most cells migrated orthogonal to the grooves and downstream with flow. Despite the change in the migration direction of the cells under high shear stress, most FAs and actin microfilaments maintained their original alignment parallel to the grooves, suggesting that topographic cues were more effective than those derived from shear stress in guiding the orientation of cytoskeletal and adhesion proteins during the initial exposure to flow.

  20. Where bone meets implant: the characterization of nano-osseointegration

    NASA Astrophysics Data System (ADS)

    Grandfield, Kathryn; Gustafsson, Stefan; Palmquist, Anders

    2013-05-01

    The recent application of electron tomography to the study of biomaterial interfaces with bone has brought about an awareness of nano-osseointegration and, to a further extent, demanded increasingly advanced characterization methodologies. In this study, nanoscale osseointegration has been studied via laser-modified titanium implants. The micro- and nano-structured implants were placed in the proximal tibia of New Zealand white rabbits for six months. High-resolution transmission electron microscopy (HRTEM), analytical microscopy, including energy dispersive X-ray spectroscopy (EDXS) and energy-filtered TEM (EFTEM), as well as electron tomography studies were used to investigate the degree of nano-osseointegration in two- and three-dimensions. HRTEM indicated the laser-modified surface encouraged the formation of crystalline hydroxyapatite in the immediate vicinity of the implant. Analytical studies suggested the presence of a functionally graded interface at the implant surface, characterized by the gradual intermixing of bone with oxide layer. Yet, the most compelling of techniques, which enabled straightforward visualization of nano-osseointegration, proved to be segmentation of electron tomographic reconstructions, where thresholding techniques identified bone penetrating into the nanoscale roughened surface features of laser-modified titanium. Combining high-resolution, analytical and three-dimensional electron microscopy techniques has proven to encourage identification and understanding of nano-osseointegration.The recent application of electron tomography to the study of biomaterial interfaces with bone has brought about an awareness of nano-osseointegration and, to a further extent, demanded increasingly advanced characterization methodologies. In this study, nanoscale osseointegration has been studied via laser-modified titanium implants. The micro- and nano-structured implants were placed in the proximal tibia of New Zealand white rabbits for six months

  1. Advances in surfaces and osseointegration in implantology. Biomimetic surfaces

    PubMed Central

    Albertini, Matteo; Fernandez-Yague, Marc; Lázaro, Pedro; Herrero-Climent, Mariano; Bullon, Pedro; Gil, Francisco-Javier

    2015-01-01

    The present work is a revision of the processes occurring in osseointegration of titanium dental implants according to different types of surfaces -namely, polished surfaces, rough surfaces obtained from subtraction methods, as well as the new hydroxyapatite biomimetic surfaces obtained from thermochemical processes. Hydroxyapatite’s high plasma-projection temperatures have proven to prevent the formation of crystalline apatite on the titanium dental implant, but lead to the formation of amorphous calcium phosphate (i.e., with no crystal structure) instead. This layer produce some osseointegration yet the calcium phosphate layer will eventually dissolve and leave a gap between the bone and the dental implant, thus leading to osseointegration failure due to bacterial colonization. A new surface -recently obtained by thermochemical processes- produces, by crystallization, a layer of apatite with the same mineral content as human bone that is chemically bonded to the titanium surface. Osseointegration speed was tested by means of minipigs, showing bone formation after 3 to 4 weeks, with the security that a dental implant can be loaded. This surface can be an excellent candidate for immediate or early loading procedures. Key words:Dental implants, implants surfaces, osseointegration, biomimetics surfaces. PMID:25662555

  2. [Oromandibular reconstruction with free peroneal flap and osseointegrated implants].

    PubMed

    Navarro Cuéllar, C; Cuesta Gil, M; Plasencia Delgado, J; Guerra Martínez, B; Acero Sanz, J; López de Atalaya, F J; Ochandiano Caicoya, S; Navarro Vila, C

    2003-01-01

    Free fibula flaps have proved to be one of the most versatile for oromandibular reconstruction due to the available length of bone and the possibility of incorporating a long skin paddle to cover intraoral soft tissues. The use of a osseointegrated dental implants is an important technique for the oral rehabilitation of these patients. Osseointegrated implants provide the most rigid prosthetic stabilization available to withstand masticatory forces. These implants can be placed immediately or in second time procedure. In our case, implantation in the fibula free flap is done after 6-9 months because of the large amount of osteosynthesis material required for the fixation of the flap. Four or six months later, when osseointegration has taken place, the implants are loaded with a dental rehabilitation. We analize 10 cases of mandibular reconstruction with fibula free flap and their aesthetic and functional rehabilitation with osseointegrated implants with a 2 year follow up. Forty-six dental implants were placed developing all of them but one a correct osseointegration. All these patients recovered masticatory function and underwent a considerable improvement in labial competence, salivary continence, speech articulation and facial harmony.

  3. Osseointegrated implants for auricular defects: operative techniques and complication management.

    PubMed

    Rocke, Daniel J; Tucci, Debara L; Marcus, Jeffrey; McClennen, Jay; Kaylie, David

    2014-10-01

    Auricular defects are challenging to reconstruct with native tissue. We describe operative techniques and complication management for patients undergoing osseointegrated implants for auriculectomy defects and microtia. Tertiary referral center. All patients at Duke University Medical Center with auricular defects treated with osseointegrated implants for prosthetic (OIP) auricles from January 1, 2010, until September 16, 2013. Osseointegrated implantation for auricular defects. Description of operative techniques, complications, and complication management. Sixteen patients met inclusion criteria. Five patients had microtia and atresia. Two of these patients had bilateral microtia and atresia and underwent bilateral simultaneous implantation of both OIP and osseointegrated hearing implants (OHIs). Two other microtia/atresia patients underwent simultaneous unilateral OIP and OHI. Eleven patients had unilateral defects from either trauma or skin cancer resection. Three patients received adjuvant radiation before implantation. Complications included tissue overgrowth requiring revision surgery (two patients), inadequate bone stock requiring split calvarial bone graft and later implantation, loss of implant secondary to osteoradionecrosis requiring hyperbaric oxygen therapy, and skin infection requiring antibiotic therapy. Reconstruction of auriculectomy defects and microtia is difficult to accomplish using native tissue. Complications are common, and these complications can have devastating consequences on the final result. Osseointegrated implantation offers an outstanding alternative for reconstructing these defects. We describe our multidisciplinary team approach, examine operative techniques, and focus on the unique challenges of simultaneous and bilateral simultaneous OIP and OHI implantation.

  4. MICROTOPOGRAPHY AND GRAZING IN DESERT RANGE LAND: A LESSON IN STATISTICS VERSUS REALITY IN THE FIELD

    EPA Science Inventory

    This presentation summarizes two experiments on the effects of grazing on soil microtopography in a Chihuahuan Desert rangeland. In the first experiment, we measured the effect of three consecutive years of short duration <48 hours per year) intense grazing (20--40 yearling cows ...

  5. MICROTOPOGRAPHY AND GRAZING IN DESERT RANGE LAND: A LESSON IN STATISTICS VERSUS REALITY IN THE FIELD

    EPA Science Inventory

    This presentation summarizes two experiments on the effects of grazing on soil microtopography in a Chihuahuan Desert rangeland. In the first experiment, we measured the effect of three consecutive years of short duration <48 hours per year) intense grazing (20--40 yearling cows ...

  6. Relevance of mytilid shell microtopographies for fouling defence--a global comparison.

    PubMed

    Bers, A V; Díaz, E R; da Gama, B A P; Vieira-Silva, F; Dobretsov, S; Valdivia, N; Thiel, M; Scardino, A J; McQuaid, C D; Sudgen, H E; Thomason, J C; Wahl, M

    2010-04-01

    Prevention of epibiosis is of vital importance for most aquatic organisms, which can have consequences for their ability to invade new areas. Surface microtopography of the shell periostracum has been shown to have antifouling properties for mytilid mussels, and the topography shows regional differences. This article examines whether an optimal shell design exists and evaluates the degree to which shell microstructure is matched with the properties of the local fouling community. Biomimics of four mytilid species from different regional provenances were exposed at eight different sites in both northern and southern hemispheres. Tendencies of the microtopography to both inhibit and facilitate fouling were detected after 3 and 6 weeks of immersion. However, on a global scale, all microtopographies failed to prevent fouling in a consistent manner when exposed to various fouling communities and when decoupled from other shell properties. It is therefore suggested that the recently discovered chemical anti-microfouling properties of the periostracum complement the anti-macrofouling defence offered by shell microtopography.

  7. EFFECTS OF INTENSE, SHORT DURATION GRAZING ON MICROTOPOGRAPHY IN A CHIHUAHUAN DESERT GRASSLAND

    EPA Science Inventory

    Microtopography describes variations in soil surface elevation (nim or cm) for a scale of a few meters of horizontal distance, Small-scale (few centimeters) changes in vegetation communities synchronized with the elevation differences were observed in drained marsh (Zedler & Zedl...

  8. EFFECTS OF INTENSE, SHORT-DURATION GRAZING ON MICROTOPOGRAPHY IN A CHIHUAHUAN DESERT GRASSLAND

    EPA Science Inventory

    We measured the effects of short-term intense grazing by domestic cattle on the microtopography of a black-grama grass (Bouteloua eriopoda) dominated desert grassland. Plots were grazed during winter or summer for 24-36 hours by 20-40 yearlings in 1995 and 1996. Soil microtopogra...

  9. EFFECTS OF INTENSE, SHORT DURATION GRAZING ON MICROTOPOGRAPHY IN A CHIHUAHUAN DESERT GRASSLAND

    EPA Science Inventory

    Microtopography describes variations in soil surface elevation (nim or cm) for a scale of a few meters of horizontal distance, Small-scale (few centimeters) changes in vegetation communities synchronized with the elevation differences were observed in drained marsh (Zedler & Zedl...

  10. EFFECTS OF INTENSE, SHORT-DURATION GRAZING ON MICROTOPOGRAPHY IN A CHIHUAHUAN DESERT GRASSLAND

    EPA Science Inventory

    We measured the effects of short-term intense grazing by domestic cattle on the microtopography of a black-grama grass (Bouteloua eriopoda) dominated desert grassland. Plots were grazed during winter or summer for 24-36 hours by 20-40 yearlings in 1995 and 1996. Soil microtopogra...

  11. Osseointegrated alloplastic versus autogenous ear reconstruction: criteria for treatment selection.

    PubMed

    Wilkes, G H; Wolfaardt, J F

    1994-04-01

    Fifty-five patients with major ear deformities were reconstructed during the period 1982-1993 with autogenous tissue. Fourteen patients were reconstructed with osseointegrated auricular prostheses during the period 1989-1993. Both procedures were done at the same institution by the same surgeon. The advantages and disadvantages of each approach were considered, and our criteria for treatment selection were developed. Our main indications for autogenous reconstruction include classical microtia, relatively normal lower one-third of the ear, patient preference, and less compliant patients. The main indications for osseointegrated alloplastic reconstruction include following major cancer extirpation, poor local tissue, absence of the lower half of the ear, salvage following unsuccessful autogenous reconstruction, and poor operative risks. Because of their success, osseointegrated auricular reconstructions should be added to the armamentarium of the reconstructive surgeon.

  12. Osseointegration and guided bone regeneration in ectodermal dysplasia patients.

    PubMed

    Garagiola, Umberto; Umberto, Garagiola; Maiorana, Carlo; Ghiglione, Valentino; Marzo, Giuseppe; Santoro, Franco; Szabò, Gyorgy

    2007-11-01

    Dental and surgical implant treatment for patients affected by ectodermal dysplasia syndrome can be very complicated. The guided bone regeneration (GBR) membrane technique together with bone grafting is used to facilitate the placement of osseointegrated implants in a prosthetically guided position. Two groups with the same bony anatomical features were assessed. The first consisted of 13 ectodermal dysplasia patients in whom 66 implants with bone grafts and membranes were inserted. In the second control group, 120 implants with GBR were placed in 20 patients. The implants were assessed at the second stage of surgery, and at a follow-up after 1, 2, and 3 years of functional loading. There was no statistically significant difference in the osseointegration rate between the two groups. Despite the anatomical defects associated with the decreased occlusal vertical dimension and the reduced edentulous alveolar ridges, both in height and width, osseointegrated implants together with GBR and bone grafts can be used successfully in patients with ectodermal dysplasia syndrome.

  13. Resonance Frequency Analysis for Osseointegration in Four Surgical Conditions of Dental Implants

    DTIC Science & Technology

    2001-10-25

    Abstract-The establishment of osseointegration following dental implant placement is a major contributing factor to the clinical success and long...period. Our results showed that there was an increase in resonance frequency related to stiffness increment during osseointegration. Keywords – dental ...implant, osseointegration, resonance frequency, stability I. INTRODUCTION Dental implants are being used increasingly to provide support and retention

  14. A review of improved fixation methods for dental implants. Part I: Surface optimization for rapid osseointegration.

    PubMed

    Shibata, Yo; Tanimoto, Yasuhiro

    2015-01-01

    Titanium is a primary metallic biomaterial used in load-bearing orthopedic or dental implants because of its favorable mechanical properties and osseointegration capability. This article reviews the current status of surface optimization techniques for titanium implants, whether such concepts are in the form of sufficiently evidence-based, and highlights the related experimental tools. A strong emphasis was placed on the enhanced biological responses to titanium implants by modifying the surface finishing process. On this basis, a clear partition of surface chemistry and topography was critical. The intrinsic host tissue response to titanium implants is facilitated by the chemistry or topography of a passive oxide film, although the extent to which the surface characteristics enable rapid osseointegration is still uncertain. Besides the fundamental requirements, such as the promotion of osteogenic differentiation, the titanium implant surface should accelerate wound-healing phenomena prior to bone ingrowth toward the surface. Moreover, because initial bacterial attachment to the implant surface is unavoidable, infection control by surface modification is also an important determinant in reducing surgical failure. A desirable surface-biological relationship often needs to be characterized at the nanoscale by means of advanced technologies. Copyright © 2014 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  15. Decreased fibrous encapsulation and enhanced osseointegration in vitro by decorin-modified titanium surface.

    PubMed

    He, Ronghan; Lu, Yunxiang; Ren, Jianhua; Wang, Zhe; Huang, Junqi; Zhu, Lei; Wang, Kun

    2017-07-01

    Orthopedic implants, using materials such as titanium, are extensively used in clinical surgeries. Despite its popularity, titanium is still inadequate to reliable osseointegration due to aseptic loosing. Fibrous encapsulation on the titanium implant interface prevents osseointegration and leads to the loosing of orthopedic implant. In this study, decorin was loaded on titanium surface by polydopamine film to examine fibrous encapsulation inhibition and bone growth acceleration. The coating of decorin was evaluated by X-ray photoelectron spectroscopy (XPS) and fluorescence microscopy. Quantitative analysis showed increased decorin coating on titanium surface when decorin in the loading solution increases. To test the effect of decorin modification, fibroblast and osteoblast cultures were utilized in vitro. The results showed that the functions of fibroblasts (proliferation, migration and collagen synthesis) were significantly attenuated on the decorin-modified surfaces and this anti-fibrous effect could be due to fibrotic gene suppression by decorin. In contrast, osteoblastic activities, such as calcium deposition and alkaline phosphatase (ALP) activity, were enhanced by the modified decorin. These results suggest that decorin coating on titanium surface inhibited proliferation and function of fibroblasts and improved that of osteoblasts. Therefore, this study is potentially useful for enhancing orthopedic implant. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. RADIOGRAPHIC ASSESSMENT OF EXTREMITY OSSEOINTEGRATION FOR THE AMPUTEE.

    PubMed

    Al Muderis, Munjed; Bosley, Belinda A; Florschutz, Anthony V; Lunseth, Paul A; Klenow, Tyler D; Highsmith, M Jason; Kahle, Jason T

    2016-09-01

    Osseointegration (OI) is a bone-anchoring procedure that allows the direct skeletal attachment of a prosthesis through the use of an implant. Transcutaneous OI implants are similar to subcutaneous intramedullary joint implants with some exceptions. Particularly, OI implants are inserted at the distal aspect of the femur, while intramedullary implants are inserted at the proximal aspect of the femur. In this report, an additional adaptation of the radiographic zonal analysis used for intramedullary implants, known as Gruen zones, is introduced to include OI implants of extremity prosthetics. Radiographic zonal analyses and interpretations are proposed. Gruen zones are used for intramedullary implants, which are generally inserted from the proximal aspect of the bone. OI extremity implants are inserted from the distal end of the bone. Therefore, the zonal analysis is inverted. A radiographic zonal analysis has been introduced by the Osseointegration Group of Australia (OGA). This analysis is needed specifically for the clinical evaluation of extremity OI, as significant changes to the bone and OI implant have been reported and need to be clinically described. A classification technique is necessary for establishing treatment guidelines for the extremity osseointegrated implant. The OGA Zonal analysis addresses this need by adapting a common reference standard to osseointegration of the extremity amputee.

  17. Osseointegrated prostheses for rehabilitation following amputation : The pioneering Swedish model.

    PubMed

    Li, Yan; Brånemark, Rickard

    2017-04-01

    The direct attachment of osseointegrated (OI) prostheses to the skeleton avoids the inherent problems of socket suspension. It also provides physiological weight bearing, improved range of motion in the proximal joint, as well as osseoperceptive sensory feedback, enabling better control of the artificial limbs by amputees. The present article briefly reviews the pioneering efforts on extremity osseointegration surgeries in Sweden and the development of the OPRA (Osseointegrated Prostheses for the Rehabilitation of Amputees) program. The standard implant design of the OPRA system and surgical techniques are described as well as the special rehabilitation protocols based on surgical sites. The results of long-term follow-up for transradial, transhumeral, and thumb amputee operations are briefly reported including the prospective study of transfemoral amputees according to OPRA protocol. The importance of refinement on implant designs and surgical techniques based on the biomechanical analysis and early clinical trials is emphasized. Future aspects on osseointegration surgery are briefly described, including novel treatment options using implanted electrodes.

  18. RADIOGRAPHIC ASSESSMENT OF EXTREMITY OSSEOINTEGRATION FOR THE AMPUTEE

    PubMed Central

    Al Muderis, Munjed; Bosley, Belinda A.; Florschutz, Anthony V.; Lunseth, Paul A.; Klenow, Tyler D.; Highsmith, M. Jason; Kahle, Jason T.

    2016-01-01

    Osseointegration (OI) is a bone-anchoring procedure that allows the direct skeletal attachment of a prosthesis through the use of an implant. Transcutaneous OI implants are similar to subcutaneous intramedullary joint implants with some exceptions. Particularly, OI implants are inserted at the distal aspect of the femur, while intramedullary implants are inserted at the proximal aspect of the femur. In this report, an additional adaptation of the radiographic zonal analysis used for intramedullary implants, known as Gruen zones, is introduced to include OI implants of extremity prosthetics. Radiographic zonal analyses and interpretations are proposed. Gruen zones are used for intramedullary implants, which are generally inserted from the proximal aspect of the bone. OI extremity implants are inserted from the distal end of the bone. Therefore, the zonal analysis is inverted. A radiographic zonal analysis has been introduced by the Osseointegration Group of Australia (OGA). This analysis is needed specifically for the clinical evaluation of extremity OI, as significant changes to the bone and OI implant have been reported and need to be clinically described. A classification technique is necessary for establishing treatment guidelines for the extremity osseointegrated implant. The OGA Zonal analysis addresses this need by adapting a common reference standard to osseointegration of the extremity amputee. PMID:28066531

  19. Efficacy of Vitamin D3 Supplementation on Osseointegration of Implants.

    PubMed

    Javed, Fawad; Malmstrom, Hans; Kellesarian, Sergio Varela; Al-Kheraif, Abdulaziz A; Vohra, Fahim; Romanos, Georgios E

    2016-04-01

    The aim was to systematically review the efficacy of vitamin D3 (VD3) supplementation on the osseointegration of implants. The addressed focused question was "does VD3 supplementation affect osseointegration around implants?" Indexed databases were searched from 1969 up to and including March 2015 using various key words including: "Bone to implant contact"; "implant"; "vitamin D"; and "osseointegration." Letters to the editor, case reports/case series, reviews, and articles published in languages other than English were excluded. The pattern of the present systematic review was customized to primarily summarize the pertinent data. Six experimental studies (4 in rodents and 2 in rabbits) were included. Number of titanium implants placed ranged between 28 and 100 implants. Results from 5 studies showed that VD3 supplementation enhanced new bone formation and/or bone to implant contact (BIC) around implants. One study showed no significant difference in BIC and new bone formation around VD3 coated and noncoated implants. One study reported that insulin therapy with adjunct VD3 supplementation enhances new bone formation around implants in diabetic rats than when insulin replacement therapy is used alone. Efficacy of VD3 supplementation on osseointegration of implants remains controversial and requires further investigations.

  20. Osseointegration and osseoconductivity of hydroxyapatite of different microporosities.

    PubMed

    Rosa, A L; Beloti, M M; Oliveira, P T; Van Noort, R

    2002-11-01

    The aim of this study was to determine the relationship between changes in microporosity and the osseointegration and the osseoconductivity of hydroxyapatite (HAp). HAp cylinders were manufactured by a combination of uniaxial powder pressing and different sintering conditions, with different percentages of microporosity: HAp-I with 3.96+/-0.75% microporosity, HAp-II with 15.66+/-1.60% microporosity, and HAp-III with 29.72+/-0.69% microporosity. These HAp cylinders were surgically implanted in rabbit femurs. After 8 and 12 weeks, the femurs were removed, fixed, sectioned, ground, and stained by Stevenel's blue/Van Gieson for light microscopy and histomorphometry. Some ground sections were routinely processed for SEM. The osseointegration and the osseoconductivity were determined by means of image analysis and the data were submitted to ANOVA. In all cases the cortical bone was repaired and the HAp facing the medullary canal was lined with endosteum, which in some areas exhibited thin bone tissue formation. SEM observations showed no differences in the morphology of tissue-HAp interfaces for the three different porosities of HAp. There were no statistical differences between the groups related to either osseointegration or osseoconductivity. These results suggest that neither osseointegration nor osseoconductivity of HAp are influenced by changes in HAp microporosity.

  1. Laser-Modified Surface Enhances Osseointegration and Biomechanical Anchorage of Commercially Pure Titanium Implants for Bone-Anchored Hearing Systems

    PubMed Central

    Omar, Omar; Simonsson, Hanna; Palmquist, Anders; Thomsen, Peter

    2016-01-01

    Osseointegrated implants inserted in the temporal bone are a vital component of bone-anchored hearing systems (BAHS). Despite low implant failure levels, early loading protocols and simplified procedures necessitate the application of implants which promote bone formation, bone bonding and biomechanical stability. Here, screw-shaped, commercially pure titanium implants were selectively laser ablated within the thread valley using an Nd:YAG laser to produce a microtopography with a superimposed nanotexture and a thickened surface oxide layer. State-of-the-art machined implants served as controls. After eight weeks’ implantation in rabbit tibiae, resonance frequency analysis (RFA) values increased from insertion to retrieval for both implant types, while removal torque (RTQ) measurements showed 153% higher biomechanical anchorage of the laser-modified implants. Comparably high bone area (BA) and bone-implant contact (BIC) were recorded for both implant types but with distinctly different failure patterns following biomechanical testing. Fracture lines appeared within the bone ~30–50 μm from the laser-modified surface, while separation occurred at the bone-implant interface for the machined surface. Strong correlations were found between RTQ and BIC and between RFA at retrieval and BA. In the endosteal threads, where all the bone had formed de novo, the extracellular matrix composition, the mineralised bone area and osteocyte densities were comparable for the two types of implant. Using resin cast etching, osteocyte canaliculi were observed directly approaching the laser-modified implant surface. Transmission electron microscopy showed canaliculi in close proximity to the laser-modified surface, in addition to a highly ordered arrangement of collagen fibrils aligned parallel to the implant surface contour. It is concluded that the physico-chemical surface properties of laser-modified surfaces (thicker oxide, micro- and nanoscale texture) promote bone bonding

  2. Laser-Modified Surface Enhances Osseointegration and Biomechanical Anchorage of Commercially Pure Titanium Implants for Bone-Anchored Hearing Systems.

    PubMed

    Shah, Furqan A; Johansson, Martin L; Omar, Omar; Simonsson, Hanna; Palmquist, Anders; Thomsen, Peter

    2016-01-01

    Osseointegrated implants inserted in the temporal bone are a vital component of bone-anchored hearing systems (BAHS). Despite low implant failure levels, early loading protocols and simplified procedures necessitate the application of implants which promote bone formation, bone bonding and biomechanical stability. Here, screw-shaped, commercially pure titanium implants were selectively laser ablated within the thread valley using an Nd:YAG laser to produce a microtopography with a superimposed nanotexture and a thickened surface oxide layer. State-of-the-art machined implants served as controls. After eight weeks' implantation in rabbit tibiae, resonance frequency analysis (RFA) values increased from insertion to retrieval for both implant types, while removal torque (RTQ) measurements showed 153% higher biomechanical anchorage of the laser-modified implants. Comparably high bone area (BA) and bone-implant contact (BIC) were recorded for both implant types but with distinctly different failure patterns following biomechanical testing. Fracture lines appeared within the bone ~30-50 μm from the laser-modified surface, while separation occurred at the bone-implant interface for the machined surface. Strong correlations were found between RTQ and BIC and between RFA at retrieval and BA. In the endosteal threads, where all the bone had formed de novo, the extracellular matrix composition, the mineralised bone area and osteocyte densities were comparable for the two types of implant. Using resin cast etching, osteocyte canaliculi were observed directly approaching the laser-modified implant surface. Transmission electron microscopy showed canaliculi in close proximity to the laser-modified surface, in addition to a highly ordered arrangement of collagen fibrils aligned parallel to the implant surface contour. It is concluded that the physico-chemical surface properties of laser-modified surfaces (thicker oxide, micro- and nanoscale texture) promote bone bonding which

  3. Plasma electrolytic oxidation of titanium and improvement in osseointegration.

    PubMed

    Chung, Chi-Jen; Su, Rein-Teng; Chu, Hou-Jen; Chen, Hsien-Te; Tsou, Hsi-Kai; He, Ju-Liang

    2013-08-01

    Reducing the osseointegration time for biomedical titanium implants in surgical patients is an important goal. However, a huge controversy exists over the effectiveness of osseointegration of the surface layer by plasma electrolytic oxidation (PEO), which is a widely favored surface modification for titanium-based implants. In this study, various surface coatings, including anatase-TiO2 (A-TiO2 ), rutile-TiO2 (R-TiO2 ), hydroxyapatite (HAp), strontium-containing hydroxyapatite (Sr-HAp), and dual-phase HAp-TiO2 were synthesized on titanium implants by PEO. A comparative study of osseointegration performance (both in vitro and in vivo) and bone/implant adhesion strength conducted using push-out thrust tests were demonstrated. The in vitro experimental test results agree strongly with the in vivo test results: the dual-phase HAp-TiO2 coating exhibits the superior cell adhesion and differentiation condition among all of the coatings in the in vitro tests and therefore has the highest push-out bonding strength of 5.37 MPa after 12 wk of implantation in the in vivo test. The HAp-containing coatings benefit from its bioactivity and therefore perform the others in terms of long-term osteocyte growth (from the in vitro results) and the extent of osseointegration (from the in vivo results). The dual-phase HAp-TiO2 coating provides the advantages of both the bioactive HAp and structural enhancement by the TiO2 , effectively promoting osseointegration.

  4. Osseointegration of hydroxyapatite and remodeling-resorption of tricalciumphosphate ceramics.

    PubMed

    Draenert, Miriam; Draenert, Alice; Draenert, Klaus

    2013-04-01

    Cancellous bone defects surrounded by still intact bone structures never heal. Ceramics offer a solution providing osteoconductive scaffolds. The purpose of the study is to evaluate whether structured β-TCP and HA implants can reconstruct cancellous bone defects, which role micro- and macro-porosity, stiffness and surface area play; finally the indication for both materials based on its resorbability. 10 German Shepard dogs were operated on both tibial heads implanting shell-like fully interconnected ceramic cylinders, using a wet grinding hollow drill coated with diamonds. β-TCP was compared with HA. A polychromatic sequential labelling with 4 different fluorochromes controlled bone formation dynamics. Non-decalcifying histology after perfusion fixation and vessel casting was performed. μ-CT was combined with high resolution microradiography and histology on thin ground crossections. The stages after 6 weeks, 2, 3, 4 months and 15 months were evaluated. In spite of osseointegration of HA and β-TCP, the osseointegration of both materials was completely different. Both shell-like bone void fillers were osseointegrated in a sandwich-like manner. HA yielded primarily a reinforcement of the recipient's cancellous-bone bed and full osseointegration after 4 months, whereas β-TCP-implants were fully osseointegrated after 6 weeks. HA did not show signs of resorption. The resorption of the β-TCP resulted during remodelling. The final stage showed restitution "ad integrum" of the β-TCP defects with a physiological architecture, whereas HA was integrated in the cancellous bone construction providing 600 μm measuring macropores showing osteoinductive properties. Copyright © 2013 Wiley Periodicals, Inc.

  5. Osseointegrated fixture placement with simultaneous tooth extraction.

    PubMed

    Schabes, G A; Sacks, H G; Kaufman, P S

    1992-03-01

    Three cases are presented that illustrate the potential for accelerating the healing phase with fixture-based treatment. Depending on the clinical circumstances, techniques may include radical alveolectomy, the use of fresh extraction sockets, and fixture placement in inter-radicular bone.

  6. [AFM study on microtopography of NOM and newly formed hydrous manganese dioxide adsorbed on mica].

    PubMed

    Guo, Jin; Ma, Jun; Shi, Xue-hua

    2006-05-01

    With the methods of mica adsorbing, the microtopography of the newly formed hydrous manganese dioxide was perfectly captured. The tapping mode AFM study results revealed that the newly formed hydrous manganese dioxide possesses a perforated sheet (with a thickness of 0-1.75 nm) as well as some spheric particle structures compared with the hydrous manganese dioxide with 2 h aging time, which demonstrated that the newly formed hydrous manganese dioxide have a large surface area and adsorption capacity. When 1 mmol/L newly formed hydrous manganese dioxide was added, the microtopography of NOM molecules shifted from loosely dispersed pancake shape (with adsorption height of 5-8.5 nm) to densely dispersed and uniform spheric structure. NOM was prone to adsorb on the surface of the newly formed hydrous manganese dioxide, which provided a valid proof for the coagulation-aid mechanism of permanganate preoxidation.

  7. Predicting the roughness length of turbulent flows over landscapes with multi-scale microtopography

    NASA Astrophysics Data System (ADS)

    Pelletier, Jon D.; Field, Jason P.

    2016-05-01

    The fully rough form of the law of the wall is commonly used to quantify velocity profiles and associated bed shear stresses in fluvial, aeolian, and coastal environments. A key parameter in this law is the roughness length, z0. Here we propose a predictive formula for z0 that uses the amplitude and slope of each wavelength of microtopography within a discrete-Fourier-transform-based approach. Computational fluid dynamics (CFD) modeling is used to quantify the effective z0 value of sinusoidal microtopography as a function of the amplitude and slope. The effective z0 value of landscapes with multi-scale roughness is then given by the sum of contributions from each Fourier mode of the microtopography. Predictions of the equation are tested against z0 values measured in ˜ 105 wind-velocity profiles from southwestern US playa surfaces. Our equation is capable of predicting z0 values to 50 % accuracy, on average, across a 4 order of magnitude range. We also use our results to provide an alternative formula that, while somewhat less accurate than the one obtained from a full multi-scale analysis, has an advantage of being simpler and easier to apply.

  8. Asymmetric Nano/Microtopography Biases Cytoskeletal Dynamics and Promotes Unidirectional Cell Guidance

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoyu; Driscoll, Meghan; Guven, Can; Das, Satarupa; Parent, Carole; Fourkas, John; Losert, Wolfgang

    Many biological and physiological processes depend upon directed migration of cells, which is typically mediated by chemical or physical gradients or by signal relay. Here we show that cells can be guided in a single preferred direction based solely on local asymmetries in nano/microtopography on subcellular scales. These asymmetries can be repeated, and thereby provide directional guidance, over arbitrarily large areas. The direction and strength of the guidance is sensitive to the details of the nano/microtopography, suggesting that this phenomenon plays a context-dependent role in vivo. We demonstrate that asymmetric nano/microtopography guides the direction of internal actin polymerization waves (esotaxis), and that cells move in the same direction as these waves (microthigmotaxis). This phenomenon is observed both for the pseudopod-dominated migration of the amoeboid Dictyostelium discoideum and for the lamellipod-driven migration of human neutrophils. The conservation of this mechanism across cell types and the asymmetric shape of many natural scaffolds suggests that actin-wave-based guidance is important in biology and physiology.

  9. A new modeling approach for simulating microtopography-dominated, discontinuous overland flow on infiltrating surfaces

    NASA Astrophysics Data System (ADS)

    Yang, Jun; Chu, Xuefeng

    2015-04-01

    Realistic modeling of discontinuous overland flow on irregular topographic surfaces has been proven to be a challenge. This study is aimed to develop a new modeling framework to simulate the discontinuous puddle-to-puddle (P2P) overland flow dynamics for infiltrating surfaces with various microtopographic characteristics. In the P2P model, puddles were integrated in a well-delineated, cascaded drainage system to facilitate explicit simulation of their dynamic behaviors and interactions. Overland flow and infiltration were respectively simulated by using the diffusion wave model and a modified Green-Ampt model for the DEM-derived flow drainage network that consisted of a series of puddle-based units (PBUs). The P2P model was tested by using a series of data from laboratory overland flow experiments for various microtopography, soil, and rainfall conditions. The modeling results indicated that the hierarchical relationships and microtopographic properties of puddles significantly affected their connectivity, filling-spilling dynamics, and the associated threshold flow. Surface microtopography and rainfall characteristics also exhibited strong influences on the spatio-temporal distributions of infiltration rates, runoff fluxes, and unsaturated flow. The model tests demonstrated its applicability in simulating microtopography-dominated overland flow on infiltrating surfaces.

  10. Microtopography of bare peat: an objective classification from high-resolution topographic survey data

    NASA Astrophysics Data System (ADS)

    Smith, Mark; Warburton, Jeff

    2017-04-01

    Peatlands globally are at risk of degradation through increased susceptibility to erosion as a result of climate change. For peatland restoration practices to be designed efficiently and evaluated effectively, quantification of eroded peat volumes is required alongside an understanding of the processes responsible for their degradation. Owing to the unique material properties of peat, fine-scale microtopographic expressions of surface processes are especially pronounced and present a potentially rich source of geomorphological information; providing valuable insights into the stability and dominant surface process regimes. Bare peat is highly responsive to changing environmental forces acting at the near surface and characteristic microtopographies emerge in response to rainfall, surface wash, wind action and fluctuations in surface temperature (both drying and freezing). Spatial and temporal variations in surface roughness reflect contrasts in the physical properties of the peat and key erosion processes acting in combination. We present the first conceptual framework to rigorously describe bare peat microtopography and use Structure-from-Motion (SfM) surveys to quantify roughness for different peat surfaces. Through application of a survey-grade structured-light hand-held 3D imager (Mantis Vision F5-Short Range) which can represent sub-millimetre topographic variability in field conditions, we present the most reliable field validation of SfM at the plot scale (<1 m2). Peat microtopography is quantified using 26 roughness metrics that cover a range of surface features (including amplitude, spacing, hybrid, multi-scale and anisotropy parameters). SfM reconstructs peat microtopography effectively, although some smoothing is observed. Over 55 plots, the roughness of microtopographic types is quantified and an objective classification system derived from decision tree analysis. After training on 66% of the data, the decision tree correctly classified 85% of plots

  11. Osseointegration of Titanium Prostheses on the Stapes Footplate

    PubMed Central

    Beleites, Thomas; Ney, Michael; Kluge, Anne; Lasurashvili, Nikoloz; Bornitz, Matthias; Scharnweber, Dieter; Zahnert, Thomas

    2010-01-01

    The success of middle ear reconstructive surgery depends on stable coupling between the prosthesis and residual ossicles. To establish a stable fixed point on the stapes footplate for subsequent prosthesis reconstruction, a titanium footplate anchor was coated with osteoinductive substances to induce a controlled osseointegration on the footplate. Various studies have shown that collagen-based matrices with and without bone growth and differentiation factors can induce and enhance bone formation and consequently increase implant stability. The ears of 23 one-year-old Merino sheep (n = 46) were divided into five groups and implanted with a specially designed footplate anchor. The surface of each implant was modified by applying a collagenous matrix (collagen I or II) either with immobilized bone morphogenic protein (BMP-4) or transforming growth factor-ß, respectively, to stimulate osteoblastic activation and differentiation on the stapes footplate with subsequent osseointegration. Polychrome labeling was used to assess new bone formation and remodeling during the study. After study termination on day 84, synchrotron radiation-based computed microtomography and histomorphometry were used to identify bone implant contact. Eight implants showed radiographical and/or histological evidence of integration by newly formed bone. An osseointegration could histologically be proven in two of these eight specimens, and additional ectopic bone formations were seen in another 21 specimens. In all animals, bone turnover on the footplate was proven by polychrome labeling. This study proves the general ability to induce a controlled osseointegration of titanium implants biologically activated with artificial extracellular matrices on their surfaces on the stapes footplate in a mammalian organism. PMID:20066460

  12. Gene Expression Dynamics During Bone Healing and Osseointegration

    PubMed Central

    Lin, Zhao; Rios, Hector F.; Volk, Sarah L.; Sugai, James V.; Jin, Qiming; Giannobile, William V.

    2012-01-01

    Background Understanding the molecular features of bone repair and osseointegration may aid in the development of therapeutics to improve implant outcomes. The purpose of this investigation is to determine the gene expression dynamics during alveolar bone repair and implant osseointegration. Methods An implant osseointegration preclinical animal model was used whereby maxillary defects were created at the time of oral implant placement, while a tooth extraction socket healing model was established on the contralateral side of each animal. The surrounding tissues in the zone of the healing defects were harvested during regeneration for temporal evaluation using histology, immunohistochemistry, laser capture microdissection, and quantitative reverse transcription–polymerase chain reaction for the identification of a panel of 17 putative genes associated with wound repair. Results In both models, three distinct expression patterns were displayed: 1) genes that are slowly increased during the healing process, such as bone morphogenetic protein 4, runt-related transcription factor 2, and osteocalcin; 2) genes that are upregulated at the early stage of healing and then downregulated at later stages, such as interleukin and chemokine (C-X-C motif) ligands 2 and 5; and 3) genes that are constitutively expressed over time, such as scleraxis. Although some similarities between osseointegration and tooth extraction socket were seen, distinct features developed and triggered a characteristic coordinated expression and orchestration of transcription factors, growth factors, extracellular matrix molecules, and chemokines. Conclusions Characterization of these events contributes to a better understanding of cooperative molecular dynamics in alveolar bone healing, and highlights potential pathways that could be further explored for the enhancement of osseous regenerative strategies. PMID:21142982

  13. Osseointegration of standard and mini dental implants: a histomorphometric comparison.

    PubMed

    Dhaliwal, Jagjit S; Albuquerque, Rubens F; Murshed, Monzur; Feine, Jocelyne S

    2017-12-01

    Mini dental implants (MDIs) are becoming increasingly popular for rehabilitation of edentulous patients because of their several advantages. However, there is a lack of evidence on the osseointegration potential of the MDIs. The objective of the study was to histomorphometrically evaluate and compare bone apposition on the surface of MDIs and standard implants in a rabbit model. Nine New Zealand white rabbits were used for the study to meet statistical criteria for adequate power. Total 18 3M(™)ESPE(™) MDIs and 18 standard implants (Ankylos(®) Friadent, Dentsply) were inserted randomly into the tibia of rabbits (four implants per rabbit); animals were sacrificed after a 6-week healing period. The specimens were retrieved en bloc and preserved in 10% formaldehyde solution. Specimens were prepared for embedding in a light cure acrylic resin (Technovit 9100). The most central sagittal histological sections (30-40 μm thick) were obtained using a Leica SP 1600 saw microtome. After staining, the Leica DM2000 microscope was used, the images were captured using Olympus DP72 camera and associated software. Bone implant contact (BIC) was measured using Infinity Analyze software. All implants were osseointegrated. Histologic measures show mineralized bone matrix in intimate contact with the implant surface in both groups. The median BIC was 57.5% (IQR 9.0) in the MDI group and 55.0% (IQR 4.5) in the control group (P > 0.05, Mann-Whitney test). There were no statistical differences in osseointegration at 6 weeks between MDIs and standard implants in rabbit tibias. Based on these results, it is concluded that osseointegration of MDIs is similar to that of standard implants.

  14. An evaluation of impression techniques for osseointegrated implants.

    PubMed

    Spector, M R; Donovan, T E; Nicholls, J I

    1990-04-01

    A passive fit between osseointegrated implants and the prosthesis they will support has been advocated. An experimental model was developed to test the accuracy of three impression techniques and the components used to make the transfer records. Statistically, no significant difference was found between the three methods tested. From this initial study, it appears that further work is needed to isolate techniques that will predictably provide accurate registration of the position of endosseous implants.

  15. The effect of osteoprotegerin on implant osseointegration in ovariectomized rats

    PubMed Central

    Liu, Yiming; Hu, Jing; Liu, Biao; Jiang, Xiliang

    2017-01-01

    Introduction Osteoprotegerin (OPG), the endogenous inhibitor of RANKL, prevents or reverses bone loss in a variety of preclinical models of bone disease. Preclinical studies indicate that osteoporosis significantly impairs implant fixation. This study aims to investigate the role of OPG in implant osseointegration in ovariectomized rats. Material and methods Twelve weeks after bilateral ovariectomy, each rat accepted two titanium screws in the proximal tibiae. All animals were then randomly divided into two groups: the control (10 rats) and OPG group (10 rats). Subcutaneous injection of OPG (10 mg/kg) or vehicle was performed three times a week. Eight weeks later, tibiae with screws were harvested for micro-computed tomography (μCT), histological and biomechanical analysis. Results Compared to control, OPG increased the percent bone volume by 124%, the percent osseointegration by 167%, the mean trabecular number by 111%, the mean trabecular thickness by 92% (p < 0.01), the mean connective density by 95% (p < 0.05); and decreased the mean trabecular separation by 64% in μCT analysis (p < 0.05). Osteoprotegerin also increased bone area density by 160% and bone-to-implant contact by 234% in histomorphometric evaluation (p < 0.01), and increased the maximal push-out force by 228% in biomechanical test (p < 0.01). Conclusions Systemic administration of OPG improved implant osseointegration and fixation in ovariectomized rats, resulting from the increased peri-implant bone mass and improved trabecular microarchitecture. PMID:28261305

  16. The Ultrastructural Relationship Between Osteocytes and Dental Implants Following Osseointegration.

    PubMed

    Du, Zhibin; Ivanovski, Saso; Hamlet, Stephen M; Feng, Jian Q; Xiao, Yin

    2016-04-01

    Osteocytes, the most abundant cells in bone, have multiple functions, including acting as mechanosensors and regulating mineralization. It is clear that osteocytes influence bone remodeling by controlling the differentiation and activity of osteoblasts and osteoclasts. Determining the relationship between titanium implants and osteocytes may therefore benefit our understanding of the process of osseointegration. The aim of this study was to visualize the ultrastructural relationship between osteocytes and the titanium implant surface following osseointegration in vivo. Titanium implants were placed in the maxillary molar regions of eight female Sprague Dawley rats, 3 months old. The animals were sacrificed 8 weeks after implantation, and undecalcified tissue sections were prepared. Resin-cast samples were subsequently acid-etched with 37% phosphoric acid prior to examination using scanning electron microscopy. Compared with mature bone, where the osteocytes were arranged in an ordered fashion, the osteocytes appeared less organized in the newly formed bone around the titanium implant. Further, a layer of mineralization with few organic components was observed on the implant surface. This study shows for the first time that osteocytes and their dendrites are directly connected with the implant surface. This study shows the direct anchorage of osteocytes via dendritic processes to a titanium implant surface in vivo. This suggests an important regulatory role for osteocytes and their lacunar-canalicular network in maintaining long-term osseointegration. © 2014 Wiley Periodicals, Inc.

  17. Relative significance of microtopography and vegetation as controls on surface water flow on a low-gradient floodplain

    USGS Publications Warehouse

    Choi, Jungyill; Harvey, Judson W.

    2014-01-01

    Surface water flow controls water velocities, water depths, and residence times, and influences sediment and nutrient transport and other ecological processes in shallow aquatic systems. Flow through wetlands is substantially influenced by drag on vegetation stems but is also affected by microtopography. Our goal was to use microtopography data directly in a widely used wetland model while retaining the advantages of the model’s one-dimensional structure. The base simulation with no explicit treatment of microtopography only performed well for a period of high water when vegetation dominated flow resistance. Extended simulations using microtopography can improve the fit to low-water conditions substantially. The best fit simulation had a flow conductance parameter that decreased in value by 70 % during dry season such that mcrotopographic features blocked 40 % of the cross sectional width for flow. Modeled surface water became ponded and flow ceased when 85 % of the cross sectional width became blocked by microtopographic features. We conclude that vegetation drag dominates wetland flow resistance at higher water levels and microtopography dominates at low water levels with the threshold delineated by the top of microtopographic features. Our results support the practicality of predicting flow on floodplains using relatively easily measured physical and biological variables.

  18. Osseointegration of metallic devices: current trends based on implant hardware design.

    PubMed

    Coelho, Paulo G; Jimbo, Ryo

    2014-11-01

    Osseointegration of metallic devices has been one of the most successful treatments in rehabilitative dentistry and medicine over the past five decades. While highly successful, the quest for designing surgical instrumentation and associated implantable devices that hastens osseointegration has been perpetual and has often been approached as single variable preclinical investigations. The present manuscript presents how the interplay between surgical instrumentation and device macrogeometry not only plays a key role on both early and delayed stages of osseointegration, but may also be key in how efficient smaller length scale designing (at the micrometer and nanometer scale levels) may be in hastening early stages of osseointegration. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Engineered antifouling microtopographies: kinetic analysis of the attachment of zoospores of the green alga Ulva to silicone elastomers.

    PubMed

    Cooper, Scott P; Finlay, John A; Cone, Gemma; Callow, Maureen E; Callow, James A; Brennan, Anthony B

    2011-09-01

    Microtopography has been demonstrated as an effective deterrent to biofouling. The majority of published studies are fixed-time assays that raise questions regarding the kinetics of the attachment process. This study investigated the time-dependent attachment density of zoospores of Ulva, in a laboratory assay, on a micropatterned and smooth silicone elastomer. The attachment density of zoospores was reduced on average 70-80% by the microtopography relative to smooth surfaces over a 4 h exposure. Mapping the zoospore locations on the topography revealed that they settled preferentially in specific, recessed areas of the pattern. The kinetic data fit, with high correlation (r(2) > 0.9), models commonly used to describe the adhesion of bacteria to surfaces. The grouping of spores on the microtopography indicated that the pattern inhibited the ability of attached spores to recruit neighbors. This study demonstrates that the antifouling mechanism of topographies may involve disruption of the cooperative effects exhibited by fouling organisms such as Ulva.

  20. Surface microtopographies of tropical sea stars: lack of an efficient physical defence mechanism against fouling.

    PubMed

    Guenther, Jana; De Nys, Rocky

    2007-01-01

    The role of surface topography as a defence against fouling in tropical sea stars was investigated. The sea stars Linckia laevigata, Fromia indica, Cryptasterina pentagona and Archaster typicus are not fouled and have paxillae (modified ossicles with a median vertical pillar) on their aboral surfaces, which varied in diameter, height and distance depending on species and position on the aboral surface, providing unique and complex surface microtopographies for each species. The surfaces of the sea stars L. laevigata, F. indica and A. typicus were moderately wettable, with their mean seawater contact angles, calculated from captive bubble measurements, being 60.1 degrees, 70.3 degrees and 57.3 degrees, respectively. The seawater contact angle of C. pentagona could not be measured. To evaluate the effectiveness of the surface microtopographies in deterring the settlement of fouling organisms, field experiments with resin replicas of the four sea star species were conducted at three sites around Townsville, Australia, for 8 weeks during the dry and wet seasons. The fouling community and total fouling cover did not differ significantly between replicas of L. laevigata, F. indica, C. pentagona, A. typicus and control surfaces at any site during the dry season. Significant differences between fouling communities on the replicas of the sea stars and control surfaces were detected at two sites during the wet season. However, these differences were transitory, and the total fouling cover did not differ significantly between replicas of sea stars and control surfaces at two of the three sites. In contrast to recent literature on the effects of biofouling control by natural surfaces in the marine environment, the surface microtopographies of tropical sea stars alone were not effective in deterring the settlement and growth of fouling organisms.

  1. The influence of direct laser metal sintering implants on the early stages of osseointegration in diabetic mini-pigs.

    PubMed

    Tan, Naiwen; Liu, Xiangwei; Cai, Yanhui; Zhang, Sijia; Jian, Bo; Zhou, Yuchao; Xu, Xiaoru; Ren, Shuai; Wei, Hongbo; Song, Yingliang

    2017-01-01

    High failure rates of oral implants have been reported in diabetic patients due to the disruption of osseointegration. The aim of this study was to investigate whether direct laser metal sintering (DLMS) could improve osseointegration in diabetic animal models. Surface characterizations were carried out on two types of implants. Cell morphology and the osteogenic-related gene expression of MG63 cells were observed under conditions of DLMS and microarc oxidation (MAO). A diabetes model in mini-pigs was established by intravenous injection of streptozotocin (150 mg/kg), and a total of 36 implants were inserted into the mandibular region. Micro-computed tomography (micro-CT) and histologic evaluations were performed 3 and 6 months after implantation. The Ra (the average of the absolute height of all points) of MAO surface was 2.3±0.3 µm while the DLMS surface showed the Ra of 27.4±1.1 µm. The cells on DLMS implants spread out more podia than those on MAO implants through cell morphology analysis. Osteogenic-related gene expression was also dramatically increased in the DLMS group. Obvious improvement was observed in the micro-CT and Van Gieson staining analyses of DLMS implants compared with MAO at 3 months, although this difference disappeared by 6 months. DLMS implants showed a higher bone-implant contact percentage (33.2%±11.2%) at 3 months compared with MAO group (18.9%±7.3%) while similar results were showed at 6 months between DLMS group (42.8%±10.1%) and MAO group (38.3%±10.8%). The three-dimensional environment of implant surfaces with highly porous and fully interconnected channel and pore architectures can improve cell spreading and accelerate the progress of osseointegration in diabetic mini-pigs.

  2. The influence of direct laser metal sintering implants on the early stages of osseointegration in diabetic mini-pigs

    PubMed Central

    Tan, Naiwen; Liu, Xiangwei; Cai, Yanhui; Zhang, Sijia; Jian, Bo; Zhou, Yuchao; Xu, Xiaoru; Ren, Shuai; Wei, Hongbo; Song, Yingliang

    2017-01-01

    Background High failure rates of oral implants have been reported in diabetic patients due to the disruption of osseointegration. The aim of this study was to investigate whether direct laser metal sintering (DLMS) could improve osseointegration in diabetic animal models. Methods Surface characterizations were carried out on two types of implants. Cell morphology and the osteogenic-related gene expression of MG63 cells were observed under conditions of DLMS and microarc oxidation (MAO). A diabetes model in mini-pigs was established by intravenous injection of streptozotocin (150 mg/kg), and a total of 36 implants were inserted into the mandibular region. Micro-computed tomography (micro-CT) and histologic evaluations were performed 3 and 6 months after implantation. Results The Ra (the average of the absolute height of all points) of MAO surface was 2.3±0.3 µm while the DLMS surface showed the Ra of 27.4±1.1 µm. The cells on DLMS implants spread out more podia than those on MAO implants through cell morphology analysis. Osteogenic-related gene expression was also dramatically increased in the DLMS group. Obvious improvement was observed in the micro-CT and Van Gieson staining analyses of DLMS implants compared with MAO at 3 months, although this difference disappeared by 6 months. DLMS implants showed a higher bone–implant contact percentage (33.2%±11.2%) at 3 months compared with MAO group (18.9%±7.3%) while similar results were showed at 6 months between DLMS group (42.8%±10.1%) and MAO group (38.3%±10.8%). Conclusion The three-dimensional environment of implant surfaces with highly porous and fully interconnected channel and pore architectures can improve cell spreading and accelerate the progress of osseointegration in diabetic mini-pigs. PMID:28814861

  3. Characterization of microtopography and its influence on vegetation patterns in created wetlands

    USGS Publications Warehouse

    Moser, K.; Ahn, C.; Noe, G.

    2007-01-01

    Created wetlands are increasingly used to mitigate wetland loss. Thus, identifying wetland creation methods that enhance ecosystem development might increase the likelihood of mitigation success. Noting that the microtopographic variation found in natural wetland settings may not commonly be found in created wetlands, this study explores relationships between induced microtopography, hydrology, and plant species richness/ diversity in non-tidal freshwater wetlands, comparing results from two created wetland complexes with those from a mature reference wetland complex in northern Virginia. Elevation, steel rod oxidation depth, and species cover were measured along replicate multiscale (0.5 m-, 1 m-, 2 m-, and 4 m-diameter) tangentially conjoined circular transects in each wetland. Microtopography was surveyed using a total station and results used to derive three roughness indices: tortuosity, limiting slope, and limiting elevation difference. Steel rod oxidation depth was used to estimate water table depth, with data collected four times during the growing season for each study site. Plant species cover was estimated visually in 0.2 m2 plots surveyed at peak growth and used to assess species richness, diversity, and wetland prevalence index. Differences in each attribute were examined among disked and non-disked created wetlands and compared to a natural wetland as a reference. Disked and non-disked created wetlands differed in microtopography, both in terms of limiting elevation difference and tortuosity. However, both were within the range of microtopography encompassed by natural wetlands. Disked wetlands supported higher plant diversity and species richness than either natural or non-disked wetlands, as well as greater within-site species assemblage variability than non-disked wetlands. Irrespective of creation method, plant diversity in created wetlands was correlated with tortuosity and limiting elevation difference, similar to correlations observed for

  4. Microdeflectometry--a novel tool to acquire three-dimensional microtopography with nanometer height resolution.

    PubMed

    Häusler, Gerd; Richter, Claus; Leitz, Karl-Heinz; Knauer, Markus C

    2008-02-15

    We introduce "microdeflectometry," a novel technique for measuring the microtopography of specular surfaces. The primary data are the local slope of the surface under test. Measuring the slope instead of the height implies high information efficiency and extreme sensitivity to local shape irregularities. The lateral resolution can be better than 1 microm, whereas the resulting height resolution is in the range of 1nm. Microdeflectometry can be supplemented by methods to expand the depth of field, with the potential to provide quantitative 3D imaging with scanning-electron-microscope-like features.

  5. Spatial heterogeneity of microtopography and its influence on the flow convergence of slopes under different rainfall patterns

    NASA Astrophysics Data System (ADS)

    Luo, Jian; Zheng, Zicheng; Li, Tingxuan; He, Shuqin

    2017-02-01

    This study aimed to reveal the spatial heterogeneity of the microtopography and its influence on flow convergence on sloping farmland of purple soil area in China. Methods involving artificial rainfall, pin meter and photographic measurements were adopted to generate DEM (digital elevation model). Geographic statistics and multifractal theory were used for quantitative and hydrological analyses of microtopography based on ArcGIS. Two artificial tillage practices (ridge tillage and conservation tillage) were used to simulate different types of microtopography. Ridge tillage (RT) was designed according to local agricultural customs in China, with conservation tillage (CK) used for comparison purposes. A total of 12 rainfall simulation experiments were conducted in two 1 m by 2 m boxes under increased rainfall series (1.0, 1.5, and 2.0 mm min-1) and decreased rainfall series (2.0, 1.5, and 1.0 mm min-1) on a typical slope gradient of 15°. Artificial tillage was the major contributing factor to the spatial heterogeneity of microtopography on sloping farmland of the purple soil area. Spatiotemporal variability of microtopography was expressed using semivariogram and multifractal spectrum, and spatial heterogeneity of drainage networks was expressed using general fractal dimension ΔD based on multifractal theory. In general, the drainage networks was mostly effected by microrelief. The drainage density of ridge tillage was smaller than that of the conservation tillage under different rainfall patterns, and the drainage density decreased remarkably with the increasing microrelief. Moreover, the ΔD values of ridge tillage ranged from 0.1817 to 0.5677. By contrast, the ΔD values of the conservation tillage ranged from 0.9662 to 1.3013, and thus the lower spatial heterogeneity of drainage networks in ridge tillage compared to conservation tillage. In this study, we established a novel method for analysis of the spatial heterogeneity of microtopography and demonstrated

  6. Bone dynamics of osseointegration, ankylosis, and tooth movement.

    PubMed

    Roberts, W E

    1999-01-01

    Masticatory function challenges the strength and adaptive capability of supporting bone. When osseous tissue is loaded, it accumulates fatigue damage which must be repaired by bone modeling and remodeling. The three principal masticatory abutments (normal teeth, ankylosed teeth and osseointegrated implants) are a dynamic physiologic continuum relative to bone biomechanics. Implants are rigidly integrated units that can only be moved by fracturing the interface. Normal teeth and some ankylosed teeth can be moved using implants for orthodontic and orthopedic anchorage. Because orthodontic translation generates new bone and attached gingiva, it is a form of tissue engineering. Modern interdisciplinary practice requires a thorough knowledge of the principles of bone physiology and biomechanics.

  7. Prosthesis auricular with osseointegrated implants and quality of life.

    PubMed

    dos Santos, Daniela Micheline; Goiato, Marcelo Coelho; Pesqueira, Aldiéres Alves; Bannwart, Lisiane Cristina; Rezende, Maria Cristina Rosifini Alves; Magro-Filho, Osvaldo; Moreno, Amália

    2010-01-01

    Implants in craniofacial reconstructions improve prostheses retention and stability, comfort, and safety for the patient. According to biomechanical principles, the treatment success regarding osseointegration maintenance depends on an adequate surgery technique associated to a retention system that provides favorable tension distribution to implants. Implants in the mastoid area are a very important aid for retention of auricular prostheses. Color stability of resin and silicone is an important factor for longevity of auricular prostheses, and the high degree of satisfaction of patients with head and neck defects receiving epithesial reconstruction in the maxillofacial region is demonstrated.

  8. Microtopography alters self-organized vegetation patterns in water-limited ecosystems

    NASA Astrophysics Data System (ADS)

    McGrath, Gavan S.; Paik, Kyungrock; Hinz, Christoph

    2012-09-01

    In terrestrial systems limited by water availability the spatial distribution of vegetation can self-organize into a mosaic of vegetated patches and bare soil. Spatially extensive competition for water and short-range facilitation underpin many models that describe the process of vegetation pattern formation. Earlier studies investigating this self-organized patchiness have largely considered smooth landscapes. However, topographic variations can significantly alter the redistribution of surface water flow and therefore the pattern-forming process. Here, we consider how microtopographic variations, at the scale of individual plants, alters self-organized vegetation patterns with the use of a simple ecohydrological model. We show that increasing microtopography can induce a change from banded vegetation, oriented across the slope, to irregular drainage patterns, oriented in the downslope direction. The mechanism responsible is shown to be a change in the spatial redistribution of infiltration around plants and plant patches. Only small increases in microtopography are required to cause banded systems with weak facilitation to change to downslope-oriented patterns. When non-periodic boundary conditions were considered, band orientation tended to become oblique to the topographic contour and in some circumstances their migration upslope ceased. These results suggest that diffusive sediment transport processes may be essential for the maintenance of regular periodic vegetation patterns, which implies that erosion may be critical for understanding the susceptibility of these ecosystems to catastrophic shifts.

  9. Long-term neurite orientation on astrocyte monolayers aligned by microtopography.

    PubMed

    Sørensen, Annette; Alekseeva, Tijna; Katechia, Kashyap; Robertson, Mary; Riehle, Mathis O; Barnett, Susan C

    2007-12-01

    After spinal cord injury neuronal connections are not easily re-established. Success has been hampered by the lack of orientation of neurites inside scar tissue and a lack of neurites crossing out of the site of injury. Oriented scaffolds in biodegradable polymers could be an excellent way to support both the orientation of neurites within the injury site as well as aiding their crossing out of the lesion. To establish the validity of using grooved micro-topography in polycaprolactone in combination with glia we have studied the long-term (3 weeks) orientation of neuronal cells on monolayers of astrocytes on the top of grooved topographies of various dimensions. We find that neurites are significantly aligned by groove/ridge type topographies which are "buried" under a monolayer of astrocytes for up to 3 weeks. This alignment is significantly lower than that of neurites growing directly on the topography, but these neurons do not survive on the poly-l-lysine coated polymer for more than a week. The alignment of neurites on the astrocyte layer to the underlying topography decreases over time, and with groove width. Topographies with 12.5 or 25 microm lateral dimension appear optimal for the long-term alignment and can support myelination. We have shown for the first time that micro-topography can act through an overlaid astrocyte layer and results in aligned neurites in long-term culture and that these can be myelinated by endogenous oligodendrocytes.

  10. Surface roughness variations in time - modelling the effects of precipitation on microtopography

    NASA Astrophysics Data System (ADS)

    Schwanghart, W.; Kuhn, N. J.; Anderson, K.

    2009-04-01

    Microtopography strongly affects velocities and patterns of overland flow, water retention and mineralization of soil organic matter. Bare surfaces experience a restructuring of the small-scale relief during rainfall events due to rainsplash, crusting, sealing and rill initiation. Such restructuring in turn affects hydrologic processes at larger scales. Considering these processes in rainfall-runoff models is challenging due to the different scales involved. (Semi-)variograms provide valuable parameters about the spatial organization of microrelief, which can be used as measure of surface roughness at different scales. Our work focuses on the changes of the variogram parameters during rainfall events and how topographic variations can be parameterized based on these changes. We applied rainfall experiments on bare soil surfaces and surveyed relief evolution at fixed timesteps using a laser scanner. We also used the grid representation of the initial surface conditions to simulate relief evolution with a diffusion equation. Our study shows that the variogram parameters significantly change during a rainfall event. This variability can be reproduced by analyzing variogram parameters of surfaces simulated by the diffusion equation. With the development of distinct flow pathways a significant reorganization of microtopography occurs. These surface patterns can be parameterized by anisotropic variogram models. Anisotropy in variogram models offers another parameter for surface roughness characterization in hydrologic models and may have the potential to serve as parameter describing surface conditions relevant for runoff concentration. Therefor anisotropy could provide a measure to bridge the gap between micro-scale processes and catchment scale hydrology.

  11. Effects of TiO2 nanotubes with different diameters on gene expression and osseointegration of implants in minipigs.

    PubMed

    Wang, Na; Li, Hongyi; Lü, Wulong; Li, Jinghui; Wang, Jinshu; Zhang, Zhenting; Liu, Yiran

    2011-10-01

    Titanium dioxide (TiO(2)) nanotubes can accelerate the adhesion and differentiation of osteoblasts, yet little is known how this nano-modified implant surface affects osseointegration at molecular level in vivo. The aim of this study was to investigate the effects of TiO(2) nanotubes with different diameters (30 nm, 70 nm and 100 nm) on biological attachment mechanism of implants to bone in vivo by studying the gene expression and bone formation around the implants. The histological features and fluorochrome labeling changes of bone around implants on the non-decalcified sections (at 3, 5 and 8 weeks after implantation) were investigated by using traditional light- and fluorescent microscopy, and the gene expression of alkaline phosphatase (ALP), osterix (Osx), collagen-I (Col-I) and tartrate-resistant acid phosphatase (TRAP) was examined by using real-time PCR at 1, 2, 3, 4 and 5 weeks after implantation. Comparing with machined titanium implants, a significant increase in bone-implant contact (BIC) and gene expression levels was found in the bone attached to implants with TiO(2) nanotubes, especially with 70 nm diameter nanotubes. At the same time, the sequential fluorescent labeling images illustrated dynamic bone deposition. In conclusion, TiO(2) nanotubes can modulate bone formation events at the bone-implant interface as to reach favorable molecular response and osseointegration; in addition, the diameters of nanotubes can be precisely controlled in order to obtain better bone formation.

  12. Impact of Lanice conchilega on seafloor microtopography off the island of Sylt (German Bight, SE North Sea)

    NASA Astrophysics Data System (ADS)

    Schönke, M.; Feldens, P.; Wilken, D.; Papenmeier, S.; Heinrich, C.; von Deimling, J. Schneider; Held, P.; Krastel, S.

    2016-12-01

    This study presents a new in situ method to explore the impact of macrofauna on seafloor microtopography and corresponding microroughness based on underwater laser line scanning. The local microtopography was determined with mm-level accuracy at three stations colonised by the tubeworm Lanice conchilega offshore of the island of Sylt in the German Bight (south-eastern North Sea), covering approximately 0.5 m2 each. Ground truthing was done using underwater video data. Two stations were populated by tubeworm colonies of different population densities, and one station had a hydrodynamically rippled seafloor. Tubeworms caused an increased skewness of the microtopography height distribution and an increased root mean square roughness at short spatial wavelengths compared with hydrodynamic bedforms. Spectral analysis of the 2D Fourier transformed microtopography showed that the roughness magnitude increased at spatial wavelengths between 0.020 and 0.003 m independently of the tubeworm density. This effect was not detected by commonly used 1D roughness profiles but required consideration of the complete spectrum. Overall, the results reveal that new indicator variables for benthic organisms may be developed based on microtopographic data. An example demonstrates the use of local slope and skewness to detect tubeworms in the measured digital elevation model.

  13. Impact of Lanice conchilega on seafloor microtopography off the island of Sylt (German Bight, SE North Sea)

    NASA Astrophysics Data System (ADS)

    Schönke, M.; Feldens, P.; Wilken, D.; Papenmeier, S.; Heinrich, C.; von Deimling, J. Schneider; Held, P.; Krastel, S.

    2017-06-01

    This study presents a new in situ method to explore the impact of macrofauna on seafloor microtopography and corresponding microroughness based on underwater laser line scanning. The local microtopography was determined with mm-level accuracy at three stations colonised by the tubeworm Lanice conchilega offshore of the island of Sylt in the German Bight (south-eastern North Sea), covering approximately 0.5 m2 each. Ground truthing was done using underwater video data. Two stations were populated by tubeworm colonies of different population densities, and one station had a hydrodynamically rippled seafloor. Tubeworms caused an increased skewness of the microtopography height distribution and an increased root mean square roughness at short spatial wavelengths compared with hydrodynamic bedforms. Spectral analysis of the 2D Fourier transformed microtopography showed that the roughness magnitude increased at spatial wavelengths between 0.020 and 0.003 m independently of the tubeworm density. This effect was not detected by commonly used 1D roughness profiles but required consideration of the complete spectrum. Overall, the results reveal that new indicator variables for benthic organisms may be developed based on microtopographic data. An example demonstrates the use of local slope and skewness to detect tubeworms in the measured digital elevation model.

  14. Metacarpophalangeal joint arthroplasty based on the osseointegration concept.

    PubMed

    Lundborg, G; Brånemark, P I; Carlsson, I

    1993-12-01

    The osseointegration concept has been used for fixation of 68 MP joint endoprostheses in 31 patients operated on at the Department of Hand Surgery, Malmö General Hospital during the period 1988-1992. The indications were rheumatoid arthritis (50 joints), primary osteoarthrosis (three joints), post-traumatic osteoarthrosis (three joints), post-traumatic osteoarthrosis (five joints), post-infectious osteoarthrosis (seven joints) and joint deformities secondary to spastic conditions (three joints). The average follow-up time was 2.5 years (6-54 months). The surgical procedure included resection of the joint followed by introduction of screw-shaped titanium fixtures into the bone marrow cavities of the metacarpal and the phalangeal base. Rheumatoid cases usually required grafting of cancellous bone and marrow from the iliac crest. At the same time a flexible constrained silicone spacer was connected to the titanium fixtures in such a way as to allow later replacement of the spacer if accessory. The average active range of motion (ROM) was 57 degrees in the rheumatoid cases and 50 degrees in all cases. Radiological and clinical osseointegration occurred in every case, and there were no clinical signs of loosening. In four cases (6%) there was a fracture of the joint mechanism. Patient satisfaction was high, with pain relief, increased range of motion, improved hand function and good cosmetic appearance.

  15. Assessment of Atmospheric Pressure Plasma Treatment for Implant Osseointegration

    PubMed Central

    Danna, Natalie R.; Beutel, Bryan G.; Tovar, Nick; Witek, Lukasz; Marin, Charles; Granato, Rodrigo; Suzuki, Marcelo; Coelho, Paulo G.

    2015-01-01

    This study assessed the osseointegrative effects of atmospheric pressure plasma (APP) surface treatment for implants in a canine model. Control surfaces were untreated textured titanium (Ti) and calcium phosphate (CaP). Experimental surfaces were their 80-second air-based APP-treated counterparts. Physicochemical characterization was performed to assess topography, surface energy, and chemical composition. One implant from each control and experimental group (four in total) was placed in one radius of each of the seven male beagles for three weeks, and one implant from each group was placed in the contralateral radius for six weeks. After sacrifice, bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were assessed. X-ray photoelectron spectroscopy showed decreased surface levels of carbon and increased Ti and oxygen, and calcium and oxygen, posttreatment for Ti and CaP surfaces, respectively. There was a significant (P < 0.001) increase in BIC for APP-treated textured Ti surfaces at six weeks but not at three weeks or for CaP surfaces. There were no significant (P = 0.57) differences for BAFO between treated and untreated surfaces for either material at either time point. This suggests that air-based APP surface treatment may improve osseointegration of textured Ti surfaces but not CaP surfaces. Studies optimizing APP parameters and applications are warranted. PMID:26090443

  16. Titanium alloys (AoN) and their involvement in osseointegration

    PubMed Central

    Danza, Matteo; Zollino, Ilaria; Candotto, Valentina; Cura, Francesca; Carinci, Francesco

    2012-01-01

    Background: Osseointegration is essential for a long-term successful and inflammation-free dental implant. Such a result depends on osteoblastic cells growth and differentiation at the tissue-implant interface. The aim of this study was to compare two different AoN titanium layers (GR4 and GR5) to investigate which one had a greater osteoconductive power using human osteoblasts (HOb) culture at two different time-points. Materials and Methods: The expression levels of some bone-related (ALPL, COL1A1, COL3A1, SPP1, RUNX2, and SPARC) were analyzed using real time reverse transcription-polymerase chain reaction (real time RT-PCR). Results: Real-time RT-PCR data showed that after 3 days of treatment with TiA4GR, the genes up-regulated were COL3A1, ALPL, SPP1, and RUNX2. Moreover, no difference in gene expression was noticed 4 days later. On the other hand, the genes that overexpressed after 3 days of treatment with AoN5GR were ALPL, SPP1, and RUNX2. In both cases, the expression of COL1A1 and SPARC was negatively regulated. Conclusion: Our data showed that both titanium surfaces led to osteoblasts recruitment, maturation, and differentiation, thus promoting osseointegration at the tissue-implant interface. PMID:23814585

  17. Titanium alloys (AoN) and their involvement in osseointegration.

    PubMed

    Danza, Matteo; Zollino, Ilaria; Candotto, Valentina; Cura, Francesca; Carinci, Francesco

    2012-12-01

    Osseointegration is essential for a long-term successful and inflammation-free dental implant. Such a result depends on osteoblastic cells growth and differentiation at the tissue-implant interface. The aim of this study was to compare two different AoN titanium layers (GR4 and GR5) to investigate which one had a greater osteoconductive power using human osteoblasts (HOb) culture at two different time-points. The expression levels of some bone-related (ALPL, COL1A1, COL3A1, SPP1, RUNX2, and SPARC) were analyzed using real time reverse transcription-polymerase chain reaction (real time RT-PCR). Real-time RT-PCR data showed that after 3 days of treatment with TiA4GR, the genes up-regulated were COL3A1, ALPL, SPP1, and RUNX2. Moreover, no difference in gene expression was noticed 4 days later. On the other hand, the genes that overexpressed after 3 days of treatment with AoN5GR were ALPL, SPP1, and RUNX2. In both cases, the expression of COL1A1 and SPARC was negatively regulated. Our data showed that both titanium surfaces led to osteoblasts recruitment, maturation, and differentiation, thus promoting osseointegration at the tissue-implant interface.

  18. Electrical Implications of Corrosion for Osseointegration of Titanium Implants

    PubMed Central

    Gittens, R.A.; Olivares-Navarrete, R.; Tannenbaum, R.; Boyan, B.D.; Schwartz, Z.

    2011-01-01

    The success rate of titanium implants for dental and orthopedic applications depends on the ability of surrounding bone tissue to integrate with the surface of the device, and it remains far from ideal in patients with bone compromised by physiological factors. The electrical properties and electrical stimulation of bone have been shown to control its growth and healing and can enhance osseointegration. Bone cells are also sensitive to the chemical products generated during corrosion events, but less is known about how the electrical signals associated with corrosion might affect osseointegration. The metallic nature of the materials used for implant applications and the corrosive environments found in the human body, in combination with the continuous and cyclic loads to which these implants are exposed, may lead to corrosion and its corresponding electrochemical products. The abnormal electrical currents produced during corrosion can convert any metallic implant into an electrode, and the negative impact on the surrounding tissue due to these extreme signals could be an additional cause of poor performance and rejection of implants. Here, we review basic aspects of the electrical properties and electrical stimulation of bone, as well as fundamental concepts of aqueous corrosion and its electrical and clinical implications. PMID:21555775

  19. Osteoporotic rat models for evaluation of osseointegration of bone implants.

    PubMed

    Alghamdi, Hamdan S; van den Beucken, Jeroen J J P; Jansen, John A

    2014-06-01

    Osseointegration of dental and orthopedic bone implants is the important process that leads to mechanical fixation of implants and warrants implant functionality. In view of increasing numbers of osteoporotic patients, bone implant surface optimization strategies with instructive and drug-loading ability have been heavily explored. However, few animal models are available to study the effect of novel implant surface modifications in osteoporotic conditions. Since laboratory rats comply with a number of practical advantages, including the reliability of several methods for rapid induction of osteoporotic conditions, the present work aimed to define the use of the femoral condyle in osteoporotic female and male rats as a suitable implantation model to study osseointegration of bone implants. The method describes the procedures for induction (by hypogonadism) and assessment (by in vivo micro-computed tomography [CT]) of osteoporotic conditions in both female and male rats. The implantation site architecture (femoral condyle bone properties and dimensions) was comparatively evaluated for female and male rats, and the implant installation procedures are described. Finally, the possible analytical techniques to evaluate bone responses via mechanical tests, ex vivo micro-CT, and histological methods are provided.

  20. Osseointegration of alumina bioceramic granules: A comparative experimental study

    NASA Astrophysics Data System (ADS)

    Rerikh, V. V.; Avetisyan, A. R.; Zaydman, A. M.; Anikin, K. A.; Bataev, V. A.; Nikulina, A. A.; Sadovoy, M. A.; Aronov, A. M.; Semantsova, E. S.

    2016-08-01

    To perform a comparative analysis of osseointegration of bioceramic alumina-based granules, hydroxyapatite-based granules, and deproteinized bone granules. The experiment was conducted on 52 adult male Kyoto-Wistar rats weighing 350 to 520 g. The animals were divided into five matched groups that differed only in the type of an implanted material. The granules were implanted in the lumbar vertebral bodies and in the distal right femur of each laboratory animal. Two months after surgery, the animals were euthanized, followed by tissue sampling for morphological studies. An examination of specimens from the groups with implanted alumina granules revealed the newly formed trabecular bone with remodeling signs. The bone tissue filled the intragranular space, tightly adhering to the granule surface. There was no connective tissue capsule on the border between bone tissue and alumina granules. Cylindrical bioceramic alumina-based granules with an open internal channel have a higher strength surpassing than that of analogs and the osseointegration ability close to that of hydroxyapatite and deproteinized bone granules.

  1. Impact of Dental Implant Surface Modifications on Osseointegration

    PubMed Central

    Smeets, Ralf; Stadlinger, Bernd; Schwarz, Frank; Beck-Broichsitter, Benedicta; Jung, Ole; Precht, Clarissa; Kloss, Frank; Gröbe, Alexander; Heiland, Max

    2016-01-01

    Objective. The aim of this paper is to review different surface modifications of dental implants and their effect on osseointegration. Common marketed as well as experimental surface modifications are discussed. Discussion. The major challenge for contemporary dental implantologists is to provide oral rehabilitation to patients with healthy bone conditions asking for rapid loading protocols or to patients with quantitatively or qualitatively compromised bone. These charging conditions require advances in implant surface design. The elucidation of bone healing physiology has driven investigators to engineer implant surfaces that closely mimic natural bone characteristics. This paper provides a comprehensive overview of surface modifications that beneficially alter the topography, hydrophilicity, and outer coating of dental implants in order to enhance osseointegration in healthy as well as in compromised bone. In the first part, this paper discusses dental implants that have been successfully used for a number of years focusing on sandblasting, acid-etching, and hydrophilic surface textures. Hereafter, new techniques like Discrete Crystalline Deposition, laser ablation, and surface coatings with proteins, drugs, or growth factors are presented. Conclusion. Major advancements have been made in developing novel surfaces of dental implants. These innovations set the stage for rehabilitating patients with high success and predictable survival rates even in challenging conditions. PMID:27478833

  2. Novel Zirconia Surface Treatments for Enhanced Osseointegration: Laboratory Characterization

    PubMed Central

    Ewais, Ola H.; Al Abbassy, Fayza; Ghoneim, Mona M.; Aboushelib, Moustafa N.

    2014-01-01

    Purpose. The aim of this study was to evaluate three novel surface treatments intended to improve osseointegration of zirconia implants: selective infiltration etching treatment (SIE), fusion sputtering (FS), and low pressure particle abrasion (LPPA). The effects of surface treatments on roughness, topography, hardness, and porosity of implants were also assessed. Materials and Methods. 45 zirconia discs (19 mm in diameter × 3 mm in thickness) received 3 different surface treatments: selective infiltration etching, low pressure particle abrasion with 30 µm alumina, and fusion sputtering while nontreated surface served as control. Surface roughness was evaluated quantitatively using profilometery, porosity was evaluated using mercury prosimetry, and Vickers microhardness was used to assess surface hardness. Surface topography was analyzed using scanning and atomic force microscopy (α = 0.05). Results. There were significant differences between all groups regarding surface roughness (F = 1678, P < 0.001), porosity (F = 3278, P < 0.001), and hardness (F = 1106.158, P < 0.001). Scanning and atomic force microscopy revealed a nanoporous surface characteristic of SIE, and FS resulted in the creation of surface microbeads, while LPPA resulted in limited abrasion of the surface. Conclusion. Within the limitations of the study, changes in surface characteristics and topography of zirconia implants have been observed after different surface treatment approaches. Thus possibilities for enhanced osseointegration could be additionally offered. PMID:25349610

  3. Investigating the Lack of Pit/Mound Microtopography in Subalpine Forests of the Canadian Rockies

    NASA Astrophysics Data System (ADS)

    Martin, Y.; Johnson, E.; Chaikina, O.

    2012-04-01

    This investigation is a followup to our earlier study analyzing tree throw and associated sediment transport in Hawk Creek Watershed, Canadian Rockies (Gallaway et al., 2009). The motivation for the present study is that landscapes in subalpine forests in the Canadian Rockies do not show the pronounced pit/mound microtopography found in some other forests, such as some deciduous forests of eastern North America or coniferous forests in western British Columbia, Canada. Given the impact that pit/mound topography can have on both soils and hydrology, it was decided to investigate why some forests demonstrate notable pit/mound microtopography while other forests do not. First, we analyze field data from our study drainage basin in the Canadian Rockies to define the sizes of pit/mound features in these forests and how slope gradient influences pit/mound dimensions. Next, we test a series of possible formulae to simulate degradation for different sizes of pit/mound features in profile form for slopes ranging from 10 to 30 degrees. For slopes of zero or near-zero gradient, our field results show that the majority of sediment from the root plate is returned to the pit and does not form a distinct pit/mound feature; this finding is in agreement with other studies in the published literature. Our model results show that the magnitude of a pit/mound feature and the choice of formula to simulate pit/mound degradation play key roles in determining pit/mound longevity. Finally, we connect our earlier numerical model of tree population dynamics in the Canadian Rockies to a numerical model of pit/mound degradation to explore how these elements combine to influence landscape microtopography over time. At any time, the density and size of pit-mound features on the landscape is a function of pit/mound formation rates (not necessarily constant) and the rate of pit/mound degradation (Schaetzl and Follmer, 1990). Our tree population dynamics model is driven by wildfire disturbance

  4. Adherent Lipopolysaccharide Inhibits the Osseointegration of Orthopaedic Implants by Impairing Osteoblast Differentiation

    PubMed Central

    Bonsignore, Lindsay A.; Anderson, J. Robert; Lee, Zhenghong; Goldberg, Victor M.; Greenfield, Edward M.

    2012-01-01

    Osseointegration is the process by which an orthopaedic implant makes direct bone-to-implant contact and is crucial for the long-term function of the implant. Surface contaminants, such as bacterial debris and manufacturing residues, may remain on orthopaedic implants after sterilization and impair osseointegration. For example, specific lots of implants that were associated with impaired osseointegration and high failure rates were discovered to have contaminants including bacterial debris. Therefore, the goals of this study were to determine if bacterial debris exists on sterile orthopaedic implants and if adherent bacterial debris inhibits the osseointegration of orthopaedic implants. We found that debris containing lipopolysaccharide (LPS) from Gram-negative bacteria exists on both sterile craniofacial implants and wrist implants. Levels of bacterial debris vary not only between different lots of implants but within an individual lot. Using our murine model of osseointegration, we found that ultrapure LPS adherent to the implants inhibited bone-to-implant contact and biomechanical pullout measures. Analysis of osseointegration in knock-out mice demonstrated that adherent LPS inhibited osseointegration by signaling through its primary receptor, Toll-like receptor 4, and not by signaling through Toll-like receptor 2. Ultrapure LPS adherent to titanium alloy discs had no detectable effect on early stages of MC3T3-E1 osteogenesis in vitro such as attachment, spreading or growth. However, later stages of osteogenic differentiation and mineralization were inhibited by adherent LPS. Thus, LPS may inhibit osseointegration in part through cell autonomous effects on osteoblasts. These results highlight bacterial debris as a type of surface contaminant that can impair the osseointegration of orthopaedic implants. PMID:22995462

  5. Effect of hydroxyapatite/tricalcium-phosphate coating on osseointegration of plasma-sprayed titanium alloy implants.

    PubMed

    Stewart, Matthew; Welter, Jean F; Goldberg, Victor M

    2004-04-01

    This study determined the effects of a plasma-sprayed hydroxyapatite/tricalcium phosphate (HA/TCP) coating on osseointegration of plasma-sprayed titanium alloy implants in a lapine, distal femoral intramedullary model. The effects of the HA/TCP coating were assessed at 1, 3, and 6 months after implant placement. The HA/TCP coating significantly increased new bone apposition onto the implant surfaces at all time points. The ceramic coating also stimulated intramedullary bone formation at the middle and distal levels of the implants. Fluorescent bone labeling indicated that new bone formation occurred primarily during the first 3 months after implantation, with comparatively little activity detected in the latter stages of the study. There was no associated increase in pullout strength at either 3 or 6 months; however, post-pullout evaluation of the implants indicated that the HA/TCP coating itself was not the primary site of construct failure. Rather, failure was most commonly observed through the periprosthetic osseous struts that bridged the medullary cavity. The demonstrated osteoconductive activity of HA/TCP coating on plasma-sprayed titanium alloy implant surfaces may have considerable clinical relevance to early host-implant interactions, by accelerating the establishment of a stable prosthesis-bone interface. Copyright 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 1-10, 2004

  6. The joint effect of surface microtopography and near-surface structure on microcontact conditions

    SciTech Connect

    McCool, J.I.

    1990-11-01

    This is the Final Technical Report of the project The Joint Effect of Surface Microtopography and Near Surface Structure on Microcontact Conditions The purpose of this project was to extend, apply, and evaluate the usefuleness of, microcontact models for assessing the tribological performance of machine elements in rolling/sliding contact. Because of their projected importance to the field of energy conservation, emphasis was placed on application to ceramic and coated specimens. The project was multi-institutional as well as multi-disciplinary with technical contributions in testing and the evaluation of specimens by the Argonne National Laboratory (G. Fenske), Oak Ridge National Laboratory (P. Blau), and the University of Michigan (K. Ludema and Layo Ajayi). To accomplish the Project aims it was necessary to extend the state-of-the-art of microcontact modelling. 59 refs., 46 figs., 35 tabs.

  7. The Topographic Mapping Flash Lidar for micro-topography of river systems

    NASA Astrophysics Data System (ADS)

    Donley, B.; Ramond, T.; Weimer, C. S.; Ruppert, L.; Delker, T.; Applegate, J.

    2010-12-01

    The Topographic Mapping Flash Lidar (TMFL) instrument built by Ball Aerospace is a pushbroom lidar operating at 1064nm that provides the ability to map the topographic structure of river beds and surrounding terrain. The receiver is a pixilated array, allowing small-scale resolution of micro-topography that is critical to understanding river dynamics and the biodiversity of the area. The instrument uses no mechanical scanning, which is a key feature allowing the design to be applicable to space flight like the NASA Decadal Survey mission LIST. The TMFL instrument has been flown on a Twin Otter aircraft. This poster will exhibit examples of river topography over dry and wet riverbeds. Examples are given of imaging a river even when partially obscured under trees in an area of high canopy density.

  8. Evaluation of Surface Microtopography Engineered by Direct Laser Interference for Bacterial Anti-Biofouling.

    PubMed

    Valle, Jaione; Burgui, Saioa; Langheinrich, Denise; Gil, Carmen; Solano, Cristina; Toledo-Arana, Alejandro; Helbig, Ralf; Lasagni, Andrés; Lasa, Iñigo

    2015-08-01

    Modification of the biomaterial surface topography is a promising strategy to prevent bacterial adhesion and biofilm formation. In this study, we use direct laser interference patterning (DLIP) to modify polystyrene surface topography at sub-micrometer scale. The results revealed that three-dimensional micrometer structures have a profound impact on bacterial adhesion. Thus, line- and pillar-like patterns enhanced S. aureus adhesion, whereas complex lamella microtopography reduced S. aureus adhesion in static and continuous flow culture conditions. Interestingly, lamella-like textured surfaces retained the capacity to inhibit S. aureus adhesion both when the surface is coated with human serum proteins and when the material is implanted subcutaneously in a foreign-body associated infection model.

  9. [Myxomatous remnants in the human middle ear. Histologic studies of their regression and microtopography].

    PubMed

    Rauchfuss, A

    1985-08-01

    Remnants of embryonic mesenchyma in the human middle ear are visible until the end of the first year of life. They occur in the lateral part of the epitympanon as well as in the region of the cochlear fenestra. However, as a result of an incomplete pneumatisation of the middle ear, they undergo regressive changes via differentiation to precollageneous tissue to form, finally, the tunica propria of the mucoperiosteal layer of the middle ear. Microtopography of these remnants is due to genetic factors but also depends on the function of the Eustachian tube. Alterations of the impedance of the tympanic membrane and the ossicular chain are possible because of the location of these remnants. The importance of obstructions of the Eustachian tube for the persistence of the remnants is discussed, as well as the part that they play in the pathogenesis of cholesteatoma of the middle ear.

  10. Microtopography for Ductile Fracture Process Characterization - Part 2: Application for CTOA Analysis

    SciTech Connect

    Lloyd, Wilson Randolph; F. A. McClintock

    2003-02-01

    The crack tip opening angle (CTOA) is seeing increased use to characterize fracture in so-called "low constraint" geometries, such as thin sheet aerospace structures and thin-walled pipes. With this increase in application comes a need to more fully understand and measure actual CTOA behavior. CTOA is a measure of the material response during ductile fracture, a "crack tip response function". In some range of crack extension following growth initiation, a constant value of CTOA is often assumed. However, many questions concerning the use of CTOA as a material response-characterizing parameter remain. For example, when is CTOA truly constant? What three-dimensional effects may be involved (even in thin sheet material)? What are the effects of crack tunneling on general CTOA behavior? How do laboratory specimen measurements of CTOA compare to actual structural behavior? Measurements of CTOA on the outer surface of test specimens reveal little about threedimensional effects in the specimen interior, and the actual measurements themselves are frequently difficult. The Idaho National Engineering and Environmental Laboratory (INEEL) use their microtopography system to collect data from the actual fracture surfaces following a test. Analyses of these data provide full three-dimensional CTOA distributions, at any amount of crack extension. The analysis is accomplished using only a single specimen and is performed entirely after the completion of a test. The resultant CTOA distributions allow development of full and effective understanding of CTOA behaviors. This paper presents underlying principles, various sources of measurement error and their corrections, and experimental and analytical verification of CTOA analysis with the microtopography method.

  11. The influence of microtopography on soil nutrients in created mitigation wetlands

    USGS Publications Warehouse

    Moser, K.F.; Ahn, C.; Noe, G.B.

    2009-01-01

    This study explores the relationship between microtopography and soil nutrients (and trace elements), comparing results for created and reference wetlands in Virginia, and examining the effects of disking during wetland creation. Replicate multiscale tangentially conjoined circular transects were used to quantify microtopography both in terms of elevation and by two microtopographic indices. Corresponding soil samples were analyzed for moisture content, total C and N, KCl-extractable NH4-N and NO3-N, and Mehlich-3 extractable P, Ca, Mg, K, Al, Fe, and Mn. Means and variances of soil nutrient/element concentrations were compared between created and natural wetlands and between disked and nondisked created wetlands. Natural sites had higher and more variable soil moisture, higher extractable P and Fe, lower Mn than created wetlands, and comparatively high variability in nutrient concentrations. Disked sites had higher soil moisture, NH4-N, Fe, and Mn than did nondisked sites. Consistently low variances (Levene test for inequality) suggested that nondisked sites had minimal nutrient heterogeneity. Across sites, low P availability was inferred by the molar ratio (Mehlich-3 [P/(Al + Fe)] < 0.06); strong intercorrelations among total C, total N, and extractable Fe, Al, and P suggested that humic-metal-P complexes may be important for P retention and availability. Correlations between nutrient/element concentrations and microtopographic indices suggested increased Mn and decreased K and Al availability with increased surface roughness. Disking appears to enhance water and nutrient retention, as well as nutrient heterogeneity otherwise absent from created wetlands, thus potentially promoting ecosystem development. ?? 2008 Society for Ecological Restoration International.

  12. Osseointegration in arthroplasty: can simvastatin promote bone response to implants?

    PubMed Central

    Erdemli, Bülent; Can, Alp; Erdemli, Esra; Zeyrek, Tuğba

    2007-01-01

    Cementless fixation depends on bone ingrowth for long-term success. Simvastatin as a lipid lowering agent has been demonstrated to have osteoanabolic effects. This study was designed to measure the possible effect of simvastatin on implant osseointegration. Bilateral femoral implantation of titanium cylinders was performed in 20 rabbits. Blood lipid levels were measured pre- and postoperatively. Scanning electron microscopy (SEM) was used to measure the percentage of the surface of each implant in contact with bone and mechanical pull-out testing was performed. The blood lipid levels were significantly reduced in the simvastatin group. Histomorphometric examination revealed increased bone ingrowth and mechanical examination showed increased interface strength in the simvastatin group. Mechanical and histological data showed superior stability and osseous adaptation at the bone/implant interface for the simvastatin group. We conclude that simvastatin has potential as a means of enhancing bone ingrowth, which is a key factor in the longevity of cementless implants. PMID:18157535

  13. Advanced glycation endproducts and rat dental implant osseointegration.

    PubMed

    Quintero, David G; Winger, Julia N; Khashaba, Rania; Borke, James L

    2010-01-01

    Advanced glycation endproducts (AGEs) are a diverse group of molecular adducts formed in environments high in reducing sugars that accumulate with aging and in diabetes. This study tests the hypothesis that AGEs inhibit the stabile osseointegration of dental implants through tissue interactions that interfere with bone turnover and compromise the biomechanical properties at the bone-implant interface. Maxillary first molars were extracted from 32 rats and allowed to heal for 4 weeks. Titanium implants (1 mm x 3 mm) were placed in the healed sockets of 2 groups of 16 rats consisting of 8 rats injected 3 times/wk for 1 month with AGE (prepared from glucose and lysine) and 8 rats injected with vehicle as a control. AGE injections continued for an additional 14 or 28 days before sacrifice. X-ray images, blood, and tissues were collected to examine bone/implant contact ratio, serum pyridinoline ([PYD] a collagen breakdown marker), osteocalcin ([OSC] a bone formation marker), and for immunohistochemistry with antibodies to AGE and the bone turnover-marker protein matrix metalloproteinase1. Compared with the AGE-treated groups, the controls showed significantly higher bone/implant contact at both 14- and 28-day time points. PYD (P < .05) and OSC (trend) levels from controls showed decreases at 28 days when compared with AGE-treated groups. Immunohistochemistry with AGE-specific and bone turnover marker antibodies showed stronger staining associated with the implant/tissue interface in AGE-treated rats. Our studies indicate an association between AGE and inhibition of bone turnover, suggesting that the formation of AGE in high glycemic conditions, such as diabetes, may contribute to a slower rate of osseointegration that negatively affects implant stability.

  14. Osseointegrated Finger Prostheses Using a Tripod Titanium Mini-Plate

    PubMed Central

    Ciudad, Pedro; Doscher, Matthew; Lo Torto, Federico; Liebling, Ralph; Galan, Ricardo

    2017-01-01

    Background Digital amputation is a common upper extremity injury and can cause significant impairment in hand function, as well as psychosocial stigma. Currently, the gold standard for the reconstruction of such injuries involves autologous reconstruction. However, when this or other autologous options are not available, prosthetic reconstruction can provide a functionally and aesthetically viable alternative. This study describes a novel technique, known as a tripod titanium mini-plate, for osseointegrated digit prostheses, and reviews the outcomes in a set of consecutive patients. Methods A retrospective review of patients who underwent 2-stage prosthetic reconstruction of digit amputations was performed. Demographic information, occupation, mechanism of injury, number of amputated fingers, and level of amputation were reviewed. Functional and aesthetic outcomes were assessed using the quick disabilities of the arm, shoulder, and hand (Q-DASH) scale and a visual analog scale (VAS) score, respectively. In addition, complications during the postoperative period were recorded. Results Seven patients were included in this study. Their average age was 29 years. Five patients had single-digit amputations and 2 patients had multiple-digit amputations. Functional and aesthetic outcomes were assessed using the Q-DASH score (average, 10.4) and VAS score (average, 9.1), respectively. One episode of mild cellulitis was seen at 24 months of follow-up. However, it was treated successfully with oral antibiotics. No other complications were reported. Conclusions When autologous reconstruction is not suitable for digit reconstruction, prosthetic osseointegrated reconstruction can provide good aesthetic and functional results. However, larger series with longer-term follow-up are required in order to rule out the possibility of other complications. PMID:28352604

  15. Multifractal spectrum and lacunarity as measures of complexity of osseointegration.

    PubMed

    de Souza Santos, Daniel; Dos Santos, Leonardo Cavalcanti Bezerra; de Albuquerque Tavares Carvalho, Alessandra; Leão, Jair Carneiro; Delrieux, Claudio; Stosic, Tatijana; Stosic, Borko

    2016-07-01

    The goal of this study is to contribute to a better quantitative description of the early stages of osseointegration, by application of fractal, multifractal, and lacunarity analysis. Fractal, multifractal, and lacunarity analysis are performed on scanning electron microscopy (SEM) images of titanium implants that were first subjected to different treatment combinations of i) sand blasting, ii) acid etching, and iii) exposition to calcium phosphate, and were then submersed in a simulated body fluid (SBF) for 30 days. All the three numerical techniques are applied to the implant SEM images before and after SBF immersion, in order to provide a comprehensive set of common quantitative descriptors. It is found that implants subjected to different physicochemical treatments before submersion in SBF exhibit a rather similar level of complexity, while the great variety of crystal forms after SBF submersion reveals rather different quantitative measures (reflecting complexity), for different treatments. In particular, it is found that acid treatment, in most combinations with the other considered treatments, leads to a higher fractal dimension (more uniform distribution of crystals), lower lacunarity (lesser variation in gap sizes), and narrowing of the multifractal spectrum (smaller fluctuations on different scales). The current quantitative description has shown the capacity to capture the main features of complex images of implant surfaces, for several different treatments. Such quantitative description should provide a fundamental tool for future large scale systematic studies, considering the large variety of possible implant treatments and their combinations. Quantitative description of early stages of osseointegration on titanium implants with different treatments should help develop a better understanding of this phenomenon, in general, and provide basis for further systematic experimental studies. Clinical practice should benefit from such studies in the long

  16. Effects of alveolar ridge preservation on delayed implant osseointegration

    PubMed Central

    Shao, Shan; Li, Bin; Xue, Hui-Min; Huang, Hai-Yun; Liu, Gang-Li

    2015-01-01

    To evaluate the effects of alveolar ridge preservation with Bio-Oss bone substitute (Geistlich Pharma) on delayed implant osseointegration. The 3rd and 4th left and right mandibular premolars were extracted from four adult healthy male and female dogs. For the experimental group, we randomly selected two extraction sockets in each dog to be filled with Bio-Oss bone substitute (Geistlich Pharma). The two remaining extraction sockets remained untreated and served as the control group. Three months after Bio-Oss placement, dental implants were inserted into the alveolar bone of the experimental group and the control group. The osteogenic activity of the bone around the implants was assessed by evaluating the histological morphology and by estimating histomorphometric parameters at 3 and 6 months after delayed implantation. At 3 months, Goldner’s trichrome staining analysis showed that the bone-implant contact rate and mineralised bone area around the implant were significantly higher in the experimental group (75.98% ± 8.97% and 69.52% ± 9.63%, respectively) than in the control group (56.13% ± 8.18% and 52.82% ± 7.25%, respectively; P < 0.05). However, at 6 months, the two groups showed no significant difference. Fluorescence microscopy analysis revealed that the average mineralisation apposition rate of the bone tissue around the dental implant in the experimental group at 3 and 6 months was 6.80 ± 0.43 μm and 8.38 ± 0.84 μm, respectively, which was significantly higher than the rate in the control group (P < 0.05). These data indicated that alveolar ridge preservation by using Bio-Oss placement can promote osseointegration of delayed implantation. This may be a promising option for clinical use. PMID:26379871

  17. Osseointegrated Finger Prostheses Using a Tripod Titanium Mini-Plate.

    PubMed

    Manrique, Oscar J; Ciudad, Pedro; Doscher, Matthew; Lo Torto, Federico; Liebling, Ralph; Galan, Ricardo

    2017-03-01

    Digital amputation is a common upper extremity injury and can cause significant impairment in hand function, as well as psychosocial stigma. Currently, the gold standard for the reconstruction of such injuries involves autologous reconstruction. However, when this or other autologous options are not available, prosthetic reconstruction can provide a functionally and aesthetically viable alternative. This study describes a novel technique, known as a tripod titanium mini-plate, for osseointegrated digit prostheses, and reviews the outcomes in a set of consecutive patients. A retrospective review of patients who underwent 2-stage prosthetic reconstruction of digit amputations was performed. Demographic information, occupation, mechanism of injury, number of amputated fingers, and level of amputation were reviewed. Functional and aesthetic outcomes were assessed using the quick disabilities of the arm, shoulder, and hand (Q-DASH) scale and a visual analog scale (VAS) score, respectively. In addition, complications during the postoperative period were recorded. Seven patients were included in this study. Their average age was 29 years. Five patients had single-digit amputations and 2 patients had multiple-digit amputations. Functional and aesthetic outcomes were assessed using the Q-DASH score (average, 10.4) and VAS score (average, 9.1), respectively. One episode of mild cellulitis was seen at 24 months of follow-up. However, it was treated successfully with oral antibiotics. No other complications were reported. When autologous reconstruction is not suitable for digit reconstruction, prosthetic osseointegrated reconstruction can provide good aesthetic and functional results. However, larger series with longer-term follow-up are required in order to rule out the possibility of other complications.

  18. Osseointegration in porous coated knee arthroplasty. The influence of component coating type in sheep.

    PubMed

    Bellemans, J

    1999-10-01

    Although cementless knee arthroplasty is a commonly performed procedure, to date very little was known about the process of osseointegration of knee arthroplasty components. Using a knee prosthesis that was specially designed for the sheep stifle joint, this process of osseointegration could be studied in vivo, together with its effects on clinical and functional performance, its influence on mechanical fixation, and its influence on component stability or migration over time. Additionally, the osseointegration capacity of a newly developed cast mesh porous coating could be examined. The rationale for this newly developed coating was to provide a surface texture with theoretically superior osseointegration capacity, by offering a larger and better controlled pore size, with higher ingrowth area compared to conventional bead type coatings. In summary, the conclusions that are drawn from this work are the following: 1. The degree of osseointegration of knee arthroplasty components is not correlated with clinical and functional performance. Knee arthroplasty components with fibrous integration can function as well as osseointegrated components at least during the first years after implantation. This explains the occasional reports in the literature of post mortem retrieved, well functioning knee arthroplasty components, with purely fibrous integration on histomorphometric analysis. 2. Fibrous integration of tibial knee arthroplasty components, however, leads to less mechanical fixation strength of these components. Osseointegrated components are much more strongly fixed to the underlying bone. This difference in mechanical fixation strength is detectable under physiologic loads. 3. Fibrous integration of tibial knee arthroplasty components leads to increased migration, becoming apparent after 1 year with radiostereometric analysis (RSA). Osseointegrated components are significantly more stable over time. 4. Fibrous integration is less desirable, since it leads to

  19. Osseointegration properties of titanium dental implants modified with a nanostructured coating based on ordered porous silica and bioactive glass nanoparticles

    NASA Astrophysics Data System (ADS)

    Covarrubias, Cristian; Mattmann, Matías; Von Marttens, Alfredo; Caviedes, Pablo; Arriagada, Cristián; Valenzuela, Francisco; Rodríguez, Juan Pablo; Corral, Camila

    2016-02-01

    The fabrication of a nanoporous silica coating loaded with bioactive glass nanoparticles (nBG/NSC) on titanium dental implant surface and its in vitro and in vivo evaluation is presented. The coating was produced by a combined sol-gel and evaporation induced self-assembly process. In vitro bioactivity was assessed in simulated body fluid (SBF) and investigating the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs). A rat tibial model was employed to analyze the bone response to nBG/NSC-modified titanium implant surface in vivo. The nBG/NSC coating was confirmed at nano level to be constituted by a highly ordered nanoporous silica structure. The coating nanotopography in conjunction with the bioactivity of the BG particles accelerate the in vitro apatite formation and promote the osteogenic differentiation of hBMSCs in absence of osteogenic supplements. These properties accelerate the formation of bone tissue in the periphery of the implant after 3 weeks of implantation. Backscattered scanning electron microscopy images revealed the presence of gaps and soft tissue in the unmodified implant after 6 weeks, whereas the nBG/NSC-modified implant showed mature bone in intimate contact with the implant surface. The nBG/NSC coating appears promising for accelerating the osseointegration of dental implants.

  20. A comparative study on three methods of soil quality evaluation of microtopography in the semi-arid Loess Plateau, China.

    PubMed

    Bo, Yaojun; Zhu, Qingke; Bao, Yaoxian; Zhao, Weijun; Zhao, Yanming; Zhang, Hongzhi

    2015-01-01

    Three soil property test data of microtopography in the semi-arid Loess Plateau were used to compare the following three soil quality evaluation methods: correlation coefficient method, factor analysis method and Nemoro index method. The results of these methods were analyzed and compared to determine the most suitable method for comprehensive evaluation of soil quality. While correlation coefficient method and factor analysis method produced similar results, Nemoro index method showed several differences from the othertwo methods and exhibited higher sensitivity in its assessment results. The soil quality index (SQI) parameters of three methods showed consistent scales and variation trends among the various microtopographies, and there was a highly significant linear positive correlation between the SQI parameters of any two given methods. This result suggested that the three methods were all reliable and could be employed for comprehensive assessment of soil quality of microtopography in the study region. However, the Nemoro index method involves relatively uncomplicated mathematics and is very easy to absorb, and thus should be preferentially employed when three grading standards can be identified. The factor analysis method is the next most preferable, followed by correlation coefficient method.

  1. Systematic variation of microtopography, surface chemistry and elastic modulus and the state dependent effect on endothelial cell alignment.

    PubMed

    Feinberg, Adam W; Wilkerson, Wade R; Seegert, Charles A; Gibson, Amy L; Hoipkemeier-Wilson, Leslie; Brennan, Anthony B

    2008-08-01

    We examined how variations in elastic modulus, surface chemistry and the height and spacing of micro-ridges interact and effect endothelial cell (EC) alignment. Specifically, we employed independent control of the surface properties in order to elucidate the relative importance of each factor. Polydimethylsiloxane elastomer (PDMSe) was fabricated with 1.5 or 5 microm tall, 5 microm spaced and 5, 10, or 20 microm wide ridge microtopographies. Elastic modulus was varied from 0.3, 1.0, 1.4, and 2.3 MPa by controlling oligomeric additives and crosslink density. Surface chemistry was left untreated, argon plasma treated, coated with fibronectin (Fn) or patterned with Fn tracks on flat PDMSe or the tops of micro-ridges. Primary porcine vascular ECs were cultured on the PDMSe substrates and nuclear form factor (NFF) was used to determine cell orientation relative to surface microtopography. Experimental results showed that microtopographical variation strongly altered EC alignment on Fn coated surfaces, but not on plasma treated surfaces. Interestingly, similar alignment was achieved with different orientation cues, either micropatterned chemistry (2D) or microtopography (3D). In total, the effect of varying one of the experimental parameters depended strongly on the state of the others, highlighting the need for multi-factor analysis of surface properties for applications where cells and tissue will contact synthetic materials.

  2. Skin microtopography as a measure of photoaging and risk of squamous cell carcinoma of the skin in a US population.

    PubMed

    Kuklinski, Lawrence Fitzgerald; Zens, Michael Scot; Perry, Ann E; Green, Adele C; Karagas, Margaret R

    2017-01-01

    Skin microtopography as a measure of photoaging is a noninvasive approach to measuring chronic ultraviolet radiation exposure and reflects the degree of dermal elastosis in populations of European descent in the subtropics. Less is known about the utility of this approach in populations at different latitudes, and whether it relates to skin cancer risk. A population-based case-control study of 342 squamous cell carcinoma (SCC) cases and 331 age- and gender-matched controls were evaluated for histologic evidence of solar damage and severity of photoaging based on microtopography on a six-grade scale. Odds ratios (OR) for SCC associated with degree of photoaging were estimated using logistic regression analysis adjusted for potentially confounding factors. After adjustment for known risk factors, SCC was associated with increasing photoaging grade (OR = 1.7, 95% CI = 0.9-3.0 for severe photoaging; OR = 2.8, 95% CI = 1.6-5.0 for very severe photoaging). Associations remained among those with actinic keratosis (OR = 3.4, 95% CI = 0.9-12.4 for severe photoaging, OR = 5.7, 95% CI = 1.7-19.6 for very severe photoaging). There was limited statistical power, particularly for subgroup analyses. Our findings provide further evidence of microtopography as an independent, objective indicator of risk of SCC. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Osseointegrative Properties of Electrospun Hydroxyapatite-Containing Nanofibrous Chitosan Scaffolds

    PubMed Central

    Frohbergh, Michael E.; Katsman, Anya; Mondrinos, Mark J.; Stabler, Collin T.; Hankenson, Kurt D.; Oristaglio, Jeffrey T.

    2015-01-01

    Our long-term goal is to develop smart biomaterials that can facilitate regeneration of critical-size craniofacial lesions. In this study, we tested the hypothesis that biomimetic scaffolds electrospun from chitosan (CTS) will promote tissue repair and regeneration in a critical size calvarial defect. To test this hypothesis, we first compared in vitro ability of electrospun CTS scaffolds crosslinked with genipin (CTS-GP) to those of mineralized CTS-GP scaffolds containing hydroxyapatite (CTS-HA-GP), by assessing proliferation/metabolic activity and alkaline phosphatase (ALP) levels of murine mesenchymal stem cells (mMSCs). The cells' metabolic activity exhibited a biphasic behavior, indicative of initial proliferation followed by subsequent differentiation for all scaffolds. ALP activity of mMSCs, a surrogate measure of osteogenic differentiation, increased over time in culture. After 3 weeks in maintenance medium, ALP activity of mMSCs seeded onto CTS-HA-GP scaffolds was approximately two times higher than that of cells cultured on CTS-GP scaffolds. The mineralized CTS-HA-GP scaffolds were also osseointegrative in vivo, as inferred from the enhanced bone regeneration in a murine model of critical size calvarial defects. Tissue regeneration was evaluated over a 3 month period by microCT and histology (Hematoxylin and Eosin and Masson's Trichrome). Treatment of the lesions with CTS-HA-GP scaffolds induced a 38% increase in the area of de novo generated mineralized tissue area after 3 months, whereas CTS-GP scaffolds only led to a 10% increase. Preseeding with mMSCs significantly enhanced the regenerative capacity of CTS-GP scaffolds (by ∼3-fold), to 35% increase in mineralized tissue area after 3 months. CTS-HA-GP scaffolds preseeded with mMSCs yielded 45% new mineralized tissue formation in the defects. We conclude that the presence of HA in the CTS-GP scaffolds significantly enhances their osseointegrative capacity and that mineralized chitosan-based scaffolds

  4. Osteoblast-mediated mineral deposition in culture is dependent on surface microtopography.

    PubMed

    Boyan, B D; Bonewald, L F; Paschalis, E P; Lohmann, C H; Rosser, J; Cochran, D L; Dean, D D; Schwartz, Z; Boskey, A L

    2002-12-01

    Osteoblast phenotypic expression in monolayer culture depends on surface microtopography. Here we tested the hypothesis that mineralized bone nodule formation in response to osteotropic agents such as bone morphogenetic protein-2 (BMP-2) and dexamethasone is also influenced by surface microtopography. Fetal rat calvarial (FRC) cells were cultured on Ti implant materials (PT [pretreated], Ra = 0.6 microm; SLA [course grit blasted and acid etched], Ra = 4.0 microm; TPS [Ti plasma sprayed], Ra = 5.2 microm) in the presence of either BMP-2 (20 ng/ml) or 10(-8) M dexamethasone (Dex). At 14 days post-confluence, a homogenous layer of cells covered the surfaces, and stacks of cells that appeared to be nodules emerging from the culture surface were present in some areas on all three Ti surfaces. Cell proliferation decreased while alkaline phosphatase specific activity (ALPase) and nodule number generally increased with increasing surface roughness in both control and treated cultures. There was no difference in cell number between the control and Dex-treated cultures for a particular surface, but BMP-2 significantly reduced cell number compared with control or Dex-treated cultures. Treatment with Dex or BMP-2 further increased ALPase on all surfaces except for PT cultures with Dex. Dex had no effect on nodule area in cultures grown on PT or SLA disks, yet increased nodule number by more than 100% in cultures on PT disks. Though the effect of BMP-2 on nodule number was the same as Dex, BMP-2 increased nodule area on all surfaces except TPS, where area was decreased. Ca and P content of the cell layers in control cultures did not vary with surface roughness. However, cultures treated with Dex had increased Ca content on all surfaces, but the greatest increase was seen on SLA and TPS. BMP-2 increased Ca content in cultures on all surfaces, with the greatest increase on the PT surface. BMP-2 treatment increased P content on all surfaces, whereas Dex only increased P on rough

  5. Hortonian surface runoff in flat areas due to microtopography and spatially varying infiltration characteristics

    NASA Astrophysics Data System (ADS)

    Appels, Willemijn M.; Bogaart, Patrick W.; van der Zee, Sjoerd E. A. T. M.

    2010-05-01

    In flat groundwater-dominated areas surface runoff is a commonly neglected phenomenon despite its frequent occurrence and the relevance this fast flow route can have for water quality issues. When the regional surface gradient is weak, the routing of runoff is mainly determined by microtopography. Local depressions fill, full depressions merge and eventually connect with the field boundary. Rainfall rate and duration, soil hydraulic properties and groundwater levels determine the speed with which these depressions fill and whether or not they connect to ditches or channels. We investigate the relative contributions of microtopography and soil hydraulic properties in runoff generation in these flat areas. The topographies of the system were simulated with a Gaussian distribution of which we varied the standard deviation and the correlation length. Non-Gaussian topographies with the same first-order statistics were also included in the analysis. Saturated hydraulic conductivity and sorptivity were appointed to every cell of the elevation grid. For the distribution of these parameters different spatial correlation distances were used. Surface runoff was allowed at all boundaries of the topographies, simulating a system surrounded by ditches. We developed an algorithm that explicitly deals with the filling, merging, and connecting of depressions in a field. The routine has a successive steady-state setup: in every time step the excess water in each cell is routed to its ultimate sink, either in the field or in the surrounding surface water, under the assumption of instantaneous water transfer. When the capacity of a depression is exceeded, water is routed to a neighbouring depression, or depressions are merged to form a new, larger depression. We coupled Philip's Two-Term infiltration model to this algorithm. The volumes of water involved in ponding and surface runoff are scale-dependent: the larger a topography or the standard deviation of the elevation distribution

  6. Enhancement of biomechanical behavior on osseointegration of implant with SLAffinity.

    PubMed

    Chu, Kuo-Tien; Cheng, Han-Yi; Pan, Yung-Ning; Chen, Shyuan-Yow; Ou, Keng-Liang

    2013-04-01

    The purpose of this study was to investigate stresses resulting from different thicknesses of hydroxyapatite- and titanium dioxide (TiO(2))-treated layers at the interface between temporomandibular joint (TMJ) implants and bones using three-dimensional finite element models. For ensuring osseointegration of implant treatment, one must examine the stresses of interface between implant and bone tissue. Treated layers on TMJ implants are a very important factor in clinical application. Several studies have investigated finite element models for TMJs, but few have examined a model for TMJ implants with treated layers. In this study, TMJ models were reconstructed using computer tomography data, and the effects of treated layer thickness on the stress field during jaw movement were investigated; this index has not yet been reported with respect to TMJ implant. The maximum stresses in the bone occurred at the position of the first screw. Data analysis indicated a greater decrease in this stress in the case of using TMJ implants with TiO(2)-treated layers, and the stresses decreased with increasing layer thicknesses. Results confirmed that the treated layers improve biomechanical properties of the TMJ implants and release abnormal stress concentration in them. The results of our study offer the potential clinical benefit of inducing superior biomechanical behavior in TMJ implants.

  7. The Utility of the MAUDE Database for Osseointegrated Auditory Implants.

    PubMed

    Coelho, Daniel H; Tampio, Alex J

    2017-01-01

    To determine the utility of Manufacturer and User Friendly Device Experience (MAUDE) database in studying osseointegrated auditory implant (OAI)-related complications. The MAUDE database was searched for all reports involving OAIs (ie, Baha, Ponto, Sophono). Complications were classified into 1 or more of 6 categories-implant, abutment, processor, skin, surgery, and other. Subcategories were generated to prevent overgeneralization. Other variables recorded included date of report, number of complications per report, manufacturer, and time from complication to report. Over the study period, there were 269 complications listed from 238 reports divided into the following categories: implant related (n = 145), abutment related (n = 16), processor related (n = 13), skin and soft tissue related (n = 79), surgery related (n = 11), and other (n = 5). No demographic data were available. There were no discernible trends from the data, and when compared to published literature, MAUDE data appear to under- or misrepresent complications. The MAUDE database is limited in its design and given fairly disparate reporting quality may not be ideally suited for quantifying risks of OAIs. These findings suggest the necessity for a substantially improved central registry for otologic implants and highlight the need for further research to investigate the root causes of their associated complication. © The Author(s) 2016.

  8. Patient satisfaction after insertion of an osseointegrated implant bridge.

    PubMed

    Hoogstraten, J; Lamers, L M

    1987-09-01

    The general and specific satisfaction of patients treated with a jawbone-anchored bridge was compared with their pretreatment satisfaction with dentures (condition 1, n = 31). Patients who asked for information on the osseointegration method but did not apply for treatment (condition 2, n = 32), and a group of patients that did not ask for information (condition 3, n = 10) were also questioned on their satisfaction with dentures. The results indicated that condition 1 subjects were both socially and physically substantially more satisfied with their bridge than with their earlier dentures. On all satisfaction measures condition 3 subjects indicated more satisfaction with dentures than either condition 1 or condition 2 subjects. There were no significant differences between the three groups on several personality characteristics (neuroticism, test-taking attitudes, internal/external control). Condition 3 subjects were less extrovert (socially oriented) than the other subjects. Condition 1 subjects made several suggestions towards improvement of the pre- and post-operation phase, concerning the amount of pain involved and the cleaning of the bridge, etc.

  9. Vibrotactile evaluation: osseointegrated versus socket-suspended transfemoral prostheses.

    PubMed

    Häggström, Eva; Hagberg, Kerstin; Rydevik, Björn; Brånemark, Rickard

    2013-01-01

    This study investigated detection thresholds of vibrometric stimuli in patients with transfemoral amputation supplied with osseointegrated (OI) and socket-suspended prostheses. It included 17 patients tested preoperatively with socket-suspended prostheses and after 2 yr with OI prostheses and a control group (n = 17) using socket-suspended prostheses, evaluated once. Assessments on the prosthetic and intact feet were conducted at six frequencies (8, 16, 32, 64, 125, and 250 Hz). Furthermore, measurements were conducted to investigate how vibrometric signals are transmitted through a test prosthesis. The results showed that the OI group had improved ability to detect vibrations through the prosthesis at 125 Hz (p = 0.01) at follow-up compared with the preoperative measurement. Compared with the control group, the OI group at follow-up had better ability to detect high frequency vibrations through the prosthesis (125 Hz, p = 0.02; 250 Hz, p = 0.03). The vibrometric signal transmitted through the test prosthesis was reduced at 8, 125, and 250 Hz but was amplified at 16, 32, and 64 Hz. Differences between the OI and the control groups were found in the highest frequencies in which the test prosthesis showed reduction of the vibrometric signal. The study provides insight into the mechanisms of vibration transmission between the exterior and bone-anchored as well as socket-suspended amputation prostheses.

  10. Machine oil inhibits the osseointegration of orthopaedic implants by impairing osteoblast attachment and spreading.

    PubMed

    Bonsignore, Lindsay A; Goldberg, Victor M; Greenfield, Edward M

    2015-07-01

    The most important factor contributing to short-term and long-term success of cementless total joint arthroplasties is osseointegration. Osseointegration leads to a direct structural and functional connection between living bone and the surface of an implant. Surface contaminants may remain on orthopaedic implants after sterilization procedures and impair osseointegration. For example, specific lots of hip replacement Sulzer Inter-OP(TM) acetabular shells that were associated with impaired osseointegration and early failure rates were found to be contaminated with both bacterial debris and machine oil residues. However, the effect of machine oil on implant integration is unknown. Therefore, the goal of this study was to determine if machine oil inhibits the osseointegration of orthopaedic implants. To test this hypothesis in vivo we used our murine model of osseointegration where titanium alloy implants are implanted into a unicortical pilot hole in the mid-diaphysis of the femur. We found that machine oil inhibited bone-to-implant contact and biomechanical pullout measures. Machine oil on titanium alloy discs inhibited early stages of MC3T3-E1 osteogenesis in vitro such as attachment and spreading. Inhibition of osteoblast attachment and spreading occurred in both areas with and without detectable oil. Osteoblast growth was in turn inhibited on discs with machine oil due to both a decrease in proliferation and an increase in cell death. Later stages of osteogenic differentiation and mineralization on titanium alloy discs were also inhibited. Thus, machine oil can inhibit osseointegration through cell autonomous effects on osteoblast cells. These results support routine testing by manufacturers of machine oil residues on orthopaedic implants.

  11. Microtopography for Ductile Fracture Process Characterization - Part 1: Theory and Methodology

    SciTech Connect

    Lloyd, Wilson Randolph

    2003-02-01

    The mechanics of ductile fracture is receiving increased focus as the importance of integrity of structures constructed from ductile materials is increasing. The non-linear, irreversible mechanical response of ductile materials makes generalized models of ductile cracking very difficult to develop. Therefore, research and testing of ductile fracture have taken a path leading to deformation-based parameters such as crack tip opening displacement (CTOD) and crack tip opening angle (CTOA). Constrained by conventional test techniques and instrumentation, physical values (e.g. crack mouth opening displacement, CMOD, and CTOA angles) are measured on the test specimen exterior and a single through-thickness "average" interior value is inferred. Because of three-dimensional issues such as crack curvature, constraint variation, and material inhomogeneity, inference of average parameter values may introduce errors. The microtopography methodology described here measures and maps three-dimensional fracture surfaces. The analyses of these data provide direct extraction of the parameters of interest at any location within the specimen interior, and at any desired increment of crack opening or extension. A single test specimen can provide all necessary information for the analysis of a particular material and geometry combination.

  12. Impact of engineered surface microtopography on biofilm formation of Staphylococcus aureus.

    PubMed

    Chung, Kenneth K; Schumacher, James F; Sampson, Edith M; Burne, Robert A; Antonelli, Patrick J; Brennan, Anthony B

    2007-06-01

    The surface of an indwelling medical device can be colonized by human pathogens that can form biofilms and cause infections. In most cases, these biofilms are resistant to antimicrobial therapy and eventually necessitate removal or replacement of the device. An engineered surface microtopography based on the skin of sharks, Sharklet AF, has been designed on a poly(dimethyl siloxane) elastomer (PDMSe) to disrupt the formation of bacterial biofilms without the use of bactericidal agents. The Sharklet AF PDMSe was tested against smooth PDMSe for biofilm formation of Staphylococcus aureus over the course of 21 days. The smooth surface exhibited early-stage biofilm colonies at 7 days and mature biofilms at 14 days, while the topographical surface did not show evidence of early biofilm colonization until day 21. At 14 days, the mean value of percent area coverage of S. aureus on the smooth surface was 54% compared to 7% for the Sharklet AF surface (p<0.01). These results suggest that surface modification of indwelling medical devices and exposed sterile surfaces with the Sharklet AF engineered topography may be an effective solution in disrupting biofilm formation of S. aureus.

  13. The effect of surface microtopography of poly(dimethylsiloxane) on protein adsorption, platelet and cell adhesion.

    PubMed

    Chen, Hong; Song, Wei; Zhou, Feng; Wu, Zhongkui; Huang, He; Zhang, Junhu; Lin, Quan; Yang, Bai

    2009-07-01

    Chemical homogeneous poly(dimethylsiloxane) (PDMS) surface with dot-like protrusion pattern was used to investigate the individual effect of surface microtopography on protein adsorption and subsequent biological responses. Fibrinogen (Fg) and fibronectin (Fn) were chosen as model proteins due to their effect on platelet and cell adhesion, respectively. Fg labeled with (125)I and fluorescein isothiocyanate (FITC) was used to study its adsorption on flat and patterned surfaces. Patterned surface has a 46% increase in the adsorption of Fg when compared with flat surface. However, the surface area of the patterned surface was only 8% larger than that of the flat surface. Therefore, the increase in the surface area was not the only factor responsible for the increase in protein adsorption. Clear fluorescent pattern was visualized on patterned surface, indicating that adsorbed Fg regularly distributed and adsorbed most on the flanks and valleys of the protrusions. Such distribution and local enrichment of Fg presumably caused the specific location of platelets adhered from platelet-rich plasma (PRP) and flowing whole blood (FWB) on patterned surface. Furthermore, the different combination of surface topography and pre-adsorbed Fn could influence the adhesion of L929 cells. The flat surface with pre-adsorbed Fn was the optimum substrate while the virgin patterned surface was the poor substrate in terms of L929 cells spread.

  14. Analysis of surface microtopography of biodegradable polymer matrices using confocal reflection microscopy.

    PubMed

    Semler, E J; Tjia, J S; Moghe, P V

    1997-01-01

    Currently, synthetic degradable polymers are frequently employed as culture substrates prior to cell transplantation and as implantable scaffolds for cellular infiltration during soft and hard tissue repair. The surface microstructure of matrices based on such polymers may be important in controlling cellular anchorage, spreading, and growth on the external surface, as well as infiltration into the voids of porous polymer scaffolds. While the chemistry, bulk structure, and mechanical properties of such polymers have been extensively studied, the surface microstructure has not yet been systematically examined, particularly following polymer degradation. In this study, we present the first account of the use of confocal laser-scanning reflection microscopy (CLSM) to visualize and quantitate the microtopography of the surface of porous matrices of poly(lactic acid)/poly(glycolic acid) (PLAGA) copolymers following polymer degradation. Utilizing this technique, we report that the surface morphology of PLAGA matrices changes significantly upon degradation, with increased local clustering of textured regions. Our quantitative analysis suggests that polymer degradation results in a lower spatially-averaged surface roughness, with significant cyclical variations observed at later time points. The computed surface correlation function was observed to increase upon degradation, confirming the results from our morphological studies. Finally, we demonstrate the efficacy of CLSM to concomitantly image both the polymer surface and locally attached cells, in real time.

  15. Combined effects of microtopography and cyclic strain on vascular smooth muscle cell orientation.

    PubMed

    Houtchens, Graham R; Foster, Michael D; Desai, Tejal A; Morgan, Elise F; Wong, Joyce Y

    2008-01-01

    Cellular alignment studies have shown that cell orientation has a large effect on the expression and behavior of cells. Cyclic strain and substrate microtopography have each been shown to regulate cellular alignment. This study examined the combined effects of these two stimuli on the alignment of bovine vascular smooth muscle cells (VSMCs). Cells were cultured on substrates with microgrooves of varying widths oriented either parallel or perpendicular to the direction of an applied cyclic tensile strain. We found that microgrooves oriented parallel to the direction of the applied strain limited the orientation response of VSMCs to the mechanical stimulus, while grooves perpendicular to the applied strain enhanced cellular alignment. Further, the extent to which parallel grooves limited cell alignment was found to be dependent on the groove width. It was found that for both a small (15microm) and a large (70microm) groove width, cells were better able to reorient in response to the applied strain than for an intermediate groove width (40microm). This study indicates that microtopographical cues modulate the orientation response of VSMCs to cyclic strain. The results suggest that there is a range of microgroove dimensions that is most effective at maintaining the orientation of the cells in the presence of an opposing stimulus induced by cyclic strain.

  16. Surface microtopography modulates sealing zone development in osteoclasts cultured on bone.

    PubMed

    Shemesh, Michal; Addadi, Lia; Geiger, Benjamin

    2017-02-01

    Bone homeostasis is continuously regulated by the coordinated action of bone-resorbing osteoclasts and bone-forming osteoblasts. Imbalance between these two cell populations leads to pathological bone diseases such as osteoporosis and osteopetrosis. Osteoclast functionality relies on the formation of sealing zone (SZ) rings that define the resorption lacuna. It is commonly assumed that the structure and dynamic properties of the SZ depend on the physical and chemical properties of the substrate. Considering the unique complex structure of native bone, elucidation of the relevant parameters affecting SZ formation and stability is challenging. In this study, we examined in detail the dynamic response of the SZ to the microtopography of devitalized bone surfaces, taken from the same area in cattle femur. We show that there is a significant enrichment in large and stable SZs (diameter larger than 14 µm; lifespan of hours) in cells cultured on rough bone surfaces, compared with small and fast turning over SZ rings (diameter below 7 µm; lifespan approx. 7 min) formed on smooth bone surfaces. Based on these results, we propose that the surface roughness of the physiologically relevant substrate of osteoclasts, namely bone, affects primarily the local stability of growing SZs.

  17. Advanced in-production hotspot prediction and monitoring with micro-topography

    NASA Astrophysics Data System (ADS)

    Fanton, P.; Hasan, T.; Lakcher, A.; Le-Gratiet, B.; Prentice, C.; Simiz, J.-G.; La Greca, R.; Depre, L.; Hunsche, S.

    2017-03-01

    At 28nm technology node and below, hot spot prediction and process window control across production wafers have become increasingly critical to prevent hotspots from becoming yield-limiting defects. We previously established proof of concept for a systematic approach to identify the most critical pattern locations, i.e. hotspots, in a reticle layout by computational lithography and combining process window characteristics of these patterns with across-wafer process variation data to predict where hotspots may become yield impacting defects [1,2]. The current paper establishes the impact of micro-topography on a 28nm metal layer, and its correlation with hotspot best focus variations across a production chip layout. Detailed topography measurements are obtained from an offline tool, and pattern-dependent best focus (BF) shifts are determined from litho simulations that include mask-3D effects. We also establish hotspot metrology and defect verification by SEM image contour extraction and contour analysis. This enables detection of catastrophic defects as well as quantitative characterization of pattern variability, i.e. local and global CD uniformity, across a wafer to establish hotspot defect and variability maps. Finally, we combine defect prediction and verification capabilities for process monitoring by on-product, guided hotspot metrology, i.e. with sampling locations being determined from the defect prediction model and achieved prediction accuracy (capture rate) around 75%

  18. Micro-topographies promote late chondrogenic differentiation markers in the ATDC5 cell line.

    PubMed

    Bach, Le Q; Vasilevich, Aliaksei; Vermeulen, Steven; Hulshof, Frits; Stamatialis, Dimitrios; van Blitterswijk, Clemens; de Boer, Jan

    2017-02-03

    Chemical and mechanical cues are well-established influencers of the in vitro chondrogenic differentiation of ATDC5 cells. Here, we investigate the role of topographical cues in this differentiation process. Previously using a library of surface micro-topographies, we found some distinct patterns that induced alkaline phosphatase (ALP) production in human mesenchymal stromal cells. ALP is also a marker for hypertrophy, the end stage of chondrogenic differentiation. Thus, we hypothesized that these patterns could influence chondrogenic differentiation of ATDC5 cells. We randomly selected seven topographies among the ALP influencing hits. Cells grown on these surfaces displayed varying nuclear shape and actin filament structure. When stimulated with Insulin-Transferrin-Selenium (ITS) medium, nodule formation occurred and in some cases showed alignment to the topographical patterns. Gene expression analysis of cells growing on topographical surfaces in the presence of ITS medium revealed a down-regulation of early markers and up-regulation of late markers of chondrogenic differentiation compared to cells grown on a flat surface. In conclusion, we demonstrated that surface topography in addition with other cues can promote hypertrophic differentiation suitable for bone tissue engineering.

  19. Establishing Multiscale Models for Simulating Whole Limb Estimates of Electric Fields for Osseointegrated Implants

    PubMed Central

    Isaacson, Brad M.; Stinstra, Jeroen G.; Bloebaum, Roy D.; Pasquina, COL Paul F.; MacLeod, Rob S.

    2011-01-01

    Although the survival rates of warfighters in recent conflicts are among the highest in military history, those who have sustained proximal limb amputations, may pose additional rehabilitation concerns. In some of these cases, traditional prosthetic limbs may not provide adequate function for returning to an active lifestyle. Osseointegration has emerged as a potential prosthetic alternative for those with limited residual limb length. Using this technology, direct skeletal attachment occurs between a transcutaneous osseointegrated implant (TOI) and the host bone, thereby eliminating the need for a socket. While reports from the first 100 patients with a TOI have been promising, some rehabilitation regimens require 12–18 months of restricted weight bearing to prevent overloading at the bone implant-interface. Electrically induced osseointegration has been proposed as an option for expediting periprosthetic fixation and preliminary studies have demonstrated the feasibility of adapting the TOI into a functional cathode. To assure safe and effective electrical fields that are conducive for osseoinduction and osseointegration, we have developed multiscale modeling approaches to simulate the expected electric metrics at the bone-implant interface. We have used computed tomography scans and volume segmentation tools to create anatomically accurate models that clearly distinguish tissue parameters and serve as the basis for finite element analysis. This translational computational biological process has supported biomedical electrode design, implant placement, and experiments to date have demonstrated the clinical feasibility of electrically induced osseointegration. PMID:21712151

  20. Osseointegration amputation prostheses on the upper limbs: methods, prosthetics and rehabilitation.

    PubMed

    Jönsson, Stewe; Caine-Winterberger, Kerstin; Brånemark, Rickard

    2011-06-01

    The osseointegration programme for upper extremity amputation started in Sweden in 1990, when a titanium fixture was first implanted into a thumb. This method has since been used for transhumeral and below-elbow amputation. The treatment involves two surgical procedures. During the first a titanium fixture is surgically attached to the skeleton, and a second procedure six months later involves a skin penetrating abutment to which the prosthesis is attached. To describe the osseointegration procedure for surgery, prosthetics and rehabilitation. Patients with short stumps and previous problems with prosthetic fitting were selected. From 1990 to April 2010, 37 upper limb cases were treated and fitted with prosthesis: 10 thumbs, 1 partial hand, 10 transradial and 16 transhumeral amputations. Of these, 7 patients are currently not prosthetic users. Patients indicated that function and quality of life had improved since osseointegration. Osseointegration is an important platform for present and future prosthetic technology. The prosthetic situation is improved due to the stable fixation, freedom of motion and functionality. The two-stage osseointegration procedure has the potential to change the rehabilitation strategy for selected upper limb amputees. The method eliminates the need for a socket and the prosthesis will always fit. The stable prosthetic fixation and increased freedom of motion generates improved function. Specially designed components and rehabilitation procedures have been developed.

  1. Osseointegrated total knee replacement connected to a lower limb prosthesis: 4 cases

    PubMed Central

    Khemka, Aditya; Frossard, Laurent; Lord, Sarah J; Bosley, Belinda; Al Muderis, Munjed

    2015-01-01

    Background and purpose — Osseointegrated implants are an alternative for prosthetic attachment in individuals with amputation who are unable to wear a socket. However, the load transmitted through the osseointegrated fixation to the residual tibia and knee joint can be unbearable for those with transtibial amputation and knee arthritis. We report on the feasibility of combining total knee replacement (TKR) with an osseointegrated implant for prosthetic attachment. Patients and methods — We retrospectively reviewed all 4 cases (aged 38–77 years) of transtibial amputations managed with osseointegration and TKR in 2012–2014. The below-the-knee prosthesis was connected to the tibial base plate of a TKR, enabling the tibial residuum and knee joint to act as weight-sharing structures. A 2-stage procedure involved connecting a standard hinged TKR to custom-made implants and creation of a skin-implant interface. Clinical outcomes were assessed at baseline and after 1–3 years of follow-up using standard measures of health-related quality of life, ambulation, and activity level including the questionnaire for transfemoral amputees (Q-TFA) and the 6-minute walk test. Results — There were no major complications, and there was 1 case of superficial infection. All patients showed improved clinical outcomes, with a Q-TFA improvement range of 29–52 and a 6-minute walk test improvement range of 37–84 meters. Interpretation — It is possible to combine TKR with osseointegrated implants. PMID:26145721

  2. Implant osseointegration in the absence of primary bone anchorage: a clinical report.

    PubMed

    Villa, Roberto; Polimeni, Giuseppe; Wikesjö, Ulf M E

    2010-11-01

    The authors identified no report describing implant primary stability obtained by external fixation as a means to achieve osseointegration in craniofacial settings. This article describes a situation in which an implant was placed without direct contact with the resident bone; primary stability was provided by an external device. An edentulous patient was restored with 5 endosseous titanium implants to support a mandibular fixed prosthesis. An implant placed in the right central incisor position was removed after 48 hours and replaced with a shorter and narrower implant without contact with resident bone. Thus, primary stability for the implant was provided by rigid fixation to the prosthesis rather than by bone anchorage. At recall examinations after 6 and 27 months, all implants, including the implant in the right central incisor position, showed clinical and radiographic signs of osseointegration. Resonance frequency analysis indicated acceptable stability and osseointegration for all implants. Observations of this patient suggest that implant osseointegration can be achieved by providing primary stability using a fixed complete denture. Primary bone anchorage/contact does not appear to be critical to the osseointegration process. Copyright © 2010 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  3. Effects of local melatonin application on implant osseointegration.

    PubMed

    Tresguerres, Isabel F; Clemente, Celia; Blanco, Luis; Khraisat, Ameen; Tamimi, Faleh; Tresguerres, Jesús A F

    2012-06-01

    The aim of this study was to assess the effect of local melatonin administration on bone osseointegration around implants in rabbit tibiae. Ten female, 6-month-old New Zealand rabbits were randomly divided into two groups: the experimental group, where five rabbits were treated with local application of melatonin (3 mg) to implant sites when placed into the rabbit tibia, and the control group, those who where without additive materials. Four weeks later, animals were sacrificed; tibiae were dissected from soft tissues and fixed in buffered formaldehyde, and then included in methacrylate. Histological sections were performed to be studied under light microscopy and analyzed morphometrically to evaluate the amount of bone to implant contact (BIC), trabecular area density, and cortical area density. One-way analysis of variance test was used for statistical evaluation. p < .05 was considered to be significant. Histological evaluation showed more trabecular reaction in the melatonin group. Morphometrical analysis showed a statistically significant increase in trabecular BIC in the melatonin group when compared with the control group (24.61% ± 2.87 vs 13.62% ± 1.44; p < .01). Cortical BIC was decreased in the melatonin group, without statistical significance (71.08 ± 3.63 vs 76.28 ± 2.57; p = 0.31). Trabecular area density was increased significantly in the melatonin group (8.68 ± 1.61 vs 4.02 ± 0.36; p < .05). Cortical area density was decreased significantly in the melatonin group (91.31 ± 1.6 vs 95.7 ± 0.5; p < .05). Within the limitation of this animal study, local melatonin application at the time of implant placement might induce more trabecular bone at implant contact and higher trabecular area density. © 2010 Wiley Periodicals, Inc.

  4. Influence of Simvastatin-Loaded Implants on Osseointegration in an Ovariectomized Animal Model

    PubMed Central

    Fang, Wen; Zhao, Shifang; He, Fuming; Liu, Li; Yang, Guoli

    2015-01-01

    The success of bone implants in the presence of osteoporosis is limited by lack of osseointegration between the implant and the natural bone. This study applied an electrochemical process to deposit simvastatin-nanohydroxyapatite (HA) coatings on porous implant surfaces and investigated the effects of these simvastatin-HA coatings on implant surfaces in an animal model of osteoporosis. In this study, simvastatin-HA coated implants were inserted into the tibia of osteoporotic rats. After 2, 4, and 12 weeks, tissue was retrieved for histomorphometric evaluation. The results indicated that the simvastatin-HA coatings increased bone-implant contact and new bone formation around implant surfaces. In conclusion, implants loaded with simvastatin by an electrochemical process improved implant osseointegration in osteoporotic rats. Furthermore, the increased concentration of simvastatin could affect the osseointegration, but the dose-effects also need further investigation. PMID:25893198

  5. Radiographic evaluation of bone adaptation adjacent to percutaneous osseointegrated prostheses in a sheep model.

    PubMed

    Jeyapalina, Sujee; Beck, James Peter; Bachus, Kent N; Chalayon, Ornusa; Bloebaum, Roy D

    2014-10-01

    Percutaneous osseointegrated prostheses (POPs) are being investigated as an alternative to conventional socket suspension and require a radiographic followup in translational studies to confirm that design objectives are being met. In this 12-month animal study, we determined (1) radiographic signs of osseointegration and (2) radiographic signs of periprosthetic bone hypertrophy and resorption (adaptation) and (3) confirmed them with the histologic evidence of host bone osseointegration and adaptation around a novel, distally porous-coated titanium POP with a collar. A POP device was designed to fit the right metacarpal bone of sheep. Amputation and implantation surgeries (n = 14) were performed, and plane-film radiographs were collected quarterly for 12 months. Radiographs were assessed for osseointegration (fixation) and bone adaptation (resorption and hypertrophy). The cortical wall and medullary canal widths were used to compute the cortical index and expressed as a percentage. Based on the cortical index changes and histologic evaluations, bone adaptation was quantified. Radiographic data showed signs of osseointegration including those with incomplete seating against the collar attachment. Cortical index data indicated distal cortical wall thinning if the collar was not seated distally. When implants were bound proximally, bone resorbed distally and the diaphyseal cortex hypertrophied. Histopathologic evidence and cortical index measurements confirmed the radiographic indications of adaptation and osseointegration. Distal bone loading, through collar attachment and porous coating, limited the distal bone resorption. Serial radiographic studies, in either animal models or preclinical trials for new POP devices, will help to determine which designs are likely to be safe over time and avoid implant failures.

  6. Biosorption of thorium on the external shell surface of bivalve mollusks: the role of shell surface microtopography.

    PubMed

    Zuykov, Michael; Pelletier, Emilien; Saint-Louis, Richard; Checa, Antonio; Demers, Serge

    2012-02-01

    External shell surface (ESS) of bivalve mollusks is known to adsorb various metals dissolved in ambient water in high concentration. It is hypothesized here that the surface microtopography of the thin organic coating layer, periostracum, or calcareous shell (if periostracum was destroyed) plays a major role in the adsorption of actinides on ESS. Thorium (natural alpha-emitter) was used in short-term biosorption experiment with shell fragments of five bivalve mollusks. After a 72 h exposure to Th (~6 kBq L(-1)), thorium concentration was measured on ESS using laser ablation inductively coupled plasma mass spectrometry; the distribution and density of alpha tracks were subsequently visualized by α-track autoradiography. A trend in reduced Th concentrations on the ESS was observed depending upon the species tested: (group 1 ~4000 μg g(-1)) Chlamys islandica (M.), Mercenaria mercenaria (L.), Dreissena polymorpha (P.)>(group 2 ~1200 μg g(-1)) Crassostrea virginica (G.)≫(group 3 ~150 μg g(-1)) Mytilus edulis L. The microtopography of ESS was characterized by scanning electron microscopy revealing the high porosity of the calcareous surface of C. islandica and M. mercenaria, lamellate surface of periostracum in D. polymorpha, uneven but a weakly porous surface of periostracum of C. virginica, and a nearly smooth surface of the periostracum of M. edulis. This work has demonstrated, for the first time, the presence of a strong correlation between concentration of adsorbed Th and ESS microtopography, and the role of the periostracum in this process is discussed.

  7. Fine morphological characteristics and microtopography of the free nerve endings of the human digital skin.

    PubMed

    Cauna, N

    1980-12-01

    Blocks of osmium-fixed human digital skin, representing a total area of 5 sq mm, were cut serially parallel to the skin surface starting with the epidermis for electron microscopical studies. At intervals, single 1-mu sections were taken and used for recording the microtopography of the receptor organs at various levels. Graphic reconstructions of 28 nerve endings were made. It was found that the digital skin accommodated up to 80 dermal papillae and three to four sweat duct orifices per square millimeter. Each papilla contained one to three fenestrated capillary loops. More than 60% of all papillae contained free nerve endings, sometimes up to five in a single papilla. As a result, up to 100 free nerve endings were counted per square millimeter. Intraepidermal endings were also present, one to five per square millimeter. No endings of any kind were found within the boundary zones between the papillary ridges and in the immediate vicinity of the sweat ducts. The origin of a free ending was marked by the perikaryon of a modified Schwann cell, which constituted the terminal cell of the Schwann sheath. The perikaryon was situated at the base of the dermal papilla, while its distal process provided the cytoplasmic sheath to the axon terminals and their branches. Sometimes two endings merged into a single receptor organ. The terminal Schwann cell frequently served as a rallying point of endings. Three morphological kinds of free endings were observed: open endings, beaded endings, and plain endings. The intraepidermal endings were the derivatives of the plain endings. The free endings in the digital skin had essentially vertical distribution. Each ending covered a minute surface area of skin in a punctate pattern. This is in contrast to the mode of distribution of the free (penicillate) endings of the human hairy skin. Each penicillus covers a large horizontal skin area and overlaps that of their neighbors.

  8. Substrate microtopography can enhance cell adhesive and migratory responsiveness to matrix ligand density.

    PubMed

    Ranucci, C S; Moghe, P V

    2001-02-01

    The regulation of cell motility by ligand density on substrates with variable microtopography is not well understood. In this report, we studied the adhesion and motility behavior of HepG2 cells on microtextured poly(glycolic-co-lactic)acid (PGLA) copolymer substrates, whose surface bioactivity was differentially modified through the adsorption of 0-5.5 ng/cm(2) collagen. Microtextured PGLA substrates were fabricated as thin films with a uniform surface distribution of micropores of median size of 3.1 +/- 1.5 microm and three-dimensional root mean squared roughness of 0.253 microm. Even in the absence of collagen, cells on microtextured substrates responded to substrate topography by exhibiting a 200% increase in adhesion strength compared with untextured controls and ventral localization of the intracellular adhesion protein vinculin. Further enhancement in adhesion strength (420% over untextured, untreated substrates) was demonstrated with bioactivated, microtextured surfaces, indicating that cell adhesion responses to topography and surface ligand density were cooperative. Our motility studies of cells on untextured substrates adsorbed with different levels of collagen demonstrated that a classical biphasic relationship between the cell population averaged migration rate, mu, and the collagen ligand density was preserved. However, comparison of cell motility responses between untextured and microtextured substrates indicates that the motility versus ligand density curve shifted, such that equivalent levels of cell motility were achieved at lower ligand density on microtextured surfaces. Furthermore, the maximum mu values achieved on the microtextured substrates exceeded those on untextured substrates by twofold. Taken together, we show that the magnitude of subcellular scale microtexture of a polymer substrate can sensitize the cell motility responsiveness to substrate ligand concentration; we suggest that the underlying mechanisms involve alteration in the

  9. Inhibition of fibroblast proliferation in cardiac myocyte cultures by surface microtopography.

    PubMed

    Boateng, Samuel Y; Hartman, Thomas J; Ahluwalia, Neil; Vidula, Himabindu; Desai, Tejal A; Russell, Brenda

    2003-07-01

    Cardiac myocyte cultures usually require pharmacological intervention to prevent overproliferation of contaminating nonmyocytes. Our aim is to prevent excessive fibroblast cell proliferation without the use of cytostatins. We have produced a silicone surface with 10-microm vertical projections that we term "pegs," to which over 80% of rat neonatal cardiac fibroblasts attach within 48 h after plating. There was a 50% decrease in cell proliferation by 5 days of culture compared with flat membranes (P < 0.001) and a concomitant 60% decrease (P < 0.01) in cyclin D1 protein levels, suggesting a G1/S1 cell cycle arrest due to microtopography. Inhibition of Rho kinase with 5 or 20 microM Y-27632 reduced attachment of fibroblasts to the pegs by over 50% (P < 0.001), suggesting that this signaling pathway plays an important role in the process. Using mobile and immobile 10-microm polystyrene spheres, we show that reactive forces are important for inhibiting fibroblast cell proliferation, because mobile spheres failed to reduce cell proliferation. In primary myocyte cultures, pegs also inhibit fibroblast proliferation in the absence of cytostatins. The ratio of aminopropeptide of collagen protein from fibroblasts to myosin from myocytes was significantly reduced in cultures from pegged surfaces (P < 0.01), suggesting an increase in the proportion of myocytes on the pegged surfaces. Connexin43 protein expression was also increased, suggesting improved myocyte-myocyte interaction in the presence of pegs. We conclude that this microtextured culture system is useful for preventing proliferation of fibroblasts in myocyte cultures and may ultimately be useful for tissue engineering applications in vivo.

  10. Comparison of self-reported lifetime sun exposure with two methods of cutaneous microtopography.

    PubMed

    Weiler, Lynn; Knight, Julia A; Vieth, Reinhold; Barnett, Heidi; Wong, Ansely

    2007-01-15

    There is currently no "gold standard" for measuring lifetime sun exposure. Exploration of alternatives to self-reports is important for examining illnesses related to ultraviolet light exposure. Using skin replicas obtained from 184 controls in a breast cancer case-control study (Toronto, Ontario, Canada, 2004-2005), the authors compared self-reported indicators of lifetime sun exposure with two measures of cutaneous microtopography, the Beagley-Gibson system and skin line counts. With the Beagley-Gibson system, significantly increased odds ratios were found for age (odds ratio (OR) = 1.10, 95% confidence interval (CI): 1.05, 1.16), spending 7 days outside per week during the summer (OR = 3.33, 95% CI: 1.48, 7.50), and lifetime number of sunlamp sessions. Significantly decreased odds ratios were found for having darker skin, ever giving birth, and ever using sunlamps. With the skin line count approach, significant positive associations were found for age (OR = 2.31, 95% CI: 1.23, 4.35), age squared, duration of working in outdoor jobs (OR = 0.88, 95% CI: 0.79, 0.98), and average number of outdoor activities per week at ages 20-29 years (OR = 1.05, 95% CI: 1.00, 1.10). While the Beagley-Gibson method was associated with more variables than the skin line count method, both methods require further refinement before graded skin replicas can be recommended as a substitute for self-report measures.

  11. Representing northern peatland microtopography and hydrology within the Community Land Model

    NASA Astrophysics Data System (ADS)

    Shi, X.; Thornton, P. E.; Ricciuto, D. M.; Hanson, P. J.; Mao, J.; Sebestyen, S. D.; Griffiths, N. A.; Bisht, G.

    2015-11-01

    Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to represent the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. The new model provides improved predictive capacity for seasonal hydrological dynamics in northern

  12. Representing northern peatland microtopography and hydrology within the Community Land Model

    SciTech Connect

    Shi, X.; Thornton, P. E.; Ricciuto, D. M.; Hanson, P. J.; Mao, J.; Sebestyen, S. D.; Griffiths, N. A.; Bisht, G.

    2015-02-20

    Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to represent the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts significant hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. The new model provides improved predictive capacity for seasonal hydrological dynamics

  13. Representing northern peatland microtopography and hydrology within the Community Land Model

    SciTech Connect

    Shi, Xiaoying; Thornton, Peter E.; Ricciuto, Daniel M.; Hanson, Paul J.; Mao, Jiafu; Sebestyen, Stephen D.; Griffiths, Natalie A.; Bisht, Gautam

    2015-11-12

    Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to represent the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. Furthermore, the new model provides improved predictive capacity for seasonal hydrological dynamics

  14. Representing northern peatland microtopography and hydrology within the Community Land Model

    DOE PAGES

    Shi, X.; Thornton, P. E.; Ricciuto, D. M.; ...

    2015-02-20

    Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to representmore » the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts significant hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. The new model provides improved predictive capacity for seasonal hydrological

  15. Representing northern peatland microtopography and hydrology within the Community Land Model

    DOE PAGES

    Shi, Xiaoying; Thornton, Peter E.; Ricciuto, Daniel M.; ...

    2015-11-12

    Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to representmore » the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. Furthermore, the new model provides improved predictive capacity for seasonal hydrological

  16. Influence of steel implant surface microtopography on soft and hard tissue integration.

    PubMed

    Hayes, J S; Klöppel, H; Wieling, R; Sprecher, C M; Richards, R G

    2017-03-21

    After implantation of an internal fracture fixation device, blood contacts the surface, followed by protein adsorption, resulting in either soft-tissue adhesion or matrix adhesion and mineralization. Without protein adsorption and cell adhesion under the presence of micro-motion, fibrous capsule formation can occur, often surrounding a liquid filled void at the implant-tissue interface. Clinically, fibrous capsule formation is more prevalent with electropolished stainless steel (EPSS) plates than with current commercially pure titanium (cpTi) plates. We hypothesize that this is due to lack of micro-discontinuities on the standard EPSS plates. To test our hypothesis, four EPSS experimental surfaces with varying microtopographies were produced and characterized for morphology using the scanning electron microscope, quantitative roughness analysis using laser profilometry and chemical analysis using X-ray photoelectron spectroscopy. Clinically used EPSS (smooth) and cpTi (microrough) were included as controls. Six plates of each type were randomly implanted, one on both the left and right intact tibia of 18 white New Zealand rabbits for 12 weeks, to allow for a surface interface study. The results demonstrate that the micro-discontinuities on the upper surface of internal steel fixation plates reduced the presence of liquid filled voids within soft-tissue capsules. The micro-discontinuities on the plate under-surface increased bony integration without the presence of fibrous tissue interface. These results support the hypothesis that the fibrous capsule and the liquid filled void formation occurs mainly due to lack of micro-discontinuities on the polished smooth steel plates and that bony integration is increased to surfaces with higher amounts of micro-discontinuities. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017.

  17. Characteristics of soil moisture in relation to microtopography in the Loess region of Northern Shaanxi, China.

    PubMed

    Bo, Yaojun; Zhu, Qingke; Zhao, Weijun

    2014-07-01

    Soil moisture is the primary factor limiting plant growth and vegetation rehabilitation in the loess region of northern Shaanxi, China. This 5-year (2008-2012) study investigated methods of selecting appropriate microsites for vegetation restoration based on efficient use of soil moisture; 5-year data were compared with 56 years of precipitation data using standardized precipitation index. In addition, the effects of microtopography on the spatiotemporal variations of soil moisture were analyzed at the Wuqi Ecological Station of Beijing Forestry University. Results showed that average annual precipitation during last 5 years fell by 12.4% during the growing season compared with 1957-2012 data and soil moisture content at depth of 0-160 cm under went dramatic changes and became relatively low in July and August. Soil moisture content varied in different microtopographical units as follows: gullies > gently-sloped terraces > collapsed soils > undisturbed slopes (control) > furrows > escarpments. The vertical distribution of soil moisture content in different microtopographical units showed dramatic changes at depth of 0-40 cm. Soil moisture content of gently-sloped terraces, gullies, collapsed areas, furrows, and undisturbed slopes was highest at depth of 80-160 cm with a level of instability at depth of 40-80 cm. For gently-sloped terraces and gullies, soil moisture content followed the order of 40-80 cm > 0-40 cm; for collapsed areas, furrows, and undisturbed slopes, soil moisture content follows the order of 0-40 cm > 40-80 cm. For escarpments, soil moisture content varied with depth in a different pattern: 0-40 cm > 80-160 cm > 40-80 cm. This study is of theoretical significance and will help guide the sustainable development of ecological restoration and vegetation rehabilitation in the Loess region.

  18. Spatial patterns of vegetation, soils, and microtopography from terrestrial laser scanning on two semiarid hillslopes of contrasting lithology

    NASA Astrophysics Data System (ADS)

    Harman, Ciaran J.; Lohse, Kathleen A.; Troch, Peter A.; Sivapalan, Murugesu

    2014-02-01

    Shrublands in semiarid regions are heterogeneous landscapes consisting of infertile bare areas separated by nutrient rich vegetated areas known as resource islands. Spatial patterns in these landscapes are structured by feedbacks driven by the transport of water and nutrient resources from the intershrub space to areas below shrubs, and the retention of these resources to locally drive productivity and tight biogeochemical cycles. Most understanding of plant-soil feedbacks is based predominantly on studies of low topographic gradient landscapes, and it is unclear whether the patterns of association between soils and vegetation, and the autogenic processes that create them, also occur on more steeply sloping terrain. Here we analyze the spatial patterns of soils, vegetation, and microtopography on hillslopes of contrasting lithology (one granite at 16°, one schist at 27°) in the Sonoran desert foothills of the Catalina Mountains. We also describe a method of extracting vegetation density from terrestrial laser scanning point cloud data at 5 cm × 5 cm scales and find that it correlates well with soil organic carbon measurements. Vegetation was associated with microtopographic mounds (relative to the mean slope) extending 0.3 m downslope and 1.8 m (schist) and 0.9 m (granite) upslope on the study hillslopes. Soils below the shrub canopies exhibited 2-3 times more soil organic matter and 2-4 times higher hydraulic conductivity than the interspaces. Soils enriched with organic matter were found to extend at least two canopy radii downslope of woody shrubs, but not upslope. These plumes were clearest in the lower gradient granite site where vegetation mounds created distinct patterns of microtopographic convergence and divergence. At the steeper schist site, microtopography appeared to have a weaker control on topographic flow accumulation. Collectively, our findings suggest that the spatial structure of association between soils and microtopography and vegetation on

  19. Osseointegration of a hydroxyapatite-coated multilayered mesh stem.

    PubMed

    Kusakabe, Hiroshi; Sakamaki, Toyonori; Nihei, Kotaro; Oyama, Yasuo; Yanagimoto, Shigeru; Ichimiya, Masaru; Kimura, Jun; Toyama, Yoshiaki

    2004-07-01

    -coated multilayered mesh surface. The difference between the break sites was significant at 12 months (p<0.05). The HA-coated multilayered mesh stem provided faster, stronger, and more durable osseointegration than the conventional bead stem.

  20. The extracellular matrix microtopography drives critical changes in cellular motility and Rho A activity in colon cancer cells.

    PubMed

    Rapier, Rebecca; Huq, Jameela; Vishnubhotla, Ramana; Bulic, Marinka; Perrault, Cecile M; Metlushko, Vitali; Cho, Michael; Tay, Roger Tran Son; Glover, Sarah C

    2010-07-28

    We have shown that the microtopography (mT) underlying colon cancer changes as a tumor de-differentiates. We distinguish the well-differentiated mT based on the increasing number of "pits" and poorly differentiated mT on the basis of increasing number of "posts." We investigated Rho A as a mechanosensing protein using mT features derived from those observed in the ECM of colon cancer. We evaluated Rho A activity in less-tumorogenic (Caco-2 E) and more tumorigenic (SW620) colon cancer cell-lines on microfabricated pits and posts at 2.5 mum diameter and 200 nm depth/height. In Caco-2 E cells, we observed a decrease in Rho A activity as well as in the ratio of G/F actin on surfaces with either pits or posts but despite this low activity, knockdown of Rho A led to a significant decrease in confined motility suggesting that while Rho A activity is reduced on these surfaces it still plays an important role in controlling cellular response to barriers. In SW620 cells, we observed that Rho A activity was greatest in cells plated on a post microtopography which led to increased cell motility, and an increase in actin cytoskeletal turnover.

  1. Proliferation of mouse embryonic stem cell progeny and the spontaneous contractile activity of cardiomyocytes are affected by microtopography.

    PubMed

    Biehl, Jesse K; Yamanaka, Satoshi; Desai, Tejal A; Boheler, Kenneth R; Russell, Brenda

    2009-08-01

    The niche in which stem cells reside and differentiate is a complex physicochemical microenvironment that regulates cell function. The role played by three-dimensional physical contours was studied on cell progeny derived from mouse embryonic stem cells using microtopographies created on PDMS (poly-dimethyl-siloxane) membranes. While markers of differentiation were not affected, the proliferation of heterogeneous mouse embryonic stem cell-derived progeny was attenuated by 15 microm-, but not 5 microm-high microprojections. This reduction was reversed by Rho kinase and myosin light chain kinase inhibition, which diminishes the tension generating ability of stress fibers. Purified cardiomyocytes derived from embryonic stem cells also showed significant blunting of proliferation and increased beating rates compared with cells grown on flat substrates. Thus, proliferation of stem cell-derived progeny appears to be regulated by microtopography through tension-generation of contractility in the third-dimension. These results emphasize the importance of topographic cues in the modulation of stem cell progeny behavior.

  2. Weight-bearing-induced changes in the microtopography and structural stiffness of human skin in vivo following immobility periods.

    PubMed

    Dobos, Gabor; Gefen, Amit; Blume-Peytavi, Ulrike; Kottner, Jan

    2015-01-01

    Pressure ulcers (PUs) are injuries to the skin and underlying tissues, caused by sustained deformations and occur frequently in aged patients. Skin microtopography and stiffness affect the interaction of skin with contact surfaces contributing to PU development. We simulated immobility in 20 healthy females (mean age 69.9 years). Skin microtopography and stiffness were measured at the PU predilection sites before and after loading. Skin roughness decreased at the heels by 18.1% after 90 minutes (p = 0.022), but remained unchanged at the sacrum and the upper back. Structural elasticity and elastic deformations increased at all skin areas; changes over time were significant at the sacrum (p = 0.005) and the heel, (p = 0.002). The residual skin deformation increased at all skin areas after loading significantly at the sacrum (32.0%, p = 0.013) and upper back (20.6%, p = 0.007). The structural "biological" elasticity of the skin decreased significantly at the upper back after loading, but remained unchanged at the heels. All skin changes recovered after unloading. Results indicate that prolonged loading causes structural skin changes in humans in vivo in PU predilection sites. The pathogenesis of PUs is different at the heels, the sacral and upper back skin.

  3. Enhancing the settlement and attachment strength of pediveligers of Mytilus galloprovincialis by changing surface wettability and microtopography.

    PubMed

    Carl, C; Poole, A J; Sexton, B A; Glenn, F L; Vucko, M J; Williams, M R; Whalan, S; de Nys, R

    2012-01-01

    Surface wettability and microtopography can either enhance or deter larval settlement of many sessile marine organisms. This study quantifies the effect of these surface properties on the settlement of pediveligers of Mytilus galloprovincialis, using polymers spanning a range of wettability and microtextured polydimethylsiloxane (PDMS). Furthermore, the adhesion strength of settled pediveligers on microtextured PDMS surfaces was quantified using a flow chamber. Settlement was enhanced at the hydrophilic end of the wettability spectrum, where mean settlement on nylon reached 33.5 ± 13.1%. In contrast, mean settlement on the most hydrophobic polymer (PDMS) was 4.2 ± 3.2%. Microtopography had a much stronger effect compared to wettability, where 400 μm textured PDMS enhanced settlement above 90%. Settlement preferences were also positively correlated to adhesion strength at flow rates of 4 knots, with all initially settled pediveligers on smooth PDMS detaching, while 79.9 ± 5.7% of pediveligers remained on the 400 μm texture.

  4. Cyclic strain dominates over microtopography in regulating cytoskeletal and focal adhesion remodeling of human mesenchymal stem cells.

    PubMed

    Doroudian, Golnar; Curtis, Matthew W; Gang, Anjulie; Russell, Brenda

    2013-01-18

    Human bone marrow-derived mesenchymal stem cell (hMSCs) function depends on chemical factors and also on the physical cues of the microenvironmental niche. Here, this physical microenvironment is recapitulated with controlled modes of mechanical strain applied to substrata containing three-dimensional features in order to analyze the effects on cell morphology, focal adhesion distribution, and gene expression. Ten percentage of strain at 1 Hz is delivered for 48 h to hMSCs cultured on flat surfaces, or on substrata with 15 μm-high microtopographic posts spaced 75 μm apart. Adding strain to microtopography produced stable semicircular focal adhesions, and actin spanning from post to post. Strain dominated over microtopography for expression of genes for the cytoskeleton (caldesmon-1 and calponin 3), cell adhesion (integrin-α2, vinculin, and paxillin), and extracellular matrix remodeling (MMP13) (p<0.05). Overall, attention to external mechanical stimuli is necessary for optimizing the stem cell niche for regenerative medicine.

  5. Effects of hydrophilicity and microtopography of titanium implant surfaces on initial supragingival plaque biofilm formation. A pilot study.

    PubMed

    Schwarz, F; Sculean, A; Wieland, M; Horn, N; Nuesry, E; Bube, C; Becker, J

    2007-12-01

    The aim of the present pilot study is to investigate the effects of hydrophilicity and microtopography of titanium implant surfaces on initial supragingival plaque biofilm formation. Test specimens were manufactured from commercially pure grade 2 titanium according to one of the following procedures: polished (P), acid-etched (A), chemically modified (mod) A (modA), sand-blasted large grit and A (SLA), and modSLA. Intraoral splints were used to collect an in vivo supragingival plaque biofilm in each group at 12, 24, and 48 h. Stained plaque biofilm (PB) areas (%) were morphometrically assessed. All groups exhibited significant increases of mean PB areas over time (p < 0.001; respectively). Morphometrical analysis revealed the following mean PB areas: 12h: SLA = modSLA > P > A =modA (p < 0.001; respectively); 24h: SLA > modSLA = P > A = modA (p < 0.001; respectively); 48h: SLA = modSLA = P > A = modA (p < 0.001; respectively). Within the limits of a pilot study, it could be concluded that hydrophilicity had no apparent effect, while microtopography had a highly uneven and unpredictable influence on supragingival plaque biofilm formation.

  6. Fractal analysis of surface micro-topography for a rolled anisotropic thick sheet of aluminium alloy AA2024-T351

    NASA Astrophysics Data System (ADS)

    Pirva, E.; Tudor, A.; Gavrus, A.

    2016-08-01

    Fractal geometry has gained attention in recent years and represents a problem of high interest for the characterization of surface topography. In this study it was analyzed the surface micro-topography for a rolled thick sheet anisotropic metallic material of type 2000 series aluminium alloy (AA2024-T351). In order to analyze and to characterize the corresponding anisotropic surfaces, profile of particular samples were recorded with a specialized apparatus Mitutoyo SJ-301 (Japan). The random nature of the roughness height is described through statistical analysis. The irregularity of the surface profile has been measured using a lot of conventional surface roughness parameters such as: arithmetic average, mean square root, maximum height of the profile, etc. Fractal analysis provides a useful way to characterize the observed spatial complexity of surface micro-topography. For this study it was used the structural function method to calculate two specific fractal parameters: D (fractal dimension) and L (topothesy). The fractal dimension of all samples it's been be calculated by plotting curves on log-log axes.

  7. Continuous topical administration of a petrolatum formulation by a novel disposable diaper. 1. Effect on skin surface microtopography.

    PubMed

    Odio, M R; O'Connor, R J; Sarbaugh, F; Baldwin, S

    2000-01-01

    Cutaneous problems are commonly associated with the use of diapers. Aiming to help reduce them, we have explored the use of the inner layer of diapers as a means to deliver to the skin dermatological formulations intended to help protect it from overhydration and irritation. To determine the feasibility of using the inner layer of the diaper as a vehicle for topical delivery of a petrolatum-based formulation and to determine its impact on skin surface microtopography. Two independent, blinded, randomized clinical trials were conducted, on children 16-24 months of age. All comparisons were done versus a control diaper, identical to the test product except for the absence of the petrolatum formulation. The studies determined the effects of the novel diaper on transfer of formulation to the skin and skin surface microtopography. During normal diaper use, formulation transfer from the diaper to the skin occurred in a cumulative, time-dependent manner and use of the formulation-treated diaper was associated with significant reductions in skin surface roughness compared to the control diaper. The results demonstrated the feasibility and skin surface benefits associated with continuous topical administration of a petrolatum-based formulation by this novel diaper. This unprecedented dosimetric approach offers new avenues to reduce further the dermatological problems commonly associated with diaper use. Copyright 2000 S. Karger AG, Basel.

  8. Significance of osteogenic surface coatings on implants to enhance osseointegration under osteoporotic-like conditions.

    PubMed

    Javed, Fawad; Vohra, Fahim; Zafar, Sohail; Almas, Khalid

    2014-12-01

    The aim was to assess the significance of osteogenic surface coatings on implants to enhance osseointegration under osteoporotic-like (OP-like) conditions. To address the focused question "Do osteogenic surface coatings on implants enhance osseointegration under OP-like conditions?" PubMed/MEDLINE and Google-Scholar databases were searched from 1995 up to and including February 2014 using various keywords. Unpublished data, letters to the editor, review articles, and articles published in languages other than English were excluded. Of the 28 studies identified, 11 experimental studies were included. These studies were performed on bilaterally ovariectomized animals. In all studies, implant surface roughness was increased by various osteogenetic surface coatings including alumina, hydroxyapatite, calcium phosphate, and zoledronic acid. Nine studies reported that compared with non-coated surfaces, osteogenic coatings on implant surfaces increases bone volume and bone-to-implant contact (BIC) under OP-like conditions. In 2 studies, there was no difference in BIC around hydroxyapatite-coated implants placed in animals with and without OP-like conditions. Osteogenic coatings on implant surfaces enhanced osseointegration in animals with OP-like conditions. However, additional clinical studies are warranted to assess the role of osteogenic coatings in increasing osseointegration in patients with osteoporosis.

  9. Clinical Factors, Disease Parameters, and Molecular Therapies Affecting Osseointegration of Orthopedic Implants

    PubMed Central

    Kremers, Hilal Maradit; Lewallen, Eric A.; van Wijnen, Andre J.; Lewallen, David G.

    2016-01-01

    Total hip and knee arthroplasty are effective interventions for management of end-stage arthritis. Indeed, about 7 million Americans are currently living with artificial hip and knee joints. The majority of these individuals, however, will outlive their implants and require revision surgeries, mostly due to poor implant osseointegration and aseptic loosening. Revisions are potentially avoidable with better management of patient-related risk factors that affect the osseointegration of orthopedic implants. In this review, we summarize the published clinical literature on the role of demographics, biologic factors, comorbidities, medications and aseptic loosening risk. We focus on several systemic and local factors that are particularly relevant to implant osseointegration. Examples include physiological and molecular processes that are linked to hyperglycemia, oxidative stress, metabolic syndrome and dyslipidemia. We discuss how orthopedic implant osseointegration can be affected by a number of molecular therapies that are antiresorptive or bone anabolic (i.e. calcium, vitamin D, bisphosphonates, calcitonin, strontium, hormone replacement therapy, selective estrogen-receptor modulators). PMID:28008373

  10. Berberine in Combination with Insulin Has Additive Effects on Titanium Implants Osseointegration in Diabetes Mellitus Rats

    PubMed Central

    Lu, Li; Zhijian, Huang; Lei, Li; Wenchuan, Chen; Zhimin, Zhu

    2015-01-01

    This study evaluated the effects of berberine in combination with insulin on early osseointegration of implants in diabetic rats. Fifty male Sprague-Dawley rats were randomly divided into 5 groups: healthy rats were used as control (HC), and streptozotocin-induced diabetic rats were treated with insulin, berberine, berberine + insulin (IB), or no treatment. Each rat received one machined-surface cp-Ti implant into the right tibia and was given insulin injection and/or gavage feeding with berberine daily for 8 weeks until being sacrificed. Serum levels of alkaline phosphatase (ALP) and bone gamma-carboxyglutamic acid-containing protein (BGP) were analyzed in each group. Peri-implant mineral apposition was marked by fluorochrome double-labeling and osseointegration was histomorphologically examined. The ALP and BGP levels decreased in diabetic rats but were successfully corrected by insulin and berberine combined treatment. Moreover, untreated diabetic rats had less labeled mineral apposition and impaired osseointegration. In contrast, Groups I, B, and IB were observed with increased peri-implant bone formation. The combination treatment of insulin and berberine was more effective than each administrated as a monotherapy. These results suggest that berberine combined with insulin could promote osseointegration in diabetic rats, thereby highlighting its potential application to patients, though further studies are needed. PMID:26783411

  11. Berberine in Combination with Insulin Has Additive Effects on Titanium Implants Osseointegration in Diabetes Mellitus Rats.

    PubMed

    Lu, Li; Zhijian, Huang; Lei, Li; Wenchuan, Chen; Zhimin, Zhu

    2015-01-01

    This study evaluated the effects of berberine in combination with insulin on early osseointegration of implants in diabetic rats. Fifty male Sprague-Dawley rats were randomly divided into 5 groups: healthy rats were used as control (HC), and streptozotocin-induced diabetic rats were treated with insulin, berberine, berberine + insulin (IB), or no treatment. Each rat received one machined-surface cp-Ti implant into the right tibia and was given insulin injection and/or gavage feeding with berberine daily for 8 weeks until being sacrificed. Serum levels of alkaline phosphatase (ALP) and bone gamma-carboxyglutamic acid-containing protein (BGP) were analyzed in each group. Peri-implant mineral apposition was marked by fluorochrome double-labeling and osseointegration was histomorphologically examined. The ALP and BGP levels decreased in diabetic rats but were successfully corrected by insulin and berberine combined treatment. Moreover, untreated diabetic rats had less labeled mineral apposition and impaired osseointegration. In contrast, Groups I, B, and IB were observed with increased peri-implant bone formation. The combination treatment of insulin and berberine was more effective than each administrated as a monotherapy. These results suggest that berberine combined with insulin could promote osseointegration in diabetic rats, thereby highlighting its potential application to patients, though further studies are needed.

  12. Proton Pump Inhibitors and the Risk of Osseointegrated Dental Implant Failure: A Cohort Study.

    PubMed

    Wu, Xixi; Al-Abedalla, Khadijeh; Abi-Nader, Samer; Daniel, Nach G; Nicolau, Belinda; Tamimi, Faleh

    2017-04-01

    Proton pump inhibitors (PPIs) have a negative impact on bone accrual. Because osseointegration is influenced by bone metabolism, this study investigates the association between PPIs and the risk of osseointegrated implant failure. This retrospective cohort study included a total of 1,773 osseointegrated dental implants in 799 patients (133 implants in 58 PPIs users and 1,640 in 741 non-users) who were treated at the East Coast Oral Surgery Clinic in Moncton, Canada, from January 2007 to September 2015. Kaplan-Meier estimator was used to describe the hazard function of dental implant failure by PPIs usage. Multilevel mixed effects parametric survival analyses were used to test the association between PPIs exposure and risk of implant failure adjusting for potential confounders. The failure rates were 6.8% for people using PPIs compared to 3.2% for non-users. Subjects using PPIs had a higher risk of dental implant failure (HR = 2.73; 95% CI = 1.10-6.78) compared to those who did not use the drugs. The findings suggest that treatment with PPIs may be associated with an increased risk of osseointegrated dental implant failure.

  13. Efficacy of parathyroid hormone supplementation on the osseointegration of implants: a systematic review.

    PubMed

    Javed, Fawad; Al Amri, Mohammad D; Kellesarian, Sergio Varela; Al-Kheraif, Abdulaziz A; Vohra, Fahim; Calvo-Guirado, José Luis; Malmstrom, Hans; Romanos, Georgios E

    2016-05-01

    The aim of the present systematic review was to assess the efficacy of parathyroid hormone supplementation on the osseointegration of implants. The addressed focused question was Does parathyroid hormone supplementation affect osseointegration around implants? Indexed databases were searched from 1965 up to and including April 2015 using various key words including: Bone to implant contact; implant; parathyroid hormone; and osseointegration. Letters to the Editor, case-reports/case-series, historic reviews, commentaries and articles published in languages other than English were excluded. The pattern of the present systematic review was customized to primarily summarize the pertinent data. Eighteen studies fulfilled the eligibility criteria. Evidence was limited to preclinical animal studies only (11 studies in rodents, 4 in dogs and 3 in rabbits). Number of titanium implants placed ranged between 20 and 80 implants. Results from 16 studies showed that PTH supplementation enhanced new bone formation and/or BIC around implants. One study suggests that PTH-coated implants improve BIC and BA. One study showed no significant difference in BIC and new bone formation around implants with PTH hydrogel placement. Efficacy of PTH supplementation on osseointegration of implants shows promising results in animal models, however further investigation is necessary to assess the effectiveness in humans.

  14. A strontium-incorporated nanoporous titanium implant surface for rapid osseointegration.

    PubMed

    Zhang, Wenjie; Cao, Huiliang; Zhang, Xiaochen; Li, Guanglong; Chang, Qing; Zhao, Jun; Qiao, Yuqin; Ding, Xun; Yang, Guangzheng; Liu, Xuanyong; Jiang, Xinquan

    2016-03-07

    Rapid osseointegration of dental implants will shorten the period of treatment and enhance the comfort of patients. Due to the vital role of angiogenesis played during bone development and regeneration, it might be feasible to promote rapid osseointegration by modifying the implant surface to gain a combined angiogenesis/osteogenesis inducing capacity. In this study, a novel coating (MAO-Sr) with strontium-incorporated nanoporous structures on titanium implants was generated via a new micro-arc oxidation, in an attempt to induce angiogenesis and osteogenesis to enhance rapid osseointegration. In vitro, the nanoporous structure significantly enhanced the initial adhesion of canine BMSCs. More importantly, sustained release of strontium ions also displayed a stronger effect on the BMSCs in facilitating their osteogenic differentiation and promoting the angiogenic growth factor secretion to recruit endothelial cells and promote blood vessel formation. Advanced mechanism analyses indicated that MAPK/Erk and PI3K/Akt signaling pathways were involved in these effects of the MAO-Sr coating. Finally, in the canine dental implantation study, the MAO-Sr coating induced faster bone formation within the initial six weeks and the osseointegration effect was comparable to that of the commercially available ITI implants. These results suggest that the MAO-Sr coating has the potential for future use in dental implants.

  15. Fabrication of an educational model for patients considering prostheses retained by osseointegrated implants.

    PubMed

    Morrison, David C; Kubon, Todd M; Anderson, James

    2002-06-01

    Patients considering the use of implant-retained craniofacial prostheses are faced with a large body of new information. This article describes the fabrication of a 3-dimensional teaching aid that helps educate such patients about the role of osseointegration in prosthetic treatment. The model illustrates the stages of auricular prosthesis fabrication and can be used to demonstrate proper prosthesis hygiene.

  16. Osseointegration of zirconia implants: an SEM observation of the bone-implant interface

    PubMed Central

    Depprich, Rita; Zipprich, Holger; Ommerborn, Michelle; Mahn, Eduardo; Lammers, Lydia; Handschel, Jörg; Naujoks, Christian; Wiesmann, Hans-Peter; Kübler, Norbert R; Meyer, Ulrich

    2008-01-01

    Background The successful use of zirconia ceramics in orthopedic surgery led to a demand for dental zirconium-based implant systems. Because of its excellent biomechanical characteristics, biocompatibility, and bright tooth-like color, zirconia (zirconium dioxide, ZrO2) has the potential to become a substitute for titanium as dental implant material. The present study aimed at investigating the osseointegration of zirconia implants with modified ablative surface at an ultrastructural level. Methods A total of 24 zirconia implants with modified ablative surfaces and 24 titanium implants all of similar shape and surface structure were inserted into the tibia of 12 Göttinger minipigs. Block biopsies were harvested 1 week, 4 weeks or 12 weeks (four animals each) after surgery. Scanning electron microscopy (SEM) analysis was performed at the bone implant interface. Results Remarkable bone attachment was already seen after 1 week which increased further to intimate bone contact after 4 weeks, observed on both zirconia and titanium implant surfaces. After 12 weeks, osseointegration without interposition of an interfacial layer was detected. At the ultrastructural level, there was no obvious difference between the osseointegration of zirconia implants with modified ablative surfaces and titanium implants with a similar surface topography. Conclusion The results of this study indicate similar osseointegration of zirconia and titanium implants at the ultrastructural level. PMID:18990214

  17. Intermittent Parathyroid Hormone Enhances Cancellous Osseointegration of a Novel Murine Tibial Implant

    PubMed Central

    Yang, Xu; Ricciardi, Benjamin F.; Dvorzhinskiy, Aleksey; Brial, Caroline; Lane, Zachary; Bhimani, Samrath; Burket, Jayme C.; Hu, Bin; Sarkisian, Alexander M.; Ross, F. Patrick; van der Meulen, Marjolein C.H.; Bostrom, Mathias P.G.

    2015-01-01

    Background: Long-term fixation of uncemented joint implants requires early mechanical stability and implant osseointegration. To date, osseointegration has been unreliable and remains a major challenge in cementless total knee arthroplasty. We developed a murine model in which an intra-articular proximal tibial titanium implant with a roughened stem can be loaded through the knee joint. Using this model, we tested the hypothesis that intermittent injection of parathyroid hormone (iPTH) would increase proximal tibial cancellous osseointegration. Methods: Ten-week-old female C57BL/6 mice received a subcutaneous injection of PTH (40 μg/kg/day) or a vehicle (n = 45 per treatment group) five days per week for six weeks, at which time the baseline group was killed (n = 6 per treatment group) and an implant was inserted into the proximal part of the tibiae of the remaining mice. Injections were continued until the animals were killed at one week (n = 7 per treatment group), two weeks (n = 14 per treatment group), or four weeks (n = 17 per treatment group) after implantation. Outcomes included peri-implant bone morphology as analyzed with micro-computed tomography (microCT), osseointegration percentage and bone area fraction as shown with backscattered electron microscopy, cellular composition as demonstrated by immunohistochemical analysis, and pullout strength as measured with mechanical testing. Results: Preimplantation iPTH increased the epiphyseal bone volume fraction by 31.6%. When the data at post-implantation weeks 1, 2, and 4 were averaged for the iPTH-treated mice, the bone volume fraction was 74.5% higher in the peri-implant region and 168% higher distal to the implant compared with the bone volume fractions in the same regions in the vehicle-treated mice. Additionally, the trabecular number was 84.8% greater in the peri-implant region and 74.3% greater distal to the implant. Metaphyseal osseointegration and bone area fraction were 28.1% and 70.1% higher

  18. Historical landscape elements in preserving steppic species - vegetation responses on micro-topography and human disturbances

    NASA Astrophysics Data System (ADS)

    Deák, Balázs; Valkó, Orsolya; Török, Péter; Tóthmérész, Béla

    2017-04-01

    Land use changes of past centuries resulted in a considerable loss and isolation of grassland habitats worldwide which also led to a serious loss in ecosystem functions. In intensively used agricultural landscapes remnants of natural flora persisted only in small habitat islands embedded in a hostile matrix, which are inadequate for arable farming or construction. In the steppe zone of Eurasia burial mounds, so-called kurgans, have a great potential to preserve the natural flora and habitats and act as local biodiversity hotspots. Their special micro-topography and historical origin makes kurgans characteristic landscape elements of the steppe region. These features also result in a specific soil development and micro-climate, which makes kurgans especially adequate habitats for several steppe specialist plant species. Furthermore, they are proper objects for studying the effects of present and past human disturbances on the vegetation of semi-natural habitats. Exploration of the main factors driving biodiversity in isolated habitat fragments is crucial for understanding the ecological processes shaping their vegetation and for designing effective strategies for their protection. We surveyed the vegetation of 44 isolated kurgans in East-Hungary and studied the effects of habitat area, slope, recent disturbance, past destruction and the level of woody encroachment on the species richness and cover of grassland specialist and weedy species. We used model selection techniques and linear models for testing relevant factors affecting specialist species in grassland fragments. We found that the biodiversity conservation potential of kurgans is supported by their steep slopes, which provide adequate habitat conditions and micro-climate for steppic specialist plant species. By harbouring several grassland specialist species, kurgans have a great potential for preserving the natural species pool of even considerably altered agricultural landscapes, and can mitigate the

  19. Current-controlled, abyssal microtopography and sedimentation in Mozambique Basin, southwest Indian Ocean

    USGS Publications Warehouse

    Kolla, V.; Eittreim, S.; Sullivan, L.; Kostecki, J.A.; Burckle, L.H.

    1980-01-01

    The Antarctic Bottom Water (AABW) activity and the variations in the abundance and grain size of the terrigenous sediments, derived from Africa and Madagascar land masses, are reflected in different types of microtopography in the Mozambique Basin. In southerly areas, where the sediment supply is much less, the bottom-current activity has resulted in the presence of manganese nodules, a thin veneer of sediments, and the absence of sediment waves. Farther north, along the marginal areas of the basin where the fine-grained sediments from the Africa-Madagascar source have been supplied in abundance, wavy bedforms have been generated by AABW. Wavy bedforms do not exist even in the northerly areas if coarse-grained, turbidite sediments are present on the sea floor. The continuation of acoustic reflectors from the zone of turbidites in the central areas of the basin into the zone of sediment waves along the margins, and the lithology and structures in sediment cores from these zones suggest that the turbidity-current-fed, fine-grained sediments were deposited as wavy bedforms by AABW flow. Thus, sediment waves formed readily during Pleistocene times. The enrichment of quartz and displaced Antarctic diatoms, and the relatively low kaolinite/chlorite ratios in the sediments, the north-pointing current lineations on the sea floor, the lack of any perceptible sedimentary fill in the troughs of waves, and the dense nepheloid layer in the westerly areas of the Mozambique Basin, attest to the current-controlled sedimentation and generation of wavy bedforms during Holocene time also. The formation of sediment waves in the Mozambique Basin can be modeled after a fluvial antidune mechanism. This model envisages that internal waves, focussed on a benthic boundary layer cap, have been locked in phase with sediment waves in the presence of an 8-10 cm/sec current in the Mozambique Basin. A density contrast of 2??10-6 g/cm3 appears to exist at the tops of benthic boundary layers in the

  20. Importance of the Roughness and Residual Stresses of Dental Implants on Fatigue and Osseointegration Behavior. In Vivo Study in Rabbits.

    PubMed

    Velasco, Eugenio; Monsalve-Guil, Loreto; Jimenez, Alvaro; Ortiz, Iván; Moreno-Muñoz, Jesús; Nuñez-Marquez, Enrique; Pegueroles, Marta; Pérez, Román A; Gil, Francisco Javier

    2016-12-01

    This study focuses on the fatigue behavior and bone-implant attachment for the more usual surfaces of the different CP-titanium dental implants. The implants studied were: as-received (CTR), acid etching (AE), spark-anodization (SA), and with a grit-blasted surface (GB). Residual stresses were determined by means of X-ray diffraction. The fatigue tests were carried out at 37°C on 160 dental implants, and the stress-failure (S-N) curve was determined. The fatigue tests showed that the grit-blasting process improved fatigue life. This is a consequence of the layer of compressive residual stresses that the treatment generates in titanium surfaces. Further, our aim was to assess and compare the short- and midterm bone regenerative potential and mechanical retention of the implants in bone of New Zealand rabbits. The mechanical retention after 4 and 10 weeks of implantation was evaluated with histometric and pull-out tests, respectively, as a measure of the osseointegration of the implants. The results demonstrated that the GB treatment produced microrough that accelerated bone tissue regeneration and increased mechanical retention in the bone bed at short periods of implantation in comparison with all other implants tested. The GB surface produced an improvement in mechanical long-time behavior and improved bone growth. These types of treated implants can have great potential in clinical applications, as evidenced by the outcomes of the current study.

  1. Assessing the performance of structure-from-motion photogrammetry and terrestrial lidar 1 at reconstructing soil surface microtopography of naturally vegetated plots

    USDA-ARS?s Scientific Manuscript database

    Soil microtopography or soil roughness is a property of critical importance in many earth surface processes but is often difficult to measure. Advances in computer vision technologies have made image-based 3D depiction of the soil surface or Structure-from-Motion (SfM) available to many scientists ...

  2. Osseointegration and biocompatibility of different metal implants - a comparative experimental investigation in sheep

    PubMed Central

    2012-01-01

    Background In the present study, 4 different metallic implant materials, either partly coated or polished, were tested for their osseointegration and biocompatibility in a pelvic implantation model in sheep. Methods Materials to be evaluated were: Cobalt-Chrome (CC), Cobalt-Chrome/Titanium coating (CCTC), Cobalt-Chrome/Zirconium/Titanium coating (CCZTC), Pure Titanium Standard (PTST), Steel, TAN Standard (TANST) and TAN new finish (TANNEW). Surgery was performed on 7 sheep, with 18 implants per sheep, for a total of 63 implants. After 8 weeks, the specimens were harvested and evaluated macroscopically, radiologically, biomechanically (removal torque), histomorphometrically and histologically. Results Cobalt-Chrome screws showed significantly (p = 0.031) lower removal torque values than pure titanium screws and also a tendency towards lower values compared to the other materials, except for steel. Steel screws showed no significant differences, in comparison to cobalt-chrome and TANST, however also a trend towards lower torque values than the remaining materials. The results of the fluorescence sections agreed with those of the biomechanical test. Histomorphometrically, there were no significant differences of bone area between the groups. The BIC (bone-to-implant-contact), used for the assessment of the osseointegration, was significantly lower for cobalt-chrome, compared to steel (p = 0.001). Steel again showed a lower ratio (p = 0.0001) compared to the other materials. Conclusion This study demonstrated that cobalt-chrome and steel show less osseointegration than the other metals and metal-alloys. However, osseointegration of cobalt-chrome was improved by zirconium and/or titanium based coatings (CCTC, TANST, TAN, TANNEW) being similar as pure titanium in their osseointegrative behavior. PMID:22400715

  3. Influence of bone marrow on osseointegration in long bones: an experimental study in sheep.

    PubMed

    Morelli, Fabrizio; Lang, Niklaus P; Bengazi, Franco; Baffone, Davide; Vila Morales, C Dadonim; Botticelli, Daniele

    2015-03-01

    To evaluate the influence of yellow bone marrow on osseointegration of titanium oral implants using a long bone model. The two tibiae of eight sheep were used as experimental sites. Two osteotomies for implant installation were prepared in each tibia. At the control sites, no further treatments were performed while, at the test sites, bone marrow was removed from the osteotomy site with a curette to an extent that exceeded the implant dimensions. As a result, the apical portion of the implants at the control sites was in contact with bone marrow while, at the test sites, it was in contact with the blood clot. After 2 months, the same procedures were performed in the contralateral side. After another month, the animal was sacrificed. Ground sections were obtained for histological analysis. After 1 month of healing, no differences between test and control sites were found in the apical extension of osseointegration and the percentage of new bone-to-implant contact. However, after 3 months of healing, a higher percentage of new bone-to-implant contact was found at the test compared to the control sites in the marrow compartment. The apical extension of osseointegration, however, was similar to that found at the 1-month healing period both for test and control sites. Osseointegration appeared to be favored by the presence of a blood clot when compared to the presence of yellow fatty bone marrow. Moreover, the contact with cortical bone appeared to be a prerequisite for the osseointegration process in the long bone model. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Enhancing osseointegration of orthopedic implants with titania nanotube surfaces

    NASA Astrophysics Data System (ADS)

    Baker, Erin A.

    Introduction: As joint arthroplasty surgical procedures increase annually, the development of new strategies, including novel materials and surface modifications, to attain solid bone-implant fixation are needed to increase implant terms of service. In this study, we evaluate two morphologies of titania nanotubes in both in vitro and in vivo experiments to quantify osseointegrative potential and material-level biocompatibility. Materials and Methods: Samples were prepared via an electrochemical etching process. Two different titania nanotube (TiNT) morphologies were produced, Aligned and Trabecular. For the in vitro experiment, Sprague Dawley (SD) rat marrow-derived bone marrow cells (BMC) were seeded on samples. Alkaline phosphatase (ALP) activity, osteocalcin (OC) expression, expression of relevant genes as well as cell attachment and morphology were assessed. In the first in vivo experiment, Kirschner wires were implanted unilaterally into SD rat femora with a TiNT-etched or unmodified (Control) implant. General health assessments and weekly body weights were recorded. At a 12-week endpoint, hematologic, systemic metal ion, and histologic analyses were performed. For the second in vivo experiment, Kirschner wires were implanted bilaterally into SD rat femora, with a TiNT-etched implant in one femora and unmodified (Control) implant as an internal control. At 4- and 12-week endpoints, femora were assessed via biomechanics, undecalcified histology, micro-computed tomography (muCT), and backscattered electron imaging (BEI) to characterize de novo bone formation. Results: In vitro experiments demonstrated BMC attachment and differentiation into osteoblasts as well as greater ALP activity, OC expression, total cell counts, and gene expression (of Col1a1, IGF-1, and osteonectin) on TiNT surfaces versus Controls. Cells on TiNT-etched substrates were smaller in diameter and more eccentric than Controls. In the first in vivo experiment, there were significant differences

  5. Nonlinear effects of microtopography on macroscopic rainfall-runoff partitioning a the hillslope scale: a modelling study

    NASA Astrophysics Data System (ADS)

    Caviedes-Voullième, Daniel; Domin, Andrea; Hinz, Christoph

    2017-04-01

    The quantitative description and prediction of hydrological response of hillslopes or hillslope-scale catchments to rainfall events is becoming evermore relevant. At the hillslope scale, the onset of runoff and the overall rainfall-runoff transformation are controlled by multiple interacting small-scale processes, that, when acting together produce a response described in terms of hydrological variables well-defined at the catchment and hillslope scales. We hypothesize that small scale features such microtopography of the land surface will will govern large scale signatures of temporal runoff evolution. This can be tested directly by numerical modelling of well-defined surface geometries and adequate process description. It requires a modelling approach consistent with fundamental fluid mechanics, well-designed numerical methods, and computational efficiency. In this work, an idealized rectangular domain representing a hillslope with an idealized 2D sinusoidal microtopography is studied by simulating surface water redistribution by means of a 2D diffusive-wave (zero-inertia) shallow water model. By studying more than 500 surfaces and performing extensive sensitivity analysis forced by a single rainfall pulse, the dependency of characteristic hydrological responses to microtopographical properties was assessed. Despite of the simplicity of periodic surface and the rain event, results indicate complex surface flow dynamics during the onset of runoff observed at the macro and micro scales. Macro scale regimes were defined in terms of characteristics hydrograph shapes and those were related to surface geometry. The reference regime was defined for smooth topography and consisted of a simple hydrograph with smoothly rising and falling limbs with an intermediate steady state. In constrast, rough surface geometry yields stepwise rising limbs and shorter steady states. Furthermore, the increase in total infiltration over the whole domain relative to the smooth reference

  6. Defective implant osseointegration under protein undernutrition: prevention by PTH or pamidronate.

    PubMed

    Dayer, Romain; Badoud, Isabelle; Rizzoli, René; Ammann, Patrick

    2007-10-01

    Protein deficiency is associated with impaired titanium osseointegration. We studied whether systemic treatment with PTH or pamidronate could influence the resistance to pull-out of titanium rods implanted into rats proximal tibia under normal and isocaloric low protein intake. PTH or pamidronate prevented the deleterious effects of protein undernutrition on bone microarchitecture close to the implant and on mechanical fixation. PTH even significantly improved implant osseointegration. Protein deficiency is highly prevalent among elderly patients hospitalized in orthopedic wards. Reduced protein intake impairs titanium osseointegration in rats. Whether stimulator of bone formation or inhibitor of bone resorption could improve implant osseointegration under protein deprivation is not known. We studied the effects of systemic treatment with PTH or pamidronate on the resistance to pull-out of titanium rods implanted into rats proximal tibia under normal and isocaloric low protein intake. We measured the resistance to pull-out 1-mm-diameter titanium rods implanted into the proximal tibias of 49 adult female rats receiving a normal or an isocaloric low protein diet. After 2 wk on either diet, the implants were inserted, and the rats received PTH(1-34), pamidronate or saline vehicle for 8 wk. The tibias were removed for microCT morphometry, followed by the evaluation of pull-out strength. Pull-out strength was lower in rats fed an isocaloric low protein diet compared with rats fed a normal protein intake (-29%). PTH and pamidronate significantly increased pull-out strength in animals fed a normal or a low protein diet, the effect of PTH being of higher magnitude. The PTH- or pamidronate-mediated increase in pull-out strength was associated with significant increases of relative bone volume, bone-to-implant contact, and trabecular thickness, whereas trabecular spacing was reduced, in the vicinity of the implants. We confirmed that isocaloric low protein intake impairs

  7. Effect of micro-topography and undrained shear strength on soil erosion

    NASA Astrophysics Data System (ADS)

    Todisco, Francesca; Vergni, Lorenzo; Vinci, Alessandra; Torri, Dino

    2017-04-01

    An experiment to evaluate the effect of the pre-event soil surface conditions on the dynamics of the interrill erosion process was performed at the Masse experimental station (Italy) in a replicated 1mx1m plot, located in a 16% slope in a silt-clay-loam soil equipped with a nozzle-type rainfall simulator. Two experiments was performed, each experiment started from a just ploughed bare surface and included 3 simulations (I, II and III in the first experiment and IV, V and VI in the second experiment) carried out in the range of few days. A 30 min pre-wetting phase ensures almost constant initial soil moisture (mean=31%, CV=5%) and bulk density (mean=1.3 g/cm3, CV=3%). Rainfall intensity was maintained constant (mean=67mm/h, CV=2.7%). The independent variables were the initial soil surface conditions that, progressively modified by the rainfall runoff process, were different for the three subsequent simulations. The soil surface initial and final micro-topography and undrained shear strength, T, were monitored through photogrammetric surveys (with I-Phone 6plus) and Torvane test (with pocket-torvane, obliged shear surface at 0.5 cm from soil surface, plate diameter 5 cm, 0.2186 full scale complete revolution 360°, test done on saturated soil surface, with water standing at the surface). Runoff, Q, runoff coefficient, Qr, soil loss, SL and sediment concentration, C, were measured every 5 min. The particle size distribution were also determined. During the simulations Q increases monotonically with typically concave trend. Almost similar consideration can be made for the other variables. A higher frequency of the roughness, RR, (i.e. vertical distance between the surface and a reference horizontal plane, obtained by removing the slope effect) lower than a fixed amount, was measured at the final than the initial step of each simulation and within the single experiment between successive simulations. Therefore, the roughness decreases along with the Q, SL and C increase

  8. Numerical analysis of ponding and surface runoff in flat areas due to microtopography

    NASA Astrophysics Data System (ADS)

    Appels, W. M.; Bogaart, P. W.; van der Zee, S. E. A. T. M.

    2009-04-01

    When the storage capacity of a soil has been depleted or the precipitation intensity of a rainstorm exceeds the infiltration capacity of a soil, water accumulates at the soil surface. The excess water fills small depressions, that may connect and eventually form a fast overland flow route to surrounding surface waters. We hypothesize that even in relatively flat areas such as the Netherlands, surface runoff forms a significant factor on the local water balance during a rainfall event. In particular if solute fluxes towards surface water are of concern (as in the EU Water Framework Directive), the relatively fast runoff pathway may be of major importance for surface water quality. Classic studies on depression storage and surface runoff focus on a small spatial scale (1-2 m2) with a microtopography in order of magnitude of centimeters. State-of-the-art modelling of surface runoff focuses on solving physical flow equations for this type of plots. When upscaling to field or basin studies depression storage and connectivity are often parameterized as a roughness parameter since solving the flow equations on a complex topography is computationally too intensive. When flow equations are solved in a model, the basins are monotonuously descending. When studying depression storage, pool formation, connectivity, and surface runoff on a field scale in flat areas, we have to account for complex topography (in orders of magnitude of decimeters) and hydrological processes in the subsoil. Since these demands cannot be met with current hydrological models, we developed a routine that explicitly deals with the filling, merging, and connecting of depressions in a field. The routine has a successive steady-state setup: in every timestep the excess water in each cell is routed to its ultimate sink, either in the field or in the surrounding surface water, under the assumption of instantaneous water transfer. When the capacity of a depression is exceeded, water is routed to a

  9. Water-table height and microtopography control biogeochemical cycling in an Arctic coastal tundra ecosystem

    NASA Astrophysics Data System (ADS)

    Lipson, D. A.; Zona, D.; Raab, T. K.; Bozzolo, F.; Mauritz, M.; Oechel, W. C.

    2012-01-01

    Drained thaw lake basins (DTLB's) are the dominant land form of the Arctic Coastal Plain in northern Alaska. The presence of continuous permafrost prevents drainage and so water tables generally remain close to the soil surface, creating saturated, suboxic soil conditions. However, ice wedge polygons produce microtopographic variation in these landscapes, with raised areas such as polygon rims creating more oxic microenvironments. The peat soils in this ecosystem store large amounts of organic carbon which is vulnerable to loss as arctic regions continue to rapidly warm, and so there is great motivation to understand the controls over microbial activity in these complex landscapes. Here we report the effects of experimental flooding, along with seasonal and spatial variation in soil chemistry and microbial activity in a DTLB. The flooding treatment generally mirrored the effects of natural landscape variation in water-table height due to microtopography. The flooded portion of the basin had lower dissolved oxygen, lower oxidation-reduction potential (ORP) and higher pH, as did lower elevation areas throughout the entire basin. Similarly, soil pore water concentrations of organic carbon and aromatic compounds were higher in flooded and low elevation areas. Dissolved ferric iron (Fe(III)) concentrations were higher in low elevation areas and responded to the flooding treatment in low areas, only. The high concentrations of soluble Fe(III) in soil pore water were explained by the presence of siderophores, which were much more concentrated in low elevation areas. All the aforementioned variables were correlated, showing that Fe(III) is solubilized in response to anoxic conditions. Dissolved carbon dioxide (CO2) and methane (CH4) concentrations were higher in low elevation areas, but showed only subtle and/or seasonally dependent effects of flooding. In anaerobic laboratory incubations, more CH4 was produced by soils from low and flooded areas, whereas anaerobic CO2

  10. Linear Accelerators

    NASA Astrophysics Data System (ADS)

    Sidorin, Anatoly

    2010-01-01

    In linear accelerators the particles are accelerated by either electrostatic fields or oscillating Radio Frequency (RF) fields. Accordingly the linear accelerators are divided in three large groups: electrostatic, induction and RF accelerators. Overview of the different types of accelerators is given. Stability of longitudinal and transverse motion in the RF linear accelerators is briefly discussed. The methods of beam focusing in linacs are described.

  11. Linear Accelerators

    SciTech Connect

    Sidorin, Anatoly

    2010-01-05

    In linear accelerators the particles are accelerated by either electrostatic fields or oscillating Radio Frequency (RF) fields. Accordingly the linear accelerators are divided in three large groups: electrostatic, induction and RF accelerators. Overview of the different types of accelerators is given. Stability of longitudinal and transverse motion in the RF linear accelerators is briefly discussed. The methods of beam focusing in linacs are described.

  12. Engineered antifouling microtopographies - effect of feature size, geometry, and roughness on settlement of zoospores of the green alga Ulva.

    PubMed

    Schumacher, James F; Carman, Michelle L; Estes, Thomas G; Feinberg, Adam W; Wilson, Leslie H; Callow, Maureen E; Callow, James A; Finlay, John A; Brennan, Anthony B

    2007-01-01

    The effect of feature size, geometry, and roughness on the settlement of zoospores of the ship fouling alga Ulva was evaluated using engineered microtopographies in polydimethylsiloxane elastomer. The topographies studied were designed at a feature spacing of 2 microm and all significantly reduced spore settlement compared to a smooth surface. An indirect correlation between spore settlement and a newly described engineered roughness index (ERI) was identified. ERI is a dimensionless ratio based on Wenzel's roughness factor, depressed surface fraction, and the degree of freedom of spore movement. Uniform surfaces of either 2 mum diameter circular pillars (ERI=5.0) or 2 microm wide ridges (ERI=6.1) reduced settlement by 36% and 31%, respectively. A novel multi-feature topography consisting of 2 mum diameter circular pillars and 10 microm equilateral triangles (ERI=8.7) reduced spore settlement by 58%. The largest reduction in spore settlement, 77%, was obtained with the Sharklet AF topography (ERI=9.5).

  13. Microtopography and antifouling properties of the shell surface of the bivalve molluscs Mytilus galloprovincialis and Pinctada imbricata.

    PubMed

    Scardino, Andrew; De Nys, Rocky; Ison, Odette; O'Connor, Wayne; Steinberg, Peter

    2003-04-01

    Biofouling rapidly covers most submerged surfaces in the marine environment. However, some marine organisms remain clean despite strong fouling pressure. Potential physical inhibitors of fouling were investigated by comparing the thickness, cover, and microtopographic structure of the periostracum of two bivalve molluscs, the blue mussel, Mytilus galloprovincialis, and the pearl oyster, Pinctada imbricata. The cover and thickness of the periostracum were measured on four size classes of each species using histological and microscopic techniques. The periostracum of M. galloprovincialis was significantly thicker than that of P. imbricata and did not differ significantly between size classes. In contrast, the periostracum of P. imbricata decreased significantly with increasing size in both thickness and cover. The microtopography of the shell surface of both species was measured using atomic force microscopy (AFM) and scanning electron microscopy (SEM), which revealed a homogeneous ridged surface for M. galloprovincialis with a uniform distance of 1-2 microns between ridges with a mean depth of 1.5 microns. P. imbricata had a heterogeneous surface structure without a repeating structural pattern. To compare the potential antifouling properties of the shell surface the four size classes of both species were tested in fourteen-week field exposure trials. M. galloprovincialis was rarely fouled over the trial period with less than 10% of M. galloprovincialis shell across all size classes being fouled. In contrast, P. imbricata had significantly higher levels of fouling. Both the proportion of P. imbricata shells fouled and the density of fouling organisms were positively correlated with the age of the shell and the amount of intact periostracum. The relationship between the shell surface microtopography and the intensity of fouling is discussed.

  14. Microtopography-Guided Conductive Patterns of Liquid-Driven Graphene Nanoplatelet Networks for Stretchable and Skin-Conformal Sensor Array.

    PubMed

    Park, Youngjin; Shim, Jongwon; Jeong, Suyeon; Yi, Gi-Ra; Chae, Heeyeop; Bae, Jong Wook; Kim, Sang Ouk; Pang, Changhyun

    2017-06-01

    Flexible thin-film sensors have been developed for practical uses in invasive or noninvasive cost-effective healthcare devices, which requires high sensitivity, stretchability, biocompatibility, skin/organ-conformity, and often transparency. Graphene nanoplatelets can be spontaneously assembled into transparent and conductive ultrathin coatings on micropatterned surfaces or planar substrates via a convective Marangoni force in a highly controlled manner. Based on this versatile graphene assembled film preparation, a thin, stretchable and skin-conformal sensor array (144 pixels) is fabricated having microtopography-guided, graphene-based, conductive patterns embedded without any complicated processes. The electrically controlled sensor array for mapping spatial distributions (144 pixels) shows high sensitivity (maximum gauge factor ≈1697), skin-like stretchability (<48%), high cyclic stability or durability (over 10(5) cycles), and the signal amplification (≈5.25 times) via structure-assisted intimate-contacts between the device and rough skin. Furthermore, given the thin-film programmable architecture and mechanical deformability of the sensor, a human skin-conformal sensor is demonstrated with a wireless transmitter for expeditious diagnosis of cardiovascular and cardiac illnesses, which is capable of monitoring various amplified pulse-waveforms and evolved into a mechanical/thermal-sensitive electric rubber-balloon and an electronic blood-vessel. The microtopography-guided and self-assembled conductive patterns offer highly promising methodology and tool for next-generation biomedical devices and various flexible/stretchable (wearable) devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Multifunctional Coatings to Simultaneously Promote Osseointegration and Prevent Infection of Orthopaedic Implants

    PubMed Central

    Raphel, Jordan; Holodniy, Mark; Goodman, Stuart B.; Heilshorn, Sarah C.

    2016-01-01

    The two leading causes of failure for joint arthroplasty prostheses are aseptic loosening and periprosthetic joint infection. With the number of primary and revision joint replacement surgeries on the rise, strategies to mitigate these failure modes have become increasingly important. Much of the recent work in this field has focused on the design of coatings either to prevent infection while ignoring bone mineralization or vice versa, to promote osseointegration while ignoring microbial susceptibility. However, both coating functions are required to achieve long-term success of the implant; therefore, these two modalities must be evaluated in parallel during the development of new orthopaedic coating strategies. In this review, we discuss recent progress and future directions for the design of multifunctional orthopaedic coatings that can inhibit microbial cells while still promoting osseointegration. PMID:26851394

  16. Biomaterial strategies for engineering implants for enhanced osseointegration and bone repair

    PubMed Central

    Agarwal, Rachit; García, Andrés J.

    2015-01-01

    Bone tissue has a remarkable ability to regenerate and heal itself. However, large bone defects and complex fractures still present a significant challenge to the medical community. Current treatments center on metal implants for structural and mechanical support and auto- or allo-grafts to substitute long bone defects. Metal implants are associated with several complications such as implant loosening and infections. Bone grafts suffer from donor site morbidity, reduced bioactivity, and risk of pathogen transmission. Surgical implants can be modified to provide vital biological cues, growth factors and cells in order to improve osseointegration and repair of bone defects. Here we review strategies and technologies to engineer metal surfaces to promote osseointegration with the host tissue. We also discuss strategies for modifying implants for cell adhesion and bone growth via integrin signaling and growth factor and cytokine delivery for bone defect repair. PMID:25861724

  17. Long-term outcomes of osseointegrated digital prostheses for proximal amputations.

    PubMed

    Sierakowski, A; Watts, C; Thomas, K; Elliot, D

    2011-02-01

    This paper presents outcomes after 13, 4, and 3½ years in three digital amputees treated with osseointegrated prostheses. One had prosthetic replacement of the index and middle fingers at the PIP level. The second had four fingers replaced at the PIP level, but only three prostheses were retained. The third had a thumb replacement at the MCP level. All patients scored their reconstructed hand highly in terms of appearance and frequency of use. The first and third patients rated the function of the reconstructed hand as similar to the normal hand, and this was confirmed by the Jebsen Test, but the second patient had poor function. All patients could detect pressure and vibration through their prostheses, although grip and pinch strengths were weaker in all three. All three also experienced some pain in the implanted fingers. This study identifies osseointegration as a stable long-term reconstructive option.

  18. Biomaterial strategies for engineering implants for enhanced osseointegration and bone repair.

    PubMed

    Agarwal, Rachit; García, Andrés J

    2015-11-01

    Bone tissue has a remarkable ability to regenerate and heal itself. However, large bone defects and complex fractures still present a significant challenge to the medical community. Current treatments center on metal implants for structural and mechanical support and auto- or allo-grafts to substitute long bone defects. Metal implants are associated with several complications such as implant loosening and infections. Bone grafts suffer from donor site morbidity, reduced bioactivity, and risk of pathogen transmission. Surgical implants can be modified to provide vital biological cues, growth factors and cells in order to improve osseointegration and repair of bone defects. Here we review strategies and technologies to engineer metal surfaces to promote osseointegration with the host tissue. We also discuss strategies for modifying implants for cell adhesion and bone growth via integrin signaling and growth factor and cytokine delivery for bone defect repair.

  19. A strontium-incorporated nanoporous titanium implant surface for rapid osseointegration

    NASA Astrophysics Data System (ADS)

    Zhang, Wenjie; Cao, Huiliang; Zhang, Xiaochen; Li, Guanglong; Chang, Qing; Zhao, Jun; Qiao, Yuqin; Ding, Xun; Yang, Guangzheng; Liu, Xuanyong; Jiang, Xinquan

    2016-02-01

    Rapid osseointegration of dental implants will shorten the period of treatment and enhance the comfort of patients. Due to the vital role of angiogenesis played during bone development and regeneration, it might be feasible to promote rapid osseointegration by modifying the implant surface to gain a combined angiogenesis/osteogenesis inducing capacity. In this study, a novel coating (MAO-Sr) with strontium-incorporated nanoporous structures on titanium implants was generated via a new micro-arc oxidation, in an attempt to induce angiogenesis and osteogenesis to enhance rapid osseointegration. In vitro, the nanoporous structure significantly enhanced the initial adhesion of canine BMSCs. More importantly, sustained release of strontium ions also displayed a stronger effect on the BMSCs in facilitating their osteogenic differentiation and promoting the angiogenic growth factor secretion to recruit endothelial cells and promote blood vessel formation. Advanced mechanism analyses indicated that MAPK/Erk and PI3K/Akt signaling pathways were involved in these effects of the MAO-Sr coating. Finally, in the canine dental implantation study, the MAO-Sr coating induced faster bone formation within the initial six weeks and the osseointegration effect was comparable to that of the commercially available ITI implants. These results suggest that the MAO-Sr coating has the potential for future use in dental implants.Rapid osseointegration of dental implants will shorten the period of treatment and enhance the comfort of patients. Due to the vital role of angiogenesis played during bone development and regeneration, it might be feasible to promote rapid osseointegration by modifying the implant surface to gain a combined angiogenesis/osteogenesis inducing capacity. In this study, a novel coating (MAO-Sr) with strontium-incorporated nanoporous structures on titanium implants was generated via a new micro-arc oxidation, in an attempt to induce angiogenesis and osteogenesis to

  20. Osseointegration of nanohydroxyapatite- or nano-calcium silicate-incorporated polyetheretherketone bioactive composites in vivo.

    PubMed

    Ma, Rui; Yu, Zhifeng; Tang, Songchao; Pan, Yongkang; Wei, Jie; Tang, Tingting

    Polyetheretherketone (PEEK) exhibits appropriate biomechanical strength as well as good biocompatibility and stable chemical properties but lacks bioactivity and cannot achieve highly efficient osseointegration after implantation. Incorporating bioceramics into the PEEK matrix is a feasible approach for improving its bioactivity. In this study, nanohydroxyapatite (n-HA) and nano-calcium silicate (n-CS) were separately incorporated into PEEK to prepare n-HA/PEEK and n-CS/PEEK biocomposites, respectively, using a compounding and injection-molding technique, and the in vitro degradation characteristics were evaluated. Discs with a diameter of 8 mm were inserted in 8 mm full-thickness cranial defects in rabbits for 4 and 8 weeks, and implantation of pure PEEK was used as the control. Three-dimensional microcomputed tomography, histological analysis, fluorescence microscopy of new bone formation, and scanning electron microscopy were used to evaluate the osseointegration performance at the bone/implant interface. The results of the in vitro degradation study demonstrated that degradation of n-CS on the surface of n-CS/PEEK could release Ca and Si ions and form a porous structure. In vivo tests revealed that both n-CS/PEEK and n-HA/PEEK promoted osseointegration at the bone/implant interface compared to PEEK, and n-CS/PEEK exhibited higher bone contact ratio and more new bone formation compared with those of n-HA/PEEK, implying that n-CS/PEEK possessed a stronger ability to promote osseointegration. These two PEEK biocomposites are promising materials for the preparation of orthopedic or craniofacial implants.

  1. Dental Implant Macro-Design Features Can Impact the Dynamics of Osseointegration.

    PubMed

    Vivan Cardoso, Marcio; Vandamme, Katleen; Chaudhari, Amol; De Rycker, Judith; Van Meerbeek, Bart; Naert, Ignace; Duyck, Joke

    2015-08-01

    The purpose of this study was to compare the clinical performance of two dental implant types possessing a different macro-design in the in vivo pig model. Titanium Aadva(TM) implants (GC, Tokyo, Japan) were compared with OsseoSpeed(TM) implants (Astra, Mölndal, Sweden), with the Aadva implant displaying significant larger inter-thread dimensions than the OsseoSpeed implant. Implants were installed in the parietal bone of 12 domestic pigs and left for healing for either 1 or 3 months. Implant osseointegration was evaluated by quantitative histology (bone volume relative to the tissue volume [BV/TV]; bone-to-implant contact [BIC]) for distinct implant regions (collar, body, total implant length) with specific implant thread features. The Wilcoxon-Mann-Whitney nonparametric test with α = 0.05 was performed. An inferior amount of bone enveloping the Aadva implant compared with the OsseoSpeed implant was observed, in particular at the implant body part with its considerable inter-thread gaps (p < .05). Concomitantly, the Aadva macro-design negatively affected the amount of bone in direct contact with the implant for this specific implant part (p < .05), and resulted in an overall impaired implant osseointegration at the initial healing stage (total implant length; 1-month healing; p < .05). Although the Aadva implant displayed a clinically acceptable level of osseointegration, the findings demonstrate that implant macro-design features can impact the dynamics of implant osseointegration. Consideration of specific implant macro-design features should be made relative to the biological and mechanical microenvironment. © 2013 Wiley Periodicals, Inc.

  2. Titanium Implant Osseointegration Problems with Alternate Solutions Using Epoxy/Carbon-Fiber-Reinforced Composite.

    PubMed

    Petersen, Richard C

    2014-12-01

    The aim of the article is to present recent developments in material research with bisphenyl-polymer/carbon-fiber-reinforced composite that have produced highly influential results toward improving upon current titanium bone implant clinical osseointegration success. Titanium is now the standard intra-oral tooth root/bone implant material with biocompatible interface relationships that confer potential osseointegration. Titanium produces a TiO2 oxide surface layer reactively that can provide chemical bonding through various electron interactions as a possible explanation for biocompatibility. Nevertheless, titanium alloy implants produce corrosion particles and fail by mechanisms generally related to surface interaction on bone to promote an inflammation with fibrous aseptic loosening or infection that can require implant removal. Further, lowered oxygen concentrations from poor vasculature at a foreign metal surface interface promote a build-up of host-cell-related electrons as free radicals and proton acid that can encourage infection and inflammation to greatly influence implant failure. To provide improved osseointegration many different coating processes and alternate polymer matrix composite (PMC) solutions have been considered that supply new designing potential to possibly overcome problems with titanium bone implants. Now for important consideration, PMCs have decisive biofunctional fabrication possibilities while maintaining mechanical properties from addition of high-strengthening varied fiber-reinforcement and complex fillers/additives to include hydroxyapatite or antimicrobial incorporation through thermoset polymers that cure at low temperatures. Topics/issues reviewed in this manuscript include titanium corrosion, implant infection, coatings and the new epoxy/carbon-fiber implant results discussing osseointegration with biocompatibility related to nonpolar molecular attractions with secondary bonding, carbon fiber in vivo properties, electrical

  3. Titanium Implant Osseointegration Problems with Alternate Solutions Using Epoxy/Carbon-Fiber-Reinforced Composite

    PubMed Central

    Petersen, Richard C.

    2014-01-01

    The aim of the article is to present recent developments in material research with bisphenyl-polymer/carbon-fiber-reinforced composite that have produced highly influential results toward improving upon current titanium bone implant clinical osseointegration success. Titanium is now the standard intra-oral tooth root/bone implant material with biocompatible interface relationships that confer potential osseointegration. Titanium produces a TiO2 oxide surface layer reactively that can provide chemical bonding through various electron interactions as a possible explanation for biocompatibility. Nevertheless, titanium alloy implants produce corrosion particles and fail by mechanisms generally related to surface interaction on bone to promote an inflammation with fibrous aseptic loosening or infection that can require implant removal. Further, lowered oxygen concentrations from poor vasculature at a foreign metal surface interface promote a build-up of host-cell-related electrons as free radicals and proton acid that can encourage infection and inflammation to greatly influence implant failure. To provide improved osseointegration many different coating processes and alternate polymer matrix composite (PMC) solutions have been considered that supply new designing potential to possibly overcome problems with titanium bone implants. Now for important consideration, PMCs have decisive biofunctional fabrication possibilities while maintaining mechanical properties from addition of high-strengthening varied fiber-reinforcement and complex fillers/additives to include hydroxyapatite or antimicrobial incorporation through thermoset polymers that cure at low temperatures. Topics/issues reviewed in this manuscript include titanium corrosion, implant infection, coatings and the new epoxy/carbon-fiber implant results discussing osseointegration with biocompatibility related to nonpolar molecular attractions with secondary bonding, carbon fiber in vivo properties, electrical

  4. Engineered PlyCB as a Novel Implant Coating for Osseointegration

    DTIC Science & Technology

    2012-03-01

    The lack of osseointegration is the primary cause of implant failure or shortened lifespan under physiological loads. Coatings such as hydroxyapatite ...the mineral component of bone, are often used to promote integration of bone with implant. However, hydroxyapatite coatings do not contain any...protein, was found to have a particularly high affinity for hydroxyapatite (Nelson, 2006). Based on the crystal structure, we plan to introduce mutants

  5. [Osseointegrated endosseous implants, University of Liège concepts. Various clinical applications].

    PubMed

    Lahmouzi, J; Simain, F; Legrand, R

    1998-04-01

    Based on fundamental experimental studies performed by the research teams of Professor Bränemark (Göteborg, Sweden), the use of dental implants has become a scientifically accepted treatment concept in Dentistry to replace lost or missing teeth in fully and partially edentulous patients. The use of dental implants was initiated by the discovery that dental implants made of titanium can be anchored in the jawbone with direct bone contact (osseointegration).

  6. Osseointegration of nanohydroxyapatite- or nano-calcium silicate-incorporated polyetheretherketone bioactive composites in vivo

    PubMed Central

    Ma, Rui; Yu, Zhifeng; Tang, Songchao; Pan, Yongkang; Wei, Jie; Tang, Tingting

    2016-01-01

    Polyetheretherketone (PEEK) exhibits appropriate biomechanical strength as well as good biocompatibility and stable chemical properties but lacks bioactivity and cannot achieve highly efficient osseointegration after implantation. Incorporating bioceramics into the PEEK matrix is a feasible approach for improving its bioactivity. In this study, nanohydroxyapatite (n-HA) and nano-calcium silicate (n-CS) were separately incorporated into PEEK to prepare n-HA/PEEK and n-CS/PEEK biocomposites, respectively, using a compounding and injection-molding technique, and the in vitro degradation characteristics were evaluated. Discs with a diameter of 8 mm were inserted in 8 mm full-thickness cranial defects in rabbits for 4 and 8 weeks, and implantation of pure PEEK was used as the control. Three-dimensional microcomputed tomography, histological analysis, fluorescence microscopy of new bone formation, and scanning electron microscopy were used to evaluate the osseointegration performance at the bone/implant interface. The results of the in vitro degradation study demonstrated that degradation of n-CS on the surface of n-CS/PEEK could release Ca and Si ions and form a porous structure. In vivo tests revealed that both n-CS/PEEK and n-HA/PEEK promoted osseointegration at the bone/implant interface compared to PEEK, and n-CS/PEEK exhibited higher bone contact ratio and more new bone formation compared with those of n-HA/PEEK, implying that n-CS/PEEK possessed a stronger ability to promote osseointegration. These two PEEK biocomposites are promising materials for the preparation of orthopedic or craniofacial implants. PMID:27881916

  7. Effect of TiO2 nanotubes arrays on osseointegration of orthodontic miniscrew.

    PubMed

    Jang, Insan; Shim, Seong-Cheol; Choi, Dong-Soon; Cha, Bong-Kuen; Lee, Jae-Kwan; Choe, Byung-Hak; Choi, Won-Youl

    2015-08-01

    To increase the stability of orthodontic miniscrews, TiO2 nanotube arrays were fabricated on the surface of Ti miniscrews and the effect of those arrays on the osseointegration of miniscrews was evaluated. Highly ordered TiO2 nanotube arrays were grown on the surface of orthodontic miniscrews. Ethylene glycol based electrolyte was used in the anodic oxidation process. Two-step anodic oxidation was conducted to obtain clean and open windows in TiO2 nanotube arrays. The diameter and length of the TiO2 nanotube arrays were ~ 70 nm and ~ 5 μm, respectively. The miniscrews with TiO2 nanotube arrays were implanted in the legs of New Zealand white rabbits for 8 weeks. Histological osseointegration was assessed by bone-to-implant contact ratio, and three-dimensional bone volume ratio was measured by micro-computed tomography analysis. The miniscrews with TiO2 nanotube arrays had a greater mean bone-to-implant contact ratio of 52.8 % than the control, 29.3 %. Mean bone volume ratio (BV/TV) was also higher in the miniscrews with TiO2 nanotube arrays, at 81.2 % than those in the control via micro-CT analysis. Our findings support that TiO2 nanotube arrays on the surface of miniscrews enhance osseointegration and improve the stability of the miniscrew.

  8. A comparative study of zirconium and titanium implants in rat: osseointegration and bone material quality.

    PubMed

    Hoerth, Rebecca M; Katunar, María R; Gomez Sanchez, Andrea; Orellano, Juan C; Ceré, Silvia M; Wagermaier, Wolfgang; Ballarre, Josefina

    2014-02-01

    Permanent metal implants are widely used in human medical treatments and orthopedics, for example as hip joint replacements. They are commonly made of titanium alloys and beyond the optimization of this established material, it is also essential to explore alternative implant materials in view of improved osseointegration. The aim of our study was to characterize the implant performance of zirconium in comparison to titanium implants. Zirconium implants have been characterized in a previous study concerning material properties and surface characteristics in vitro, such as oxide layer thickness and surface roughness. In the present study, we compare bone material quality around zirconium and titanium implants in terms of osseointegration and therefore characterized bone material properties in a rat model using a multi-method approach. We used light and electron microscopy, micro Raman spectroscopy, micro X-ray fluorescence and X-ray scattering techniques to investigate the osseointegration in terms of compositional and structural properties of the newly formed bone. Regarding the mineralization level, the mineral composition, and the alignment and order of the mineral particles, our results show that the maturity of the newly formed bone after 8 weeks of implantation is already very high. In conclusion, the bone material quality obtained for zirconium implants is at least as good as for titanium. It seems that the zirconium implants can be a good candidate for using as permanent metal prosthesis for orthopedic treatments.

  9. Negative effects of alcohol intake and estrogen deficiency combination on osseointegration in a rat model.

    PubMed

    de Deco, Camila Porto; da Silva Marchini, Adriana Mathias Pereira; Bárbara, Mary Anne Moreira; de Vasconcellos, Luana Marotta Reis; da Rocha, Rosilene Fernandes; Marchini, Leonardo

    2011-12-01

    Alcohol intake and estrogen deficiency can both affect bone physiology and have shown to have an adverse effect on dental implant therapy. However, the combination of both factors on osseointegration is unknown. The aim of this study was to evaluate osseointegration in rats fed with alcohol and presenting induced estrogen deficiency. Ninety-six female rats were divided according to diet and hormonal condition into 6 groups as follows: group Sh-W: sham (simulated ovariectomy) control, food and water ad libitum; group Sh-Et: sham, food and 20% ethanol solution ad libitum; group Sh-Su: sham, food and sucrose solution controlled to ensure an isocaloric diet in relation to Sh-Et; group Ov-W: ovariectomy, food and water ad libitum; group Ov-Et: ovariectomy, food and 20% ethanol solution ad libitum; and group Ov-Su: ovariectomy, food and sucrose solution controlled to ensure an isocaloric diet as Ov-Et. The groups were subdivided according to time of euthanasia: 30 and 45 days after placement of implants. Implant surgery was performed 1 month after ovariectomy or sham. After euthanasia, the femurs were removed and evaluated by histomorphometry. Groups Ov-Et and Ov-Su showed the lowest percentage of bone-to-implant contact. The combination of alcohol intake and estrogen deficiency, and the combination of estrogen deficiency and reduced ingestion of food can negatively affect osseointegration in rats.

  10. Chitosan/siCkip-1 biofunctionalized titanium implant for improved osseointegration in the osteoporotic condition

    PubMed Central

    Zhang, Li; Wu, Kaimin; Song, Wen; Xu, Haiyan; An, Ran; Zhao, Lingzhou; Liu, Bin; Zhang, Yumei

    2015-01-01

    Biofunctionalization with siRNA targeting the key negative modulators of bone turnover involved in the molecular mechanism of osteoporosis, such as casein kinase-2 interacting protein-1 (Ckip-1), may lead to enhanced Ti osseointegration in the osteoporotic condition. In this study, even siRNA loading was accomplished by the thermal alkali (TA) treatment to make the Ti ultrahydrophilic and negatively charged to facilitate the physical adsorption of the positively charged CS/siR complex, designated as TA-CS/siR. The intracellular uptake of the CS/siR complex and the gene knockdown efficiency were assessed with bone marrow mesenchymal stem cells (MSCs) as well as the green fluorescent protein (GFP) expressing H1299 cells. In vitro osteogenic activity of TA-CS/siCkip-1 targeting Ckip-1 was assessed with MSCs. In vivo osseointegration of TA-CS/siCkip-1 was assessed in the osteoporotic rat model. TA-CS/siR showed excellent siRNA delivery efficiency and gene silencing effect. TA-CS/siCkip-1 significantly improved the in vitro osteogenic differentiation of MSCs in terms of the enhanced alkaline phosphatase and collagen product and extracellular matrix mineralization, and led to dramatically enhanced in vivo osseointegration in the osteoporostic rat model, showing promising clinical potential for the osteoporotic condition application. TA-CS/siR may constitute a general approach for developing the advanced Ti implants targeting specific molecular mechanism. PMID:26040545

  11. In vivo osseointegration of Ti implants with a strontium-containing nanotubular coating

    PubMed Central

    Dang, Yonggang; Zhang, Li; Song, Wen; Chang, Bei; Han, Tianxiao; Zhang, Yumei; Zhao, Lingzhou

    2016-01-01

    Novel biomedical titanium (Ti) implants with high osteogenic ability for fast and good osseointegration under normal as well as osteoporotic conditions are urgently needed. Expanding on our previous in vitro results, we hypothesized that nanotubular, strontium-loaded (NT-Sr) structures on Ti implants would have favorable osteogenic effects and evaluated the in vivo osseointegration of these implants in rats. The structures with nanotubes of different diameters were fabricated by electrochemical anodization at 10 and 40 V, and the amounts of Sr loaded were adjusted by using two hydrothermal treatment times of 1 and 3 hours. Qualitative microcomputed tomography in two and three dimensions showed that the NT-Sr formed with an anodization voltage of 10 V and hydrothermal treatment time of 3 hours best supported bone growth in vivo. Histomorphometric examination of osseointegration also showed that more newly formed bone was found at its surface. The bone–implant contact percentage was highest (92.48%±0.76%) at 12 weeks. In conclusion, the NT-Sr formed with an anodization voltage of 10 V and hydrothermal treatment time of 3 hours showed excellent osteogenic properties, making it an attractive option for Ti surface modification with considerable clinical potential. PMID:27042055

  12. Improving oral implant osseointegration in a murine model via Wnt signal amplification

    PubMed Central

    Mouraret, Sylvain; Hunter, Daniel J.; Bardet, Claire; Popelut, Antoine; Brunski, John B.; Chaussain, Catherine; Bouchard, Philippe; Helms, Jill A.

    2016-01-01

    Aim To determine the key biological events occurring during implant failure and then we use this knowledge to develop new biology-based strategies that improve osseointegration. Materials and Methods Wild-type and Axin2LacZ/LacZ adult male mice underwent oral implant placement, with and without primary stability. Peri-implant tissues were evaluated using histology, alkaline phosphatase (ALP) activity, tartrate resistant acid phosphatase (TRAP) activity and TUNEL staining. In addition, mineralization sites, collagenous matrix organization and the expression of bone markers in the peri-implant tissues were assessed. Results Maxillary implants lacking primary stability show histological evidence of persistent fibrous encapsulation and mobility, which recapitulates the clinical problems of implant failure. Despite histological and molecular evidence of fibrous encapsulation, osteoblasts in the gap interface exhibit robust ALP activity. This mineralization activity is counteracted by osteoclast activity that resorbs any new bony matrix and consequently, the fibrous encapsulation remains. Using a genetic mouse model, we show that implants lacking primary stability undergo osseointegration, provided that Wnt signalling is amplified. Conclusions In a mouse model of oral implant failure caused by a lack of primary stability, we find evidence of active mineralization. This mineralization, however, is outpaced by robust bone resorption, which culminates in persistent fibrous encapsulation of the implant. Fibrous encapsulation can be prevented and osseointegration assured if Wnt signalling is elevated at the time of implant placement. PMID:24164629

  13. FGF23 neutralization improves bone quality and osseointegration of titanium implants in chronic kidney disease mice

    PubMed Central

    Sun, Ningyuan; Guo, Yuchen; Liu, Weiqing; Densmore, Michael; Shalhoub, Victoria; Erben, Reinhold G.; Ye, Ling; Lanske, Beate; Yuan, Quan

    2015-01-01

    Chronic kidney disease (CKD) is a worldwide health problem. Serum levels of FGF23, a phosphaturic hormone, increase at the earliest stages of CKD, and have been found to be independently associated with the mortality and morbidity of CKD patients. The purpose of this study was to evaluate whether FGF23 neutralization was able to improve bone quality and osseointegration of titanium implants. Uremia was induced by 5/6 nephrectomy in adult female mice. Postsurgery, the mice were injected with vehicle or FGF23 neutralizing antibody (5 mg/kg body weight) 3 times a week. Experimental titanium implants were inserted in the distal end of the femurs. FGF23 neutralization significantly increased serum phosphate, 1,25(OH)2D and BUN, and decreased serum PTH and FGF23, relative to vehicle-treated CKD mice. Histomorphometric analysis of the tibiae indicated that FGF23 neutralization normalized the osteoidosis observed in vehicle-treated CKD mice. Although bone-implant contact ratio remained unchanged by anti-FGF23 antibody treatment, the strength of osseointegration, as evidenced by a biomechanical push-in test, was significantly improved by FGF23 neutralization. Our findings revealed that FGF23 neutralization effectively improves bone quality and osseointegration of titanium implants in CKD mice, suggesting FGF23 as a key factor of CKD related bone diseases. PMID:25665715

  14. Evaluating the osseointegration of nanostructured titanium implants in animal models: Current experimental methods and perspectives (Review).

    PubMed

    Babuska, Vaclav; Moztarzadeh, Omid; Kubikova, Tereza; Moztarzadeh, Amin; Hrusak, Daniel; Tonar, Zbynek

    2016-09-15

    The aim of this paper is to review the experimental methods currently being used to evaluate the osseointegration of nanostructured titanium implants using animal models. The material modifications are linked to the biocompatibility of various types of oral implants, such as laser-treated, acid-etched, plasma-coated, and sand-blasted surface modifications. The types of implants are reviewed according to their implantation site (endoosseous, subperiosteal, and transosseous implants). The animal species and target bones used in experimental implantology are carefully compared in terms of the ratio of compact to spongy bone. The surgical technique in animal experiments is briefly described, and all phases of the histological evaluation of osseointegration are described in detail, including harvesting tissue samples, processing undemineralized ground sections, and qualitative and quantitative histological assessment of the bone-implant interface. The results of histological staining methods used in implantology are illustrated and compared. A standardized and reproducible technique for stereological quantification of bone-implant contact is proposed and demonstrated. In conclusion, histological evaluation of the experimental osseointegration of dental implants requires careful selection of the experimental animals, bones, and implantation sites. It is also advisable to use larger animal models and older animals with a slower growth rate rather than small or growing experimental animals. Bones with a similar ratio of compact to spongy bone, such as the human maxilla and mandible, are preferred. A number of practical recommendations for the experimental procedures, harvesting of samples, tissue processing, and quantitative histological evaluations are provided.

  15. Surface thermal oxidation on titanium implants to enhance osteogenic activity and in vivo osseointegration

    NASA Astrophysics Data System (ADS)

    Wang, Guifang; Li, Jinhua; Lv, Kaige; Zhang, Wenjie; Ding, Xun; Yang, Guangzheng; Liu, Xuanyong; Jiang, Xinquan

    2016-08-01

    Thermal oxidation, which serves as a low-cost, effective and relatively simple/facile method, was used to modify a micro-structured titanium surface in ambient atmosphere at 450 °C for different time periods to improve in vitro and in vivo bioactivity. The surface morphology, crystallinity of the surface layers, chemical composition and chemical states were evaluated by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Cell behaviours including cell adhesion, attachment, proliferation, and osteogenic differentiation were observed in vitro study. The ability of the titanium surface to promote osseointegration was evaluated in an in vivo animal model. Surface thermal oxidation on titanium implants maintained the microstructure and, thus, both slightly changed the nanoscale structure of titanium and enhanced the crystallinity of the titanium surface layer. Cells cultured on the three oxidized titanium surfaces grew well and exhibited better osteogenic activity than did the control samples. The in vivo bone-implant contact also showed enhanced osseointegration after several hours of oxidization. This heat-treated titanium enhanced the osteogenic differentiation activity of rBMMSCs and improved osseointegration in vivo, suggesting that surface thermal oxidation could potentially be used in clinical applications to improve bone-implant integration.

  16. Implant Osseointegration and the Role of Microroughness and Nanostructures: Lessons for Spine Implants

    PubMed Central

    Gittens, Rolando A.; Olivares-Navarrete, Rene; Schwartz, Zvi; Boyan, Barbara D.

    2014-01-01

    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 surface structure, on osseointegration, drawing examples from other implantology fields when required. Our findings revealed that surface properties such as micro-roughness and nanostructures can directly affect early cell behavior and long-term osseointegration. Micro-roughness 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 micro-rough surfaces. Still, long-term clinical results are necessary to establish the full implications of surface nanomodifications. PMID:24721613

  17. Surface thermal oxidation on titanium implants to enhance osteogenic activity and in vivo osseointegration

    PubMed Central

    Wang, Guifang; Li, Jinhua; Lv, Kaige; Zhang, Wenjie; Ding, Xun; Yang, Guangzheng; Liu, Xuanyong; Jiang, Xinquan

    2016-01-01

    Thermal oxidation, which serves as a low-cost, effective and relatively simple/facile method, was used to modify a micro-structured titanium surface in ambient atmosphere at 450 °C for different time periods to improve in vitro and in vivo bioactivity. The surface morphology, crystallinity of the surface layers, chemical composition and chemical states were evaluated by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Cell behaviours including cell adhesion, attachment, proliferation, and osteogenic differentiation were observed in vitro study. The ability of the titanium surface to promote osseointegration was evaluated in an in vivo animal model. Surface thermal oxidation on titanium implants maintained the microstructure and, thus, both slightly changed the nanoscale structure of titanium and enhanced the crystallinity of the titanium surface layer. Cells cultured on the three oxidized titanium surfaces grew well and exhibited better osteogenic activity than did the control samples. The in vivo bone-implant contact also showed enhanced osseointegration after several hours of oxidization. This heat-treated titanium enhanced the osteogenic differentiation activity of rBMMSCs and improved osseointegration in vivo, suggesting that surface thermal oxidation could potentially be used in clinical applications to improve bone-implant integration. PMID:27546196

  18. Improvements in hip- and pelvic motion for patients with osseointegrated trans-femoral prostheses.

    PubMed

    Tranberg, R; Zügner, R; Kärrholm, J

    2011-02-01

    This study describes the changes in hip and pelvic kinematics in 19 trans-femoral amputees, who were treated with an osseointegrated trans-femoral prosthesis. Patients were studied with 3-dimensional gait analysis, walking with socket prosthesis within two days before the osseointergration procedure. The post-operative gait analysis was carried out at the 2 year follow-up visit. Fifty-seven; age-, side- and gender-matched healthy subjects served as controls. Post-operative data showed that patients who had an osseointegrated transfemoral prosthesis increased their hip extension by 7.3° (p=0.007), changing from -2.6° (range -13.4° to 10.7°) to -9.9° (range -29.4° to 5°). Moreover, the pre-operative anterior pelvic tilt was reduced by 4.0° (p=0.016), changing from 21.7° (range 11.9-34.8°) to 17.7° (range 5.5-25.7°). Values for hip extension and pelvic tilt changed toward those of controls. These results confirm that patients treated with osseointegrated trans-femoral prosthesis encounter significant changes of their kinematic pattern in terms of hip extension and anterior pelvic tilt. Even though the changes were moderate they may, in the long-term have a positive influence on low-back biomechanics and could contribute to reducing the risk of further problems with low back pain.

  19. In vivo osseointegration of Ti implants with a strontium-containing nanotubular coating.

    PubMed

    Dang, Yonggang; Zhang, Li; Song, Wen; Chang, Bei; Han, Tianxiao; Zhang, Yumei; Zhao, Lingzhou

    2016-01-01

    Novel biomedical titanium (Ti) implants with high osteogenic ability for fast and good osseointegration under normal as well as osteoporotic conditions are urgently needed. Expanding on our previous in vitro results, we hypothesized that nanotubular, strontium-loaded (NT-Sr) structures on Ti implants would have favorable osteogenic effects and evaluated the in vivo osseointegration of these implants in rats. The structures with nanotubes of different diameters were fabricated by electrochemical anodization at 10 and 40 V, and the amounts of Sr loaded were adjusted by using two hydrothermal treatment times of 1 and 3 hours. Qualitative microcomputed tomography in two and three dimensions showed that the NT-Sr formed with an anodization voltage of 10 V and hydrothermal treatment time of 3 hours best supported bone growth in vivo. Histomorphometric examination of osseointegration also showed that more newly formed bone was found at its surface. The bone-implant contact percentage was highest (92.48%±0.76%) at 12 weeks. In conclusion, the NT-Sr formed with an anodization voltage of 10 V and hydrothermal treatment time of 3 hours showed excellent osteogenic properties, making it an attractive option for Ti surface modification with considerable clinical potential.

  20. Implant osseointegration and the role of microroughness and nanostructures: lessons for spine implants.

    PubMed

    Gittens, Rolando A; Olivares-Navarrete, Rene; Schwartz, Zvi; Boyan, Barbara D

    2014-08-01

    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.

  1. Plasma Surface Functionalized Polyetheretherketone for Enhanced Osseo-Integration at Bone-Implant Interface.

    PubMed

    Zhao, Ying; Wong, Hoi Man; Lui, So Ching; Chong, Eva Y W; Wu, Guosong; Zhao, Xiaoli; Wang, Chong; Pan, Haobo; Cheung, Kenneth M C; Wu, Shuilin; Chu, Paul K; Yeung, Kelvin W K

    2016-02-17

    This study aims at improving osseo-integration at the bone-implant interface of polyetheretherketone (PEEK) by water (H2O) and ammonia (NH3) plasma immersion ion implantation (PIII). The pertinent surface characteristics including surface energy, roughness, morphology, and chemical composition are investigated systematically and the in vitro biological performance is evaluated by cell adhesion and proliferation, alkaline phosphatase (ALP) activity, real-time RT-PCR evaluation, and mineralization tests. In vivo osseo-integration is examined via implanting samples into the distal femur of the rats. The hydrophilicity, surface roughness, cell adhesion, and proliferation, ALP activity, and osteogenic differentiation after H2O PIII or NH3 PIII are improved significantly. Furthermore, substantially enhanced osseo-integration is achieved in vivo. Nonline-of-sight plasma surface functionalization, which is particularly suitable for biomedical implants with an irregular geometry, does not alter the bulk compressive yield strength and elastic modulus of the materials. Consequently, the favorable bulk attributes of PEEK are preserved while the surface biological properties are enhanced thus boding well for wider orthopedic application of the biopolymer.

  2. FGF23 neutralization improves bone quality and osseointegration of titanium implants in chronic kidney disease mice.

    PubMed

    Sun, Ningyuan; Guo, Yuchen; Liu, Weiqing; Densmore, Michael; Shalhoub, Victoria; Erben, Reinhold G; Ye, Ling; Lanske, Beate; Yuan, Quan

    2015-02-10

    Chronic kidney disease (CKD) is a worldwide health problem. Serum levels of FGF23, a phosphaturic hormone, increase at the earliest stages of CKD, and have been found to be independently associated with the mortality and morbidity of CKD patients. The purpose of this study was to evaluate whether FGF23 neutralization was able to improve bone quality and osseointegration of titanium implants. Uremia was induced by 5/6 nephrectomy in adult female mice. Postsurgery, the mice were injected with vehicle or FGF23 neutralizing antibody (5 mg/kg body weight) 3 times a week. Experimental titanium implants were inserted in the distal end of the femurs. FGF23 neutralization significantly increased serum phosphate, 1,25(OH)2D and BUN, and decreased serum PTH and FGF23, relative to vehicle-treated CKD mice. Histomorphometric analysis of the tibiae indicated that FGF23 neutralization normalized the osteoidosis observed in vehicle-treated CKD mice. Although bone-implant contact ratio remained unchanged by anti-FGF23 antibody treatment, the strength of osseointegration, as evidenced by a biomechanical push-in test, was significantly improved by FGF23 neutralization. Our findings revealed that FGF23 neutralization effectively improves bone quality and osseointegration of titanium implants in CKD mice, suggesting FGF23 as a key factor of CKD related bone diseases.

  3. Numerical investigations on the osseointegration of uncemented endoprostheses based on bio-active interface theory

    NASA Astrophysics Data System (ADS)

    Lutz, André; Nackenhorst, Udo

    2012-09-01

    In order to simulate the osseointegration of bone implants, a bio-active interface theory is necessary. The thin bone-implant interface layer is described by the Drucker-Prager plasticity model. The formulation of bone mineral density depends on the local mechanical environment. For the simulation of the osseointegration of bone implants a bio-active interface theory is suggested. A thin bone-implant interface layer is described by a Drucker-Prager plasticity model. An evolution rule for the bone mineral density is formulated in dependency of the local mechanical environment. The time dependent ingrowth is modeled by a hardening rule which modifies the Drucker-Prager yield-surface cone in the principle stress state in dependency of the local bone mineral density. The osseointegration process is limited by the violation of a so called micromotion threshold. This relative motion in the implant-bone interface is computed by dynamic loads of daily motion activity. For parameter studies on detailed 3D models model reduction techniques are introduced. The applicability is demonstrated on a hip-joint prosthesis which is in clinical usage.

  4. Development of a porous 3D graphene-PDMS scaffold for improved osseointegration.

    PubMed

    Li, Jianfeng; Liu, Xiao; Crook, Jeremy M; Wallace, Gordon G

    2017-08-01

    Osseointegration in orthopedic surgery plays an important role for bone implantation success. Traditional treatment of implant surface aimed at improved osseointegration has limited capability for its poor performance in supporting cell growth and proliferation. Polydimethylsiloxane (PDMS) is a widely used silicon-based organic polymer material with properties that are useful in cosmetics, domestic applications and mechanical engineering. In addition, the biocompatibility of PDMS, in part due to the high solubility of oxygen, makes it an ideal material for cell-based implants. Notwithstanding its potential, a property that can inhibit PDMS bioactivity is the high hydrophobicity, limiting its use to date in tissue engineering. Here, we describe an efficient approach to produce porous, durable and cytocompatible PDMS-based 3D structures, coated with reduced graphene oxide (RGO). The RGO/PDMS scaffold has good mechanical strength and with pore sizes ranging from 10 to 600μm. Importantly, the scaffold is able to support growth and differentiation of human adipose stem cells (ADSCs) to an osteogenic cell lineage, indicative of its potential as a transition structure of an osseointegrated implant. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. In vivo osseointegration of dental implants with an antimicrobial peptide coating.

    PubMed

    Chen, X; Zhou, X C; Liu, S; Wu, R F; Aparicio, C; Wu, J Y

    2017-05-01

    This study aimed to evaluate the in vivo osseointegration of implants with hydrophobic antimicrobial GL13K-peptide coating in rabbit femoral condyles by micro-CT and histological analysis. Six male Japanese Rabbits (4 months old and weighing 2.5 kg each) were included in this study. Twelve implants (3.75 mm wide, 7 mm long) were randomly distributed in two groups, with six implants in the experimental group coated with GL13K peptide and six implants in the control group without surface coating. Each implant in the test and the control group was randomly implanted in the left or right side of femoral condyles. On one side randomly-selected of the femur, each rabbit received a drill that was left without implant as control for the natural healing of bone. After 3 weeks of healing radiographic evaluation of the implant sites was taken. After 6 weeks of healing, rabbits were sacrificed for evaluation of the short-term osseointegration of the dental implants using digital radiography, micro-CT and histology analysis. To perform evaluation of osseointegration, implant location and group was double blinded for surgeon and histology/radiology researcher. Two rabbits died of wound infection in sites with non-coated implants 2 weeks after surgery. Thus, at least four rabbits per group survived after 6 weeks of healing. The wounds healed without suppuration and inflammation. No implant was loose after 6 weeks of healing. Radiography observations showed good osseointegration after 3 and 6 weeks postoperatively, which proved that the tissues followed a natural healing process. Micro-CT reconstruction and analysis showed that there was no statistically significant difference (P > 0.05) in volume of bone around the implant between implants coated with GL13K peptide and implants without coating. Histomorphometric analysis also showed that the mineralized bone area was no statistically different (P > 0.05) between implants coated with GL13K peptide and

  6. Can Accelerators Accelerate Learning?

    NASA Astrophysics Data System (ADS)

    Santos, A. C. F.; Fonseca, P.; Coelho, L. F. S.

    2009-03-01

    The 'Young Talented' education program developed by the Brazilian State Funding Agency (FAPERJ) [1] makes it possible for high-schools students from public high schools to perform activities in scientific laboratories. In the Atomic and Molecular Physics Laboratory at Federal University of Rio de Janeiro (UFRJ), the students are confronted with modern research tools like the 1.7 MV ion accelerator. Being a user-friendly machine, the accelerator is easily manageable by the students, who can perform simple hands-on activities, stimulating interest in physics, and getting the students close to modern laboratory techniques.

  7. Can Accelerators Accelerate Learning?

    SciTech Connect

    Santos, A. C. F.; Fonseca, P.; Coelho, L. F. S.

    2009-03-10

    The 'Young Talented' education program developed by the Brazilian State Funding Agency (FAPERJ)[1] makes it possible for high-schools students from public high schools to perform activities in scientific laboratories. In the Atomic and Molecular Physics Laboratory at Federal University of Rio de Janeiro (UFRJ), the students are confronted with modern research tools like the 1.7 MV ion accelerator. Being a user-friendly machine, the accelerator is easily manageable by the students, who can perform simple hands-on activities, stimulating interest in physics, and getting the students close to modern laboratory techniques.

  8. PARTICLE ACCELERATOR

    DOEpatents

    Teng, L.C.

    1960-01-19

    ABS>A combination of two accelerators, a cyclotron and a ring-shaped accelerator which has a portion disposed tangentially to the cyclotron, is described. Means are provided to transfer particles from the cyclotron to the ring accelerator including a magnetic deflector within the cyclotron, a magnetic shield between the ring accelerator and the cyclotron, and a magnetic inflector within the ring accelerator.

  9. Nocturnal Near-Surface Temperature, but not Flow Dynamics, can be Predicted by Microtopography in a Mid-Range Mountain Valley

    NASA Astrophysics Data System (ADS)

    Pfister, Lena; Sigmund, Armin; Olesch, Johannes; Thomas, Christoph K.

    2017-07-01

    We investigate nocturnal flow dynamics and temperature behaviour near the surface of a 170-m long gentle slope in a mid-range mountain valley. In contrast to many existing studies focusing on locations with significant topographic variations, gentle slopes cover a greater spatial extent of the Earth's surface. Air temperatures were measured using the high-resolution distributed-temperature-sensing method within a two-dimensional fibre-optic array in the lowest metre above the surface. The main objectives are to characterize the spatio-temporal patterns in the near-surface temperature and flow dynamics, and quantify their responses to the microtopography and land cover. For the duration of the experiment, including even clear-sky nights with weak winds and strong radiative forcing, the classical cold-air drainage predicted by theory could not be detected. In contrast, we show that the airflow for the two dominant flow modes originates non-locally. The most abundant flow mode is characterized by vertically-decoupled layers featuring a near-surface flow perpendicular to the slope and strong stable stratification, which contradicts the expectation of a gravity-driven downslope flow of locally produced cold air. Differences in microtopography and land cover clearly affect spatio-temporal temperature perturbations. The second most abundant flow mode is characterized by strong mixing, leading to vertical coupling with airflow directed down the local slope. Here variations of microtopography and land cover lead to negligible near-surface temperature perturbations. We conclude that spatio-temporal temperature perturbations, but not flow dynamics, can be predicted by microtopography, which complicates the prediction of advective-heat components and the existence and dynamics of cold-air pools in gently sloped terrain in the absence of observations.

  10. Enhancement of biodegradation and osseointegration of poly(ε-caprolactone)/calcium phosphate ceramic composite screws for osteofixation using calcium sulfate.

    PubMed

    Wu, Chang-Chin; Hsu, Li-Ho; Tsai, Yuh-Feng; Sumi, Shoichiro; Yang, Kai-Chiang

    2016-04-04

    Internal fixation devices, which can stabilize and realign fractured bone, are widely used in fracture management. In this paper, a biodegradable composite fixator, composed of poly(ε-caprolactone), calcium phosphate ceramic and calcium sulfate (PCL/CPC/CS), is developed. The composition of CS, which has a high dissolution rate, was expected to create a porous structure to improve osteofixation to the composite fixator. PCL, PCL/CPC, and PCL/CPC/CS samples were prepared and their physical properties were characterized in vitro. In vivo performance of the composite screws was verified in the distal femurs of rabbits. Results showed that the PCL/CPC/CS composite had a higher compressive strength (28.55 ± 3.32 MPa) in comparison with that of PCL (20.64 ± 1.81 MPa) (p < 0.05). A larger amount of apatite was formed on PCL/CPC/CS than on PCL/CPC, while no apatite was found on PCL after simulated body fluid immersion. In addition, PCL/CPC/CS composites also had a faster in vitro degradation rate (13.05 ± 3.42% in weight loss) relative to PCL (1.79 ± 0.23%) and PCL/CPC (4.32 ± 2.18%) (p < 0.001). In animal studies, PCL/CPC/CS screws showed a greater volume loss than that of PCL or PCL/CPC at 24 weeks post-implantation. Under micro-computerized tomography observation, animals with PCL/CPC/CS implants had better osseointegration in terms of the structural parameters of the distal metaphysis, including trabecular number, trabecular spacing, and connectivity density, than the PCL screw. This study reveals that the addition of CS accelerates the biodegradation and enhanced apatite formation of the PCL/CPC composite screw. This osteoconductive PCL/CPC/CS is a good candidate material for internal fixation devices.

  11. Influence of diamond wheel grinding process on surface micro-topography and properties of SiO2/SiO2 composite

    NASA Astrophysics Data System (ADS)

    Cao, Xiaoyan; Lin, Bin; Wang, Yan; Wang, Shaolei

    2014-02-01

    According to anisotropic and inhomogeneous structure of fiber-reinforced ceramic matrix composites (FRCMC), it is difficult to control the surface quality with the traditional method used in metal material. The present paper studies the influence of diamond wheel grinding process on surface micro-topography and properties of SiO2/SiO2 composite. The research is based on some new discovery that the material enhanced fiber orientations play a key role in micro-topography of FRCMC grinding surface. Through a series of experiments, we investigate the relationship between grinding process and the quality of composites surface. We also analyze characteristics of the material surface topography height, wave distribution and surface support properties in details. This paper employs the orthogonal design to optimize grinding process parameters and also successfully models a critical condition to modify the surface characteristics. The results show that speed of grinding wheel has the greatest influence on height and surface support properties, the next is grain mesh size and depth of cut. The grain mesh size is the key factor for surface micro-topography modification. Compared to the surface with woven texture, the modified surface has better symmetrical characteristic. The research obtained will be an important technical support on improving the processing quality of FRCMC.

  12. Biofunctionalization strategies on tantalum-based materials for osseointegrative applications.

    PubMed

    Mas-Moruno, Carlos; Garrido, Beatriz; Rodriguez, Daniel; Ruperez, Elisa; Gil, F Javier

    2015-02-01

    The use of tantalum as biomaterial for orthopedic applications is gaining considerable attention in the clinical practice because it presents an excellent chemical stability, body fluid resistance, biocompatibility, and it is more osteoconductive than titanium or cobalt-chromium alloys. Nonetheless, metallic biomaterials are commonly bioinert and may not provide fast and long-lasting interactions with surrounding tissues. The use of short cell adhesive peptides derived from the extracellular matrix has shown to improve cell adhesion and accelerate the implant's biointegration in vivo. However, this strategy has been rarely applied to tantalum materials. In this work, we have studied two immobilization strategies (physical adsorption and covalent binding via silanization) to functionalize tantalum surfaces with a cell adhesive RGD peptide. Surfaces were used untreated or activated with either HNO3 or UV/ozone treatments. The process of biofunctionalization was characterized by means of physicochemical and biological methods. Physisorption of the RGD peptide on control and HNO3-treated tantalum surfaces significantly enhanced the attachment and spreading of osteoblast-like cells; however, no effect on cell adhesion was observed in ozone-treated samples. This effect was attributed to the inefficient binding of the peptide on these highly hydrophilic surfaces, as evidenced by contact angle measurements and X-ray photoelectron spectroscopy. In contrast, activation of tantalum with UV/ozone proved to be the most efficient method to support silanization and subsequent peptide attachment, displaying the highest values of cell adhesion. This study demonstrates that both physical adsorption and silanization are feasible methods to immobilize peptides onto tantalum-based materials, providing them with superior bioactivity.

  13. Decontamination of titanium implant surface and re-osseointegration to treat peri-implantitis: a literature review.

    PubMed

    Subramani, Karthikeyan; Wismeijer, Daniel

    2012-01-01

    To review the literature on decontamination of titanium implant surfaces following peri-implantitis and the effect of various cleaning methods on re-osseointegration. An electronic search of the literature at PubMed was conducted on the studies published between 1966 and October 2010. In vitro, animal, and clinical studies were included. Of 597 studies retrieved, 74 manuscripts were selected for the review. Various implant surface decontamination methods using various chemical and mechanical agents have been suggested for treatment and re-osseointegration following periimplantitis. It has been shown that re-osseointegration of contaminated implant surfaces is possible; this largely depends upon the surface of the implant and the types of decontamination techniques and bone regenerative materials used. Complete re-osseointegration cannot be achieved by surface decontamination alone. Titanium implants with titanium plasma-sprayed or sandblasted and acid-etched surfaces may be effectively decontaminated by applying chlorhexidine and saline-soaked gauze or by repeated rinsing with these solutions. Both mechanical and chemical decontamination techniques should be applied alongside regenerative surgical procedures to obtain optimum re-osseointegration and successfully treat peri-implantitis. In recent years, lasers and photodynamic therapy have shown minor beneficial results, which need to be confirmed by long-term clinical studies with comparable groups.

  14. Immobilized nerve growth factor and microtopography have distinct effects on polarization versus axon elongation in hippocampal cells in culture.

    PubMed

    Gomez, Natalia; Lu, Yi; Chen, Shaochen; Schmidt, Christine E

    2007-01-01

    Cell interfacing with biomaterial surfaces dictates important aspects of cell behavior. In particular, axon extension in neurons is effectively influenced by surface properties, both for the initial formation of an axon as well as for the maintenance of axon growth. Here, we investigated how neurons behaved on poly(dimethyl siloxane) (PDMS) surfaces decorated with biochemical and physical cues presented individually or in combination. In particular, nerve growth factor (NGF) was covalently tethered to PDMS to create a bioactive surface, and microtopography was introduced to the material in the form of microchannels. Embryonic hippocampal neurons were used to investigate the impact of these surface cues on polarization (i.e., axon initiation or axogenesis) and overall axon length. We found that topography had a more pronounced effect on polarization (68% increase over controls) compared to immobilized NGF (0.1 ng/mm(2)) (27% increase). However, the effect of NGF was negligible when both types of stimuli were simultaneously presented on the biomaterial surface. In addition to axon formation, chemical and physical cues are also involved in axon growth following the initiation process. Interestingly, for the same studies described above, the effects of microchannels and NGF were opposite from the effects on polarization; the most evident effect was for the immobilized growth factor (10% increase in axon length with respect to controls) whereas there was no effect in general for the microtopography. More importantly, when the two surface stimuli were presented in combination, a synergistic increase in axon length was detected (25% increase with respect to controls), which could be a result of faster polarization triggered by topography plus enhanced growth from NGF. Additionally, axon orientation was also analyzed and we found the well-known tendency of perpendicular or parallel axonal alignment to be dependent on the width and depth of the channels. This investigation

  15. How Often Does Spindle Failure Occur in Compressive Osseointegration Endoprostheses for Oncologic Reconstruction?

    PubMed

    Goldman, Lauren H; Morse, Lee J; O'Donnell, Richard J; Wustrack, Rosanna L

    2016-07-01

    Compressive osseointegration is a promising modality for limb salvage in distal femoral oncologic tumors. However, few studies have explored short-term survival rates in a large patient cohort of distal femur compressive endoprostheses or highlighted the risk factors for spindle failures. We asked: (1) What is the frequency of compressive osseointegration spindle failure in distal femoral reconstructions? (2) What are the characteristics of rotational failure cases with distal femur compressive osseointegration endoprostheses? (3) What are the risk factors for mechanical and rotational failure of distal femur compressive osseointegration implantation? (4) What are other modalities of failure or causes of revision surgery, which affect patients undergoing distal femur compressive osseointegration implantation for oncologic reconstruction? Between 1996 and 2013, 127 distal femoral reconstructions with the Compress(®) prosthesis were performed in 121 patients. During that time, 116 Compress(®) prostheses were implanted for aggressive primary tumors of the distal femur and/or failure of previous oncologic reconstruction. This approach represented approximately 91% of the distal femoral reconstructions performed during that time. Of the patients with prostheses implanted, four patients (four of 116, 3%) had died, and 37 (37 of 116, 32%) were lost to followup before 24 months. The median followup was 84 months (range, 24-198 months), and 71 patients (66% of all patients) were seen within the last 3 years. A retrospective chart review was performed to determine failure modality as defined by radiographs, clinical history, and intraoperative findings. Risk factors including age, sex, BMI, resection length, and perioperative chemotherapy were analyzed to determine effect on spindle and rotational failure rates. Survival analysis was determined using the Kaplan-Meier estimator. Differences in survival between groups were analyzed using the log rank test. Risk factors were

  16. Basis of bone metabolism around dental implants during osseointegration and peri-implant bone loss.

    PubMed

    Insua, Angel; Monje, Alberto; Wang, Hom-Lay; Miron, Richard J

    2017-07-01

    Despite the growing number of publications in the field of implant dentistry, there are limited studies to date investigating the biology and metabolism of bone healing around dental implants and their implications in peri-implant marginal bone loss. The aim of this review article is to provide a thorough understanding of the biological events taking place during osseointegration and the subsequent early and late phases of bone remodeling around dental implants. An update on the coupling mechanism occurring during bone resorption-bone remodeling is provided, focused on the relevance of the osteocytes, bone lining cells and immune cells during bone maintenance. An electronic and manual literature search was conducted by three independent reviewers in several databases, including MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Oral Health Group Trials Register databases for articles up to September 2016 with no language restriction. Local bone metabolism is subject to signals from systemic calcium-phosphate homeostasis and bone remodeling. Three areas of interest were reviewed due to recent reported compromises in bone healing including the putative effects of (1) cholesterol, (2) hyperlipidemia, and (3) low vitamin D intake. Moreover, the prominent influence of osteocytes and immune cells is discussed as being key regulators during dental implant osseointegration and maintenance. These cells are of crucial importance in the presence of biofilm accumulation and their associated byproducts that leads to hard and soft tissue breakdown; the so called peri-implantitis. Factors that could negatively impact osteoclastogenesis or osteal macrophage activation should be monitored in future research including implant placement/torque protocols, bone characteristics, as well as meticulous maintenance programs to favor osseointegration and future long-term stability and success of dental implants. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res

  17. Systemic intermittent parathyroid hormone treatment improves osseointegration of press-fit inserted implants in cancellous bone

    PubMed Central

    2012-01-01

    Background and purpose Intermittent administration of parathyroid hormone (PTH) has an anabolic effect on bone, as confirmed in human osteoporosis studies, distraction osteogenesis, and fracture healing. PTH in rat models leads to improved fixation of implants in low-density bone or screw insertion transcortically. Material and methods We examined the effect of human PTH (1–34) on the cancellous osseointegration of unloaded implants inserted press-fit in intact bone of higher animal species. 20 dogs were randomized to treatment with human PTH (1–34), 5 μg/kg/day subcutaneously, or placebo for 4 weeks starting on the day after insertion of a cylindrical porous coated plasma-sprayed titanium alloy implant in the proximal metaphyseal cancellous bone of tibia. Osseointegration was evaluated by histomorphometry and fixation by push-out test to failure. Results Surface fraction of woven bone at the implant interface was statistically significantly higher in the PTH group by 1.4 fold with (median (interquartile range) 15% (13–18)) in the PTH group and 11% (7–13) in control. The fraction of lamellar bone was unaltered. No significant difference in bone or fibrous tissue was observed in the circumferential regions of 0–500, 500–1,000, and 1,000–2,000 μm around the implant. Mechanically, the implants treated with PTH showed no significant differences in total energy absorption, maximum shear stiffness, or maximum shear strength. Interpretation Intermittent treatment with PTH (1–34) improved xhistological osseointegration of a prosthesis inserted press-fit at surgery in cancellous bone, with no additional improvement of the initial mechanical fixation at this time point. PMID:22880714

  18. Experimental study on the osseointegration of foam TiC/Ti composites.

    PubMed

    Jingyu, Wang; Lin, Wu; Yong, Gao; Jinsong, Zhang; Cuicui, Zhang

    2013-08-01

    Macroporous ceramics have demonstrated osteoconductive properties because of their biocompatibility and 3D macroporous structure, and these materials have recently been widely studied as bone replacement materials. The foam TiC/Ti composites discussed in this study have good mechanical properties, balancing out metallic toughness and ceramic strength. Furthermore, because of the high porosity and pore connectivity of these TiC/Ti composites, they have the potential to be a new bone replacement material. The purpose of this study was to evaluate the osseointegration of foam TiC/Ti composites, preliminarily discuss the TiC/Ti ossification mechanism, and to obtain reliable data on the use of foam TiC/Ti composites as bone replacement materials. The foam TiC/Ti composites were sited in 40 Japanese white rabbits for 4, 8, 12 and 24 weeks. The foam TiC/Ti composites were compared to foam SiC. M-CT (micro-computed tomography) analysis, histological analysis, SEM (scanning electron microscopy) observation and EDS (energy-dispersive x-ray spectrometer) analysis were conducted to estimate the osseointegration of the materials. The histological observations and quantitative analysis exhibited significantly more ossification area (volume), trabeculae maturity, and calcium and phosphorus content in the foam TiC/Ti composites compared to the foam SiC (p < 0.05). The results from this study suggest that the foam TiC/Ti composites possess good osseointegration capacity and have the potential to be a new bone replacement material.

  19. Selective serotonin reuptake inhibitors and the risk of osseointegrated implant failure: a cohort study.

    PubMed

    Wu, X; Al-Abedalla, K; Rastikerdar, E; Abi Nader, S; Daniel, N G; Nicolau, B; Tamimi, F

    2014-11-01

    Selective serotonin reuptake inhibitors (SSRIs), the most widely used drugs for the treatment of depression, have been reported to reduce bone formation and increase the risk of bone fracture. Since osseointegration is influenced by bone metabolism, this study aimed to investigate the association between SSRIs and the risk of failures in osseointegrated implants. This retrospective cohort study was conducted on patients treated with dental implants from January 2007 to January 2013. A total of 916 dental implants in 490 patients (94 implants on 51 patients using SSRIs) were used to estimate the risk of failure associated with the use of SSRIs. Data analysis involved Cox proportional hazards, generalized estimating equation models, multilevel mixed effects parametric survival analysis, and Kaplan-Meier analysis. After 3 to 67 mo of follow-up, 38 dental implants failed and 784 succeeded in the nonusers group, while 10 failed and 84 succeeded in the SSRI-users group. The main limitation of this retrospective study was that drug compliance dose and treatment period could not be acquired from the files of the patients. The primary outcome was that compared with nonusers of SSRIs, SSRI usage was associated with an increased risk of dental implants failure (hazard ratio, 6.28; 95% confidence interval, 1.25-31.61; p = .03). The failure rates were 4.6% for SSRI nonusers and 10.6% for SSRI users. The secondary outcomes were that small implant diameters (≤4 mm; p = .02) and smoking habits (p = .01) also seemed to be associated with higher risk of implant failure. Our findings indicate that treatment with SSRIs is associated with an increased failure risk of osseointegrated implants, which might suggest a careful surgical treatment planning for SSRI users. © International & American Associations for Dental Research.

  20. Selective Serotonin Reuptake Inhibitors and the Risk of Osseointegrated Implant Failure

    PubMed Central

    Wu, X.; Al-Abedalla, K.; Rastikerdar, E.; Abi Nader, S.; Daniel, N.G.; Nicolau, B.; Tamimi, F.

    2014-01-01

    Selective serotonin reuptake inhibitors (SSRIs), the most widely used drugs for the treatment of depression, have been reported to reduce bone formation and increase the risk of bone fracture. Since osseointegration is influenced by bone metabolism, this study aimed to investigate the association between SSRIs and the risk of failures in osseointegrated implants. This retrospective cohort study was conducted on patients treated with dental implants from January 2007 to January 2013. A total of 916 dental implants in 490 patients (94 implants on 51 patients using SSRIs) were used to estimate the risk of failure associated with the use of SSRIs. Data analysis involved Cox proportional hazards, generalized estimating equation models, multilevel mixed effects parametric survival analysis, and Kaplan-Meier analysis. After 3 to 67 mo of follow-up, 38 dental implants failed and 784 succeeded in the nonusers group, while 10 failed and 84 succeeded in the SSRI-users group. The main limitation of this retrospective study was that drug compliance dose and treatment period could not be acquired from the files of the patients. The primary outcome was that compared with nonusers of SSRIs, SSRI usage was associated with an increased risk of dental implants failure (hazard ratio, 6.28; 95% confidence interval, 1.25-31.61; p = .03). The failure rates were 4.6% for SSRI nonusers and 10.6% for SSRI users. The secondary outcomes were that small implant diameters (≤4 mm; p = .02) and smoking habits (p = .01) also seemed to be associated with higher risk of implant failure. Our findings indicate that treatment with SSRIs is associated with an increased failure risk of osseointegrated implants, which might suggest a careful surgical treatment planning for SSRI users. PMID:25186831

  1. Static load bearing exercises of individuals with transfemoral amputation fitted with an osseointegrated implant: Loading compliance.

    PubMed

    Vertriest, Sofie; Coorevits, Pascal; Hagberg, Kerstin; Brånemark, Rickard; Häggström, Eva Elisabet; Vanderstraeten, Guy; Frossard, Laurent Alain

    2017-08-01

    Load-bearing exercises are performed by transfemoral amputees fitted with an osseointegrated implant to facilitate bone remodelling. This study presents the loading compliance comparing loads prescribed and applied on the three axes of the implant during static load-bearing exercises with a specific emphasis on axial and vectorial comparisons. Cohort study. A total of 11 fully rehabilitated unilateral transfemoral amputees fitted with an osseointegrated implant performed five trials in four loading conditions using a static standing frame. The load prescribed was monitored using a vertical single-axis strain gauge connected to an electronic display. The tri-axial forces applied on the implant were measured directly with an instrumented pylon including a six-channel transducer. The analysis included 'axial' and 'vectorial' comparisons corresponding to the difference between the force applied on the long axis of the implant and the load prescribed as well as the resultant of the three components of the load applied and the load prescribed, respectively. The results demonstrated that axial and vectorial differences were significant in all conditions ( p < 0.05), except for the vectorial difference for the 40 kg condition ( p = 0.182). The significant lack of axial compliance led to systematic underloading of the long axis of the implant. Clinical relevance This study contributes to a better understanding of the load applied on an osseointegrated implant during the static load-bearing exercises that could contribute to improve the design of apparatus to monitor loading exercises as well as clinical guidelines for the loading progression during rehabilitation.

  2. Raloxifene but not alendronate can compensate the impaired osseointegration in osteoporotic rats.

    PubMed

    Faverani, Leonardo Perez; Polo, Tárik Ocon Braga; Ramalho-Ferreira, Gabriel; Momesso, Gustavo Antonio Correa; Hassumi, Jaqueline Suemi; Rossi, Ana Cláudia; Freire, Alexandre Rodrigues; Prado, Felippe Bevilacqua; Luvizuto, Eloá Rodrigues; Gruber, Reinhard; Okamoto, Roberta

    2017-03-29

    Alendronate and raloxifene, a bisphosphonate and a selective estrogen modulator, respectively, are established osteoporosis therapies. Current evidence suggests that simultaneous application of osteoporosis therapies modulates osseointegration. However, alendronate shows inconsistent findings and raloxifene has not been studied comprehensively. This study aimed to evaluate the bone dynamics and molecular and microstructural features at the peri-implant bone interface in osteoporotic rats. Thirty female rats underwent ovariectomy and were fed a diet low in calcium and phosphate and treated with alendronate or raloxifene for 30 days or underwent fictional ovariectomy surgery (SHAM) prior to implant insertion in the tibia; osteoporosis therapies continued thereafter. After 42 days, peri-implant bone was evaluated by histometric and micro-CT analysis. Fluorochrome incorporation and gene expression was determined to evaluate bone turnover. We report here that alendronate had no impact on bone-to-implant contacts and the mineral apposition rate. The RANKL/OPG ratio and local bone volume, however, were increased compared to the untreated osteoporotic rats. Even though signaling to bone resorption activity through RANKL production was observed in the alendronate group, the blockade of bone resorption activity that occurs in decorrence to alendronate activity took place and resulted in an increase in bone volume. Raloxifene significantly increased osseointegration in osteoporotic rats, as indicated by bone-to-implant contacts, mineral apposition, and local bone volume. Raloxifene, however, had no considerable impact on the RANKL/OPG ratio compared to untreated osteoporotic rats. As expected, the SH group showed higher bone-to-implant contacts and mineral apposition rates than the untreated osteoporotic rats. These findings suggest that raloxifene but not alendronate can compensate for the impaired osseointegration in osteoporotic rats. Regarding the superiority of

  3. Systemic intermittent parathyroid hormone treatment improves osseointegration of press-fit inserted implants in cancellous bone.

    PubMed

    Daugaard, Henrik; Elmengaard, Brian; Andreassen, Troels Torp; Lamberg, Anders; Bechtold, Joan Elisabeth; Soballe, Kjeld

    2012-08-01

    Intermittent administration of parathyroid hormone (PTH) has an anabolic effect on bone, as confirmed in human osteoporosis studies, distraction osteogenesis, and fracture healing. PTH in rat models leads to improved fixation of implants in low-density bone or screw insertion transcortically. We examined the effect of human PTH (1-34) on the cancellous osseointegration of unloaded implants inserted press-fit in intact bone of higher animal species. 20 dogs were randomized to treatment with human PTH (1-34), 5 μg/kg/day subcutaneously, or placebo for 4 weeks starting on the day after insertion of a cylindrical porous coated plasma-sprayed titanium alloy implant in the proximal metaphyseal cancellous bone of tibia. Osseointegration was evaluated by histomorphometry and fixation by push-out test to failure. Surface fraction of woven bone at the implant interface was statistically significantly higher in the PTH group by 1.4 fold with (median (interquartile range) 15% (13-18)) in the PTH group and 11% (7-13) in control. The fraction of lamellar bone was unaltered. No significant difference in bone or fibrous tissue was observed in the circumferential regions of 0-500, 500-1,000, and 1,000-2,000 μm around the implant. Mechanically, the implants treated with PTH showed no significant differences in total energy absorption, maximum shear stiffness, or maximum shear strength. Intermittent treatment with PTH (1-34) improved histological osseointegration of a prosthesis inserted press-fit at surgery in cancellous bone, with no additional improvement of the initial mechanical fixation at this time point.

  4. Enhanced Osseointegration of Hierarchical Micro/Nanotopographic Titanium Fabricated by Microarc Oxidation and Electrochemical Treatment.

    PubMed

    Li, Guanglong; Cao, Huiliang; Zhang, Wenjie; Ding, Xun; Yang, Guangzheng; Qiao, Yuqin; Liu, Xuanyong; Jiang, Xinquan

    2016-02-17

    Rapid osseointegration is recognized as a critical factor in determining the success rate of orthopedic and dental implants. Microarc oxidation (MAO) fabricated titanium oxide coatings with a porous topography have been proven to be a potent approach to enhance osteogenic capacity. Now we report two kinds of new hierarchical coatings with similar micromorphologies but different nanotopographies (i.e., MAO and MAO-AK coatings), and both coatings significantly promote cell attachment and osteogenic differentiation through mediating the integrin β1 signaling pathway. In this study, titanium with a unique hierarchical micro/nanomorphology surface was fabricated by a novel duplex coating process, that is, the first a titanium oxide layer was coated by MAO, and then the coating was electrochemically reduced in alkaline solution (MAO-AK). A series of in vitro stem cell differentiation and in vivo osseointegration experiments were carried out to evaluate the osteogenic capacity of the resulting coatings. In vitro, the initial adhesion of the canine bone marrow stem cells (BMSCs) seeded on the MAO and MAO-AK coatings was significantly enhanced, and cell proliferation was promoted. In addition, the expression levels of osteogenesis-related genes, osteorix, alkaline phosphates (ALP), osteopontin, and osteocalcin, in the canine BMSCs, were all up-regulated after incubation on these coatings, especially on the MAO-AK coating. Also, the in vitro ALP activity and mineralization capacity of canine BMSC cultured on the MAO-AK group was better than that on the MAO group. Furthermore, 6 weeks after insertion of the titanium implants into canine femurs, both the bone formation speed and the bone-implant contact ratio of the MAO-AK group were significantly higher than those of the MAO group. All these results suggest that this duplex coating process is promising for engineering titanium surfaces to promote osseointegration for dental and orthopedic applications.

  5. Analysis of the influence of the macro- and microstructure of dental zirconium implants on osseointegration: a minipig study.

    PubMed

    Mueller, Cornelia Katharina; Solcher, Philipp; Peisker, Andrè; Mtsariashvilli, Maia; Schlegel, Karl Andreas; Hildebrand, Gerhard; Rost, Juergen; Liefeith, Klaus; Chen, Jiang; Schultze-Mosgau, Stefan

    2013-07-01

    It was the aim of this study to analyze the influence of implant design and surface topography on the osseointegration of dental zirconium implants. Six different implant designs were tested in the study. Nine or 10 test implants were inserted in the frontal skull in each of 10 miniature pigs. Biopsies were harvested after 2 and 4 months and subjected to microradiography. No significant differences between titanium and zirconium were found regarding the microradiographically detected bone-implant contact (BIC). Cylindric zirconium implants showed a higher BIC at the 2-month follow-up than conic zirconium implants. Among zirconium implants, those with an intermediate Ra value showed a significantly higher BIC compared with low and high Ra implants 4 months after surgery. Regarding osseointegration, titanium and zirconium showed equal properties. Cylindric implant design and intermediate surface roughness seemed to enhance osseointegration. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Role of primary stability for successful osseointegration of dental implants: Factors of influence and evaluation

    PubMed Central

    Ahmed, Hameeda Bashir; Crespi, Roberto; Romanos, Georgios E.

    2013-01-01

    A secure implant primary (mechanical) stability is positively associated with a successful implant integration and long-term successful clinical outcome. Therefore, it is essential to assess the initial stability at different time-points to ensure a successful osseointegration. The present study critically reviews the factors that may play a role in achieving a successful initial stability in dental implants. Databases were searched from 1983 up to and including October 2013 using different combinations of various keywords. Bone quality and quantity, implant geometry, and surgical technique adopted may significantly influence primary stability and overall success rate of dental implants. PMID:24381734

  7. Analysis of the microtopography of the skin by silicone replicas after repeated exposure to actinic radiation at high altitudes.

    PubMed

    Mazzarello, V; Cametti, M; Leone, G; Iacovelli, P; Ena, P; Leigheb, G

    2001-05-01

    We investigated the superficial microtopography of the normal skin of 11 volunteers (not exposed to sunlight during the last 4 months), before and after sun exposure for 5 days at high altitudes of 2900-4559 m. The experiments were carried out on Mount Rosa in Italy, and cutaneous replicas using silicone resin were taken every day after 7 h of sun exposure. Casts were taken from the forehead, glabella, dorsum nasi, radial side (protected with a cream SPF 9.72) and ulnar side of the back of the hands, the only areas not protected. A total of 422 replicas were metallized with gold-palladium and observed under Zeiss 940A scanning electron microscope. The images were elaborated and analysed on computer with appropriate software supplying geometrical features of cutaneous surface using parameters proposed by Takahashi (1994). A Student's test for paired series was used to analyse the differences before and after 1-5 days of exposure giving uniform and significant data compared with controls. Using cutaneous replicas we demonstrated that repeated exposure of skin to sunlight in a short time elicits temporary defence mechanisms with increased obstruction of cutaneous pores, deepening of primary cutaneous furrows and shallowing of part of the secondary furrows; the two latter alterations are the consequence of reactive oedema.

  8. The effect of substrate microtopography on focal adhesion maturation and actin organization via the RhoA/ROCK pathway.

    PubMed

    Seo, Chang Ho; Furukawa, Katsuko; Montagne, Kevin; Jeong, Heonuk; Ushida, Takashi

    2011-12-01

    Recently, a growing number of reports have reported that micro- or nanoscale topography enhances cellular functions such as cell adhesion and stem cell differentiation, but the mechanisms responsible for this topography-mediated cell behavior are not fully understood. In this study, we examine the underlying processes and mechanisms behind specific topography-mediated cellular functions. Formation of focal adhesions (FA) was studied by culturing cells on different kinds of topographies, including a flat surface and surfaces with a micropatterned topography (2 μm lattice pattern with 3 μm intervals). We found that the formation and maturation of focal adhesions were highly dependent on the topography of the substrate although the shape, morphology and spreading of cells on the different substrates were not significantly affected. Focal adhesion maturation and actin polymerization were also promoted in cells cultured on the micropatterned substrate. These differences in cell adhesion led us to focus on the Rho GTPases, RhoA and downstream pathways since a number of reports have demonstrated that RhoA-activated cells have highly enhanced focal adhesions and actin activation such as polymerization. By inhibiting the Rho-associated kinase (ROCK) and downstream myosin II, we found that the FA formation, actin organization, and FAK phosphorylation were dramatically decreased. The topographical dependency of FA formation was also highly decreased. These results show that the FA formation and actin cytoskeleton organization of cells on the microtopography is regulated by the RhoA/ROCK pathway.

  9. Three-dimensional morphological characterization of the skin surface micro-topography using a skin replica and changes with age.

    PubMed

    Masuda, Y; Oguri, M; Morinaga, T; Hirao, T

    2014-08-01

    Skin surface micro-topography (SSMT), consisting of pores, ridges and furrows, reflects the skin condition and is an important factor determining the aesthetics of the skin. Most previous studies evaluating SSMT have employed two-dimensional image analysis of magnified pictures captured by a video microscope. To improve the accuracy of SSMT analysis, we established a three-dimensional (3D) analysis method for SSMT and developed various parameters including the skin ridge number, and applied the method to study the age-dependent change in skin. Confocal laser scanning microscopy was used for 3D measurement of the surface morphology of silicon replicas taken from the cheek. We then used these data to calculate the parameters that reflect the nature of SSTM including the skin ridge number using originally developed software. Employing a superscription technique, we investigated the variation in SSMT with age for replicas taken from the cheeks of 103 Japanese females (5-85 years old). The skin surface area and roughness, the area of pores, the area, length, depth and width of skin furrows and the number of skin ridges were examined. The surface roughness, the area of pores and the depth of skin furrows increased with age. The area and length of skin furrows and the number of skin ridges decreased with age. The method proposed to analyse SSMT three dimensionally is an effective tool with which to characterize the condition of the skin. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Simulation of Runoff Hydrograph on Soil Surfaces with Different Microtopography Using a Travel Time Method at the Plot Scale.

    PubMed

    Zhao, Longshan; Wu, Faqi

    2015-01-01

    In this study, a simple travel time-based runoff model was proposed to simulate a runoff hydrograph on soil surfaces with different microtopographies. Three main parameters, i.e., rainfall intensity (I), mean flow velocity (vm) and ponding time of depression (tp), were inputted into this model. The soil surface was divided into numerous grid cells, and the flow length of each grid cell (li) was then calculated from a digital elevation model (DEM). The flow velocity in each grid cell (vi) was derived from the upstream flow accumulation area using vm. The total flow travel time through each grid cell to the surface outlet was the sum of the sum of flow travel times along the flow path (i.e., the sum of li/vi) and tp. The runoff rate at the slope outlet for each respective travel time was estimated by finding the sum of the rain rate from all contributing cells for all time intervals. The results show positive agreement between the measured and predicted runoff hydrographs.

  11. Analysis on dynamic mechanical properties and surface micro-topography of alkali-activated concrete under different temperatures

    NASA Astrophysics Data System (ADS)

    Long, Wujian; Wei, Jingjie; Fang, Changle; Xiao, Bingxu

    2017-01-01

    In this paper, with water glass as alkali activator, slag and class F fly-ash based cementing material is mixed to prepare alkali-activated concrete. The dynamic mechanical property and surface micro-topography under different temperature of -50°C-140°C was evaluated by using dynamic mechanical analyzer (DMA+1000) and ESEM technology. DMA results show that when the ambient temperature changes from 28°C to 140°C, the rigidity of alkali-activated concrete increases, but the elastic deformation ability decreases; the temperature increment stimulates surface cracks of concrete to become wider and more, and increases the dissipation factor. When the ambient temperature changes from 28°C to -50°C, the storage modulus and rigidity of alkali-activated concrete increase first, and then decrease. ESEM test results show that the storage modulus will increase, and the dissipation factor will decrease at ordinary temperature. When the temperature increases, the surface cracks become larger, and the strength of material will decrease. Therefore, the material will be damaged, resulting in increased dissipation factor. When the temperature decreases, there is less cracks on the surface of alkali-activated concrete.

  12. Biological Strategies for Improved Osseointegration and Osteoinduction of Porous Metal Orthopedic Implants

    PubMed Central

    Riester, Scott M.; Bonin, Carolina A.; Kremers, Hilal Maradit; Dudakovic, Amel; Kakar, Sanjeev; Cohen, Robert C.; Westendorf, Jennifer J.

    2015-01-01

    The biological interface between an orthopedic implant and the surrounding host tissue may have a dramatic effect upon clinical outcome. Desired effects include bony ingrowth (osseointegration), stimulation of osteogenesis (osteoinduction), increased vascularization, and improved mechanical stability. Implant loosening, fibrous encapsulation, corrosion, infection, and inflammation, as well as physical mismatch may have deleterious clinical effects. This is particularly true of implants used in the reconstruction of load-bearing synovial joints such as the knee, hip, and the shoulder. The surfaces of orthopedic implants have evolved from solid-smooth to roughened-coarse and most recently, to porous in an effort to create a three-dimensional architecture for bone apposition and osseointegration. Total joint surgeries are increasingly performed in younger individuals with a longer life expectancy, and therefore, the postimplantation lifespan of devices must increase commensurately. This review discusses advancements in biomaterials science and cell-based therapies that may further improve orthopedic success rates. We focus on material and biological properties of orthopedic implants fabricated from porous metal and highlight some relevant developments in stem-cell research. We posit that the ideal primary and revision orthopedic load-bearing metal implants are highly porous and may be chemically modified to induce stem cell growth and osteogenic differentiation, while minimizing inflammation and infection. We conclude that integration of new biological, chemical, and mechanical methods is likely to yield more effective strategies to control and modify the implant–bone interface and thereby improve long-term clinical outcomes. PMID:25348836

  13. MicroCT Analysis of Micro-Nano Titanium Implant Surface on the Osseointegration.

    PubMed

    Ban, Jaesam; Kang, Seongsoo; Kim, Jihyun; Lee, Kwangmin; Hyunpil, Lim; Vang, Mongsook; Yang, Hongso; Oh, Gyejeong; Kim, Hyunseung; Hwang, Gabwoon; Jung, Yongho; Lee, Kyungku; Park, Sangwon; Yunl, Kwidug

    2015-01-01

    This study was to investigate the effects of micro-nano titanium implant surface on the osseointegration. A total of 36 screw-shaped implants were used. The implant surfaces were classified into 3 groups (n = 12): machined surface (M group), nanosurface which is nanotube formation on the machined surface (MA group) and nano-micro surface which is nanotube formation on the RBM surface (RA group). Anodic oxidation was performed at a 20 V for 10 min with 1 M H3PO4 and 1.5 wt% HF solutions. The implants were installed on the humerus on 6 beagles. After 4 and 12 weeks, the morphometric analysis with micro CT (skyscan 1172, SKYSCAN, Antwerpen, Belgium) was done. The data were statistically analyzed with two-way ANOVA. Bone mineral density and bone volume were significantly increased depending on time. RA group showed the highest bone mineral density and bone volume at 4 weeks and 12 weeks significantly. It indicated that nano-micro titanium implant surface showed faster and more mature osseointegration.

  14. Clodronate combined with a surfactant (Tween 20) does not improve osseointegration: a rabbit immunohistomorphometric study.

    PubMed

    Berardi, D; Raffaelli, L; Perfetti, G; Paolantonio, M; Trisi, P

    2009-01-01

    Biphosphonates are compounds that inhibit bone reabsorption mediated by osteoclasts or the progression of periodontal disease independent on the host response to pathogenic bacteria that colonize the tooth surface. The use of biphosphonates in oral implantology is still in the experimental stage. The aim of this study is to evaluate the efficacy of a non-aminobiphosphonate combined with a surfactant to increase the ability of the drug to link to the implant and bone surfaces in the development of osseointegration in rabbits. Smooth titanium implants were devised to be used on rabbit femurs. A topical administration of clodronate combined with the surfactant (Tween 20) at different concentrations was made on the implant surface and in the implant site to increase the bone and implant adhesiveness. Placebo was given to the control group. New Zealand rabbits were used and sacrificed by CO2 after 8 weeks from the implantations. A histologic and histomorphometric analysis was carried out. Results did not show significant difference between the tests and the placebo groups. Our data are different from other similar studies obtaining statistically significant differences. These differences could depend on the efficacy of the drug used and on the procedure of application of the drug on the implant. This study demonstrates poor efficacy of clodronate applied topically to the implant and implant site during surgery to increase the percentage of osseointegration in the implant. Further studies using different fixation techniques of the drug may be necessary to confirm the present data.

  15. Histological and three-dimensional evaluation of osseointegration to nanostructured calcium phosphate-coated implants.

    PubMed

    Jimbo, Ryo; Coelho, Paulo G; Vandeweghe, Stefan; Schwartz-Filho, Humberto Osvaldo; Hayashi, Mariko; Ono, Daisuke; Andersson, Martin; Wennerberg, Ann

    2011-12-01

    Nanostructures on implant surfaces have been shown to enhance osseointegration; however, commonly used evaluation techniques are probably not sufficiently sensitive to fully determine the effects of this process. This study aimed to observe the osseointegration properties of nanostructured calcium phosphate (CaP)-coated implants, by using a combination of three-dimensional imaging and conventional histology. Titanium implants were coated with stable CaP nanoparticles using an immersion technique followed by heat treatment. Uncoated implants were used as the control. After topographical and chemical characterizations, implants were inserted into the rabbit femur. After 2 and 4weeks, the samples were retrieved for micro-computed tomography and histomorphometric evaluation. Scanning electron microscopy evaluation indicated that the implant surface was modified at the nanoscale by CaP to obtain surface textured with rod-shaped structures. Relative to the control, the bone-to-implant contact for the CaP-coated implant was significantly higher at 4weeks after the implant surgery. Further, corresponding 3-D images showed active bone formation surrounding the implant. 3-D quantification and 2-D histology demonstrated statistical correlation; moreover, 3-D quantification indicated a statistical decrease in bone density in the non-coated control implant group between 2 and 4weeks after the surgery. The application of 3-D evaluation further clarified the temporal characteristics and biological reaction of implants in bone. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  16. Titanium implants induce expression of matrix metalloproteinases in bone during osseointegration.

    PubMed

    Shubayev, Veronica I; Brånemark, Rickard; Steinauer, Joanne; Myers, Robert R

    2004-01-01

    Implanted pure titanium fixtures are able to completely integrate with bone, in part because of the formation of a strong extracellular matrix (ECM) bond at the titanium-bone interface. In this study, we used a rodent femur model of intramedullary osseointegration to analyze the changes in immunoreactivity of ECM-controlling matrix metalloproteinases (MMPs), tissue inhibitor of metalloproteinase-3 (TIMP-3), and tumor necrosis factor alpha (TNF-alpha) during osseointegration. We observed dramatic increases in MMP-2, MMP-9, MMP-7, TIMP-3, and TNF-alpha in osteocytes, osteoclasts, haversian canals, and the interface matrix in bone ipsilateral to the titanium implant. An increase in TIMP-3, MMP-9, and MMP-7 in hypertrophied chondrocytes and the vascular component of the epiphysial growth plate was also observed in experimental bone. These findings were not seen in contralateral or sham-operated bone, where the titanium fixtures were threaded into the femur and immediately removed. Our data link titanium-induced bone remodeling to changes in expression and distribution of MMPs.

  17. Augmenting the osseointegration of endoprostheses using laser-sintered porous collars: an in vivo study.

    PubMed

    Mumith, A; Coathup, M; Chimutengwende-Gordon, M; Aston, W; Briggs, T; Blunn, G

    2017-02-01

    Massive endoprostheses rely on extra-cortical bone bridging (ECBB) to enhance fixation. The aim of this study was to investigate the role of selective laser sintered (SLS) porous collars in augmenting the osseointegration of these prostheses. The two novel designs of porous SLS collars, one with small pores (Ø700 μm, SP) and one with large pores (Ø1500 μm, LP), were compared in an ovine tibial diaphyseal model. Osseointegration of these collars was compared with that of a clinically used solid, grooved design (G). At six months post-operatively, the ovine tibias were retrieved and underwent radiological and histological analysis. Porous collars provided a significantly greater surface (p < 0.001) for the ingrowth of bone than the standard grooved design. Significantly greater extracortical pedicle formation was seen radiologically around the grooved design (length p = 0.002, thickness p < 0.001, surface area p = 0.002) than around the porous collars. However, the ingrowth of bone occurred from the transection site into the porous structure of both types of collar. A fivefold increase in integration was seen with the SP and a threefold increase in the LP design when compared with G (p < 0.001). SLS porous collars allow the direct ingrowth of more bone and are better than current designs which rely on surface ongrowth and ECBB. Cite this article: Bone Joint J 2017;99-B:276-82. ©2017 The British Editorial Society of Bone & Joint Surgery.

  18. Cell adhesion and in vivo osseointegration of sandblasted/acid etched/anodized dental implants.

    PubMed

    Kim, Mu-Hyon; Park, Kyeongsoon; Choi, Kyung-Hee; Kim, Soo-Hong; Kim, Se Eun; Jeong, Chang-Mo; Huh, Jung-Bo

    2015-05-06

    The authors describe a new type of titanium (Ti) implant as a Modi-anodized (ANO) Ti implant, the surface of which was treated by sandblasting, acid etching (SLA), and anodized techniques. The aim of the present study was to evaluate the adhesion of MG-63 cells to Modi-ANO surface treated Ti in vitro and to investigate its osseointegration characteristics in vivo. Four different types of Ti implants were examined, that is, machined Ti (control), SLA, anodized, and Modi-ANO Ti. In the cell adhesion study, Modi-ANO Ti showed higher initial MG-63 cell adhesion and induced greater filopodia growth than other groups. In vivo study in a beagle model revealed the bone-to-implant contact (BIC) of Modi-ANO Ti (74.20%±10.89%) was much greater than those of machined (33.58%±8.63%), SLA (58.47%±12.89), or ANO Ti (59.62%±18.30%). In conclusion, this study demonstrates that Modi-ANO Ti implants produced by sandblasting, acid etching, and anodizing improve cell adhesion and bone ongrowth as compared with machined, SLA, or ANO Ti implants. These findings suggest that the application of Modi-ANO surface treatment could improve the osseointegration of dental implant.

  19. Improved osseointegration of long-term stored SLA implant by hydrothermal sterilization.

    PubMed

    Shi, Xingling; Xu, Lingli; Violin, Kalan Bastos; Lu, Sheng

    2016-01-01

    The sandblasted, large-grit and acid-etched (SLA) surface is easy to be contaminated during storage and its surface chemical state is usually changed by different sterilization methods. This causes an undesirable increase in surface hydrophobicity and results in osseointegration degradation. To overcome this problem, a low temperature hydrothermal (HT) sterilization method was proposed in this study. Briefly, 4 weeks-stored pure titanium SLA specimens were sterilized using a sealed glass bottle with pure water in an autoclave set at 121 °C for 20 min. Results showed that, stored SLA specimens were superhydrophobic before and after conventional autoclaving, whereas, HT sterilization decontaminated and endowed stored SLA surface with superhydrophilicity. Osteoblast spreading was greatly enhanced, ALP expression was upgraded and bone nodule formation was obviously promoted on HT sterilized specimens compared with autoclaved ones. More bone formation around HT sterilized specimens was observed and HT sterilization increased bonding strength of implant to bone by 95% and 127% after 2 and 4 weeks of healing, respectively. The simple, feasible HT sterilization restored osseointegration of SLA implant while diminishing recontamination as much as possible. Therefore, it is proposed as a standard sterilization method for implant practitioners and researches.

  20. Effects of Calcium Phosphate Nanocrystals on Osseointegration of Titanium Implant in Irradiated Bone

    PubMed Central

    Li, Jun Yuan; Pow, Edmond Ho Nang; Kwong, Dora Lai Wan; Cheung, Lim Kwong

    2015-01-01

    Radiotherapy may compromise the integration of implant and cause implant loss. Implant surface modifications have the possibility of promoting cell attachment, cell growth, and bone formation which ultimately enhance the osseointegration process. The present study aimed to investigate the effects of calcium phosphate nanocrystals on implant osseointegration in irradiated bone. Sixteen rabbits were randomly assigned into control and nano-CaP groups, receiving implants with dual acid-etched surface or dual acid-etched surface discretely deposited of nanoscale calcium-phosphate crystals, respectively. The left leg of all the rabbits received 15 Gy radiation, followed by implants placement one week after. Four animals in each group were sacrificed after 4 and 12 weeks, respectively. Implant stability quotient (ISQ), ratio of bone volume to total volume (BV/TV), bone growth rate, and bone-to-implant contact (BIC) were evaluated. The nano-CaP group showed significantly higher ISQ (week 12, P = 0.031) and bone growth rate (week 6, P = 0.021; week 9, P = 0.001) than that in control group. No significant differences in BV/TV and BIC were found between two groups. Titanium implant surface modified with CaP nanocrystals provides a potential alternative to improve bone healing around implant in irradiated bone. PMID:25685809

  1. Effects of Osseointegration by Bone Morphogenetic Protein-2 on Titanium Implants In Vitro and In Vivo

    PubMed Central

    Teng, Fu-Yuan; Chen, Wen-Cheng; Wang, Yin-Lai; Hung, Chun-Cheng; Tseng, Chun-Chieh

    2016-01-01

    This study designed a biomimetic implant for reducing healing time and achieving early osseointegration to create an active surface. Bone morphogenetic protein-2 (BMP-2) is a strong regulator protein in osteogenic pathways. Due to hardly maintaining BMP-2 biological function and specificity, BMP-2 efficient delivery on implant surfaces is the main challenge for the clinic application. In this study, a novel method for synthesizing functionalized silane film for superior modification with BMP-2 on titanium surfaces is proposed. Three groups were compared with and without BMP-2 on modified titanium surfaces in vitro and in vivo: mechanical grinding; electrochemical modification through potentiostatic anodization (ECH); and sandblasting, alkali heating, and etching (SMART). Cell tests indicated that the ECH and SMART groups with BMP-2 markedly promoted D1 cell activity and differentiation compared with the groups without BMP-2. Moreover, the SMART group with a BMP-2 surface markedly promoted early alkaline phosphatase expression in the D1 cells compared with the other surface groups. Compared with these groups in vivo, SMART silaning with BMP-2 showed superior bone quality and created contact areas between implant and surrounding bones. The SMART group with BMP-2 could promote cell mineralization in vitro and osseointegration in vivo, indicating potential clinical use. PMID:26977141

  2. Acid etching and plasma sterilization fail to improve osseointegration of grit blasted titanium implants.

    PubMed

    Saksø, Mikkel; Jakobsen, Stig S; Saksø, Henrik; Baas, Jørgen; Jakobsen, Thomas; Søballe, Kjeld

    2012-01-01

    Interaction between implant surface and surrounding bone influences implant fixation. We attempted to improve the bone-implant interaction by 1) adding surface micro scale topography by acid etching, and 2) removing surface-adherent pro-inflammatory agents by plasma cleaning. Implant fixation was evaluated by implant osseointegration and biomechanical fixation.The study consisted of two paired animal sub-studies where 10 skeletally mature Labrador dogs were used. Grit blasted titanium alloy implants were inserted press fit in each proximal tibia. In the first study grit blasted implants were compared with acid etched grit blasted implants. In the second study grit blasted implants were compared with acid etched grit blasted implants that were further treated with plasma sterilization. Implant performance was evaluated by histomorphometrical investigation (tissue-to-implant contact, peri-implant tissue density) and mechanical push-out testing after four weeks observation time.Neither acid etching nor plasma sterilization of the grit blasted implants enhanced osseointegration or mechanical fixation in this press-fit canine implant model in a statistically significant manner.

  3. Does HIV infection have an impact upon dental implant osseointegration? A systematic review.

    PubMed

    Ata-Ali, Javier; Ata-Ali, Fadi; Di-Benedetto, Nicolas; Bagán, Leticia; Bagán, José-Vicente

    2015-05-01

    A systematic review is made to determine whether human immunodeficiency virus (HIV) infection has an impact upon dental implant osseointegration. A PubMed (MEDLINE) literature search was made of articles published up until 14 April 2014. The systematic review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA). The quality of the studies included in the review was assessed using the Methodological Index for Nonrandomized Studies (MINORS) and levels of evidence (based on the University of Oxford's Center for Evidence Based Medicine criteria). The combinations of search terms resulted in a list of 132 titles. Nine studies finally met the inclusion criteria and were selected for inclusion in the systematic review. A total of 173 dental implants were placed in 80 patients (135 implants in 56 HIV-positive subjects and 38 implants in 24 HIV-negative patients), and a single loss of dental implant osseointegration was recorded in an HIV-positive patient. Our results suggest that dental implant placement in HIV-positive patients does not increase the dental implant failure rate. Prophylactic antibiotic treatment, the administration of highly active antiretroviral therapy, and control of the CD4+ T lymphocyte counts appear to be the main influencing factors in this respect. Given the few studies included in our systematic review, further prospective studies involving larger sample sizes and longer durations of follow-up are required in order to confirm the results obtained.

  4. [Radiological analysis of osseointegration after implantation of the Zweymüller-Alloclassic total hip system].

    PubMed

    Dohle, J; Becker, W; Braun, M

    2001-01-01

    The purpose of this study was to identify typical radiological patterns of osseointegration following implantation of the Zweymüller-Alloclassic total hip system. The follow-up included the clinical and radiological evaluation of 115 consecutive hips. For each case the screw direction of the cup was calculated individually to fully observe the bony surroundings by properly tilted X-ray beam. After 8.1 years, the Harris hip score was 88.5 points on average. Trabecular condensations leading toward the threads of the cup were observed in 100 cases, underlining the importance of the threads for load transfer. A complete intrusion of the threads into the pelvic bone was not accomplished in 23 cases with marked sclerosis of the acetabulum. The reduced connection, however, did not impair stability or function. The area of the distal stem is characterized by cortical hypertrophy and trabecular condensation of the neighbouring marrow. Linear radiolucencies were frequently observed in Gruen-Zone 1 and 7, in 5 cases extending into zone 2 and 6 without influence on the clinical function of the implant. Material and geometry of the Zweymüller total hip lead to a load transfer through the threads of the cup. The integration of the stem relies on cortical interlocking. Proximal linear radiolucencies do not impair function. The signs of osseointegration around the cup can be fully demonstrated only by a specially tilted X-ray beam at a right angle to the screw direction of the cup.

  5. Evaluating the bending response of two osseointegrated transfemoral implant systems using 3D digital image correlation.

    PubMed

    Thompson, Melanie L; Backman, David; Branemark, Rickard; Mechefske, Chris K

    2011-05-01

    Osseointegrated transfemoral implants have been introduced as a prosthetic solution for above knee amputees. They have shown great promise, providing an alternative for individuals who could not be accommodated by conventional, socket-based prostheses; however, the occurrence of device failures is of concern. In an effort to improve the strength and longevity of the device, a new design has been proposed. This study investigates the mechanical behavior of the new taper-based assembly in comparison to the current hex-based connection for osseointegrated transfemoral implant systems. This was done to better understand the behavior of components under loading, in order to optimize the assembly specifications and improve the useful life of the system. Digital image correlation was used to measure surface strains on two assemblies during static loading in bending. This provided a means to measure deformation over the entire sample and identify critical locations as the assembly was subjected to a series of loading conditions. It provided a means to determine the effects of tightening specifications and connection geometry on the material response and mechanical behavior of the assemblies. Both osseoinegrated assemblies exhibited improved strength and mechanical performance when tightened to a level beyond the current specified tightening torque of 12 N m. This was shown by decreased strain concentration values and improved distribution of tensile strain. Increased tightening torque provides an improved connection between components regardless of design, leading to increased torque retention, decreased peak tensile strain values, and a more gradual, primarily compressive distribution of strains throughout the assembly.

  6. [Transcutaneous osseointegrated prosthesis (TOP) after limb amputation : Status quo and perspectives].

    PubMed

    Willy, Christian; Krettek, Christian

    2017-04-10

    The majority of transfemoral and transtibial amputees can be functionally fitted with conventional suspension sockets; however, due to socket problems using conventional stump care, 60% of the patients have limited function and even in younger patients approximately one sixth are unable to wear the prosthesis daily. After the introduction of transcutaneous osseointegrated prostheses (TOP) the inherent problems of socket-stump care can be avoided for these patients. Against this background this article reviews the recent clinical development of TOP in Sweden, Germany, the Netherlands, Australia and USA currently in nine centers. Unanimously, all groups show that TOP enables physiological weight bearing, improved range of motion in the proximal joint, as well as osseoperceptive sensory feedback and better control of the artificial limb. Likewise, there is agreement that as a rule that there is a clinically less relevant superficial contamination of the stoma. Furthermore, TOP is nowadays also used for transhumeral amputees and after thumb amputation and the development of the indications for this technique are increasing. Future aspects include novel treatment options using implanted intramedullary electrodes allowing permanent and unlimited bidirectional communication with the human body (osseointegrated human-machine gateway). This could possibly realize an innovative form of prosthesis control as well as the combination of TOP and targeted muscle reinnervation (TMR) surgery to create more advanced prosthesis systems for upper and lower extremity amputees.

  7. Osseointegration of Titanium Implants in Onlay of Cerament™, a New Ceramic Bone Substitute

    PubMed Central

    Truedsson, Anna; Wang, Jian-Sheng; Lindberg, Pia; Warfvinge, Gunnar

    2016-01-01

    The purpose was to investigate whether a new biphasic and injectable ceramic bone substitute Cerament™ that rapidly remodels to bone, may contribute to the retention of titanium implant screws during the healing period, and to analyze the pattern of bone formation around titanium implants.Titanium screws were implanted in rat tibiae and embedded with or without Cerament™ on the cortical surface. Torsional resistance was measured after 1 day, and after 6 and 12 weeks. Implant areas without bone substitute were analyzed histologically for comparison. The torsional resistance increased over time as the screws were osseointegrated. There was no difference in resistance between screws embedded in the bone substitute and control screws. The bone apposition was more pronounced on the proximal side of the screw than on the distal side. Cerament™ is capable of conducting bone growth from a cortical bone surface. The newly formed bone in this application does not significantly add to the osseointegrative strength of the implant screw, as measured by torque resistance, during the first 12 weeks. PMID:26751485

  8. Acid Etching and Plasma Sterilization Fail to Improve Osseointegration of Grit Blasted Titanium Implants

    PubMed Central

    Saksø, Mikkel; Jakobsen, Stig S; Saksø, Henrik; Baas, Jørgen; Jakobsen, Thomas; Søballe, Kjeld

    2012-01-01

    Interaction between implant surface and surrounding bone influences implant fixation. We attempted to improve the bone-implant interaction by 1) adding surface micro scale topography by acid etching, and 2) removing surface-adherent pro-inflammatory agents by plasma cleaning. Implant fixation was evaluated by implant osseointegration and biomechanical fixation. The study consisted of two paired animal sub-studies where 10 skeletally mature Labrador dogs were used. Grit blasted titanium alloy implants were inserted press fit in each proximal tibia. In the first study grit blasted implants were compared with acid etched grit blasted implants. In the second study grit blasted implants were compared with acid etched grit blasted implants that were further treated with plasma sterilization. Implant performance was evaluated by histomorphometrical investigation (tissue-to-implant contact, peri-implant tissue density) and mechanical push-out testing after four weeks observation time. Neither acid etching nor plasma sterilization of the grit blasted implants enhanced osseointegration or mechanical fixation in this press-fit canine implant model in a statistically significant manner. PMID:22962567

  9. Effects of Osseointegration by Bone Morphogenetic Protein-2 on Titanium Implants In Vitro and In Vivo.

    PubMed

    Teng, Fu-Yuan; Chen, Wen-Cheng; Wang, Yin-Lai; Hung, Chun-Cheng; Tseng, Chun-Chieh

    2016-01-01

    This study designed a biomimetic implant for reducing healing time and achieving early osseointegration to create an active surface. Bone morphogenetic protein-2 (BMP-2) is a strong regulator protein in osteogenic pathways. Due to hardly maintaining BMP-2 biological function and specificity, BMP-2 efficient delivery on implant surfaces is the main challenge for the clinic application. In this study, a novel method for synthesizing functionalized silane film for superior modification with BMP-2 on titanium surfaces is proposed. Three groups were compared with and without BMP-2 on modified titanium surfaces in vitro and in vivo: mechanical grinding; electrochemical modification through potentiostatic anodization (ECH); and sandblasting, alkali heating, and etching (SMART). Cell tests indicated that the ECH and SMART groups with BMP-2 markedly promoted D1 cell activity and differentiation compared with the groups without BMP-2. Moreover, the SMART group with a BMP-2 surface markedly promoted early alkaline phosphatase expression in the D1 cells compared with the other surface groups. Compared with these groups in vivo, SMART silaning with BMP-2 showed superior bone quality and created contact areas between implant and surrounding bones. The SMART group with BMP-2 could promote cell mineralization in vitro and osseointegration in vivo, indicating potential clinical use.

  10. Survival rate of osseointegrated implants in atrophic maxillae grafted with calvarial bone: a retrospective study.

    PubMed

    Quiles, J C; Souza, F A; Bassi, A P F; Garcia, I R; França, M T; Carvalho, P S P

    2015-02-01

    The aim of this study was to evaluate the clinical survival rate of osseointegrated implants placed in the atrophic maxilla that has been reconstructed by means of autogenous bone grafts harvested from a cranial calvarial site. Further, we sought to analyse the level of peri-implant bone after prosthetic rehabilitation and to determine subjective patient satisfaction with the treatment performed. This study conformed to the STROBE guidelines regarding retrospective studies. Twenty-five patients who had received osseointegrated implants with late loading in the reconstructed atrophic maxilla were included in the study. The survival rate and level of peri-implant bone loss were evaluated. A questionnaire related to the surgical and prosthetic procedures was completed. The observed implant survival rate was 92.35%. The mean bone loss recorded was 1.76mm in the maxilla and 1.54mm in the mandible. The results of the questionnaire indicated a high level of patient satisfaction, little surgical discomfort, and that the patients would recommend the procedure and would undergo the treatment again. From the results obtained, it is concluded that the cranial calvarial site is an excellent donor area; calvarial grafts provided stability and maintenance of bone volume over the course of up to 11 years. Copyright © 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  11. Cutaneous complications in osseointegrated implants: comparison between classic and tissue preservation techniques.

    PubMed

    Martínez, Patricia; López, Fernando; Gómez, Justo Ramón

    2015-01-01

    The standard surgical technique for osseointegrated hearing aids involves removing a large area of subcutaneous tissue down to the periosteum. Recently, the industry has designed a new range of abutment lengths for less invasive surgery with soft tissue preservation. This study compared and evaluated the complications in the standard and the tissue preservation techniques. This was a prospective study including 29 adult patients that underwent single-stage osseointegrated hearing aids insertion between February 2009 and February 2013. We performed the standard technique in 14 patients, and the tissue preservation technique in 15. Soft tissue complications were graded according to the Holgers classification. No patient required removal of implant or revision surgery. Although the Holgers grade was always worse in the standard technique (reaction score of 3 or higher was 28% versus 7% at a month), the complication rate was not statistically significant between the 2 groups at any postoperative time a week (p=0.233), a month (p=0.470) and a year (p=0.401). In our experience the tissue preservation technique, without soft tissue reduction, is the procedure of choice for bone anchored implant surgery. The preservation technique is easier, faster and possible with local anaesthesia and has similar postoperative outcomes. Copyright © 2014 Elsevier España, S.L.U. and Sociedad Española de Otorrinolaringología y Patología Cérvico-Facial. All rights reserved.

  12. Immediate post-implantation skin immobilization decreases skin regression around percutaneous osseointegrated prosthetic implant systems.

    PubMed

    Holt, Brian Mueller; Bachus, Kent N; Beck, James Peter; Bloebaum, Roy Drake; Jeyapalina, Sujee

    2013-07-01

    A percutaneous, osseointegrated (OI) prosthetics are alternative docking systems for upper- and lower-extremity prostheses. Persistent inflammation and micro-motion are known to cause negative soft-tissue adaptation in wound healing and may also be detrimental to implant longevity. In this study, a unique single-stage sheep amputation and implantation model was developed to assess the efficacy of a porous coated sub-dermal fixation surface in the prevention of skin regression around a percutaneous osseointegrated prosthetic implant. Porous coated and smooth sub-dermal fixation surface prosthetics were implanted in the right forelimb of skeletally mature sheep for up to 12 months. Skin regression kinetics and sub-dermal fixation surface coverage were measured from histological samples. Quantitative measurements of porous coated surfaces yielded skin migration rates of 0.90 ± 0.23, 0.56 ± 0.15, 0.44 ± 0.22 mm/month for the 6, 9, and 12 month animals, respectively. In addition, three load dependent regions of skin adaptation were identified; an interface, a transition, and a stress absorbance region. Immediate post-implantation immobilization of the skin may foster improved load-bearing percutaneous device outcomes. The skin adaptations reported here will aid in informing the design and optimization of future percutaneous, OI devices intended for the treatment of upper- and lower-extremity amputees. Copyright © 2012 Wiley Periodicals, Inc.

  13. Polyetheretherketone/nano-fluorohydroxyapatite composite with antimicrobial activity and osseointegration properties.

    PubMed

    Wang, Lixin; He, Shu; Wu, Xiaomian; Liang, Shanshan; Mu, Zhonglin; Wei, Jie; Deng, Feng; Deng, Yi; Wei, Shicheng

    2014-08-01

    Lack of antibacterial activity and binding ability to natural bone tissue has significantly limited polyetheretherketone (PEEK) for many challenging dental implant applications. Here, we have developed a polyetheretherketone/nano-fluorohydroxyapatite (PEEK/nano-FHA) biocomposite with enhanced antibacterial activity and osseointegration through blending method. Smooth and rough surfaces of PEEK/nano-FHA biocomposites were also prepared. Our results showed that in vitro initial cell adhesion and proliferation on the nano-FHA reinforced PEEK composite were improved. In addition, higher alkaline phosphatase activity and cell mineralization were also detected in cells cultured on PEEK/nano-FHA biocomposites, especially for rough PEEK/nano-FHA surfaces. More importantly, the as-prepared PEEK/nano-FHA biocomposite could effectively prevent the proliferation and biofilm formation of bacterial. For in vivo test, the newly formed bone volume of PEEK/nano-FHA group was higher than that of bare PEEK group based on 3D microcomputed tomography and 2D histomorphometric analysis. These reports demonstrate that the developed PEEK/nano-FHA biocomposite has increased biocompatibility and antibacterial activity in vitro, and promoted osseointegration in vivo, which suggests that it holds potential to be applied as dental implant material in dental tissue engineering applications.

  14. Evaluation of machining methods for trabecular metal implants in a rabbit intramedullary osseointegration model.

    PubMed

    Deglurkar, Mukund; Davy, Dwight T; Stewart, Matthew; Goldberg, Victor M; Welter, Jean F

    2007-02-01

    Implant success is dependent in part on the interaction of the implant with the surrounding tissues. Porous tantalum implants (Trabecular Metal, TM) have been shown to have excellent osseointegration. Machining this material to complex shapes with close tolerances is difficult because of its open structure and the ductile nature of metallic tantalum. Conventional machining results in occlusion of most of the surface porosity by the smearing of soft metal. This study compared TM samples finished by three processing techniques: conventional machining, electrical discharge machining, and nonmachined, "as-prepared." The TM samples were studied in a rabbit distal femoral intramedullary osseointegration model and in cell culture. We assessed the effects of these machining methods at 4, 8, and 12 weeks after implant placement. The finishing technique had a profound effect on the physical presentation of the implant interface: conventional machining reduced surface porosity to 30% compared to bulk porosities in the 70% range. Bone ongrowth was similar in all groups, while bone ingrowth was significantly greater in the nonmachined samples. The resulting mechanical properties of the bone implant-interface were similar in all three groups, with only interface stiffness and interface shear modulus being significantly higher in the machined samples.

  15. Future accelerators (?)

    SciTech Connect

    John Womersley

    2003-08-21

    I describe the future accelerator facilities that are currently foreseen for electroweak scale physics, neutrino physics, and nuclear structure. I will explore the physics justification for these machines, and suggest how the case for future accelerators can be made.

  16. Reconstruction of alveolar bone defect with autogenous bone particles and osseointegrated implants: Histologic analysis and 10 years monitoring

    PubMed Central

    de Carvalho, Paulo Sérgio Perri; de Carvalho, Mariliza Comar Astolphi; Ponzoni, Daniela

    2015-01-01

    Maintaining the volume of the alveolar process after extraction can be achieved by immediate implant placement and guided bone regeneration, with or without the use of biomaterials. The authors present a case report with a 10 years follow-up, rehabilitation using osseointegrated implants in the extraction area and maintenance of the volume of the alveolar process with autogenous cortical bone shavings. PMID:26389054

  17. Installing multifunctionality on titanium with RGD-decorated polyurethane-polyurea roxithromycin loaded nanoparticles: toward new osseointegrative therapies.

    PubMed

    Rocas, Pau; Hoyos-Nogués, Mireia; Rocas, Josep; Manero, José M; Gil, Javier; Albericio, Fernando; Mas-Moruno, Carlos

    2015-09-16

    A novel class of polyurethane-polyurea nanoparticles (PUUa NPs) to install multifunctionality on biomaterials is presented. Biofunctionalization of titanium with roxithromycin loaded RGD-decorated PUUa NPs results in an outstanding improvement of osteoblast adhesion and strong suppression of bacterial attachment. This strategy represents a powerful approach to enhance the osseointegration of implant materials.

  18. The effect of osteotomy dimension on osseointegration to resorbable media-treated implants: a study in the sheep.

    PubMed

    Galli, Silvia; Jimbo, Ryo; Tovar, Nick; Yoo, Daniel Y; Anchieta, Rodolfo B; Yamaguchi, Satoshi; Coelho, Paulo G

    2015-03-01

    The drilling technique and the surface characteristics are known to influence the healing times of oral implants. The influence of osteotomy dimension on osseointegration of microroughned implant surfaces treated with resorbable blasting media was tested in an in vivo model. Ninety-six implants (ø4.5 mm, 8 mm in length) with resorbable blasting media-treated surfaces were placed in the ileum of six sheep. The final osteotomy diameters were 4.6 mm (reamer), 4.1 mm (loose), 3.7 mm (medium), and 3.2 mm (tight). After three and six weeks of healing, the implants were biomechanically tested and histologically evaluated. Statistical analysis was performed using Page L trend test for ordered and paired sample and linear regression, with significance level at p < 0.05. An overall increase in all dependent variables was observed with the reduction of osteotomy diameter. In addition, all osseointegration scores increased over time. At three weeks, the retention was significantly higher for smaller osteotomies. The histological sections depicted intimate contact of bone with all the implant surfaces and osteoblast lines were visible in all sections. The resorbable blasting media microroughed surfaces achieved successful osseointegration for all the instrumentation procedures tested, with higher osseointegration scores for the high insertion torque group.

  19. Osteopontin-deficiency disturbs direct osteogenesis in the process of achieving osseointegration following immediate placement of endosseous implants.

    PubMed

    Makishi, Sanako; Saito, Kotaro; Ohshima, Hayato

    2017-06-01

    The role of osteopontin (OPN) in the process of achieving osseointegration following implantation remains to be clarified. This study aimed to analyze the healing patterns of the bone-implant interface after immediate placement of implants in the maxillae of 4-week-old Opn-knockout (KO) and wild-type (WT) mice. After maxillary first molars were extracted, cavities were prepared with a drill and titanium implants blasted with ceramic abrasives containing hydroxyapatite/β-tricalcium phosphate were placed. Following fixation at 3, 5, 7, and 28 days after implantation, the samples were analyzed using immunohistochemistry, in situ hybridization, and an electron probe micro analyzer. Two types of bone healing were observed in the process of achieving osseointegration: "direct osteogenesis," where bone formation occurs at the implant surface, and "indirect osteogenesis," where it does at the pre-existing damaged bone surface in the WT mice. Direct osteogenesis occurred after the recruitment of tartrate resistant acid phosphatase-positive cells and the deposition of OPN on the implant surface. In contrast, the rate of osseointegration or direct osteogenesis was significantly low, and cell proliferation was disturbed in the Opn-KO mice. These results suggest that Opn-deficiency disturbs direct osteogenesis to lead the delayed osseointegration after immediate placement of endosseous implants. © 2016 Wiley Periodicals, Inc.

  20. Application and Interpretation of Resonance Frequency Analysis in Auditory Osseointegrated Implants: A Review of Literature and Establishment of Practical Recommendations.

    PubMed

    Nelissen, Rik C; Wigren, Stina; Flynn, Mark C; Meijer, Gert J; Mylanus, Emmanuel A M; Hol, Myrthe K S

    2015-09-01

    To establish standardization of implant stability measurements in auditory osseointegrated implants by means of resonance frequency analysis (RFA) through reviewing the currently published literature. Studies reporting on RFA in auditory osseointegrated implants were identified, and the outcomes and the way these were reported were evaluated. Thirteen clinical studies reporting RFA outcomes of auditory osseointegrated implants were identified and analyzed, which demonstrated variations in methodology and reporting of data. The different reporting standards made a meta-analysis impossible. Heterogeneity and limitations were found in reporting of the types of implants, abutments, and SmartPegs used; study population sizes; follow-up duration; and, reporting of the implant stability quotient (ISQ). RFA is an interesting outcome of clinical studies on auditory osseointegrated implant research and might have potential as a clinically relevant tool for assessing implant stability. Because of the heterogeneous data that have been reported to date, the following guidelines for standardization of application and reporting were established. The implant and abutment type and length, and the type of SmartPeg should always be stated. Absolute stand-alone ISQ values should not be interpreted individually. ISQ values are at this moment most meaningful as a trend in the individual patient or in a population over time. No conclusions should be based on individual ISQ values. Standardized time points for RFA in research should be determined prospectively, with surgery as a baseline. After abutment replacement, individual ISQ trends from baseline cannot be interpreted anymore if the abutments differ in length.

  1. A comparison of biocompatibility and osseointegration of ceramic and titanium implants: an in vivo and in vitro study.

    PubMed

    Möller, B; Terheyden, H; Açil, Y; Purcz, N M; Hertrampf, K; Tabakov, A; Behrens, E; Wiltfang, J

    2012-05-01

    This study compared the biocompatibility in vitro and the osseointegration in vivo of zirconium and titanium implants regarding implant surfaces and the bone-implant contacts. The different implant surfaces and the biocompatibility of zirconium versus titanium implants were determined by vitality and cytotoxic tests in vitro. The contact of the osteoblasts to the implant surface was determined by scanning electron microscopy (SEM). The in vivo study for osseointegration was performed in domestic pigs over 4 and 12 weeks. In each animal, 4 zirconium and 4 titanium implants (WhiteSky, BlueSky, Bredent, Germany) were inserted in the os frontale and analysed by histomorphometry. Cytotoxicity and SEM showed good biocompatibility in relation to the investigated implant materials. Histological results showed direct bone-implant contact of the implant surfaces. The zirconium implants showed a slight delay in osseointegration in terms of bone-implant contact as measured by histomorphometry (after 4 weeks, zirconium (59.3 ± 4.6%) versus titanium (64.1 ± 3.9%); after 12 weeks, zirconium (67.1 ± 2.3%) versus titanium (73.6 ± 3.2%). A statistically significant difference between the two groups was not observed. The results indicated similar biocompatibility and osseointegration for zirconium compared to titanium implants. Copyright © 2012 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  2. Surface Properties and Osteoblastic Cytocompatibility of Two Blasted and Acid-Etched Titanium Implant Systems with Distinct Microtopography

    PubMed Central

    Mesquita, Pedro; Gomes, Pedro de Sousa; Sampaio, Paula; Juodzbalys, Gintaras; Afonso, Américo

    2012-01-01

    ABSTRACT Objectives The aim of this study is to compare two commercially available screw-type sandblasted and acid-etched (SLA) Ti implant systems from Eckermann Laboratorium S.L., with similar geometry and distinct microtopography, regarding surface properties and osteoblastic cytocompatibility. Material and Methods Implant I (referred as a conventional SLA system) and Implant II (a system patented as Eckcyte®) were characterized for macro and microtopograpphy, surface roughness and chemical composition. For the cytocompatibility studies, human bone marrow osteoblastic cells were seeded over the implants' surface, and the cell response was assessed for cell adhesion and proliferation, alkaline phosphatase (ALP) activity and matrix mineralization. Results Implant I presented a rough surface with irregularly shaped and sized cavities among flatter-appearing areas, whereas Implant II exhibited a homogeneous rough microporous surface. Compared to Implant I, Implant II presented higher Ra values (0.8 [SD 0.008] μm and 1.21 [SD 0.15] μm, respectively, P < 0.05) and also increased values of Rz, Rt and Rsm, a more negative value of Rsk, and similar RKu values. XPS showed the expected presence of Ti, O, C and N; Al, Si, F, P and Ca were detected in low concentrations. Implant II exhibited significantly lower Al levels. Both implants supported the adhesion, proliferation and differentiation of osteoblastic cells. Implant II showed a thicker fibrilar cell layer and an earlier onset and more abundant matrix mineralization. Conclusions The homogeneous rough and microporous surface of Implant II is most probably a main contributor for its improved cell response. PMID:24422006

  3. Surface properties and osteoblastic cytocompatibility of two blasted and Acid-etched titanium implant systems with distinct microtopography.

    PubMed

    Mesquita, Pedro; Gomes, Pedro de Sousa; Sampaio, Paula; Juodzbalys, Gintaras; Afonso, Américo; Fernandes, Maria Helena

    2012-01-01

    The aim of this study is to compare two commercially available screw-type sandblasted and acid-etched (SLA) Ti implant systems from Eckermann Laboratorium S.L., with similar geometry and distinct microtopography, regarding surface properties and osteoblastic cytocompatibility. Implant I (referred as a conventional SLA system) and Implant II (a system patented as Eckcyte(®)) were characterized for macro and microtopograpphy, surface roughness and chemical composition. For the cytocompatibility studies, human bone marrow osteoblastic cells were seeded over the implants' surface, and the cell response was assessed for cell adhesion and proliferation, alkaline phosphatase (ALP) activity and matrix mineralization. Implant I presented a rough surface with irregularly shaped and sized cavities among flatter-appearing areas, whereas Implant II exhibited a homogeneous rough microporous surface. Compared to Implant I, Implant II presented higher Ra values (0.8 [SD 0.008] μm and 1.21 [SD 0.15] μm, respectively, P < 0.05) and also increased values of Rz, Rt and Rsm, a more negative value of Rsk, and similar RKu values. XPS showed the expected presence of Ti, O, C and N; Al, Si, F, P and Ca were detected in low concentrations. Implant II exhibited significantly lower Al levels. Both implants supported the adhesion, proliferation and differentiation of osteoblastic cells. Implant II showed a thicker fibrilar cell layer and an earlier onset and more abundant matrix mineralization. The homogeneous rough and microporous surface of Implant II is most probably a main contributor for its improved cell response.

  4. Microtopography of titanium suppresses osteoblastic differentiation but enhances chondroblastic differentiation of rat femoral periosteum-derived cells.

    PubMed

    Kubo, Katsutoshi; Att, Wael; Yamada, Masahiro; Ohmi, Kuzuhiro; Tsukimura, Naoki; Suzuki, Takeo; Maeda, Hatsuhiko; Ogawa, Takahiro

    2008-11-01

    Despite the clinical fact that endosseous titanium implants directly contacts periosteum, the behavior and response of the periosteum-derived cells to surface topography of titanium have rarely been studied. This study examines the effect of titanium surface microtopography on osteoblastic and possibly-modulated chondroblastic phenotypes of femoral periosteum-derived cells. Rat femoral periosteum-derived cells were cultured on either relatively smooth, machined titanium surface or acid-etched, micro-roughened titanium surface. The osteoblastic gene expressions, including collagen I, osteopontin and osteocalcin, were downregulated on the acid-etched surface, compared with the machined surface. Alkaline phosphatase and mineralization activities on the acid-etched surface were approximately 20% of those on the machined surface. Instead, chondroblastic specific genes, including collagen II and IX, and sox 9, were exclusively expressed or highly upregulated on the acid-etched surface. Alcian blue stain revealed an extensive deposition of glycosaminoglycan on the acid-etched surface. The cultured matrix on the acid-etched surface lacked the submicron globular structures that were extensively seen on the machined surface, and contained a remarkably increased percentage of sulfur relative to calcium compared with the culture on the machined surface. These results indicated that titanium microroughness suppresses the osteoblastic phenotype and induces or at least considerably enhances the chondroblastic phenotype of the periosteal cells, suggesting the unique role of titanium surface topography in regulating the periosteal cell differentiation. The suppressive effect of titanium microroughness on the periosteal cells toward the osteoblastic linage was contrasted to the known promotive effect on the bone marrow-derived osteoblasts.

  5. Microtopography of the surface of adult Schistosoma japonicum-like (Malaysian) as observed by scanning electron microscopy.

    PubMed

    Sobhon, P; Upatham, E S; Koonchornboon, T; Saitongdee, P; Khunborivan, V; Yuan, H C; Vongpayabal, P; Ow-Yang, C K; Greer, G J

    1983-12-01

    The surface of adult Schistosoma japonicum-like (Malaysian) was studied by scanning electron microscopy. The basic pattern of surface microtopography is similar to other strains of S. japonicum as previously reported. However, among male member there are some unique differences in the types, number and distribution of surface papillae and morphology of ridges. Three kinds of papillae were observed: (1) the large fungiform papillae (3.5-4 micron in diameter, most without cilia) are more numerous than in other strains of S. japonicum, they concentrate on the lateral aspect of the anterior and middle parts close to the edge of the gynecophoral canal, and on the dorso-lateral aspect of the posterior part towards the tail tip; (2) the small hemispherical papillae (1.5-2 micron in diameter, all bearing cilia) are especially numerous in the suckers, the gynecophoral canal and parts of the tegument around the suckers and close to the tail tip; on the rest of the surface they are evenly distributed; (3) the cratered papillae (3-4 micron in diameter, about half having cilia) are more numerous than on other strains, they concentrate on the lateral aspect of the middle part and on the edges of the gynecophoral canal. The surface ridges (about 0.2-0.3 micron in width) are tall, highly branching and perforated; they are most developed in the middle part. Spines were observed only in the suckers and the gynecophoral canals. In contrast to the male, the female has numerous spines on all parts of the surface except the most anterior, where a large number of long cilia were observed. All three kinds of papillae were present; fungiform papillae are more numerous than in females of other strains; they concentrate on the latero-dorsal aspect of middle and posterior parts, and around the excretory pore. Ridges are much less developed than in the male and are prominent only in the middle part.

  6. Can common adhesion molecules and microtopography affect cellular elasticity? A combined atomic force microscopy and optical study.

    PubMed

    McPhee, Gordon; Dalby, Matthew J; Riehle, Mathis; Yin, Huabing

    2010-10-01

    The phenomenon that cells respond to chemical and topographic cues in their surroundings has been widely examined and exploited in many fields ranging from basic life science research to biomedical therapeutics. Adhesion promoting molecules such as poly-L-lysine (PLL) and fibronectin (Fn) are commonly used for in vitro cell assays to promote cell spreading/proliferation on tissue culture plastic and to enhance the biocompatibility of biomedical devices. Likewise, engineered topography is often used to guide cell growth and differentiation. Little is known about how these cues affect the biomechanical properties of cells and subsequent cell function. In this study we have applied atomic force microscopy (AFM) to investigate these biomechanical properties. In the first stage of the study we formulated a rigorous approach to quantify cellular elasticity using AFM. Operational factors, including indentation depth and speed, and mathematical models for data fitting have been systematically evaluated. We then quantified how PLL, Fn and microtopography affected cellular elasticity and the organization of the cytoskeleton. Cellular elasticity after 1 day in culture was greater on a Fn-coated surface as compared to PLL or glass. These statistically significant differences disappeared after two more days in culture. In contrast, the significantly higher elasticity associated with cells grown on micrometric grooves remained for at least 3 days. This work sheds light on the apparently simple but debatable questions: "Are engineered chemical cues eventually masked by a cell's own matrix proteins and so only exert short-term influence? Does engineered topography as well as engineered chemistry affect cell elasticity?"

  7. Effects of near-bed turbulence and micro-topography on macroinvertebrate movements across contrasting gravel-bed surfaces (Invited)

    NASA Astrophysics Data System (ADS)

    Buffin-Belanger, T. K.; Rice, S. P.; Reid, I.; Lancaster, J.

    2009-12-01

    Fluvial habitats can be described from a series of physical variables but to adequately address the habitat quality it becomes necessary to develop an understanding that combines the physical variables with the behaviour of the inhabitating organisms. The hypothesis of flow refugia provide a rational that can explain the persistence of macroinvertebrate communities in gravel-bed rivers when spates occur. The movement behaviour of macroinvertebrates is a key element to the flow refugia hypothesis, but little is known about how local near-bed turbulence and bed microtopography may affect macroinvertebrate movements. We reproduced natural gravel-bed substrates with contrasting gravel bed textures in a large flume where we were able to document the movement behaviour of the cased caddisfly Potamophylax latipennis for a specific discharge. The crawling paths and drift events of animals were analysed from video recordings. Characteristics of movements differ from one substrate to another. The crawling speed is higher for the small grain-size substrates but the mean travel distance remains approximately the same between substrates. For each substrate, the animals tended to follow consistent paths across the surface. The number of drift events and mean distance drifted is higher for the small grain-size substrate. ADV measurements close to the boundary allow detailed characterisation of near-bed hydraulic variables, including : skewness coefficients, TKE, UV correlation coefficients and integral time scales from autocorrelation analysis. For these variables, the vertical patterns of turbulence parameters are similar between the substrates but the amplitude of the average values and standard errors vary significantly. The spatial distribution of this variability is considered in relation to the crawling paths. It appears that the animals tend to crawl within areas of the substrate where low flow velocities and low turbulent kinetic energies are found, while sites that

  8. Effect of microtopography and species composition on small-scale variability of CO2 fluxes in a subalpine grassland

    NASA Astrophysics Data System (ADS)

    Galvagno, Marta; Filippa, Gianluca; Cremonese, Edoardo; Morra di Cella, Umberto; Isabellon, Michel

    2015-04-01

    Grassland ecosystems cover around 30% of the Earth's land surface and consequently play an important role in the terrestrial carbon balance. Climate and land use changes have a significant effect on the sink/source strength of grasslands, especially in mountain regions. For these reasons the carbon cycle of high-altitude grasslands has recently received higher attention, however little is know on the within-ecosystem variability in CO2 fluxes. In fact, alpine and subalpine grasslands are often characterized by complex topography which generates differences in snowmelt dynamics at site level and related different microhabitats. The deriving patchy distribution of vegetation leads to the coexistence of different plant functional traits and developmental strategies within the same ecosystem. In this study we evaluated the effect of microtopography and associated vegetation types on the CO2 flux components of an unamanaged subalpine grassland located at 2160 m asl, by means of automated clear and opaque chambers. In order to disentangle the contribution of different growth forms to the whole ecosystem carbon sequestration we compare chambers with eddy covariance CO2 flux data. Results show that: i) different growth forms are associated with concave o convex shapes of the terrain and, in detail, grass species dominate in convex areas while forbs are especially found in concave ones ii) two distinct CO2 flux trajectories associated to these shapes can be distinguished in this ecosystem: graminoids show a later beginning of the carbon uptake period but higher CO2 net uptake (NEE), while forbs develop just after snowmelt but show lower NEE. The observed small-scale patterns of carbon sequestration may reflect the distinct vegetation type responses to snowmelt and different adaptations to resource use efficiency (light, temperature, nutrients) specific of their own microhabitat. Further investigations will be carried on to better evaluate the role of microhabitat

  9. Osseointegration of hollow cylinder based spinal implants in normal and osteoporotic vertebrae: a sheep study.

    PubMed

    Goldhahn, J; Neuhoff, D; Schaeren, S; Steiner, B; Linke, B; Aebi, M; Schneider, E

    2006-10-01

    Osteoporosis is not only responsible for an increased number of metaphyseal and spinal fractures but it also complicates their treatment. To prevent the initial loosening, we developed a new implant with an enlarged implant/bone interface based on the concept of perforated, hollow cylinders. We evaluated whether osseointegration of a hollow cylinder based implant takes place in normal or osteoporotic bone of sheep under functional loading conditions during anterior stabilization of the lumbar spine. Osseointegration of the cylinders and status of the fused segments (ventral corpectomy, replacement with iliac strut, and fixation with testing implant) were investigated in six osteoporotic (age 6.9 +/- 0.8 years, mean body weight 61.1 +/- 5.2 kg) and seven control sheep (age 6.1 +/- 0.2 years, mean body weight 64.9 +/- 5.7 kg). Osteoporosis was introduced using a combination protocol of ovariectomy, high-dose prednisone, calcium and phosphor reduced diet and movement restriction. Osseointegration was quantified using fluorescence and conventional histology; fusion status was determined using biomechanical testing of the stabilized segment in a six-degree-of-freedom loading device as well as with radiological and histological staging. Intact bone trabeculae were found in 70% of all perforations without differences between the two groups (P = 0.26). Inside the cylinders, bone volume/total volume was significantly higher than in the control vertebra (50 +/- 16 vs. 28 +/- 13%) of the same animal (P<0.01), but significantly less (P<0.01) than in the near surrounding (60 +/- 21%). After biomechanical testing as described in Sect. "Materials and methods", seven spines (three healthy and four osteoporotic) were classified as completely fused and six (four healthy and two osteoporotic) as not fused after a 4-month observation time. All endplates were bridged with intact trabeculae in the histological slices. The high number of perforations, filled with intact trabeculae

  10. Biological factors contributing to failures of osseointegrated oral implants. (I). Success criteria and epidemiology.

    PubMed

    Esposito, M; Hirsch, J M; Lekholm, U; Thomsen, P

    1998-02-01

    The aim of this review was to offer a critical evaluation of the literature and to provide the clinician with scientifically-based diagnostic criteria for monitoring the implant condition. The review presents the current opinions on definitions of osseointegration and implant failure. Further, distinctions between failed and failing implants are discussed together with the presently used parameters to assess the implant status. Radiographic examinations together with implant mobility tests seem to be the most reliable parameters in the assessment of the prognosis for osseointegrated implants. On the basis of 73 published articles, the rates of early and late failures of Brånemark implants, used in various anatomical locations and clinical situations, were analyzed using a metanalytic approach. Biologically related implant failures calculated on a sample of 2,812 implants were relatively rare: 7.7% over a 5-year period (bone graft excluded). The predictability of implant treatment was remarkable, particularly for partially edentulous patients, who showed failure rates about half those of totally edentulous subjects. Our analysis also confirmed (for both early and late failures) the general trend of maxillas, having almost 3 times more implant losses than mandibles, with the exception of the partially edentulous situation which displayed similar failure rates both in upper and lower jaws. Surgical trauma together with anatomical conditions are believed to be the most important etiological factors for early implant losses (3.60% of 16,935 implants). The low prevalence of failures attributable to peri-implantitis found in the literature together with the fact that, in general, partially edentulous patients have less resorbed jaws, speak in favour of jaw volume, bone quality, and overload as the three major determinants for late implant failures in the Brånemark system. Conversely, the ITI system seemed to be characterized by a higher prevalence of losses due to peri

  11. Genome Wide assessment of Early Osseointegration in Implant-Adherent Cells

    NASA Astrophysics Data System (ADS)

    Thalji, Ghadeer N.

    Objectives: To determine the molecular processes involved in osseointegration. Materials and methods: A structured literature review concerning in vitro and in vivo molecular assessment of osseointegration was performed. A rat and a human model were then used to identify the early molecular processes involved in osseointegration associated with a micro roughened and nanosurface superimposed featured implants. In the rat model, 32 titanium implants with surface topographies exhibiting a micro roughened (AT-II) and nanosurface superimposed featured implants (AT-I) were placed in the tibiae of 8 rats and subsequently harvested at 2 and 4 days after placement. Whereas in the human model, four titanium mini-implants with either a moderately roughened surface (TiOblast) or super-imposed nanoscale topography (Osseospeed) were placed in edentulous sites of eleven systemically healthy subjects and subsequently removed after 3 and 7 days. Total RNA was isolated from cells adherent to retrieved implants. A whole genome microarray using the Affymetrix 1.1 ST Array platform was used to describe the gene expression profiles that were differentially regulated by the implant surfaces. Results: The literature review provided evidence that particular topographic cues can be specifically integrated among the many extracellular signals received by the cell in its signal transduction network. In the rat model, functionally relevant categories related to ossification, skeletal system development, osteoblast differentiation, bone development and biomineral tissue development were upregulated and more prominent at AT-I compared to AT-II. In the human model, there were no significant differences when comparing the two-implant surfaces at each time point. However, the microarray identified several genes that were differentially regulated at day 7 vs. day 3 for both implant surfaces. Functionally relevant categories related to the extracellular matrix, collagen fibril organization and

  12. In vitro osteogenic capacity of bone marrow MSCs from postmenopausal women reflect the osseointegration of their cementless hip stems.

    PubMed

    Alm, Jessica J; Moritz, Niko; Aro, Hannu T

    2016-12-01

    Age-related dysfunction of mesenchymal stromal cells (MSCs) is suggested as a main cause of altered bone repair with aging. We recently showed that in postmenopausal women undergoing cementless total hip arthroplasty (THA) aging, low bone mineral density (BMD) and age-related geometric changes of the proximal femur are risk factors for increased early migration and delayed osseointegration of the femoral stems. Extending these analyses, we have here explored how the in vitro osteogenic capacity of bone marrow MSCs from these patients reflects implant osseointegration, representing the patient's in vivo bone healing capacity. A total of 19 postmenopausal women with primary hip osteoarthritis (mean age 65 years, range 50-78) and well-defined bone quality underwent successful preoperative in vitro analysis of osteogenic capacity of iliac crest bone marrow MSCs as well as two-year radiostereometric (RSA) follow-up of femoral stem migration after cementless THA. In patients with MSCs of low osteogenic capacity, the magnitude of cumulative stem subsidence after the settling period of three months was greater (p = 0.028) and the time point for translational osseointegration was significantly delayed (p = 0.030) compared to patients with MSCs of high osteogenic capacity. This study suggests that patients with MSCs of low in vitro osteogenic capacity may display increased stem subsidence after the settling period of 3 months and thereby delayed osseointegration. Our study presents a novel approach for studying the biological progress of hip implant osseointegration and to verify the impact of decreased MSCs function, especially in patients with age-related dysfunction of MSCs and bone healing capacity.

  13. Reconstruction of a complex midfacial defect with the folded fibular free flap and osseointegrated implants.

    PubMed

    Anthony, J P; Foster, R D; Sharma, A B; Kearns, G J; Hoffman, W Y; Pogrel, M A

    1996-08-01

    Refinements in microsurgical techniques, plate fixation, and osseointegration have changed the conceptual approach to midface reconstruction. Free tissue transfer has emerged as the ideal method of reconstructing complex midfacial defects. Single-stage bony restoration of the palate and orbital rim using the folded fibular osteocutaneous free flap is described. The fibular free flap is our first choice for reconstructing complex midfacial defects. The thin, soft, pliable tissue is ideal for intraoral and palatal reconstructions. The bone can be tailored precisely to fit any desired shape, and forms a sturdy support for both orbital and dental prostheses. With a single flap, rapid and reliable restoration of midfacial appearance, orbital support, and palatal function can be achieved.

  14. Osseointegration of titanium implants in the tibia. Electron microscopy of biopsies from 4 patients.

    PubMed

    Serre, C M; Boivin, G; Obrant, K J; Linder, L

    1994-06-01

    We studied the ultrastructure of bone tissue around implants of pure titanium inserted into the tibia in 4 patients with arthrosis or rheumatoid arthritis. Three main appearances of the interface were noted. First, a close contact between titanium and calcified bone with living osteocytes inside the newly-formed bone was observed in all samples. Secondly, a close contact was also seen between the implant and osteoid, the newly formed collagenous matrix being either uncalcified or calcifying. Thirdly, a loose extracellular matrix with fibrillar and nonfibrillar materials was sometimes observed between bone mineral and implant. There was no inflammatory reaction at the interface. We concluded that the titanium implants were osseointegrated, but the calcification of the bone tissue was not complete even after 20 months. However, mineralization of osteoid and living bone cells revealed the presence of an active tissue.

  15. Demographical, odontological, and psychological variables in individuals referred for osseointegrated dental implants.

    PubMed

    Hogenius, S; Berggren, U; Blomberg, S; Jemt, T; Ohman, S C

    1992-08-01

    Edentulism and/or the wearing of a removable denture always requires adaptation, not only on a functional, but also on an emotional, level. Four hundred and seventy-three patients referred for treatment with osseointegrated implants due to problems with removable prostheses entered the study and 315 (66.6%) completed it. The average age was close to 60 yr, and the majority of patients were women. The average time of edentulousness was 14.3 yr. Twelve percent experienced profound negative effects from wearing dentures, this to an extent that it led to overt psychological and social effects. Subjective ratings revealed that functional and/or intra-personal effects were of higher significance than social consequences. The group was found to be more depressed than average as well as having an external health locus of control orientation.

  16. Osseointegration of multiphase anodic spark deposition treated porous titanium implants in an ovine model.

    PubMed

    Bertollo, Nicky; Sandrini, Enrico; Dalla Pria, Paolo; Walsh, William R

    2015-03-01

    Modification of titanium oxide by multiphase anodic spark deposition (ASD) has the potential to increase bioactivity and hasten osseointegration and biological fixation in uncemented arthroplasty. This study assessed the in vivo performance of control (Ti), plasma-sprayed HA-coated (TiHA) and ASD (Biospark) treated (TiAn) porous titanium implants with a solid core using a standard uncemented implant fixation sheep model. Cortical interfacial shear-strength and bone ingrowth in cortical and cancellous sites were quantified following 12 weeks in situ. Ultimate shear-strength for the Ti, TiHA and TiAn coatings was 33±9.5, 35.4±8.4 and 33.8±7.8 MPa, respectively, which was limited by coating delamination. ASD treatment was associated with significantly higher mean bone ingrowth at both sites. These results support the osteoconductive potential of the BioSpark treatment of porous titanium.

  17. Use of osseointegrated implants in the restoration of head and neck defects.

    PubMed

    Roumanas, Eleni D; Chang, Ting-Ling; Beumer, John

    2006-09-01

    Osseointegrated implants can be applied to facilitate retention, stability, and support for facial and intraoral prostheses used to restore head and neck defects. At the University of California, Los Angeles, Maxillofacial Prosthetics Clinic, retrospective studies have indicated that in nonirradiated maxillectomy patients, implant survival rates are 82.6 percent. In mandibles reconstructed with fibula free flaps, survival rates are 94.6 percent. Similarly, high implant survival rates have been observed for most sites used to support facial prostheses. Cumulative six-year survival rates for auricular sites exceed 95 percent and for floor of nose sites, success rates exceed 87 percent. However, survival rates are low (53 percent) for implants placed in the frontal bone for retention of orbital prostheses and even lower for irradiated bone sites ranging from 63 percent in the maxilla to 27 percent in the orbit.

  18. Identification of the critical level of implantation of an osseointegrated prosthesis for above-knee amputees.

    PubMed

    Andrango Castro, Elder Michael; Konvickova, Svatava; Daniel, Matej; Horak, Zdenek

    2017-09-27

    The aim of our study was to identify potential critical levels of implantation of an osseointegrated prosthesis for above-knee amputees. The implant used was the OPRA system. It was inserted in the femur at four different amputation heights, characterized by their residual limb ratios (0.299, 0.44, 0.58 and 0.73). The stress and strain distribution was evaluated in the bone-implant system during walking, considering a body mass of 100 kg. Considerably high stimulus (11,489 με) in the tissue near the tip was found at the highest implantation level. All models presented small non-physiologic stress values in the tissue around the implant. The results revealed that the implantation level has a decisive effect on bone-implant performance. Mainly, the analysis indicates adverse biomechanical conditions for implantations in very short residual limbs.

  19. Single-stage osseointegrated implants for nasal prosthodontic rehabilitation: A clinical report.

    PubMed

    de Carvalho, Bruna M D F; Freitas-Pontes, Karina M; de Negreiros, Wagner A; Verde, Marcus A R L

    2015-08-01

    Malignant tumors in the nasal region may be treated by means of invasive surgical procedures, with large facial losses. Nasal prostheses, retained by osseointegrated facial implants, instead of plastic surgery, will, in most patients, offer good biomechanical and cosmetic results. This clinical report describes the prosthetic rehabilitation of a patient with nasal cancer who had the entire nasal vestibule removed in a single-stage surgical procedure in order to shorten the rehabilitation time. The nasal prosthesis was built on a 3-magnet bar and was made of platinum silicone with intrinsic pigmentation, thereby restoring the patient's appearance and self-esteem. The authors concluded that single-stage implants may reduce the rehabilitation time to as little as 1 month, and the correct use of materials and techniques may significantly improve the nasal prosthesis.

  20. The effect of electrical perturbation on osseointegration of titanium dental implants: a preliminary study.

    PubMed

    Shafer, D M; Rogerson, K; Norton, L; Bennett, J

    1995-09-01

    Successful osseointegration of titanium dental implants is decreased in areas of poor bone volume and density. Low amperage direct current (LADC) has been shown to perturb bone cells, which in turn promotes bone growth. The purpose of this experiment was to evaluate the effect of LADC on the osseointegration of endosseous titanium dental implants. Two implant sites were prepared in the body of the mandible of five rabbits by an extraoral approach. An LADC-stimulated 3.75 x 7 mm-titanium implant was placed in one site and an identical control implant was inserted on the contralateral side. A sterilized silicone-encased power pack producing 7.5 +/- 0.2 uA and 1.35 +/- 0.01 V was placed in a submandibular pouch. The active cathode lead was attached to the LADC implant and the anode was placed in the mandible 5 mm distal to the implant. Nonactive leads were similarly connected to the control implant. Twenty-eight days after placement, the implants were removed using a torque wrench, and the bone surrounding the implants was examined both microscopically and radiographically. The average force to initial rotation was 1,320 +/- 880 g/cm for the LADC-stimulated implants and 1,290 +/- 238 g/cm for the control implants. This was significantly different by t test (P = .94). Light microscopic evaluation demonstrated a mixture of compact and woven bone and fibrous tissue adjacent to both groups of implants. Histomorphometric analysis demonstrated an average percent of bone in relation to the total tissue adjacent to the control implants of 33.5 +/- 15.4 and 40.2 +/- 4.8 for the LADC-stimulated implants (not significantly different, t test, P = .39). CONCLUSION. It was concluded that LADC as used in this study does not positively affect the healing of bone. Its ability to enhance bone growth around titanium dental implants needs further investigation.

  1. Bone cutting capacity and osseointegration of surface-treated orthodontic mini-implants

    PubMed Central

    Kim, Ho-Young

    2016-01-01

    Objective The objective of the study was to evaluate the practicality and the validity of different surface treatments of self-drilling orthodontic mini-implants (OMIs) by comparing bone cutting capacity and osseointegration. Methods Self-drilling OMIs were surface-treated in three ways: Acid etched (Etched), resorbable blasting media (RBM), partially resorbabla balsting media (Hybrid). We compared the bone cutting capacity by measuring insertion depths into artificial bone (polyurethane foam). To compare osseointegration, OMIs were placed in the tibia of 25 rabbits and the removal torque value was measured at 1, 2, 4, and 8 weeks after placement. The specimens were analyzed by optical microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Results The bone cutting capacity of the etched and hybrid group was lower than the machined (control) group, and was most inhibited in the RBM group (p < 0.05). At 4 weeks, the removal torque in the machined group was significantly decreased (p < 0.05), but was increased in the etched group (p < 0.05). In the hybrid group, the removal torque significantly increased at 2 weeks, and was the highest among all measured values at 8 weeks (p < 0.05). The infiltration of bone-like tissue surface was evaluated by SEM, and calcium and phosphorus were detected via EDS only in the hybrid group. Conclusions Partial RBM surface treatment (hybrid type in this study) produced the most stable self-drilling OMIs, without a corresponding reduction in bone cutting capacity. PMID:27896213

  2. Effects of Untreated Periodontitis on Osseointegration of Dental Implants in a Beagle Dog Model.

    PubMed

    Lee, Daehyun; Sohn, Byungjin; Kim, Kyoung Hwa; Kim, Sungtae; Koo, Ki-Tae; Kim, Tae-Il; Seol, Yang-Jo; Lee, Yong-Moo; Rhyu, In-Chul; Ku, Young

    2016-10-01

    There have been previous studies on the relationship between periodontitis and peri-implantitis, but limited information is available on how periodontitis affects osseointegration and wound healing of newly placed dental implants adjacent to natural teeth. The objective of the present experiment is to evaluate healing around dental implants adjacent to teeth with untreated experimental periodontitis. The study included six male beagle dogs. Scaling and plaque control procedures were performed on three dogs (control group). In the other three dogs (experimental group), retraction cords and ligature wires were placed subgingivally around all premolars and the first molars. Induced experimental periodontitis was confirmed after 3 months. Each control or experimental group was divided into two subgroups depending on the timing of implant placement (immediate/delayed). Twelve dental implants (two implants for each dog) were placed immediately, and the other 12 dental implants (two implants for each dog) were placed 2 months after extraction. The animals were sacrificed 2 months after implant placement. Histologic and histometric analyses were performed. Four implants (three from the immediate placement group and one from the delayed placement group) failed in the experimental group. There were significant differences in the percentage of bone-to-implant contact and marginal bone volume density between the control and experimental groups. Both parameters were significantly lower in the experimental group than in the control group (P <0.05). There was a tendency toward more marginal bone loss in the experimental group than the control group. Immediate placement of implants is associated with a higher failure rate compared with delayed placement. Untreated experimental periodontitis was correlated with compromised osseointegration in the implants with delayed placement.

  3. [Endo-exo prostheses : Osseointegrated percutaneously channeled implants for rehabilitation after limb amputation].

    PubMed

    Aschoff, H-H; Juhnke, D-L

    2016-05-01

    In 1999 the first endo-exo femoral prosthesis (EEFP) was implanted in Germany in a patient who had suffered a traumatic above-knee amputation. This procedure involves a skeletally anchored exoprosthetic device that is inserted into the residual femur. The distal part of the implant protrudes transcutaneously and allows attachment to a prosthetic limb which provides direct force transmission to the external prosthetic components. The technique originated from dental implantology and helps to avoid possible problems resulting from treatment of amputated limbs using socket prostheses. In the meantime, durability times of over 10 years have now helped to invalidate the initially well-founded reservations held against the procedure. What advantages can be achieved by osseointegrated and percutaneously channeled prostheses and which problems had to be overcome for treatment. Critical evaluation of data from patients operated on in Lübeck, Germany from January 2003 to December 2014. With osseointegrated and percutaneously channeled prostheses permanent durability times can be achieved. Infection-associated soft tissue problems at the site of skin protrusion (stoma) can be successfully prevented. The creation of this so-called stoma means acceptance of a possible bacterial portal of entry into the body. Patient satisfaction has so far been high, postoperative rehabilitation is simplified and the technique could possibly lower the costs of medical treatment. Endo-exo prostheses have proved to be successful for more than 15 years. A critical appraisal of the indications as well as a close cooperation between the surgeon, orthopedic technician and the associated rehabilitation facilities with the patient are the basis for the long-term success of this relatively new treatment approach.

  4. Enhanced biocompatibility and osseointegration of calcium titanate coating on titanium screws in rabbit femur.

    PubMed

    Wang, Zi-Li; He, Rong-Zhen; Tu, Bin; Cao, Xu; He, Jin-Shen; Xia, Han-Song; Liang, Chi; Zou, Min; Wu, Song; Wu, Zhen-Jun; Xiong, Kun

    2017-06-01

    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 CaTiO3 coating 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 CaTiO3 were 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 CaTiO3 coating 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 CaTiO3 coating with bone tissues was significantly higher than that of uncoated titanium screws, and was comparable to that of HA coating. The study demonstrated that CaTiO3 coating in situ to titanium screws possesses great biocompatibility and osseointegration comparable to HA coating.

  5. Osseointegration of Dental Implants in a Patient with Hajdu-cheney Syndrome

    PubMed Central

    Dokou, Panagiota; Karoussis, Ioannis K.; Papavasiliou, George; Kamposiora, Phophi; Vrahopoulos, Theophilos P.; Vrotsos, John A.

    2016-01-01

    Background: Hajdu-Cheney Syndrome (HCS) is a rare hereditary bone metabolism disorder characterized by acro-osteolysis, short stature, craniofacial changes, periodontitis and premature tooth loss. Extensive search of the current literature revealed no reports of implant placement in patients with HCS. Case Report: A 22-year old woman with osteoporosis, generalized advanced chronic periodontitis and premature tooth loss was referred to the Postgraduate Clinic of Periodontology, University of Athens-Greece. The patient was diagnosed in 2001 with HCS. The patient received non-surgical periodontal treatment and several teeth were extracted due to extensive alveolar bone loss. After careful consideration of the possible implications deriving from the patient’s condition and having taken her young age into account, initially, a dental implant was placed in the upper right first premolar region. Specific protocols such as longer healing periods were implemented, so five years after placement and successful osseointegration of this implant, four additional dental implants were placed in the posterior regions of the maxilla and the mandible. Prosthetic rehabilitation followed 6 months after implant placement. Upon completion of periodontal treatment, the patient was enrolled in a periodontal maintenance program. Results: Clinical and radiographic examination of the patient during the periodontal maintenance program after implant placement revealed no abnormalities in the implant region. Conclusion: Patients with HCS suffer from periodontitis, bone destruction and premature tooth loss. This case indicates the successful osseointegration of dental implants in patients with HCS. However, further research is required in order to determine the predictability of dental implant placement in those patients. PMID:27857819

  6. Osseointegrated implants for orbito-facial prostheses: Preoperative planning tips and intraoperative pearls.

    PubMed

    Wei, Leslie A; Brown, Julie J; Hosek, Dori K; Burkat, Cat N

    2016-01-01

    Implant-retained facial prostheses are becoming increasingly sophisticated. We describe our experience with successful implant placement. Retrospective case series. Patients with severe unilateral orbital deformity who underwent socket reconstruction with placement of orbital implants were identified. Data on patient age, gender, mechanism of eye, soft tissue, and bone loss, prior reconstructive surgeries and radiation, and orbital imaging were collected and analyzed. Four patients (9 implants) between 2010 and 2014, who had osseointegrated implants placed for orbito-facial prostheses were identified. Three were male, one female. Average age was 59 years (range 34-86). Reason for eye loss was trauma in two patients, exenteration for recurrent rhabdomyosarcoma in one patient, and enucleation for retinoblastoma in one patient. All patients had Vistafix® (Gothenburg, Sweden) osseointegrated titanium implants (4 mm) placed in a 2-stage procedure over a span of 3-6 months with subsequent successful prosthesis fitting. Implant-retained orbito-facial prostheses are safe, easy, and reliable. The ideal socket has minimal dead space, robust bone, and soft tissue 4-5 mm in depth. Preoperative planning should consist of: 1) orbit CT; 2) careful clinical exam of the orbital deformity; and, 3) analysis of socket topography. Operative tips for successful implant placement include: 1) 2-3 points of fixation; 2) placement of implants in bone of adequate thickness; and 3) implant placement as a 2-stage rather than 1-stage procedure. There appears to be no difference in outcome in irradiated and non-irradiated sockets in this series, but should be a consideration and discussed with the patient.

  7. Does HIV infection have an impact upon dental implant osseointegration? A systematic review

    PubMed Central

    Ata-Ali, Fadi; Di-Benedetto, Nicolas; Bagán, Leticia; Bagán, José-Vicente

    2015-01-01

    Background A systematic review is made to determine whether human immunodeficiency virus (HIV) infection has an impact upon dental implant osseointegration. Material and Methods A PubMed (MEDLINE) literature search was made of articles published up until 14 April 2014. The systematic review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA). The quality of the studies included in the review was assessed using the Methodological Index for Nonrandomized Studies (MINORS) and levels of evidence (based on the University of Oxford’s Center for Evidence Based Medicine criteria). Results The combinations of search terms resulted in a list of 132 titles. Nine studies finally met the inclusion criteria and were selected for inclusion in the systematic review. A total of 173 dental implants were placed in 80 patients (135 implants in 56 HIV-positive subjects and 38 implants in 24 HIV-negative patients), and a single loss of dental implant osseointegration was recorded in an HIV-positive patient. Conclusions Our results suggest that dental implant placement in HIV-positive patients does not increase the dental implant failure rate. Prophylactic antibiotic treatment, the administration of highly active antiretroviral therapy, and control of the CD4+ T lymphocyte counts appear to be the main influencing factors in this respect. Given the few studies included in our systematic review, further prospective studies involving larger sample sizes and longer durations of follow-up are required in order to confirm the results obtained. Key words: Dental implants, implant failure, HIV positive, systematic review, AIDS, HAART. PMID:25662560

  8. A three-dimensional finite element analysis of the osseointegration progression in the human mandible

    NASA Astrophysics Data System (ADS)

    Esmail, Enas; Hassan, Noha; Kadah, Yasser

    2010-02-01

    In this study, three-dimensional (3D) finite element analysis was used to model the effect of the peri-implant bone geometry and thickness on the biomechanical behavior of a dental implant/supporting bone system. The 3D finite element model of the jaw bone, cancellous and cortical, was developed based on computerized tomography (CT) scan technology while the dental implant model was created based on a commercially available implant design. Two models, cylindrical and threaded, representing the peri-implant bone region were simulated. In addition, various thicknesses (0.1 mm, 0.3 mm, 0.5 mm) of the peri-implant bone region were modeled to account for the misalingnment during the drilling process. Different biomechanical properties of the peri-implant bone region were used to simulate the progression of the osseointegration process with time. Four stages of osseointegration were modeled to mimic different phases of tissue healing of the peri- implant region starting with soft connective tissue and ending with complete bone maturation. For the realistic threaded model of the peri-implant bone region, the maximum von Mises stress and displacement in the dental implant and jaw bone were higher than those computed for the simple cylindrical peri-implant bone region model. The average von Mises stress and displacement in the dental implant and the jaw bone decreased as the oseeointegration progressed with time for all thicknesses of the peri-implant bone region. On the other hand, the maximum absolute vertical displacement of the dental implant increased as the drilled thickness of the peri-implant bone region increased.

  9. Osseointegration improvement by plasma electrolytic oxidation of modified titanium alloys surfaces.

    PubMed

    Echeverry-Rendón, Mónica; Galvis, Oscar; Quintero Giraldo, David; Pavón, Juan; López-Lacomba, José Luis; Jiménez-Piqué, Emilio; Anglada, Marc; Robledo, Sara M; Castaño, Juan G; Echeverría, Félix

    2015-02-01

    Titanium (Ti) is a material frequently used in orthopedic applications, due to its good mechanical properties and high corrosion resistance. However, formation of a non-adherent fibrous tissue between material and bone drastically could affect the osseointegration process and, therefore, the mechanical stability of the implant. Modifications of topography and configuration of the tissue/material interface is one of the mechanisms to improve that process by manipulating parameters such as morphology and roughness. There are different techniques that can be used to modify the titanium surface; plasma electrolytic oxidation (PEO) is one of those alternatives, which consists of obtaining porous anodic coatings by controlling parameters such as voltage, current, anodizing solution and time of the reaction. From all of the above factors, and based on previous studies that demonstrated that bone cells sense substrates features to grow new tissue, in this work commercially pure Ti (c.p Ti) and Ti6Al4V alloy samples were modified at their surface by PEO in different anodizing solutions composed of H2SO4 and H3PO4 mixtures. Treated surfaces were characterized and used as platforms to grow osteoblasts; subsequently, cell behavior parameters like adhesion, proliferation and differentiation were also studied. Although the results showed no significant differences in proliferation, differentiation and cell biological activity, overall results showed an important influence of topography of the modified surfaces compared with polished untreated surfaces. Finally, this study offers an alternative protocol to modify surfaces of Ti and their alloys in a controlled and reproducible way in which biocompatibility of the material is not compromised and osseointegration would be improved.

  10. Heat and Radiofrequency Plasma Glow Discharge Pretreatment of a Titanium Alloy Promote Bone Formation and Osseointegration

    PubMed Central

    MacDonald, Daniel E.; Rapuano, Bruce E.; Vyas, Parth; Lane, Joseph M.; Meyers, Kathleen; Wright, Timothy

    2013-01-01

    Orthopedic and dental implants manifest increased failure rates when inserted into low density bone. We determined whether chemical pretreatments of a titanium alloy implant material stimulated new bone formation to increase osseointegration in vivo in trabecular bone using a rat model. Titanium alloy rods were untreated or pretreated with heat (600°C) or radiofrequency plasma glow discharge (RFGD). The rods were then coated with the extracellular matrix protein fibronectin (1 nM) or left uncoated and surgically implanted into the rat femoral medullary cavity. Animals were euthanized 3 or 6 weeks later, and femurs were removed for analysis. The number of trabeculae in contact with the implant surface, surface contact between trabeculae and the implant, and the length and area of bone attached to the implant were measured by histomorphometry. Implant shear strength was measured by a pull-out test. Both pretreatments and fibronectin enhanced the number of trabeculae bonding with the implant and trabeculae-to-implant surface contact, with greater effects of fibronectin observed with pretreated compared to untreated implants. RFGD pretreatment modestly increased implant shear strength, which was highly correlated (r2 = 0.87 – 0.99) with measures of trabecular bonding for untreated and RFGD-pretreated implants. In contrast, heat pretreatment increased shear strength 3 to 5-fold for both uncoated and fibronectin-coated implants at 3 and 6 weeks, suggesting a more rapid increase in implant-femur bonding compared to the other groups. In summary, our findings suggest that the heat and RFGD pretreatments can promote the osseointegration of a titanium alloy implant material. PMID:23649564

  11. Influence of pores created by laser superfinishing on osseointegration of titanium alloy implants.

    PubMed

    Stangl, R; Pries, A; Loos, B; Müller, M; Erben, R G

    2004-06-01

    The aim of this study was to assess the osseointegration of copper vapor laser-superfinished titanium alloy (Ti6Al4V) implants with pore sizes of 25, 50, and 200 microm in a rabbit intramedullary model. Control implants were prepared by corundum blasting. Each animal received all four different implants in both femora and humeri. Using static and dynamic histomorphometry, the bone-implant interface and the peri-implant bone tissue were examined 3, 6, and 12 weeks postimplantation. Among the laser-superfinished implants, total bone-implant contact was smallest for the 25-microm pores, and was similar for 50- and 200-microm pore sizes at all time points. However, all laser-superfinished surfaces were inferior to corundum-blasted (CB) control implants in terms of bone-implant contact. Within the 12-week study period, remodeling of woven bone initially formed within pores occurred only in the implants with 200-microm pores. Implants with 25-microm pores showed the highest amount of peri-implant bone volume at all time points, indicating that the amount of peri-implant bone was not correlated with the quality of the bone-implant interface. At 3 and 6 weeks postsurgery, we did not find any differences in mineral apposition rates or bone formation rates between the various implant surfaces. However, the peri-implant bone formation rate at the end of the trial was 70 and 62% higher in implants with 50- and 200-microm pores compared with CB implants, respectively. We conclude that, although laser-superfinished implants were not superior to CB control implants in terms of osseointegration, our study has provided further insights into the mechanisms of bone remodeling within pores of various sizes, and may form a basis for future experiments to design optimal implant surfaces with the help of modern laser technology.

  12. Bioactivity and Osseointegration of PEEK Are Inferior to Those of Titanium: A Systematic Review.

    PubMed

    Najeeb, Shariq; Bds, Zohaib Khurshid; Bds, Sana Zohaib; Bds, Muhammad Sohail Zafar

    2016-12-01

    Polyetheretherketone (PEEK) has been suggested as an alternative to replace titanium as a dental implant material. However, PEEK's bioactivity and osseointegration are debatable. This review has systematically analyzed studies that have compared PEEK (or PEEK-based) implants with titanium implants so that its feasibility as a possible replacement for titanium can be determined. The focused question was: "Are the bioactivity and osseointegration of PEEK implants comparable to or better than titanium implants?" Using the key words "dental implant," "implant," "polyetheretherketone," "PEEK," and "titanium" in various combinations, the following databases were searched electronically: PubMED/MEDLINE, Embase, Google Scholar, ISI Web of Knowledge, and Cochrane Database. 5 in vitro and 4 animal studies were included in the review. In 4 out of 5 in vitro studies, titanium exhibited more cellular proliferation, angiogenesis, osteoblast maturation, and osteogenesis compared to PEEK; one in vitro study observed comparable outcomes regardless of the implant material. In all animal studies, uncoated and coated titanium exhibited a more osteogenic behavior than did uncoated PEEK, while comparable bone-implant contact was observed in HA-coated PEEK and coated titanium implants. Unmodified PEEK is less osseoconductive and bioactive than titanium. Furthermore, the majority of studies had multiple sources of bias; hence, in its unmodified form, PEEK is unsuitable to be used as dental implant. Significantly more research and long-term trials must focus on improving the bioactivity of PEEK before it can be used as dental implant. More comparative animal and clinical studies are warranted to ascertain the potential of PEEK as a viable alternative to titanium.

  13. Clinical Outcomes of Osseointegrated Prosthetic Auricular Reconstruction in Patients With a Compromised Ipsilateral Temporoparietal Fascial Flap.

    PubMed

    Zuo, Kevin J; Wilkes, Gordon H

    2016-01-01

    Patients with major ear deformities and associated compromise of the superficial temporal artery are poor candidates for autogenous ear reconstruction because of a tenuous ipsilateral temporoparietal fascial flap (TPFF). Osseointegrated prosthetic auricular reconstruction (OPAR) is an alternative to contralateral free TPFF microsurgical and autogenous reconstruction, but data on clinical outcomes are limited. The records of patients with ear loss or major deformity and a compromised ipsilateral TPFF who underwent OPAR from 1989 to 2013 were reviewed. Satisfaction was assessed using a questionnaire based on a 5 point Likert scale. Thirty-two patients (8 women, 24 men) with mean age 43.0 years (range, 10-70 years) underwent OPAR. The ipsilateral TPFF was compromised due to major trauma (13 patients), cancer extirpation (9), burn injury (4), previous harvest (4), arteriovenous malformation (1), or infection (1). All but 2 patients had an associated craniofacial defect, such as soft tissue deformity (87.5%), hearing loss (46.9%), or bony deformity (31.3%). The overall implant success rate was 88.6% at mean follow-up time of 7.6 years post-OPAR. Prosthesis wear averaged 12.2 hours/day and 6.6 days/week (80.5 hours/week). All 5 patients who experienced implant failures had received prior head and neck irradiation. With their prosthesis, 76.2% (16 patients) stated that their self-consciousness and self-esteem were "better" or "much better," whereas 85.7% (18 patients) stated that their self-image was "better" or "much better." All patients declared that they would undergo the treatment again. Osseointegrated prosthetic auricular reconstruction is a reliable option in this challenging population with high patient satisfaction. Patients with prior radiotherapy may have a higher chance of implant failure and would benefit from extended annual follow-up.

  14. Bio-Oss(®) for delayed osseointegration of implants in dogs: a histological study.

    PubMed

    Liu, Hui-ying; Zheng, Hui; Hou, Xi-peng; Zhong, Wei-jian; Ying, Xiao-xia; Chai, Song-ling; Ma, Guo-wu

    2014-10-01

    We evaluated the effects of Bio-Oss® (a natural bone substitute derived from the mineral portion of bovine bone) on delayed osseointegration of implants. The bilateral third and fourth mandibular premolars of 4 adult, healthy, male and female dogs were extracted. We randomly selected 2 extraction sockets in each dog to be filled with Bio-Oss® (the experimental group); the other 2 extraction sockets, which were not treated, served as controls. Dental implants were inserted into the alveolar bone of the experimental group and the control group 3 months after insertion of the Bio-Oss®. The osteogenic activity in the bone around the implants was assessed by evaluating the histological morphology and estimating histomorphometric variables at 3 and 6 months after delayed implantation. After 3 months, Goldner's trichrome staining analysis showed that the rate of content between the bone and the implant and the mineralised area of bone around the implant were significantly higher in the experimental group (76%(9%) and 69.5% (9.6%), respectively) than those in the control group (56.1% (8.2%) and 52.8% (7.3%), respectively, p=0.003 and 0.000). However, the 2 groups did not differ significantly at 6 months. Fluorescence microscopy showed that the mean rates of mineralisation of the bony tissue around the implant in the experimental group at months 3 and 6 were 6.8 (0.4) μm and 8.4 (0.8) μm, respectively, which were significantly higher than those in the control group (p=0.000 and 0.03). These data indicate that putting Bio-Oss® into the extraction sockets can promote osseointegration after delayed implantation, and may be a promising option for clinical use. Copyright © 2014 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  15. Micro-topography and reactivity of implant surfaces: an in vitro study in simulated body fluid (SBF).

    PubMed

    Gandolfi, M G; Taddei, P; Siboni, F; Perrotti, V; Iezzi, G; Piattelli, A; Prati, C

    2015-02-01

    The creation of micro-textured dental implant surfaces possessing a stimulating activity represents a challenge in implant dentistry; particularly, the formation of a thin, biologically active, calcium-phosphate layer on their surface could help to strengthen the bond to the surrounding bone. The aim of the present study was to characterize in terms of macrostructure, micro-topography and reactivity in simulated body fluid (SBF), the surface of titanium (Ti) implants blasted with TiO2 particles, acid etched with hydrofluoric acid, and activated with Ca and Mg-containing nanoparticles. Sandblasted and acid-etched implants were analyzed by ESEM-EDX (environmental scanning electron microscope with energy dispersive X-ray system) to study the micromorphology of the surface and to perform elemental X-ray microanalysis (microchemical analyses) and element mapping. ESEM-EDX analyses were performed at time 0 and after a 28-day soaking period in SBF Hank's balanced salt solution (HBSS) following ISO 23317 (implants for surgery—in vitro evaluation for apatite-forming ability of implant materials). Microchemical analyses (weight % and atomic %) and element mapping were carried out to evaluate the relative element content, element distribution, and calcium/phosphorus (Ca/P) atomic ratio. Raman spectroscopy was used to assess the possible presence of impurities due to manufacturing and to investigate the phases formed upon HBSS soaking. Micro-morphological analyses showed a micro-textured, highly rough surface with microgrooves. Microchemical analyses showed compositional differences among the apical, middle, and distal thirds. The micro-Raman analyses of the as-received implant showed the presence of amorphous Ti oxide and traces of anatase, calcite, and a carbonaceous material derived from the decomposition of an organic component of lipidic nature (presumably used as lubricant). A uniform layer of Ca-poor calcium phosphates (CaPs) (Ca/P ratio <1.47) was observed after

  16. Radical Acceleration

    ERIC Educational Resources Information Center

    Gross, Miraca U. M.; Van Vliet, Helen E.

    2005-01-01

    Research has found that teachers' objections to accelerating gifted students are mainly based on a fear that acceleration will lead to social or emotional damage. Ironically, it is the academic and emotional maturity which characterizes intellectually gifted students, coupled with their high levels of academic achievement, which makes them such…

  17. RECIRCULATING ACCELERATION

    SciTech Connect

    BERG,J.S.; GARREN,A.A.; JOHNSTONE,C.

    2000-04-07

    This paper compares various types of recirculating accelerators, outlining the advantages and disadvantages of various approaches. The accelerators are characterized according to the types of arcs they use: whether there is a single arc for the entire recirculator or there are multiple arcs, and whether the arc(s) are isochronous or non-isochronous.

  18. The impact of glucocorticosteroids administered for systemic diseases on the osseointegration and survival of dental implants placed without bone grafting-A retrospective study in 31 patients.

    PubMed

    Petsinis, Vassilis; Kamperos, Georgios; Alexandridi, Foteini; Alexandridis, Konstantinos

    2017-08-01

    To evaluate the impact of glucocorticosteroids, administered for the treatment of systemic diseases, on the osseointegration and survival of dental implants placed without bone grafting. A retrospective study was conducted in search of patients treated with dental implants while receiving glucocorticosteroid therapy for various systemic diseases. In these cases, a conventional two-stage surgical protocol was used, without bone regeneration procedures. The osseointegration was clinically and radiographically tested at the uncovering of the implants. The follow-up after loading was set at a minimum of 3 years. A total of 31 patients were included in the study. Of the 105 dental implants placed, 104 were osseointegrated (99%). No bone absorption was radiographically noted at the uncovering of the osseointegrated implants. All of the osseointegrated implants were successfully loaded for the prosthetic restoration. The mean follow-up period after loading was 71 months, with an implant survival rate of 99%. Glucocorticosteroid intake for systemic diseases does not have a significant impact on the osseointegration and the 3-year survival of dental implants placed with a conventional two-stage surgical protocol and without bone grafting. Therefore, it should not be considered a contraindication for dental implant placement. Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  19. Osseointegration of dental implants and osteonecrosis of the jaw in patients treated with bisphosphonate therapy: A systematic review.

    PubMed

    Chadha, Gurpreet K; Ahmadieh, Azadeh; Kumar, Satish K S; Sedghizadeh, Parish P

    2012-04-16

    Abstract Bisphosphonate (BP) drugs are a commonly prescribed group of medications used in the treatment of metabolic and oncologic bone pathoses. The aim of this study was to conduct a systematic review in order to evaluate whether patients on BP therapy are appropriate candidates for dental implants as compared to patients not taking BP with respect to successful implant osseointegration and the risk of developing bisphosphonate-related osteonecrosis of the jaw (BRONJ). Based on the current literature, a history of oral or intravenous BP use is not an absolute contraindication for dental implant placement, and dental implants can osseointegrate successfully in this patient population. Importantly, the studies currently available on this topic are of moderate to weak strength of evidence with inherent bias and limitations and hence results must be interpreted in this context. Well-controlled studies with higher strength of evidence and larger population sizes are required to more accurately address this topic in the future.

  20. Osseointegration of dental implants and osteonecrosis of the jaw in patients treated with bisphosphonate therapy: a systematic review.

    PubMed

    Chadha, Gurpreet K; Ahmadieh, Azadeh; Kumar, Satish; Sedghizadeh, Parish P

    2013-08-01

    Bisphosphonate (BP) drugs are a commonly prescribed group of medications used in the treatment of metabolic and oncologic bone disorders. The aim of this study was to conduct a systematic review in order to evaluate whether patients on BP therapy are appropriate candidates for dental implants as compared to patients not taking BP drugs with respect to successful implant osseointegration and the risk of developing bisphosphonate-related osteonecrosis of the jaw. Based on the current literature, a history of oral or intravenous BP use is not an absolute contraindication for dental implant placement, and dental implants can osseointegrate successfully in this patient population. Importantly, the studies currently available on this topic are of moderate to weak strength of evidence with inherent bias and limitations, and hence results must be interpreted in this context. Well-controlled studies with higher strength of evidence and larger population sizes are required to address this topic more accurately in the future.

  1. LINEAR ACCELERATOR

    DOEpatents

    Colgate, S.A.

    1958-05-27

    An improvement is presented in linear accelerators for charged particles with respect to the stable focusing of the particle beam. The improvement consists of providing a radial electric field transverse to the accelerating electric fields and angularly introducing the beam of particles in the field. The results of the foregoing is to achieve a beam which spirals about the axis of the acceleration path. The combination of the electric fields and angular motion of the particles cooperate to provide a stable and focused particle beam.

  2. Wakefield accelerators

    SciTech Connect

    Simpson, J.D.

    1990-01-01

    The search for new methods to accelerate particle beams to high energy using high gradients has resulted in a number of candidate schemes. One of these, wakefield acceleration, has been the subject of considerable R D in recent years. This effort has resulted in successful proof of principle experiments and in increased understanding of many of the practical aspects of the technique. Some wakefield basics plus the status of existing and proposed experimental work is discussed, along with speculations on the future of wake field acceleration. 10 refs., 6 figs.

  3. Findings from the experience with the punch technique for auditory osseointegrated implants: A retrospective single center comparative study.

    PubMed

    Bonilla, Alfonso; Magri, Carlos; Juan, Eulalia

    2017-05-23

    To compare the punch technique and linear incision with soft tissue reduction for the placement of auditory osseointegrated implants (AOI) and analyze results of osseointegration obtained with the punch technique as measured with the Implant Stability Quotient (ISQ). Case review of 34 patients who received auditory osseointegrated implants between January 2010 and July 2015 and were divided into two groups according to the surgical technique: 18 with the punch technique (PT) and 16 with the linear incision technique (LI). Minimum follow-up was four months (mean: 24 months; range 4-64 months). Included in the analysis were patient profiles and records of the demographic data, surgical indications, surgical technique, implant placement, surgical time, intraoperative complications, as well as postsurgical complications (Holgers classification) and implant stability quotients (ISQ). Use of larger abutments was significantly greater in the PT group (PT, 10mm; LI, 6mm, p<0.001). The PT technique resulted in a shorter procedure than the LI (PT, 20min; LI, 45min, p<0.001). Holgers classification scores identified significantly fewer skin complications one week after surgery for the PT group; however, only small differences were seen between the two groups at the one- and three-month control visits. As shown for our cohort, the punch technique for surgical placement of AOI is faster and presents fewer immediate postoperative complications when compared to the linear incision technique. The clinical application of the ISQ is a useful, easy method to demonstrate the status of osseointegration and, thus, the stability of the device. Copyright © 2017 Elsevier España, S.L.U. and Sociedad Española de Otorrinolaringología y Cirugía de Cabeza y Cuello. All rights reserved.

  4. A novel osseointegrated percutaneous prosthetic system for the treatment of patients with transfemoral amputation: A prospective study of 51 patients.

    PubMed

    Brånemark, R; Berlin, O; Hagberg, K; Bergh, P; Gunterberg, B; Rydevik, B

    2014-01-01

    Patients with transfemoral amputation (TFA) often experience problems related to the use of socket-suspended prostheses. The clinical development of osseointegrated percutaneous prostheses for patients with a TFA started in 1990, based on the long-term successful results of osseointegrated dental implants. Between 1999 and 2007, 51 patients with 55 TFAs were consecutively enrolled in a prospective, single-centre non-randomised study and followed for two years. The indication for amputation was trauma in 33 patients (65%) and tumour in 12 (24%). A two-stage surgical procedure was used to introduce a percutaneous implant to which an external amputation prosthesis was attached. The assessment of outcome included the use of two self-report questionnaires, the Questionnaire for Persons with a Transfemoral Amputation (Q-TFA) and the Short-Form (SF)-36. The cumulative survival at two years' follow-up was 92%. The Q-TFA showed improved prosthetic use, mobility, global situation and fewer problems (all p < 0.001). The physical function SF-36 scores were also improved (p < 0.001). Superficial infection was the most frequent complication, occurring 41 times in 28 patients (rate of infection 54.9%). Most were treated effectively with oral antibiotics. The implant was removed in four patients because of loosening (three aseptic, one infection). Osseointegrated percutaneous implants constitute a novel form of treatment for patients with TFA. The high cumulative survival rate at two years (92%) combined with enhanced prosthetic use and mobility, fewer problems and improved quality of life, supports the 'revolutionary change' that patients with TFA have reported following treatment with osseointegrated percutaneous prostheses.

  5. Modulation of Host Osseointegration during Bone Regeneration by Controlling Exogenous Stem Cells Differentiation Using a Material Approach.

    PubMed

    Yu, Xiaohua; Wang, Liping; Xia, Zengmin; Chen, Li; Jiang, Xi; Rowe, David; Wei, Mei

    2014-02-01

    Stem cell-based tissue engineering for large bone defect healing has attracted enormous attention in regenerative medicine. However, sufficient osseointegration of the grafts combined with exogenous stem cells still remains a major challenge. Here we developed a material approach to modulate the integration of the grafts to the host tissue when exogenous bone marrow stromal cells (BMSCs) were used as donor cells. Distinctive osseointegration of bone grafts was observed as we varied the content of hydroxyapatite (HA) in the tissue scaffolds implanted in a mouse femur model. More than 80% of new bone was formed in the first two weeks of implantation in high HA content scaffold but lack of host integration while only less than 5% of the new bone was formed during this time period in the no HA group but with much stronger host integration. Cell origin analysis leveraging GFP reporter indicates new bone in HA containing groups was mainly derived from donor BMSCs. In comparison, both host and donor cells were found on new bone surface in the no HA groups which led to seamless bridging between host tissue and the scaffold. Most importantly, host integration during bone formation is closely dictated to the content of HA present in the scaffolds. Taken together, we demonstrate a material approach to modulate the osseointegration of bone grafts in the context of exogenous stem cell-based bone healing strategy which might lead to fully functional bone tissue regeneration.

  6. The effects of zoledronic acid and dexamethasone on osseointegration of endosseous implants: histological and histomorphometrical evaluation in rats.

    PubMed

    de Oliveira, Marcio A; Asahi, Denise A; Silveira, Celey A E; Lima, Luiz Antonio P A; Glick, Michael; Gallottini, Marina

    2015-04-01

    Bisphosphonates are a widely used class of drugs that prevent bone loss. Several side effects related to bisphosphonate therapy have been reported, including osteonecrosis of the jaws associated with invasive dental procedures and implants placement. To evaluate the influence of intravenous nitrogen-containing BPs in combination with or without dexamethasone on osseointegration of titanium implants placed in an animal model. Twenty-seven male Wistar rats were divided into three groups: group 1 was treated solely with zoledronic acid, group 2 was treated with zoledronic acid and dexamethasone, and group 3 did only receive saline solution injections. Two endosseous implants were placed in each tibia, and three animals from each group were sacrificed at postoperative times of seven, 14, and 28 days. Non-decalcified sections were observed with light microscopy for histological and histomorphometrical analyses. Histomorphometrical analysis using the animals and the implants as unit of measurement revealed no statistically significant difference regarding bone-implant contact and bone density among the three groups. Histological observation revealed that zoledronic acid-treated animals in combination with or without dexamethasone showed expressive less bone remodeling activity at 14 and 28 days after implants placement, compared with control specimens. The studied bisphosphonate regimens did not interfere with the osseointegration of the implants, cortical, or medular bone deposition, but a possible lack of bone remodeling of the original cortical bone may affect long-term osseointegration. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  7. Measurement of implant stability and auditory pure-tone thresholds of Baha patients comparing osteosysthesis and osseointegrated systems.

    PubMed

    Rahne, Torsten; Götze, Gerrit; Pein, M Katharina

    2015-03-01

    With bone-anchored hearing systems the implant-bone junction is critical for the transmission of mechanical vibrations to the skull. The implant stability might differ between available and widely applied implants and can be estimated by resonance frequency analysis. The implant stability and the audiological performance of ten adult long-time users where a bone-anchored hearing system was connected by an Baha osseointegrated implant (Cochlear Ltd, Mölnlycke, Sweden) were compared with the implant stability of fourteen adult patients provided with a Ti-epiplating osteosysthesis system (Medicon, Tuttlingen, Germany). The acute implant stability was compared between these two implants with one cadaveric skull. The results show higher resonance frequencies and thus higher implant stability for the osseointegrating system of both, measuring acute and after long-time use of the implants. The audiological outcomes show frequency dependent differences between both systems as determined by comparing pure-tone bone-conduction audiometry. However, measuring thresholds by a direct stimulation of the implant reveals better hearing with low frequencies for the osseointegrated system and for high frequencies with the osteosysthesis system. At all, the implant selection has an impact on the implant stability and on the pure-tone hearing. Copyright © 2014. Published by Elsevier GmbH.

  8. A Reductionist Approach to Extract Robust Molecular Markers from Microarray Data Series -Isolating Markers to Track Osseointegration.

    PubMed

    Barik, Anwesha; Banerjee, Satarupa; Dhara, Santanu; Chakravorty, Nishant

    2017-03-10

    Complexities in the full genome expression studies hinder the extraction of tracker genes to analyze the course of biological events. In this study, we demonstrate the applications of supervised machine learning methods to reduce the irrelevance in microarray data series and thereby extract robust molecular markers to track biological processes. The methodology has been illustrated by analyzing whole genome expression studies on bone-implant integration (ossointegration). Being a biological process, osseointegration is known to leave a trail of genetic footprint during the course. In spite of existence of enormous amount of raw data in public repositories, researchers still do not have access to a panel of genes that can definitively track osseointegrtion. The results from our study revealed panels comprising of matrix metalloproteinases and collagen genes were able to track osseointegration on implant surfaces (MMP9 and COL1A2 on micro-textured; MMP12 and COL6A3 on superimposed nano-textured surfaces) 100% classification accuracy, specificity and sensitivity. Further, our analysis showed the importance of the progression of the duration in establishment of the mechanical connection at bone-implant surface. The findings from this study are expected to be useful to researchers investigating osseointegration of novel implant materials especially at the early stage. The methodology demonstrated can be easily adapted by scientists in different fields to analyze large databases for other biological processes.

  9. Low-magnitude high-frequency loading via whole body vibration enhances bone-implant osseointegration in ovariectomized rats.

    PubMed

    Chen, BaiLing; Li, YiQiang; Xie, DengHui; Yang, XiaoXi

    2012-05-01

    Osseointegration is vital to avoid long-time implants loosening after implantation surgery. This study investigated the effect of low-magnitude high-frequency (LMHF) loading via whole body vibration on bone-implant osseointegration in osteoporotic rats, and a comparison was made between LMHF vibration and alendronate on their effects. Thirty rats were ovariectomized to induce osteoporosis, and then treated with LMHF vibration (VIB) or alendronate (ALN) or a control treatment (OVX). Another 10 rats underwent sham operation to establish Sham control group. Prior to treatment, hydroxyapatite (HA)-coated titanium implants were inserted into proximal tibiae bilaterally. Both LMHF vibration and alendronate treatment lasted for 8 weeks. Histomorphometrical assess showed that both group VIB, ALN and Sham significantly increased bone-to-implant contact and peri-implant bone fraction (p < 0.05) when compared with group OVX. Nevertheless the bone-to-implant contact and peri-implant bone fraction of group VIB were inferior to group ALN and Sham (p < 0.05). Biomechanical tests also revealed similar results in maximum push out force and interfacial shear strength. Accordingly, it is concluded that LMHF loading via whole body vibration enhances bone-to-implant osseointegration in ovariectomized rats, but its effectiveness is weaker than alendronate. Copyright © 2011 Orthopaedic Research Society.

  10. ION ACCELERATOR

    DOEpatents

    Bell, J.S.

    1959-09-15

    An arrangement for the drift tubes in a linear accelerator is described whereby each drift tube acts to shield the particles from the influence of the accelerating field and focuses the particles passing through the tube. In one embodiment the drift tube is splii longitudinally into quadrants supported along the axis of the accelerator by webs from a yoke, the quadrants. webs, and yoke being of magnetic material. A magnetic focusing action is produced by energizing a winding on each web to set up a magnetic field between adjacent quadrants. In the other embodiment the quadrants are electrically insulated from each other and have opposite polarity voltages on adjacent quadrants to provide an electric focusing fleld for the particles, with the quadrants spaced sufficienily close enough to shield the particles within the tube from the accelerating electric field.

  11. Acceleration switch

    DOEpatents

    Abbin, J.P. Jr.; Devaney, H.F.; Hake, L.W.

    1979-08-29

    The disclosure relates to an improved integrating acceleration switch of the type having a mass suspended within a fluid filled chamber, with the motion of the mass initially opposed by a spring and subsequently not so opposed.

  12. Acceleration switch

    DOEpatents

    Abbin, Jr., Joseph P.; Devaney, Howard F.; Hake, Lewis W.

    1982-08-17

    The disclosure relates to an improved integrating acceleration switch of the type having a mass suspended within a fluid filled chamber, with the motion of the mass initially opposed by a spring and subsequently not so opposed.

  13. Effects of a micro/nano rough strontium-loaded surface on osseointegration.

    PubMed

    Li, Yongfeng; Qi, Yaping; Gao, Qi; Niu, Qiang; Shen, Mingming; Fu, Qian; Hu, Kaijin; Kong, Liang

    2015-01-01

    We developed a hierarchical hybrid micro/nanorough strontium-loaded Ti (MNT-Sr) surface fabricated through hydrofluoric acid etching followed by magnetron sputtering and evaluated the effects of this surface on osseointegration. Samples with a smooth Ti (ST) surface, micro Ti (MT) surface treated with hydrofluoric acid etching, and strontium-loaded nano Ti (NT-Sr) surface treated with SrTiO3 target deposited via magnetron sputtering technique were investigated in parallel for comparison. The results showed that MNT-Sr surfaces were prepared successfully and with high interface bonding strength. Moreover, slow Sr release could be detected when the MNT-Sr and NT-Sr samples were immersed in phosphate-buffered saline. In in vitro experiments, the MNT-Sr surface significantly improved the proliferation and differentiation of osteoblasts compared with the other three groups. Twelve weeks after the four different surface implants were inserted into the distal femurs of 40 rats, the bone-implant contact in the ST, MT, NT-Sr, and MNT-Sr groups were 39.70%±6.00%, 57.60%±7.79%, 46.10%±5.51%, and 70.38%±8.61%, respectively. In terms of the mineral apposition ratio, the MNT-Sr group increased by 129%, 58%, and 25% compared with the values of the ST, MT, and NT-Sr groups, respectively. Moreover, the maximal pullout force in the MNT-Sr group was 1.12-, 0.31-, and 0.69-fold higher than the values of the ST, MT, and NT-Sr groups, respectively. These results suggested that the MNT-Sr surface has a synergistic effect of hierarchical micro/nano-topography and strontium for enhanced osseointegration, and it may be a promising option for clinical use. Compared with the MT surface, the NT-Sr surface significantly improved the differentiation of osteoblasts in vitro. In the in vivo animal experiment, the MT surface significantly enhanced the bone-implant contact and maximal pullout force than the NT-Sr surface.

  14. Effect of Osteotomy Preparation on Osseointegration of Immediately Loaded, Tapered Dental Implants.

    PubMed

    Stavropoulos, A; Cochran, D; Obrecht, M; Pippenger, B E; Dard, M

    2016-03-01

    The aim of the present preclinical in vivo study was to evaluate whether a modified "drill-only" protocol, involving slight underpreparation of the implant site, may have an effect on aspects of osseointegration of a novel bone-level tapered implant, compared with the "standard drilling" protocol involving taping and profiling of the marginal aspect of the implant socket. In each side of the edentulated and completely healed mandible of 11 minipigs, 2 tapered implants (8 mm long × 4.1 mm Ø, BLT; Institut Straumann AG, Basel, Switzerland) were installed either with the drill-only or the standard drilling protocol. Significantly lower average insertion torque values were recorded for the standard drilling protocol group (52 ± 29 Ncm) compared with the drill-only group (70 ± 27 Ncm) (t test, P ≤ 0.05); no significant difference was observed between the 2 groups regarding implant stability, by means of resonance frequency analysis (75 ± 8 vs. 75 ± 6, respectively). Half of the implants were immediately loaded and the rest were submerged, providing observation times of 8 or 4 wk, respectively. Non-decalcified histological and histomorphometric analysis of the implants with surrounding tissues showed no significant differences between the 2 drilling protocols regarding the distance from the implant platform to the first coronal bone-to-implant contact (f-BIC), the total bone-to-implant contact (BIC) as a percentage of the total implant perimeter, and the bone density in an area extending 1 mm laterally from the implant (BATA) within 2 rectangular regions of interest (ROIs) 4 mm in height, representing the coronal (parallel-walled) and apical (tapered) aspect of the implant (ROI 1 and ROI 2, respectively) in non-submerged implants. In general, marginal peri-implant bone levels were at or slightly apical to the implant platform, and large amounts of bone-to-implant contact were observed. In contrast, immediately loaded implants placed with the drill-only protocol

  15. The experimental research on two-generation BLB dental implants - part I: surface modification and osseointegration.

    PubMed

    Yin, Kaifeng; Wang, Zhifeng; Fan, Xin; Bian, Yuanyuan; Guo, Jing; Lan, Jing

    2012-07-01

    The study was designed to evaluate the comparative effect of osseointegration induced by the dental implants of Beijing Leiden Biomaterial (BLB) and BLBIII. The surface properties ofBLBI and BLBIII were studied through thermal field-scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDS) and optical profilometer. A total of 36 BLBI and BLBIII implants, with each of the two groups possessing 18, were randomly implanted into the extraction fossa of the mandibular premolar areas of six Beagles. The animals were then executed 2, 4 and 8 weeks after the surgery, which was followed by macroscopic examination and histomorphometric analysis. Typical cloud-form microstructure was found on the surface of BLBI implant, which was distributed widely yet in an irregular way. The surface of BLBIII implant was mainly featured by a highly porous layer. The EDS spectra of BLBI indicated the peaks of calcium (Ca) and phosphorous (P) compatible with apatite phase, while the peaks of Ca, P, oxygen and titanium were incorporated in the BLBIII group. The ratio of Ca and K showed no significant differences in the surface chemical composition of BLBI and BLBIII. Surface microtopographic analysis showed a statistical difference (P<0.01) in the roughness between BLBI (R(a)) and BLBIII. In the healing period, a larger amount of osteoid and bone tissues were observed in the areas surrounding the BLBIII group than those of the BLBII group. After 2 and 4 weeks of the surgery, the bone-implant contact (BIC) of BLBIII group presented higher value of statistical significance (P<0.05) than that of BLBI. However, after the 8-week healing period, the BIC difference between the two groups proved to be of no statistical significance (P>0.05). Micro-arc oxidation (MAO) and electrophoresis deposition (EPD) are able to produce a highly porous layer on the surface of BLBIII, which is characterized by a relatively stable Ca/P ratio similar to that of the hydroxyapatite layer. Therefore

  16. Effects of a micro/nano rough strontium-loaded surface on osseointegration

    PubMed Central

    Li, Yongfeng; Qi, Yaping; Gao, Qi; Niu, Qiang; Shen, Mingming; Fu, Qian; Hu, Kaijin; Kong, Liang

    2015-01-01

    We developed a hierarchical hybrid micro/nanorough strontium-loaded Ti (MNT-Sr) surface fabricated through hydrofluoric acid etching followed by magnetron sputtering and evaluated the effects of this surface on osseointegration. Samples with a smooth Ti (ST) surface, micro Ti (MT) surface treated with hydrofluoric acid etching, and strontium-loaded nano Ti (NT-Sr) surface treated with SrTiO3 target deposited via magnetron sputtering technique were investigated in parallel for comparison. The results showed that MNT-Sr surfaces were prepared successfully and with high interface bonding strength. Moreover, slow Sr release could be detected when the MNT-Sr and NT-Sr samples were immersed in phosphate-buffered saline. In in vitro experiments, the MNT-Sr surface significantly improved the proliferation and differentiation of osteoblasts compared with the other three groups. Twelve weeks after the four different surface implants were inserted into the distal femurs of 40 rats, the bone–implant contact in the ST, MT, NT-Sr, and MNT-Sr groups were 39.70%±6.00%, 57.60%±7.79%, 46.10%±5.51%, and 70.38%±8.61%, respectively. In terms of the mineral apposition ratio, the MNT-Sr group increased by 129%, 58%, and 25% compared with the values of the ST, MT, and NT-Sr groups, respectively. Moreover, the maximal pullout force in the MNT-Sr group was 1.12-, 0.31-, and 0.69-fold higher than the values of the ST, MT, and NT-Sr groups, respectively. These results suggested that the MNT-Sr surface has a synergistic effect of hierarchical micro/nano-topography and strontium for enhanced osseointegration, and it may be a promising option for clinical use. Compared with the MT surface, the NT-Sr surface significantly improved the differentiation of osteoblasts in vitro. In the in vivo animal experiment, the MT surface significantly enhanced the bone-implant contact and maximal pullout force than the NT-Sr surface. PMID:26213468

  17. Low BMD affects initial stability and delays stem osseointegration in cementless total hip arthroplasty in women

    PubMed Central

    2012-01-01

    Background and purpose Immediate implant stability is a key factor for success in cementless total hip arthroplasty (THA). Low bone mineral density (BMD) and age-related geometric changes of the proximal femur may jeopardize initial stability and osseointegration. We compared migration of hydroxyapatite-coated femoral stems in women with or without low systemic BMD. Patients and methods 61 female patients with hip osteoarthritis were treated with cementless THA with anatomically designed hydroxyapatite-coated femoral stems and ceramic-ceramic bearing surfaces (ABG-II). Of the 39 eligible patients between the ages of 41 and 78 years, 12 had normal systemic BMD and 27 had osteopenia or osteoporosis. According to the Dorr classification, 21 had type A bone and 18 had type B. Translational and rotational migration of the stems was evaluated with radiostereometric analysis (RSA) up to 2 years after surgery. Results Patients with low systemic BMD showed higher subsidence of the femoral stem during the first 3 months after surgery than did those with normal BMD (difference = 0.6, 95% CI: 0.1–1.1; p = 0.03). Low systemic BMD (odds ratio (OR) = 0.1, CI: 0.006–1.0; p = 0.02), low local hip BMD (OR = 0.3, CI: 0.1–0.7; p = 0.005) and ageing (OR = 1.1, CI: 1.0–1.2; p = 0.02) were risk factors for delayed translational stability. Ageing and low canal flare index were risk factors for delayed rotational stabilization (OR = 3, CI: 1.1–9; p = 0.04 and OR = 1.1, CI: 1.0–1.2; p = 0.02, respectively). Harris hip score and WOMAC score were similar in patients with normal systemic BMD and low systemic BMD. Interpretation Low BMD, changes in intraosseous dimensions of the proximal femur, and ageing adversely affected initial stability and delayed osseointegration of cementless stems in women. PMID:22489886

  18. LINEAR ACCELERATOR

    DOEpatents

    Christofilos, N.C.; Polk, I.J.

    1959-02-17

    Improvements in linear particle accelerators are described. A drift tube system for a linear ion accelerator reduces gap capacity between adjacent drift tube ends. This is accomplished by reducing the ratio of the diameter of the drift tube to the diameter of the resonant cavity. Concentration of magnetic field intensity at the longitudinal midpoint of the external sunface of each drift tube is reduced by increasing the external drift tube diameter at the longitudinal center region.

  19. Measurement of surface microtopography

    NASA Technical Reports Server (NTRS)

    Wall, S. D.; Farr, T. G.; Muller, J.-P.; Lewis, P.; Leberl, F. W.

    1991-01-01

    Acquisition of ground truth data for use in microwave interaction modeling requires measurement of surface roughness sampled at intervals comparable to a fraction of the microwave wavelength and extensive enough to adequately represent the statistics of a surface unit. Sub-centimetric measurement accuracy is thus required over large areas, and existing techniques are usually inadequate. A technique is discussed for acquiring the necessary photogrammetric data using twin film cameras mounted on a helicopter. In an attempt to eliminate tedious data reduction, an automated technique was applied to the helicopter photographs, and results were compared to those produced by conventional stereogrammetry. Derived root-mean-square (RMS) roughness for the same stereo-pair was 7.5 cm for the automated technique versus 6.5 cm for the manual method. The principal source of error is probably due to vegetation in the scene, which affects the automated technique but is ignored by a human operator.

  20. New cosurface capacitive stimulators for the development of active osseointegrative implantable devices

    NASA Astrophysics Data System (ADS)

    Soares Dos Santos, Marco P.; Marote, Ana; Santos, T.; Torrão, João; Ramos, A.; Simões, José A. O.; da Cruz E Silva, Odete A. B.; Furlani, Edward P.; Vieira, Sandra I.; Ferreira, Jorge A. F.

    2016-07-01

    Non-drug strategies based on biophysical stimulation have been emphasized for the treatment and prevention of musculoskeletal conditions. However, to date, an effective stimulation system for intracorporeal therapies has not been proposed. This is particularly true for active intramedullary implants that aim to optimize osseointegration. The increasing demand for these implants, particularly for hip and knee replacements, has driven the design of innovative stimulation systems that are effective in bone-implant integration. In this paper, a new cosurface-based capacitive system concept is proposed for the design of implantable devices that deliver controllable and personalized electric field stimuli to target tissues. A prototype architecture of this system was constructed for in vitro tests, and its ability to deliver controllable stimuli was numerically analyzed. Successful results were obtained for osteoblastic proliferation and differentiation in the in vitro tests. This work provides, for the first time, a design of a stimulation system that can be embedded in active implantable devices for controllable bone-implant integration and regeneration. The proposed cosurface design holds potential for the implementation of novel and innovative personalized stimulatory therapies based on the delivery of electric fields to bone cells.

  1. Design of prosthetic cantilever bridgework supported by osseointegrated implants using the finite element method.

    PubMed

    Young, F A; Williams, K R; Draughn, R; Strohaver, R

    1998-01-01

    The aim of the present work was to establish a design procedure for fixed metal prostheses supported by osseointegrated implants in order to prevent permanent deformation and hence failure following loading. Previously, the cantilever cross-sectional shape in the buccal lingual plane has been based on clinical experience and subjectivity. This work has relied on the use of linear elastic finite element analysis in order to generate a maximum effective stress at which permanent deformation commences on loading. A number of different cross-sectional shapes were investigated, both of conventional design as well as new innovative possibilities. Both straight and curved cantilever beams 26 mm long were examined. The design failure chosen was based on a von Mises plastic collapse principle by comparing the calculated effective stresses with the yield stress of the metal in simple tension. It was found that the "L" shaped design was more rigid than other designs for a given mass, while a framework based on an open "I" section offers good possibilities particularly when used as curved shapes. Assuming a failure criterion based on the von Mises principle, then "L" shaped Co/Cr or stainless steel frameworks, typically 26 mm of cantilever span, undergo permanent deformation at end loadings between 130 and 140 N depending on section curvature. Since it is known biting loads can exceed these values, good design is critical if such failures are to be avoided.

  2. Engineered protein coatings to improve the osseointegration of dental and orthopaedic implants.

    PubMed

    Raphel, Jordan; Karlsson, Johan; Galli, Silvia; Wennerberg, Ann; Lindsay, Christopher; Haugh, Matthew G; Pajarinen, Jukka; Goodman, Stuart B; Jimbo, Ryo; Andersson, Martin; Heilshorn, Sarah C

    2016-03-01

    Here we present the design of an engineered, elastin-like protein (ELP) that is chemically modified to enable stable coatings on the surfaces of titanium-based dental and orthopaedic implants by novel photocrosslinking and solution processing steps. The ELP includes an extended RGD sequence to confer bio-signaling and an elastin-like sequence for mechanical stability. ELP thin films were fabricated on cp-Ti and Ti6Al4V surfaces using scalable spin and dip coating processes with photoactive covalent crosslinking through a carbene insertion mechanism. The coatings withstood procedures mimicking dental screw and hip replacement stem implantations, a key metric for clinical translation. They promoted rapid adhesion of MG63 osteoblast-like cells, with over 80% adhesion after 24 h, compared to 38% adhesion on uncoated Ti6Al4V. MG63 cells produced significantly more mineralization on ELP coatings compared to uncoated Ti6Al4V. Human bone marrow mesenchymal stem cells (hMSCs) had an earlier increase in alkaline phosphatase activity, indicating more rapid osteogenic differentiation and mineral deposition on adhesive ELP coatings. Rat tibia and femur in vivo studies demonstrated that cell-adhesive ELP-coated implants increased bone-implant contact area and interfacial strength after one week. These results suggest that ELP coatings withstand surgical implantation and promote rapid osseointegration, enabling earlier implant loading and potentially preventing micromotion that leads to aseptic loosening and premature implant failure.

  3. The impact of a modified cutting flute implant design on osseointegration.

    PubMed

    Jimbo, R; Tovar, N; Marin, C; Teixeira, H S; Anchieta, R B; Silveira, L M; Janal, M N; Shibli, J A; Coelho, P G

    2014-07-01

    Information concerning the effects of the implant cutting flute design on initial stability and its influence on osseointegration in vivo is limited. This study evaluated the early effects of implants with a specific cutting flute design placed in the sheep mandible. Forty-eight dental implants with two different macro-geometries (24 with a specific cutting flute design - Blossom group; 24 with a self-tapping design - DT group) were inserted into the mandibular bodies of six sheep; the maximum insertion torque was recorded. Samples were retrieved and processed for histomorphometric analysis after 3 and 6 weeks. The mean insertion torque was lower for Blossom implants (P<0.001). No differences in histomorphometric results were observed between the groups. At 3 weeks, P=0.58 for bone-to-implant contact (BIC) and P=0.52 for bone area fraction occupied (BAFO); at 6 weeks, P=0.55 for BIC and P=0.45 for BAFO. While no histomorphometric differences were observed, ground sections showed different healing patterns between the implants, with better peri-implant bone organization around those with the specific cutting flute design (Blossom group). Implants with the modified cutting flute design had a significantly reduced insertion torque compared to the DT implants with a traditional cutting thread, and resulted in a different healing pattern. Copyright © 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  4. Determination of the success and failure of root-form osseointegrated dental implants.

    PubMed

    Tonetti, M S

    1999-06-01

    Permucosal osseointegrated dental implants are a highly effective and predictable treatment modality for edentulism. This review discusses some controversial aspects of the definitions for success and failure of root-form dental implants. The discussion will focus on the underlying pathologies that, if untreated, may lead to loss of the implanted device. Few clinical syndromes are described based on human pathological material and clinical presentation. The theoretical chronological relationship between implant loss and the incidence of pathology of the soft- and hard-tissue seal around implants is also discussed. The review also examines the finding that implant failures are not randomly distributed in the treated populations and that implant loss clusters in specific high-risk groups and individuals. Known risk indicators, and possible risk factors, are discussed, taking into account the patient, the reconstruction, the implant, and implant site-specific factors. Particular emphasis is placed on the need for better determination of whether periodontal patients are at higher risk for implant failures as a consequence of their increased susceptibility to infectious, inflammatory-response-driven tissue breakdown.

  5. Engineered Protein Coatings to Improve the Osseointegration of Dental and Orthopaedic Implants

    PubMed Central

    Raphel, Jordan; Karlsson, Johan; Galli, Silvia; Wennerberg, Ann; Lindsay, Christopher; Haugh, Matthew; Pajarinen, Jukka; Goodman, Stuart B.; Jimbo, Ryo; Andersson, Martin; Heilshorn, Sarah C.

    2016-01-01

    Here we present the design of an engineered, elastin-like protein (ELP) that is chemically modified to enable stable coatings on the surfaces of titanium-based dental and orthopaedic implants by novel photocrosslinking and solution processing steps. The ELP includes an extended RGD sequence to confer bio-signaling and an elastin-like sequence for mechanical stability. ELP thin films were fabricated on cp-Ti and Ti6Al4V surfaces using scalable spin and dip coating processes with photoactive covalent crosslinking through a carbene insertion mechanism. The coatings withstood procedures mimicking dental screw and hip replacement stem implantations, a key metric for clinical translation. They promoted rapid adhesion of MG63 osteoblast-like cells, with over 80% adhesion after 24 hours, compared to 38% adhesion on uncoated Ti6Al4V. MG63 cells produced significantly more mineralization on ELP coatings compared to uncoated Ti6Al4V. Human bone marrow mesenchymal stem cells (hMSCs) had an earlier increase in alkaline phosphatase activity, indicating more rapid osteogenic differentiation and mineral deposition on adhesive ELP coatings. Rat tibia and femur in vivo studies demonstrated that cell-adhesive ELP-coated implants increased bone-implant contact area and interfacial strength after one week. These results suggest that ELP coatings withstand surgical implantation and promote rapid osseointegration, enabling earlier implant loading and potentially preventing micromotion that leads to aseptic loosening and premature implant failure. PMID:26790146

  6. Effects of magnesium intake deficiency on bone metabolism and bone tissue around osseointegrated implants.

    PubMed

    Belluci, Marina Montosa; Giro, Gabriela; del Barrio, Ricardo Andrés Landazuri; Pereira, Rosa Maria Rodrigues; Marcantonio, Elcio; Orrico, Silvana Regina Perez

    2011-07-01

    This study evaluated the effect of magnesium dietary deficiency on bone metabolism and bone tissue around implants with established osseointegration. For this, 30 rats received an implant in the right tibial metaphysis. After 60 days for healing of the implants, the animals were divided into groups according to the diet received. Control group (CTL) received a standard diet with adequate magnesium content, while test group (Mg) received the same diet except for a 90% reduction of magnesium. The animals were sacrificed after 90 days for evaluation of calcium, magnesium, osteocalcin and parathyroid hormone (PTH) serum levels and the deoxypyridinoline (DPD) level in the urine. The effect of magnesium deficiency on skeletal bone tissue was evaluated by densitometry of the lumbar vertebrae, while the effect of bone tissue around titanium implants was evaluated by radiographic measurement of cortical bone thickness and bone density. The effect on biomechanical characteristics was verified by implant removal torque testing. Magnesium dietary deficiency resulted in a decrease of the magnesium serum level and an increase of PTH and DPD levels (P ≤ 0.05). The Mg group also presented a loss of systemic bone mass, decreased cortical bone thickness and lower values of removal torque of the implants (P ≤ 0.01). The present study concluded that magnesium-deficient diet had a negative influence on bone metabolism as well as on the bone tissue around the implants. © 2010 John Wiley & Sons A/S.

  7. Inhibition of cathepsin K promotes osseointegration of titanium implants in ovariectomised rats

    PubMed Central

    Yi, Chun; Hao, Ke-Yi; Ma, Ting; Lin, Ye; Ge, Xi-Yuan; Zhang, Yu

    2017-01-01

    The bone mineral deficiency in osteoporosis poses a threat to the long-term outcomes of endosseous implants. The inhibitors of cathepsin K (CatK) significantly affect bone turnover, bone mineral density (BMD) and bone strength in the patients with osteoporosis. Therefore, we hypothesised that the application of a CatK inhibitor (CatKI) could increase the osseointegration of endosseous implants under osteoporotic conditions. Odanacatib (ODN), a highly selective CatKI, was chosen as the experimental drug. Sixteen rats were randomised into 4 groups: sham, ovariectomy (OVX) with vehicle, OVX with low-dose ODN (5 mg/kg) and OVX with high-dose ODN (30 mg/kg). Titanium implants were placed into the distal metaphysis of bilateral femurs of each OVX rat. After 8 weeks of gavaging, CatKI treatment increased the removal torque, BMD and bone-to-implant contact (BIC). Moreover, high-dose CatKI exerted a better influence than low-dose CatKI. Furthermore, CatKI treatment not only robustly suppressed CatK gene (CTSK) expression, but also moderately reduced expression of the osteoblast-related genes Runx2, Collagen-1, BSP, Osterix, OPN, SPP1 and ALP. Thus, CatKI could affect the osteoblast-related genes, although the balance of bone turnover was achieved mainly by CatK inhibition. In conclusion, CatKI prevented bone loss and aided endosseous implantation in osteoporotic conditions. PMID:28304382

  8. Simple Coating with Fibronectin Fragment Enhances Stainless Steel Screw Osseointegration in Healthy and Osteoporotic Rats

    PubMed Central

    Agarwal, Rachit; González-García, Cristina; Torstrick, Brennan; Guldberg, Robert E.; Salmerón-Sánchez, Manuel; García, Andrés J.

    2015-01-01

    Metal implants are widely used to provide structural support and stability in current surgical treatments for bone fractures, spinal fusions, and joint arthroplasties as well as craniofacial and dental applications. Early implant-bone mechanical fixation is an important requirement for the successful performance of such implants. However, adequate osseointegration has been difficult to achieve especially in challenging disease states like osteoporosis due to reduced bone mass and strength. Here, we present a simple coating strategy based on passive adsorption of FN7-10, a recombinant fragment of human fibronectin encompassing the major cell adhesive, integrin-binding site, onto 316-grade stainless steel (SS). FN7-10 coating on SS surfaces promoted α5β1 integrin-dependent adhesion and osteogenic differentiation of human mesenchymal stem cells. FN7-10-coated SS screws increased bone-implant mechanical fixation compared to uncoated screws by 30% and 45% at 1 and 3 months, respectively, in healthy rats. Importantly, FN7-10 coating significantly enhanced bone-screw fixation by 57% and 32% at 1 and 3 months, respectively, and bone-implant ingrowth by 30% at 3 months compared to uncoated screws in osteoporotic rats. These coatings are easy to apply intra-operatively, even to implants with complex geometries and structures, facilitating the potential for rapid translation to clinical settings. PMID:26100343

  9. Tantalum implanted entangled porous titanium promotes surface osseointegration and bone ingrowth

    PubMed Central

    Wang, Qi; Qiao, Yuqin; Cheng, Mengqi; Jiang, Guofeng; He, Guo; Chen, Yunsu; Zhang, Xianlong; Liu, Xuanyong

    2016-01-01

    Porous Ti is considered to be an ideal graft material in orthopaedic and dental surgeries due to its similar spatial structures and mechanical properties to cancellous bone. In this work, to overcome the bioinertia of Ti, Ta-implanted entangled porous titanium (EPT) was constructed by plasma immersion ion implantation & deposition (PIII&D) method. Ca-implanted and unimplanted EPTs were investigated as control groups. Although no difference was found in surface topography and mechanical performances, both Ca- and Ta-implanted groups had better effects in promoting MG-63 cell viability, proliferation, differentiation, and mineralization than those of unimplanted group. The expression of osteogenic-related markers examined by qRT-PCR and western blotting was upregulated in Ca- and Ta-implanted groups. Moreover, Ta-implanted EPT group could reach a higher level of these effects than that of Ca-implanted group. Enhanced osseointegration of both Ca- and Ta-implanted EPT implants was demonstrated through in vivo experiments, including micro-CT evaluation, push-out test, sequential fluorescent labeling and histological observation. However, the Ta-implanted group possessed more stable and continuous osteogenic activity. Our results suggest that Ta-implanted EPT can be developed as one of the highly efficient graft material for bone reconstruction situations. PMID:27185196

  10. Shape-memory alloy overload protection device for osseointegrated transfemoral implant prosthetic limb attachment system

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Shao, Fei; Hughes, Steven

    2002-11-01

    The osseointegrated trans-femoral implant system provides a direct anchoring technique to attach prosthetic limb. This technique was first introduced PI Brenmark in Sweden. The UK had the first clinical trial in 1997 and currently has 6 active limb wearers. The success of this procedure has the potential for improved gait function and mobility, increased employability and significant long-term improvements in the quality of life for above knee amputees. However, the significant load involved in the trans-femoral implant system has caused permanent deformation and/or fractures of the implant abutment in several occasions. To protect the implant system, the implant abutment in particularly, an overloading protection device was introduced. The device uses mechanical mechanism to release torsion overload on the abutment. However, the bending overload protection remains unsolved. To solve the problem, a new overload protection device was developed. This device uses SMA component for bending overload protection. In this paper, the results of non-linear finite element modelling of the SMA and steel (AISI 1040) components were presented. Experiments were also carried out using steel components to assess the design which is based on the non-linear property of the materials.

  11. Tantalum implanted entangled porous titanium promotes surface osseointegration and bone ingrowth

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Qiao, Yuqin; Cheng, Mengqi; Jiang, Guofeng; He, Guo; Chen, Yunsu; Zhang, Xianlong; Liu, Xuanyong

    2016-05-01

    Porous Ti is considered to be an ideal graft material in orthopaedic and dental surgeries due to its similar spatial structures and mechanical properties to cancellous bone. In this work, to overcome the bioinertia of Ti, Ta-implanted entangled porous titanium (EPT) was constructed by plasma immersion ion implantation & deposition (PIII&D) method. Ca-implanted and unimplanted EPTs were investigated as control groups. Although no difference was found in surface topography and mechanical performances, both Ca- and Ta-implanted groups had better effects in promoting MG-63 cell viability, proliferation, differentiation, and mineralization than those of unimplanted group. The expression of osteogenic-related markers examined by qRT-PCR and western blotting was upregulated in Ca- and Ta-implanted groups. Moreover, Ta-implanted EPT group could reach a higher level of these effects than that of Ca-implanted group. Enhanced osseointegration of both Ca- and Ta-implanted EPT implants was demonstrated through in vivo experiments, including micro-CT evaluation, push-out test, sequential fluorescent labeling and histological observation. However, the Ta-implanted group possessed more stable and continuous osteogenic activity. Our results suggest that Ta-implanted EPT can be developed as one of the highly efficient graft material for bone reconstruction situations.

  12. The promotion of osseointegration of titanium surfaces by coating with silk protein sericin.

    PubMed

    Nayak, Sunita; Dey, Tuli; Naskar, Deboki; Kundu, Subhas C

    2013-04-01

    A promising strategy to influence the osseointegration process around orthopaedic titanium implants is the immobilization of bioactive molecules. This recruits appropriate interaction between the surface and the tissue by directing cells adhesion, proliferation, differentiation and active matrix remodelling. In this study, we aimed to investigate the functionalization of metallic implant titanium with silk protein sericin. Titanium surface was immobilized with non-mulberry Antheraea mylitta sericin using glutaraldehyde as crosslinker. To analyse combinatorial effects the sericin immobilized titanium was further conjugated with integrin binding peptide sequence Arg-Gly-Asp (RGD) using ethyl (dimethylaminopropyl) carbodiimide and N-hydroxysulfosuccinimide as coupling agents. The surface of sericin immobilized titanium was characterized biophysically. Osteoblast-like cells were cultured on sericin and sericin/RGD functionalized titanium and found to be more viable than those on pristine titanium. The enhanced adhesion, proliferation, and differentiation of osteoblast cells were observed. RT-PCR analysis showed that mRNA expressions of bone sialoprotein, osteocalcin and alkaline phosphatase were upregulated in osteoblast cells cultured on sericin and sericin/RGD immobilized titanium substrates. Additionally, no significant amount of pro-inflammatory cytokines TNF-α, IL-1β and nitric oxide production were recorded when macrophages cells and osteoblast-macrophages co culture cells were grown on sericin immobilized titanium. The findings demonstrate that the sericin immobilized titanium surfaces are potentially useful bioactive coated materials for titanium-based medical implants.

  13. Finite element simulation of bone remodelling in human mandible around osseointegrated dental implant

    NASA Astrophysics Data System (ADS)

    Lian, Z. Q.; Guan, H.; Loo, Y. C.; Ivanovski, S.; Johnson, N. W.

    2010-06-01

    Modern dental implant is a biocompatible titanium device surgically placed into a jawbone to support a prosthetic tooth crown in order to replace missing teeth. Implants are superior to conventional prostheses, in both function and long-term predictability. However, placement of an implant changes the normal mechanical environment of jawbone, which causes the bone density to redistribute and adapt to the new environment through a process of remodelling. This study aims to predict the density distribution in human jawbone around osseointegrated dental implant. Based on two popular, yet distinctive theories for bone remodelling, a new remodelling algorithm is proposed. The proposed algorithm is verified by a two-dimensional (2D) plate model. Then, a 2D finite element model of implant and jawbone is studied. The effects of two parameters, viz the reference value of strain energy density (SED) and 'lazy zone' region, on density distribution, are also examined. This study has demonstrated that consideration of the lazy zone, is less important than consideration of the stress and strain (quantified as SED) induced within the bone. Taking into account both 'lazy zone' effect and self-organisational control process, the proposed bone remodelling algorithm has overcome the shortcomings of the two existing theories.

  14. Drilling dimension effects in early stages of osseointegration and implant stability in a canine model

    PubMed Central

    Baires-Campos, Felipe-Eduardo; Jimbo, Ryo; Fonseca-Oliveira, Maiolino-Thomaz; Moura, Camila; Zanetta-Barbosa, Darceny; Coelho, Paulo-Guilherme

    2015-01-01

    Background This study histologically evaluated two implant designs: a classic thread design versus another specifically designed for healing chamber formation placed with two drilling protocols. Material and Methods Forty dental implants (4.1 mm diameter) with two different macrogeometries were inserted in the tibia of 10 Beagle dogs, and maximum insertion torque was recorded. Drilling techniques were: until 3.75 mm (regular-group); and until 4.0 mm diameter (overdrilling-group) for both implant designs. At 2 and 4 weeks, samples were retrieved and processed for histomorphometric analysis. For torque and BIC (bone-to-implant contact) and BAFO (bone area fraction occupied), a general-linear model was employed including instrumentation technique and time in vivo as independent. Results The insertion torque recorded for each implant design and drilling group significantly decreased as a function of increasing drilling diameter for both implant designs (p<0.001). No significant differences were detected between implant designs for each drilling technique (p>0.18). A significant increase in BIC was observed from 2 to 4 weeks for both implants placed with the overdrilling technique (p<0.03) only, but not for those placed in the 3.75 mm drilling sites (p>0.32). Conclusions Despite the differences between implant designs and drilling technique an intramembranous-like healing mode with newly formed woven bone prevailed. Key words: Histomorphometry, biomechanical, in vivo, initial stability, insertion torque, osseointegration. PMID:25858087

  15. Local Application of Growth Hormone to Enhance Osseointegration in Osteoporotic Bones: A Morphometric and Densitometric Study.

    PubMed

    Martin-Monge, Elena; Tresguerres, Isabel F; Clemente, Celia; Tresguerres, Jesús Af

    The aim of this study was to assess the effect of local application of growth hormone on osseointegration of dental implants inserted in osteoporotic bones. Twenty female New Zealand rabbits were used in this study. Ten were ovariectomized and fed a low-calcium diet for 6 weeks, and the others remained intact. A titanium implant was inserted into each tibia, in both groups. In half of the rabbits, 2 IU of growth hormone was placed into the ostectomy prior to the implant insertion. Two weeks after implant surgery, all animals were sacrificed. Tibiae were dissected from soft tissues, and included in methacrylate to be studied under light microscopy. Bone-to-implant contact (BIC) and bone mineral density (BMD) were measured by morphometric and densitometric analysis, respectively. Multifactorial analysis of variance (ANOVA) was used for statistical evaluation. P < .05 was considered to be significant. Ovariectomy induced less BIC and BMD in regions closer to the implant compared with the control group. Local application of growth hormone was able to increase the BIC in the ovariectomized group, with statistically significant differences with respect to the control group (P < .01). Regarding the BMD, no statistically significant differences were found. Within the limitations of this experimental study, local application of 2 IU of recombinant human growth hormone at the moment of titanium implant insertion in rabbit tibiae significantly enhanced the BIC around titanium implants 15 days after the implantation in this experimental osteoporotic animal model, without affecting the BMD.

  16. Masseteric post-stimulus EMG complex following mechanical stimulation of osseointegrated oral implants.

    PubMed

    Bonte, B; van Steenberghe, D

    1991-05-01

    Periodontal receptors can be located in the periodontal ligament itself, the alveolar bone, the periosteum and the gingiva. The aim of the present study was to quantify the contribution of the periodontal ligament receptors in eliciting a reflex response in human masseter muscles. Surface EMG recordings were made in 17 human subjects, fully or partially edentulous, and all provided with osseointegrated oral implants ad modum Brånemark. They maintained a constant clenching level. Mechanical stimulation of an oral implant in the upper central incisor region failed to elicit a reflex in fully edentulous subjects with oral implants in both jaws. The absence of a reflex response strongly suggests that the receptors in the periodontal ligament itself are mainly responsible for the reflex. Stimulation of the same area in subjects with oral implants in the upper jaw and natural teeth in the lower jaw elicited a reflex response in most subjects. Since they were instructed to clench in full habitual occlusion, transmission from the stimulated area to periodontal receptors of natural teeth is very probable.

  17. A computational model for stress reduction at the skin-implant interface of osseointegrated prostheses.

    PubMed

    Yerneni, Srinivasu; Dhaher, Yasin; Kuiken, Todd A

    2012-04-01

    Osseointegrated implants (OI)s for transfemoral prosthetic attachment offer amputees an alternative to the traditional socket attachment. Potential benefits include a natural transfer of loads directly to the skeleton via the percutaneous abutment, relief of pain and discomfort of residual limb soft tissues by eliminating sockets, increased sensory feedback, and improved function. Despite the benefits, the skin-implant interface remains a critical limitation, as it is highly prone to bacterial infection. One approach to improve clinical outcomes is to minimize stress concentrations at the skin-implant interface due to shear loading, reducing soft tissue breakdown and subsequent risk of infection. We hypothesized that broadening the bone base at the distal end of the femur would provide added surface area for skin adhesion and reduce stresses at the skin-implant interface. We tested this hypothesis using finite element models of an OI in a residual limb. Results showed a dramatic decrease in stress reduction, with up to ~90% decrease in stresses at the skin-implant interface as cortical bone thickness increased from 2 to 8 mm. The findings in this study suggests that surgical techniques could stabilize the skin-implant interface, thus enhancing a skin-to-bone seal around the percutaneous device and minimizing infection.

  18. Overview of Nanoparticle Coating of Dental Implants for Enhanced Osseointegration and Antimicrobial Purposes.

    PubMed

    Parnia, Feridoun; Yazdani, Javad; Javaherzadeh, Vahid; Maleki Dizaj, Solmaz

    2017-01-01

    Nanomaterials are suitable candidates for coating of titanium based (Ti-based) dental implants due to their unique properties. The objective of this article is to summarize the application of nanoparticles as Ti-based implant coating materials in order to control and improve the implant success rate with focus on enhanced osseointegration and antimicrobial purposes. This review was conducted using electronic databases and MeSH keywords to detect associated scientific literature published in English. The reviewed articles exhibited that a significant progress in research has occurred in the case of nanomaterial-based coatings for dental implants. Coating of Ti surfaces with nanoparticles can improve soft tissue integration and osteogeneration that leads to improved fixation of implants. Furthermore, osteoconductive nanoparticles induce a chemical bond with bone to attain good biological fixation for implants. Surface modification of implants using antibacterial properties can also decrease the potential for infection, and certainly, present improve clinical outcomes. Considering the reported success, more clinically and in vivo information on the nanoparticle-based implant coatings will add to the successful application of the device in the clinic. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.

  19. New cosurface capacitive stimulators for the development of active osseointegrative implantable devices

    PubMed Central

    Soares dos Santos, Marco P.; Marote, Ana; Santos, T.; Torrão, João; Ramos, A.; Simões, José A. O.; da Cruz e Silva, Odete A. B.; Furlani, Edward P.; Vieira, Sandra I.; Ferreira, Jorge A. F.

    2016-01-01

    Non-drug strategies based on biophysical stimulation have been emphasized for the treatment and prevention of musculoskeletal conditions. However, to date, an effective stimulation system for intracorporeal therapies has not been proposed. This is particularly true for active intramedullary implants that aim to optimize osseointegration. The increasing demand for these implants, particularly for hip and knee replacements, has driven the design of innovative stimulation systems that are effective in bone-implant integration. In this paper, a new cosurface-based capacitive system concept is proposed for the design of implantable devices that deliver controllable and personalized electric field stimuli to target tissues. A prototype architecture of this system was constructed for in vitro tests, and its ability to deliver controllable stimuli was numerically analyzed. Successful results were obtained for osteoblastic proliferation and differentiation in the in vitro tests. This work provides, for the first time, a design of a stimulation system that can be embedded in active implantable devices for controllable bone-implant integration and regeneration. The proposed cosurface design holds potential for the implementation of novel and innovative personalized stimulatory therapies based on the delivery of electric fields to bone cells. PMID:27456818

  20. Periodontal parameters of osseointegrated dental implants. A 4-year controlled follow-up study.

    PubMed

    Nishimura, K; Itoh, T; Takaki, K; Hosokawa, R; Naito, T; Yokota, M

    1997-08-01

    The aim of this study was to evaluate the periodontal parameters of osseointegrated dental implants. The condition of the peri-implant mucosa was assessed using periodontal parameters, i.e., of plaque index, bleeding on probing, probing pocket depth, probing attachment level and Periotest scores as well as a radiographic parameter, over a 4-year follow-up period. 32 non-submerged ITI dental implants, all placed in the mandible, were studied in 12 patients who had good oral hygiene. All patients were regularly recalled at 6-month intervals. The overall implant success rate was 100%. None of the implants showed any signs of inflammation, radiographic bone loss or any detectable mobility during the follow-up period. Methods similar to those used to evaluate the natural dentition were effectively employed to assess the clinical status of the dental implants. The diagnostic value of these parameters could not, however, be determined from this study due to the absence of any peri-implant tissue complications. The results indicated that some periodontal parameters of healthy peri-implant mucosa might be slightly different from healthy periodontal tissue.

  1. Principal component analysis: a novel analysis to evaluate the characteristics of osseointegration of different implant surfaces.

    PubMed

    Jimbo, Ryo; Fernandez-Rodriguez, Julia; Sul, Young-Taeg; Johansson, Carina B

    2011-10-01

    To apply a new statistical method (principle component analysis; PCA) to evaluate osseointegration. Two different commercially available implants were selected for the study. Twenty implants, 10 of each type, were placed in the rabbit tibiae (n = 10). The fluorochromes (FLCs) alizarin complexone and calcein green were administered after 20 days and 4 days before sacrifice for labeling. On the day of implantation and retrieval (6 weeks), implant stability was measured with a resonance frequency analyzer (RFA). The retrieved samples were ground sectioned for histomorphometric and FLC quantification. The collected data were analyzed by a PCA software program (Qlucore Omics Explorer, Lund, Sweden) to explore and determine the correlation between different study variables and to analyze the differences between different implants. The RFA presented no significant differences at either time point. The bone-to-implant contact was significantly higher for the TiUnite (NobelBiocare, Gothenburg, Sweden); however, the bone area and FLC quantification showed higher values for the Osseotite (3i Implant Innovation, FL). Consistent with these results, the PCA indicated a strong correlation between TiUnite and high bone-to-implant contact values and between Osseotite and high bone area and FLC values. No correlation between RFA and the biological responses were found. The application of the PCA analysis may help interpret and correlate results obtained from numerous evaluations.

  2. Osseointegration of three-dimensional designed titanium implants manufactured by selective laser melting.

    PubMed

    Shaoki, Algabri; Xu, Jia-Yun; Sun, Haipeng; Chen, Xian-Shuai; Ouyang, Jianglin; Zhuang, Xiu-Mei; Deng, Fei-Long

    2016-10-27

    The selective laser melting (SLM) technique is a recent additive manufacturing (AM) technique. Several studies have reported success in the SLM-based production of biocompatible orthopaedic implants and three-dimensional bone defect constructs. In this study, we evaluated the surface properties and biocompatibility of an SLM titanium implant in vitro and compared them with those of a machined (MA) titanium control surface. In addition, we evaluated the osseointegration capability of the SLM implants in vivo and compared it with those of MA and Nobel-speedy (Nobel-S) implants. SLM microtopographical surface analysis revealed porous and high roughness with varied geometry compared with a smooth surface in MA Ti samples but with similar favourable wettability. Osteoblast proliferation and alkaline phosphatase activity were significantly enhanced on the SLM surface. Histological analysis of the bone-implant contact ratio revealed no significant difference among SLM, MA, and Nobel-S implants. Micro-CT assessment indicated that there was no significant difference in bone volume fraction around the implant among SLM implants and other types of surface modification implants. The removal torque value measurement of SLM implants was significantly lower that of than Nobel-S implants P < 0.001 and higher than that of MA implants. The study demonstrates the capability of SLM implants to integrate with living bone. The SLM technique holds promise as a new dental implant manufacturing technique.

  3. Antimicrobial surface coatings for a permanent percutaneous passage in the concept of osseointegrated extremity prosthesis.

    PubMed

    Calliess, Tilman; Sluszniak, Magda; Winkel, Andreas; Pfaffenroth, Cornelia; Dempwolf, Wibke; Heuer, Wieland; Menzel, Henning; Windhagen, Henning; Stiesch, Meike

    2012-12-01

    The clinical implementation of percutaneous implants is still limited owing to infections at the side of the stoma. In our concept, this issue is addressed by designing copolymer surface coatings possessing biocompatibility and antimicrobial activity to improve the maintenance of a physiological skin seal at the skin-implant interface. Different copolymers with surface-active phosphonate and antimicrobial cationic groups were designed. Thus, coated titanium samples were cultured with bacterial strains or fibroblasts, respectively. Antimicrobial impact was evaluated by imaging the reduction of bacterial adherence. Biocompatibility was displayed by fibroblast proliferation and morphology. A variety of copolymers of 4-vinylpyridine with vinylbenzylphosphonate or dimethyl(2-methacryloyloxy-ethyl) phosphonate were prepared by free radical polymerization. The optimized polymer coating (copolymer D) showed a reduction of adherent bacteria up to 95%, with only a slight reduction in the adherence of human fibroblasts compared with blank titanium controls. In this study, we demonstrate in vitro that polymer surface coatings can be simultaneously antimicrobial and biocompatible. We consider this to be a promising technology for the realization of a permanent aseptic percutaneous passage as needed for the advancement of osseointegrated limb prosthesis.

  4. Simple coating with fibronectin fragment enhances stainless steel screw osseointegration in healthy and osteoporotic rats.

    PubMed

    Agarwal, Rachit; González-García, Cristina; Torstrick, Brennan; Guldberg, Robert E; Salmerón-Sánchez, Manuel; García, Andrés J

    2015-09-01

    Metal implants are widely used to provide structural support and stability in current surgical treatments for bone fractures, spinal fusions, and joint arthroplasties as well as craniofacial and dental applications. Early implant-bone mechanical fixation is an important requirement for the successful performance of such implants. However, adequate osseointegration has been difficult to achieve especially in challenging disease states like osteoporosis due to reduced bone mass and strength. Here, we present a simple coating strategy based on passive adsorption of FN7-10, a recombinant fragment of human fibronectin encompassing the major cell adhesive, integrin-binding site, onto 316-grade stainless steel (SS). FN7-10 coating on SS surfaces promoted α5β1 integrin-dependent adhesion and osteogenic differentiation of human mesenchymal stem cells. FN7-10-coated SS screws increased bone-implant mechanical fixation compared to uncoated screws by 30% and 45% at 1 and 3 months, respectively, in healthy rats. Importantly, FN7-10 coating significantly enhanced bone-screw fixation by 57% and 32% at 1 and 3 months, respectively, and bone-implant ingrowth by 30% at 3 months compared to uncoated screws in osteoporotic rats. These coatings are easy to apply intra-operatively, even to implants with complex geometries and structures, facilitating the potential for rapid translation to clinical settings.

  5. Osseointegration into a Novel Titanium Foam Implant in the Distal Femur of a Rabbit

    PubMed Central

    Willie, Bettina M.; Yang, Xu; Kelly, Natalie H.; Merkow, Justin; Gagne, Shawn; Ware, Robin; Wright, Timothy M.; Bostrom, Mathias P.G.

    2010-01-01

    A novel porous titanium foam implant has recently been developed to enhance biological fixation of orthopaedic implants to bone. The aim of this study was to examine the mechanical and histological characteristics of bone apposition into two different pore sizes of this titanium foam (565 and 464 micron mean void intercept length) and to compare these characteristics to those obtained with a fully porous conventionally sintered titanium bead implant. Cylindrical implants were studied in a rabbit distal femoral intramedullary osseointegration model at time zero and at 3, 6, and 12 weeks. The amount of bone ingrowth, amount of periprosthetic bone, and mineral apposition rate of periprosthetic bone measured did not differ among the three implant designs at 3, 6, or 12 weeks. By 12 weeks, the interface stiffness and maximum load of the beaded implant was significantly greater than either foam implant. No significant difference was found in the interface stiffness or maximum load between the two foam implant designs at 3, 6, or 12 weeks. The lower compressive modulus of the foam compared to the more dense sintered beaded implants likely contributed to the difference in failure mode. However, the foam implants have a similar compressive modulus to other clinically successful coatings, suggesting they are nonetheless clinically adequate. Additional studies are required to confirm this in weight-bearing models. Histological data suggest that these novel titanium foam implants are a promising alternative to current porous coatings and should be further investigated for clinical application in cementless joint replacement. PMID:20024964

  6. Prosthetic aspects of osseointegrated fixtures supporting overdentures. A 4-year report.

    PubMed

    Naert, I; Quirynen, M; Theuniers, G; van Steenberghe, D

    1991-05-01

    Eighty-six consecutive patients, provided with 84 resilient and two nonresilient overdentures (six in the upper and 80 in the lower jaw), were examined. The overdentures were supported by a total of 173 osseointegrated titanium fixtures (the standard Branemark abutment), with a mean loading time of 19.1 months (range 4 to 48 months). In each jaw only two fixtures anchored the overdentures. No failures occurred during the observation period but two fixtures were lost before loading. The radiographic annual bone loss around fixtures in the lower jaw was -0.8 mm for the first year and less than -0.1 mm for the following years. The change in marginal bone height did not correlate with parameters such as the occlusion and articulation pattern, the presence or absence of a soft liner around the abutments, and the magnitude of the interabutment distance. The patients' reactions to overdenture treatment were, on the whole, positive concerning chewing function, phonetics, and comfort. The need for maintenance care of the clip-bar attachment was minimal.

  7. Tantalum implanted entangled porous titanium promotes surface osseointegration and bone ingrowth.

    PubMed

    Wang, Qi; Qiao, Yuqin; Cheng, Mengqi; Jiang, Guofeng; He, Guo; Chen, Yunsu; Zhang, Xianlong; Liu, Xuanyong

    2016-05-17

    Porous Ti is considered to be an ideal graft material in orthopaedic and dental surgeries due to its similar spatial structures and mechanical properties to cancellous bone. In this work, to overcome the bioinertia of Ti, Ta-implanted entangled porous titanium (EPT) was constructed by plasma immersion ion implantation &deposition (PIII&D) method. Ca-implanted and unimplanted EPTs were investigated as control groups. Although no difference was found in surface topography and mechanical performances, both Ca- and Ta-implanted groups had better effects in promoting MG-63 cell viability, proliferation, differentiation, and mineralization than those of unimplanted group. The expression of osteogenic-related markers examined by qRT-PCR and western blotting was upregulated in Ca- and Ta-implanted groups. Moreover, Ta-implanted EPT group could reach a higher level of these effects than that of Ca-implanted group. Enhanced osseointegration of both Ca- and Ta-implanted EPT implants was demonstrated through in vivo experiments, including micro-CT evaluation, push-out test, sequential fluorescent labeling and histological observation. However, the Ta-implanted group possessed more stable and continuous osteogenic activity. Our results suggest that Ta-implanted EPT can be developed as one of the highly efficient graft material for bone reconstruction situations.

  8. Computational biomechanics of bone's responses to dental prostheses - osseointegration, remodeling and resorption

    NASA Astrophysics Data System (ADS)

    Li, Wei; Rungsiyakull, Chaiy; Field, Clarice; Lin, Daniel; Zhang, Leo; Li, Qing; Swain, Michael

    2010-06-01

    Clinical and experimental studies showed that human bone has the ability to remodel itself to better adapt to its biomechanical environment by changing both its material properties and geometry. As a consequence of the rapid development and extensive applications of major dental restorations such as implantation and fixed partial denture (FPD), the effect of bone remodeling on the success of a dental restorative surgery is becoming critical for prosthetic design and pre-surgical assessment. This paper aims to provide a computational biomechanics framework to address dental bone's responses as a result of dental restoration. It explored three important issues of resorption, apposition and osseointegration in terms of remodeling simulation. The published remodeling data in long bones were regulated to drive the computational remodeling prediction for the dental bones by correlating the results to clinical data. It is anticipated that the study will provide a more predictive model of dental bone response and help develop a new design methodology for patient-specific dental prosthetic restoration.

  9. Comparative study on the osseointegration of implants in dog mandibles according to the implant surface treatment

    PubMed Central

    2016-01-01

    Objectives This study compared the impact of implant surface treatment on the stability and osseointegration of implants in dog mandibles. Materials and Methods Six adult dogs received a total of 48 implants that were prepared using four different surface treatments; resorbable blast media (RBM), hydroxyapatite (HA), hydrothermal-treated HA, and sand blasting and acid etching (SLA). Implants were installed, and dogs were separated into 2- and 4-week groups. Implant stability was evaluated via Periotest M, Osstell Mentor, and removal torque analyzers. A histomorphometric analysis was also performed. Results The stability evaluation showed that all groups generally had satisfactory values. The histomorphometric evaluation via a light microscope revealed that the HA surface implant group had the highest ratio of new bone formation on the entire fixture. The hydrothermal-treated HA surface implant group showed a high ratio of bone-to-implant contact in the upper half of the implant area. Conclusion The hydrothermal-treated HA implant improved the bone-to-implant contact ratio on the upper fixture, which increased the implant stability. PMID:28053904

  10. Exploring LiDAR data for mapping the micro-topography and tidal hydro-dynamics of mangrove systems: An example from southeast Queensland, Australia

    NASA Astrophysics Data System (ADS)

    Knight, Jon M.; Dale, Pat E. R.; Spencer, John; Griffin, Lachlan

    2009-12-01

    The aim was to explore the use of Light Detection and Ranging (LiDAR) data to map the micro-topography of an intertidal wetland in southeast Queensland Australia. The driver for this was the need to identify and map the habitats of the immature stages of an aedine disease vector mosquito ( Aedes vigilax (Skuse)). We derived a high resolution digital elevation model (DEM) data set at a vertical resolution of 0.05 m from LiDAR data. The relative accuracy of the DEM across the site was tested by comparing water depth predictions derived from the DEM against in-situ water depth readings from pressure sensors over a 10-day tidal cycle, which included high spring tides. We found that the field observations of micro-topographic units important for mosquito management matched those delineated from the DEM. The micro-topography included a low berm or central ridge that was more or less continuous across the site, a shallow back basin and fringing mangroves. The fringing mangroves had unimpeded connection to the tidal source, however the central ridge blocked tidal water from the back basin for all but the highest tides. Eggshell survey indicated that the back basin was the area suitable for immature mosquitoes. We conclude that LiDAR data has application for understanding and mapping the structure of mangrove wetlands. We have also demonstrated (in a small area) that LiDAR is useful for modelling the effect of sea level changes on the coastal fringe. LiDAR may be the only method to inform research on changes to land use and ecosystems caused by sea level change.

  11. Effects of surface hydrophilicity and microtopography on early stages of soft and hard tissue integration at non-submerged titanium implants: an immunohistochemical study in dogs.

    PubMed

    Schwarz, Frank; Ferrari, Daniel; Herten, Monika; Mihatovic, Ilja; Wieland, Marco; Sager, Martin; Becker, Jürgen

    2007-11-01

    The aim of the present study was to investigate the effects of surface hydrophilicity and microtopography on soft and hard tissue integration at non-submerged titanium implants. Implantation of conventional sand-blasted large grit and acid-etched (SLA) and chemically modified SLA (modSLA) titanium implants with differently structured transmucosal surfaces (SLA implants: machined [M-SLA] or SLA [SLA-SLA]; modSLA implants: mod acid-etched [modA] [modA-modSLA] or modSLA [modSLA-modSLA]) was performed bilaterally in the upper and lower jaws of 15 beagle dogs. The animals were sacrificed after 1, 4, 7, 14, or 28 days. Tissue reactions were assessed histomorphometrically and immunohistochemically using monoclonal antibodies to transglutaminase II (angiogenesis) and osteocalcin. Although the junctional epithelium commonly was separated from M-SLA and SLA-SLA implants by a gap, the epithelial cells appeared to be in close contact with modA-modSLA surfaces after 14 days of healing. Moreover, modA-modSLA and modSLA-modSLA groups showed a well-vascularized subepithelial connective tissue exhibiting collagen fibers that started to extend and attach partially perpendicular to the implant surface. The highest and statistically significant mean bone-to-implant contact areas were observed in the modA-modSLA and modSLA-modSLA groups at days 7, 14, and 28. Within the limits of this study, it may be concluded that soft and hard tissue integration was influenced mainly by surface hydrophilicity rather than by microtopography.

  12. Acceleration Studies

    NASA Technical Reports Server (NTRS)

    Rogers, Melissa J. B.

    1993-01-01

    Work to support the NASA MSFC Acceleration Characterization and Analysis Project (ACAP) was performed. Four tasks (analysis development, analysis research, analysis documentation, and acceleration analysis) were addressed by parallel projects. Work concentrated on preparation for and implementation of near real-time SAMS data analysis during the USMP-1 mission. User support documents and case specific software documentation and tutorials were developed. Information and results were presented to microgravity users. ACAP computer facilities need to be fully implemented and networked, data resources must be cataloged and accessible, future microgravity missions must be coordinated, and continued Orbiter characterization is necessary.

  13. No positive effect of Acid etching or plasma cleaning on osseointegration of titanium implants in a canine femoral condyle press-fit model.

    PubMed

    Saksø, H; Jakobsen, T; Saksø, M; Baas, J; Jakobsen, Ss; Soballe, K

    2013-01-01

    Implant surface treatments that improve early osseointegration may prove useful in long-term survival of uncemented implants. We investigated Acid Etching and Plasma Cleaning on titanium implants. In a randomized, paired animal study, four porous coated Ti implants were inserted into the femurs of each of ten dogs. PC (Porous Coating; control)PC+PSHA (Plasma Sprayed Hydroxyapatite; positive control)PC+ET (Acid Etch)PC+ET+PLCN (Plasma Cleaning) After four weeks mechanical fixation was evaluated by push-out test and osseointegration by histomorphometry. The PSHA-coated implants were better osseointegrated than the three other groups on outer surface implant porosity (p<0.05) while there was no statistical difference in deep surface implant porosity when compared with nontreated implant. Within the deep surface implant porosity, there was more newly formed bone in the control group compared to the ET and ET+PCLN groups (p<0.05). In all compared groups, there was no statistical difference in any biomechanical parameter. In terms of osseointegration on outer surface implant porosity PC+PSHA was superior to the other three groups. Neither the acid etching nor the plasma cleaning offered any advantage in terms of implant osseointegration. There was no statistical difference in any of the biomechanical parameters among all groups in the press-fit model at 4 weeks of evaluation time.

  14. Accelerated Achievement

    ERIC Educational Resources Information Center

    Ford, William J.

    2010-01-01

    This article focuses on the accelerated associate degree program at Ivy Tech Community College (Indiana) in which low-income students will receive an associate degree in one year. The three-year pilot program is funded by a $2.3 million grant from the Lumina Foundation for Education in Indianapolis and a $270,000 grant from the Indiana Commission…

  15. Particle acceleration

    NASA Technical Reports Server (NTRS)

    Vlahos, L.; Machado, M. E.; Ramaty, R.; Murphy, R. J.; Alissandrakis, C.; Bai, T.; Batchelor, D.; Benz, A. O.; Chupp, E.; Ellison, D.

    1986-01-01

    Data is compiled from Solar Maximum Mission and Hinothori satellites, particle detectors in several satellites, ground based instruments, and balloon flights in order to answer fundamental questions relating to: (1) the requirements for the coronal magnetic field structure in the vicinity of the energization source; (2) the height (above the photosphere) of the energization source; (3) the time of energization; (4) transistion between coronal heating and flares; (5) evidence for purely thermal, purely nonthermal and hybrid type flares; (6) the time characteristics of the energization source; (7) whether every flare accelerates protons; (8) the location of the interaction site of the ions and relativistic electrons; (9) the energy spectra for ions and relativistic electrons; (10) the relationship between particles at the Sun and interplanetary space; (11) evidence for more than one acceleration mechanism; (12) whether there is single mechanism that will accelerate particles to all energies and also heat the plasma; and (13) how fast the existing mechanisms accelerate electrons up to several MeV and ions to 1 GeV.

  16. ACCELERATION INTEGRATOR

    DOEpatents

    Pope, K.E.

    1958-01-01

    This patent relates to an improved acceleration integrator and more particularly to apparatus of this nature which is gyrostabilized. The device may be used to sense the attainment by an airborne vehicle of a predetermined velocitv or distance along a given vector path. In its broad aspects, the acceleration integrator utilizes a magnetized element rotatable driven by a synchronous motor and having a cylin drical flux gap and a restrained eddy- current drag cap deposed to move into the gap. The angular velocity imparted to the rotatable cap shaft is transmitted in a positive manner to the magnetized element through a servo feedback loop. The resultant angular velocity of tae cap is proportional to the acceleration of the housing in this manner and means may be used to measure the velocity and operate switches at a pre-set magnitude. To make the above-described dcvice sensitive to acceleration in only one direction the magnetized element forms the spinning inertia element of a free gyroscope, and the outer housing functions as a gimbal of a gyroscope.

  17. Plasma accelerator

    DOEpatents

    Wang, Zhehui; Barnes, Cris W.

    2002-01-01

    There has been invented an apparatus for acceleration of a plasma having coaxially positioned, constant diameter, cylindrical electrodes which are modified to converge (for a positive polarity inner electrode and a negatively charged outer electrode) at the plasma output end of the annulus between the electrodes to achieve improved particle flux per unit of power.

  18. Accelerated Achievement

    ERIC Educational Resources Information Center

    Ford, William J.

    2010-01-01

    This article focuses on the accelerated associate degree program at Ivy Tech Community College (Indiana) in which low-income students will receive an associate degree in one year. The three-year pilot program is funded by a $2.3 million grant from the Lumina Foundation for Education in Indianapolis and a $270,000 grant from the Indiana Commission…

  19. Osteomyelitis Risk in Patients With Transfemoral Amputations Treated With Osseointegration Prostheses.

    PubMed

    Tillander, Jonatan; Hagberg, Kerstin; Berlin, Örjan; Hagberg, Lars; Brånemark, Rickard

    2017-09-22

    Percutaneous anchoring of femoral amputation prostheses using osseointegrating titanium implants has been in use for more than 25 years. The method offers considerable advantages in daily life compared with conventional socket prostheses, however long-term success might be jeopardized by implant-associated infection, especially osteomyelitis, but the long-term risk of this complication is unknown. (1) To quantify the risk of osteomyelitis, (2) to characterize the clinical effect of osteomyelitis (including risk of implant extraction and impairments to function), and (3) to determine whether common patient factors (age, sex, body weight, diabetes, and implant component replacements) are associated with osteomyelitis in patients with transfemoral amputations treated with osseointegrated titanium implants. We retrospectively analyzed our first 96 patients receiving femoral implants (102 implants; mean implant time, 95 months) treated at our center between 1990 and 2010 for osteomyelitis. Six patients were lost to followup. The reason for amputation was tumor, trauma, or ischemia in 97 limbs and infection in five. All patients were referred from other orthopaedic centers owing to difficulty with use or to be fitted with socket prostheses. If found ineligible for this implant procedure no other treatment was offered at our center. Osteomyelitis was diagnosed by medical chart review of clinical signs, tissue culture results, and plain radiographic findings. Proportion of daily prosthetic use when osteomyelitis was diagnosed was semiquantitatively graded as 1 to 3. Survivorship free from implant- associated osteomyelitis and extraction attributable to osteomyelitis respectively was calculated using the Kaplan-Meier estimator. Indication for extraction was infection not responsive to conservative treatment with or without minor débridement or loosening of implant. Implant-associated osteomyelitis was diagnosed in 16 patients corresponding to a 10-year cumulative risk of

  20. A large scale finite element study of a cementless osseointegrated tibial tray.

    PubMed

    Galloway, Francis; Kahnt, Max; Ramm, Heiko; Worsley, Peter; Zachow, Stefan; Nair, Prasanth; Taylor, Mark

    2013-07-26

    The aim of this study was to investigate the performance of a cementless osseointegrated tibial tray (P.F.C. ® Sigma®, Depuy® Inc, USA) in a general population using finite element (FE) analysis. Computational testing of total knee replacements (TKRs) typically only use a model of a single patient and assume the results can be extrapolated to the general population. In this study, two statistical models (SMs) were used; one of the shape and elastic modulus of the tibia, and one of the tibiofemoral joint loads over a gait cycle, to generate a population of FE models. A method was developed to automatically size, position and implant the tibial tray in each tibia, and 328 models were successfully implanted and analysed. The peak strain in the bone of the resected surface was examined and the percentage surface area of bone above yield strain (PSAY) was used to determine the risk of failure of a model. Using an arbitrary threshold of 10% PSAY, the models were divided into two groups ('higher risk' and 'lower risk') in order to explore factors that may influence potential failure. In this study, 17% of models were in the 'higher risk' group and it was found that these models had a lower elastic modulus (mean 275.7MPa), a higher weight (mean 85.3kg), and larger peak loads, of which the axial force was the most significant. This study showed the mean peak strain of the resected surface and PSAY were not significantly different between implant sizes. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. The effect of magnesium on early osseointegration in osteoporotic bone: a histological and gene expression investigation.

    PubMed

    Galli, S; Stocchero, M; Andersson, M; Karlsson, J; He, W; Lilin, T; Wennerberg, A; Jimbo, R

    2017-07-01

    Magnesium has a key role in osteoporosis and could enhance implant osseointegration in osteoporotic patients. Titanium implants impregnated with Mg ions were installed in the tibia of ovariectomized rats. The release of Mg induced a significant increase of bone formation and the expression of anabolic markers in the peri-implant bone. The success of endosseous implants is highly predictable in patients possessing normal bone status, but it may be impaired in patients with osteoporosis. Thus, the application of strategies that adjuvate implant healing in compromized sites is of great interest. Magnesium has a key role in osteoporosis prevention and it is an interesting candidate for this purpose. In this study, the cellular and molecular effects of magnesium release from implants were investigated at the early healing stages of implant integration. Osteoporosis was induced in 24 female rats by means of ovariectomy and low-calcium diet. Titanium mini-screws were coated with mesoporous titania films and were loaded with magnesium (test group) or left as native (control group). The implants were inserted in the tibia and femur of the rats. One, 2 and 7 days after implantation, the implants were retrieved and histologically examined. In addition, expression of genes was evaluated in the peri-implant bone tissue at day 7 by means of quantitative polymerase chain reactions with pathway-oriented arrays. The histological evaluation revealed that new bone formation started already during the first week of healing for both groups. However, around the test implants, new bone was significantly more abundant and spread along a larger surface of the implants. In addition, the release of magnesium induced a significantly higher expression of BMP6. These results provide evidence that the release of magnesium promoted rapid bone formation and the activation of osteogenic signals in the vicinity of implants placed in osteoporotic bone.

  2. Osseointegration of porous titanium implants with and without electrochemically deposited DCPD coating in an ovine model

    PubMed Central

    2011-01-01

    Background Uncemented fixation of components in joint arthroplasty is achieved primarily through de novo bone formation at the bone-implant interface and establishment of a biological and mechanical interlock. In order to enhance bone-implant integration osteoconductive coatings and the methods of application thereof are continuously being developed and applied to highly porous and roughened implant substrates. In this study the effects of an electrochemically-deposited dicalcium phosphate dihydrate (DCPD) coating of a porous substrate on implant osseointegration was assessed using a standard uncemented implant fixation model in sheep. Methods Plasma sprayed titanium implants with and without a DCPD coating were inserted into defects drilled into the cancellous and cortical sites of the femur and tibia. Cancellous implants were inserted in a press-fit scenario whilst cortical implants were inserted in a line-to-line fit. Specimens were retrieved at 1, 2, 4, 8 and 12 weeks postoperatively. Interfacial shear-strength of the cortical sites was assessed using a push-out test, whilst bone ingrowth, ongrowth and remodelling were investigated using histologic and histomorphometric endpoints. Results DCPD coating significantly improved cancellous bone ingrowth at 4 weeks but had no significant effect on mechanical stability in cortical bone up to 12 weeks postoperatively. Whilst a significant reduction in cancellous bone ongrowth was observed from 4 to 12 weeks for the DCPD coating, no other statistically significant differences in ongrowth or ingrowth in either the cancellous or cortical sites were observed between TiPS and DCPD groups. Conclusion The application of a DCPD coating to porous titanium substrates may improve the extent of cancellous bone ingrowth in the early postoperative phase following uncemented arthroplasty. PMID:22053991

  3. Enhancement of Implant Osseointegration by High-Frequency Low-Magnitude Loading

    PubMed Central

    Zhang, Xiaolei; Torcasio, Antonia; Vandamme, Katleen; Ogawa, Toru; van Lenthe, G. Harry; Naert, Ignace; Duyck, Joke

    2012-01-01

    Background Mechanical loading is known to play an important role in bone remodelling. This study aimed to evaluate the effect of high- and low-frequency axial loading, applied directly to the implant, on peri-implant bone healing and implant osseointegration. Methodology Titanium implants were bilaterally installed in rat tibiae. For every animal, one implant was loaded (test) while the other one was not (control). The test implants were randomly divided into 8 groups according to 4 loading regimes and 2 experimental periods (1 and 4 weeks). The loaded implants were subject to an axial displacement. Within the high- (HF, 40 Hz) or low-frequency (LF, 8 Hz) loading category, the displacements varied 2-fold and were ranked as low- or high-magnitude (LM, HM), respectively. The strain rate amplitudes were kept constant between the two frequency groups. This resulted in the following 4 loading regimes: 1) HF-LM, 40 Hz-8 µm; 2) HF-HM, 40 Hz-16 µm; 3) LF-LM, 8 Hz-41 µm; 4) LF-HM, 8 Hz-82 µm. The tissue samples were processed for resin embedding and subjected to histological and histomorphometrical analyses. Data were analyzed statistically with the significance set at p<0.05. Principal Findings After loading for 4 weeks, HF-LM loading (40 Hz-8 µm) induced more bone-to-implant contact (BIC) at the level of the cortex compared to its unloaded control. No significant effect of the four loading regimes on the peri-implant bone fraction (BF) was found in the 2 experimental periods. Conclusions The stimulatory effect of immediate implant loading on bone-to-implant contact was only observed in case of high-frequency (40 Hz) low-magnitude (8 µm) loading. The applied load regimes failed to influence the peri-implant bone mass. PMID:22808172

  4. Modification of Osseointegrated Device Parameters to Improve Speech in Noise and Localization Ability: Clinical Recommendations.

    PubMed

    Hillyer, Jake; Buchanan, P Cody; Elkins, Elizabeth; Watson, Stacey D; Cloutier, Francois; Backous, Douglas D; Parbery-Clark, Alexandra

    2016-09-01

    To determine how best to modify osseointegrated (OI) devices or environmental settings to maximize hearing performance. Prospective cohort study. Tertiary referral center. Fourteen adults with single-sided deafness (SSD) with a minimum of 6 months OI usage and nine bilaterally normal hearing controls : Speech in noise (SIN) and localization ability were assessed in a multi-speaker array (R-Space) with patients repeating sentences embedded in competing noise and verbally indicating the source speaker, respectively. SIN and localization were assessed with multiple OI microphone settings-fixed-directional, omnidirectional, and adaptive-as well as an unaided (OI off) condition. Participants completed the Abbreviated Profile of Hearing Aid Benefit questionnaire. Localization performance remains compromised for OI users with a high number of front-back confusions, but rapid learning using the fixed-directional microphone setting improved localization of sounds on the device side despite poorer localization of sounds on the normal-hearing side. SIN performance is greatly enhanced with speech presented to the contra hearing ear rather than the OI device side. Subjective report of hearing ability is highly predictive of objective SIN measures. Clinicians should consider implementing a fixed-directional microphone setting for improved localization for sounds behind the OI device, but inform patients of the trade-off in performance on the normal-hearing side. For better hearing in noise, clinicians should counsel OI recipients to orient the speech signal to their normal hearing ear rather than their OI device. The background noise subscale of the abbreviated profile of hearing aid benefit (APHAB) provides a meaningful metric by which to assess SIN performance of OI device users.

  5. External Mechanical Microstimuli Modulate the Osseointegration of Titanium Implants in Rat Tibiae

    PubMed Central

    Zacchetti, Giovanna; Cugnoni, Joël; Botsis, John; Ammann, Patrick

    2013-01-01

    Purpose. To assess the effect of external mechanical microstimuli of controlled magnitude on the microarchitecture of the peri-implant bone beds in rat tibiae. Materials and Methods. Tibiae of forty rats were fitted with two transcutaneous titanium cylinders. After healing, the implants were loaded to 1 to 3 N, five days/week for four weeks. These force levels translated into intraosseous strains of 700 ± 200 με, 1400 ± 400 με, and 2100 ± 600 με. After sacrifice, the implants' pullout strength was assessed. Second, the bone's microarchitecture was analyzed by microcomputed tomography (μCT) in three discrete regions of interest (ROIs). Third, the effect of loading on bone material properties was determined by nanoindentation. Results. The trabecular BV/TV significantly increased in an ROI of 0.98 mm away from the test implant in the 1 N versus the 3 N group with an opposite trend for cortical thickness. Pull-out strength significantly increased in the 2 N relatively to the nonstimulated group. Higher values of E-modulus and hardness were observed in the trabecular bone of the 2 N group. Conclusion. The in vivo mechanical loading of implants induces load-dependent modifications in bone microarchitecture and bone material properties in rat tibiae. In pull-out strength measurements, implant osseointegration was maximized at 2 N (1400 ± 400 με). PMID:24369009

  6. Osseointegration of fiber-reinforced composite implants: histological and ultrastructural observations.

    PubMed

    Ballo, A M; Cekic-Nagas, I; Ergun, G; Lassila, L; Palmquist, A; Borchardt, P; Lausmaa, J; Thomsen, P; Vallittu, P K; Närhi, T O

    2014-12-01

    The aim of this study was to evaluate the bone tissue response to fiber-reinforced composite (FRC) in comparison with titanium (Ti) implants after 12 weeks of implantation in cancellous bone using histomorphometric and ultrastructural analysis. Thirty grit-blasted cylindrical FRC implants with BisGMA-TEGDMA polymer matrix were fabricated and divided into three groups: (1) 60s light-cured FRC (FRC-L group), (2) 24h polymerized FRC (FRC group), and (3) bioactive glass FRC (FRC-BAG group). Titanium implants were used as a control group. The surface analyses were performed with scanning electron microscopy and 3D SEM. The bone-implant contact (BIC) and bone area (BA) were determined using histomorphometry and SEM. Transmission electron microscopy (TEM) was performed on Focused Ion Beam prepared samples of the intact bone-implant interface. The FRC, FRC-BAG and Ti implants were integrated into host bone. In contrast, FRC-L implants had a consistent fibrous capsule around the circumference of the entire implant separating the implant from direct bone contact. The highest values of BIC were obtained with FRC-BAG (58±11%) and Ti implants (54±13%), followed by FRC implants (48±10%), but no significant differences in BIC or BA were observed (p=0.07, p=0.06, respectively). TEM images showed a direct contact between nanocrystalline hydroxyapatite of bone and both FRC and FRC-BAG surfaces. Fiber-reinforced composite implants are capable of establishing a close bone contact comparable with the osseointegration of titanium implants having similar surface roughness. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Enhancement of implant osseointegration by high-frequency low-magnitude loading.

    PubMed

    Zhang, Xiaolei; Torcasio, Antonia; Vandamme, Katleen; Ogawa, Toru; van Lenthe, G Harry; Naert, Ignace; Duyck, Joke

    2012-01-01

    Mechanical loading is known to play an important role in bone remodelling. This study aimed to evaluate the effect of high- and low-frequency axial loading, applied directly to the implant, on peri-implant bone healing and implant osseointegration. Titanium implants were bilaterally installed in rat tibiae. For every animal, one implant was loaded (test) while the other one was not (control). The test implants were randomly divided into 8 groups according to 4 loading regimes and 2 experimental periods (1 and 4 weeks). The loaded implants were subject to an axial displacement. Within the high- (HF, 40 Hz) or low-frequency (LF, 8 Hz) loading category, the displacements varied 2-fold and were ranked as low- or high-magnitude (LM, HM), respectively. The strain rate amplitudes were kept constant between the two frequency groups. This resulted in the following 4 loading regimes: 1) HF-LM, 40 Hz-8 µm; 2) HF-HM, 40 Hz-16 µm; 3) LF-LM, 8 Hz-41 µm; 4) LF-HM, 8 Hz-82 µm. The tissue samples were processed for resin embedding and subjected to histological and histomorphometrical analyses. Data were analyzed statistically with the significance set at p<0.05. After loading for 4 weeks, HF-LM loading (40 Hz-8 µm) induced more bone-to-implant contact (BIC) at the level of the cortex compared to its unloaded control. No significant effect of the four loading regimes on the peri-implant bone fraction (BF) was found in the 2 experimental periods. The stimulatory effect of immediate implant loading on bone-to-implant contact was only observed in case of high-frequency (40 Hz) low-magnitude (8 µm) loading. The applied load regimes failed to influence the peri-implant bone mass.

  8. Composite morphology of the bone and associated support-tissue interfaces to osseointegrated dental implants: TEM and HVEM analyses.

    PubMed

    Steflik, D E; Corpe, R S; Lake, F T; Sisk, A L; Parr, G R; Hanes, P J; Buttle, K

    1997-01-01

    Correlated transmission electron and high-voltage electron microscopic analyses examined the undecalcified bone and associated support tissues of 60 endosseous titanium blade and titanium and ceramic root-form implants in dogs. The implants supported fixed partial dentures for up to 2 years. Data obtained from this investigation suggest that a range of tissues, both mineralized and unmineralized, support osseointegrated dental implants. This study examined the tissues apposing not just isolated aspects of the implant surface, but the entire length of the implant, and found that mineralized and unmineralized tissues existed concurrently. Much of the implant surface was apposed by mandibular bone, and both root-form and blade implants osseointegrated. The densely mineralized collagen fibril matrix was often separated from the implant by only a 20-nm to 50-nm electron-dense, ruthenium-positive deposit. High-voltage electron microscope stereology demonstrated that cellular processes extended directly to the implant from underlying osteocytes. In the same implants, areas containing an unmineralized collagen matrix interposed between the bone and implant surface were observed. In this region osteoblasts interacted with this matrix, and Howship's lacunae, containing vascular elements and osteoclasts, were also observed. The remodeling activities appear to be a homeostasis of catabolic activity (osteoclasts) and metabolic activity (osteoblasts). The apex of the implant was often apposed by a fibrofatty stroma. The support tissue response appears to be the result of the interrelations of osteoblasts, osteocytes, and osteoclasts in association with vascular elements. Therefore, the support tissue response to osseointegrated implants is a dynamic activity that involves the healthy interaction of these cells and tissues along the entire length of the implant.

  9. A comparative study of zinc, magnesium, strontium-incorporated hydroxyapatite-coated titanium implants for osseointegration of osteopenic rats.

    PubMed

    Tao, Zhou-Shan; Zhou, Wan-Shu; He, Xing-Wen; Liu, Wei; Bai, Bing-Li; Zhou, Qiang; Huang, Zheng-Liang; Tu, Kai-kai; Li, Hang; Sun, Tao; Lv, Yang-Xun; Cui, Wei; Yang, Lei

    2016-05-01

    Surface modification techniques have been applied to generate titanium implant surfaces that promote osseointegration for the implants in cementless arthroplasty. However, its effect is not sufficient for osteoporotic bone. Zinc (Zn), magnesium (Mg), and strontium (Sr) present a beneficial effect on bone growth, and positively affect bone regeneration. The aim of this study was to confirm the different effects of the fixation strength of Zn, Mg, Sr-substituted hydroxyapatite-coated (Zn-HA-coated, Mg-HA-coated, Sr-HA-coated) titanium implants via electrochemical deposition in the osteoporotic condition. Female Sprague-Dawley rats were used for this study. Twelve weeks after bilateral ovariectomy, all animals were randomly divided into four groups: group HA; group Zn-HA; group Mg-HA and group Sr-HA. Afterwards, all rats from groups HA, Zn-HA, Mg-HA and Sr-HA received implants with hydroxyapatite containing 0%, 10% Zn ions, 10% Mg ions, and 10% Sr ions. Implants were inserted bilaterally in all animals until death at 12 weeks. The bilateral femurs of rats were harvested for evaluation. All treatment groups increased new bone formation around the surface of titanium rods and push-out force; group Sr-HA showed the strongest effects on new bone formation and biomechanical strength. Additionally, there are significant differences in bone formation and push-out force was observed between groups Zn-HA and Mg-HA. This finding suggests that Zn, Mg, Sr-substituted hydroxyapatite coatings can improve implant osseointegration, and the 10% Sr coating exhibited the best properties for implant osseointegration among the tested coatings in osteoporosis rats.

  10. Three-dimensional numerical simulation of stress induced by different lengths of osseointegrated implants in the anterior maxilla.

    PubMed

    Lee, Joon-Seok; Lim, Young-Jun

    2013-01-01

    Lower survival rates were observed for the implant placed in the anterior maxilla. The purpose of this study was to investigate the influence of different implant lengths on the stress distribution around osseointegrated implants under a static loading condition in the anterior maxilla using a three-dimensional finite element analysis. The diameter of 4.0 mm external type implants of different lengths (8.5 mm, 10.0 mm, 11.5 mm, 13.0 mm, 15.0 mm) was used in this study. The anterior maxilla was assumed to be D3 bone quality. All the material was assumed to be homogenous, isotropic and linearly elastic. The implant-bone interface was constructed using a rigid element for simulating the osseointegrated condition. Then, 176 N of static force was applied on the middle of the palatoincisal line angle of the abutment at a 120°angle to the long axis of abutment. The von Mises stress value was measured with an interval of 0.25 mm along the bone-implant interface. Incremental increase in implant length causes a gradual reduction of maximum and average von Mises stress at the labial portion within the implant. In the bone, higher stress was concentrated within cortical bone area and more distributed at the labial cortex, while cancellous bone showed relatively low stress concentration and even distribution. An increase in implant length reduced stress gradients at the cortical peri-implant region. Implant length affects the mechanisms of load transmission to the osseointegrated implant. On the basis of this study the biomechanical stress-based performance of implants placed in the anterior maxilla improves when using longer implants.

  11. Particle Accelerators in China

    NASA Astrophysics Data System (ADS)

    Zhang, Chuang; Fang, Shouxian

    As the special machines that can accelerate charged particle beams to high energy by using electromagnetic fields, particle accelerators have been widely applied in scientific research and various areas of society. The development of particle accelerators in China started in the early 1950s. After a brief review of the history of accelerators, this article describes in the following sections: particle colliders, heavy-ion accelerators, high-intensity proton accelerators, accelerator-based light sources, pulsed power accelerators, small scale accelerators, accelerators for applications, accelerator technology development and advanced accelerator concepts. The prospects of particle accelerators in China are also presented.

  12. Use of osseointegrated implants in the intermaxillary suture: a new possibility for the prosthetic rehabilitation of atrophic maxillae.

    PubMed

    Januzzi, E; Leite, F M Gonçalves; Primo, B T; Grossmann, E

    2013-07-01

    Patients with atrophy of the maxillae, generally the elderly, are usually difficult to handle clinically, mainly due to the lack of retention, stability, and masticatory effectiveness of the total removable prosthesis. A new technique involving osseointegrated implants that are parallel to each other and arranged in the intermaxillary suture seems to provide great advantages over the current options for oral rehabilitation. This technique is quick and effective, being performed with local anesthesia and without a bone graft, and still presents low morbidity and cost. Copyright © 2013 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  13. The Effect of Hierarchical Micro/Nanotextured Titanium Implants on Osseointegration Immediately After Tooth Extraction in Beagle Dogs.

    PubMed

    Fu, Qian; Bellare, Anuj; Cui, Yajun; Cheng, Bingkun; Xu, Shanshan; Kong, Liang

    2017-06-01

    Owing to simplify the operation and shorten the overall duration of treatment, immediate implantation earned much satisfactory from patients and dentists. The results of immediate implantation determined by osseointegration, we fabricated a micro/nanotextured titanium implants to improve osseointegration immediately after tooth extraction. The aim of this study was to investigate the effect of hierarchical micro/nanotextured titanium implant on osseointegration immediately after tooth extraction. The micro/nanotextured titanium implants were fabricated by etching with 0.5 wt% hydrofluoric (HF) acid followed by anodization in HF electrolytes. Implants with a machined surface as well as implants a microtextured surface prepared by 0.5 wt% HF etching served as control groups. The machined, microtextured, and micro/nanotextured implants were inserted into fresh sockets immediately after tooth extraction in beagle dogs. Twelve weeks after implantation, the animals were sacrificed for micro-CT scanning, histological analysis and biomechanical test. The micro-CT imaging revealed that the bone volume/total volume (BV/TV) and trabecular thickness (Tb.Th) in the micro/nanotextured group was significantly higher than that in the machined group and microtextured group, and the trabecular separation (Tb.Sp) in the micro/nanotextured group was significantly lower than that in the other groups. For the histological analysis, the bone-to-implant contact in the machined, micro and micro/nanotextured groups were 47.13 ± 6.2%, 54.29 ± 4.18%, and 63.38 ± 7.63%, respectively, and the differences significant. The maximum pull-out force in the machined, micro, and micro/nanotextured groups were 216.58 ± 38.71 N, 259.42 ± 28.93 N, and 284.73 ± 47.09 N, respectively. The results indicated that implants with a hierarchical micro/nanotextured can promote osseointegration immediately after tooth extraction. © 2016 Wiley Periodicals, Inc.

  14. Compact accelerator

    DOEpatents

    Caporaso, George J.; Sampayan, Stephen E.; Kirbie, Hugh C.

    2007-02-06

    A compact linear accelerator having at least one strip-shaped Blumlein module which guides a propagating wavefront between first and second ends and controls the output pulse at the second end. Each Blumlein module has first, second, and third planar conductor strips, with a first dielectric strip between the first and second conductor strips, and a second dielectric strip between the second and third conductor strips. Additionally, the compact linear accelerator includes a high voltage power supply connected to charge the second conductor strip to a high potential, and a switch for switching the high potential in the second conductor strip to at least one of the first and third conductor strips so as to initiate a propagating reverse polarity wavefront(s) in the corresponding dielectric strip(s).

  15. MUON ACCELERATION

    SciTech Connect

    BERG,S.J.

    2003-11-18

    One of the major motivations driving recent interest in FFAGs is their use for the cost-effective acceleration of muons. This paper summarizes the progress in this area that was achieved leading up to and at the FFAG workshop at KEK from July 7-12, 2003. Much of the relevant background and references are also given here, to give a context to the progress we have made.

  16. BICEP's acceleration

    SciTech Connect

    Contaldi, Carlo R.

    2014-10-01

    The recent Bicep2 [1] detection of, what is claimed to be primordial B-modes, opens up the possibility of constraining not only the energy scale of inflation but also the detailed acceleration history that occurred during inflation. In turn this can be used to determine the shape of the inflaton potential V(φ) for the first time — if a single, scalar inflaton is assumed to be driving the acceleration. We carry out a Monte Carlo exploration of inflationary trajectories given the current data. Using this method we obtain a posterior distribution of possible acceleration profiles ε(N) as a function of e-fold N and derived posterior distributions of the primordial power spectrum P(k) and potential V(φ). We find that the Bicep2 result, in combination with Planck measurements of total intensity Cosmic Microwave Background (CMB) anisotropies, induces a significant feature in the scalar primordial spectrum at scales k∼ 10{sup -3} Mpc {sup -1}. This is in agreement with a previous detection of a suppression in the scalar power [2].

  17. Laser acceleration

    NASA Astrophysics Data System (ADS)

    Tajima, T.; Nakajima, K.; Mourou, G.

    2017-02-01

    The fundamental idea of Laser Wakefield Acceleration (LWFA) is reviewed. An ultrafast intense laser pulse drives coherent wakefield with a relativistic amplitude robustly supported by the plasma. While the large amplitude of wakefields involves collective resonant oscillations of the eigenmode of the entire plasma electrons, the wake phase velocity ˜ c and ultrafastness of the laser pulse introduce the wake stability and rigidity. A large number of worldwide experiments show a rapid progress of this concept realization toward both the high-energy accelerator prospect and broad applications. The strong interest in this has been spurring and stimulating novel laser technologies, including the Chirped Pulse Amplification, the Thin Film Compression, the Coherent Amplification Network, and the Relativistic Mirror Compression. These in turn have created a conglomerate of novel science and technology with LWFA to form a new genre of high field science with many parameters of merit in this field increasing exponentially lately. This science has triggered a number of worldwide research centers and initiatives. Associated physics of ion acceleration, X-ray generation, and astrophysical processes of ultrahigh energy cosmic rays are reviewed. Applications such as X-ray free electron laser, cancer therapy, and radioisotope production etc. are considered. A new avenue of LWFA using nanomaterials is also emerging.

  18. Advanced concepts for acceleration

    SciTech Connect

    Keefe, D.

    1986-07-01

    Selected examples of advanced accelerator concepts are reviewed. Such plasma accelerators as plasma beat wave accelerator, plasma wake field accelerator, and plasma grating accelerator are discussed particularly as examples of concepts for accelerating relativistic electrons or positrons. Also covered are the pulsed electron-beam, pulsed laser accelerator, inverse Cherenkov accelerator, inverse free-electron laser, switched radial-line accelerators, and two-beam accelerator. Advanced concepts for ion acceleration discussed include the electron ring accelerator, excitation of waves on intense electron beams, and two-wave combinations. (LEW)

  19. Accelerators and the Accelerator Community

    SciTech Connect

    Malamud, Ernest; Sessler, Andrew

    2008-06-01

    In this paper, standing back--looking from afar--and adopting a historical perspective, the field of accelerator science is examined. How it grew, what are the forces that made it what it is, where it is now, and what it is likely to be in the future are the subjects explored. Clearly, a great deal of personal opinion is invoked in this process.

  20. Osseointegration aspects of placed implant in bone reconstruction with newly developed block-type interconnected porous calcium hydroxyapatite

    PubMed Central

    DOI, Kazuya; KUBO, Takayasu; MAKIHARA, Yusuke; OUE, Hiroshi; MORITA, Koji; OKI, Yoshifumi; KAJIHARA, Shiho; TSUGA, Kazuhiro

    2016-01-01

    ABSTRACT Artificial bone has been employed to reconstruct bone defects. However, only few reports on implant placement after block bone grafting exist. Objectives The purpose of this study was to evaluate the osseointegration of dental implant in bone reconstructions with interconnected porous calcium hydroxyapatite (IP-CHA). Material and Methods The IP-CHA cylinders (D; 4.3 mm, H; 10.0 mm) were placed into bone sockets in each side of the femurs of four male dogs. The IP-CHA on the right side was a 24-week sample. Twelve weeks after placement, a titanium implant was placed into a socket that was prepared in half of the placed IP-CHA cylinder on the right side. On the left side, another IP-CHA cylinder was placed as a 12-week sample. After another 12 weeks, the samples were harvested, and the bone regeneration and bone-implant contact (BIC) ratios were measured. Results New bone formation area was superior in the 24-week IP-CHA compared with the 12-week IP-CHA. BIC was not significantly different between IP-CHA and the parent sites. Osseointegration was detected around the implant in IP-CHA-reconstructed bone. Conclusion Our preliminary results suggest that IP-CHA may be a suitable bone graft material for reconstructing bones that require implant placement. PMID:27556202

  1. Femtosecond laser treatment of 316L improves its surface nanoroughness and carbon content and promotes osseointegration: An in vitro evaluation.

    PubMed

    Kenar, Halime; Akman, Erhan; Kacar, Elif; Demir, Arif; Park, Haiwoong; Abdul-Khaliq, Hashim; Aktas, Cenk; Karaoz, Erdal

    2013-08-01

    Cell-material surface interaction plays a critical role in osseointegration of prosthetic implants used in orthopedic surgeries and dentistry. Different technical approaches exist to improve surface properties of such implants either by coating or by modification of their topography. Femtosecond laser treatment was used in this study to generate microspotted lines separated by 75, 125, or 175μm wide nanostructured interlines on stainless steel (316L) plates. The hydrophobicity and carbon content of the metallic surface were improved simultaneously through this method. In vitro testing of the laser treated plates revealed a significant improvement in adhesion of human endothelial cells and human bone marrow mesenchymal stem cells (hBM MSCs), the cells involved in microvessel and bone formation, respectively, and a significant decrease in fibroblast adhesion, which is implicated in osteolysis and aseptic loosening of prostheses. The hBM MSCs showed an increased bone formation rate on the laser treated plates under osteogenic conditions; the highest mineral deposition was obtained on the surface with 125μm interline distance (292±18mg/cm(2) vs. 228±43mg/cm(2) on untreated surface). Further in vivo testing of these laser treated surfaces in the native prosthetic implant niche would give a real insight into their effectiveness in improving osseointegration and their potential use in clinical applications. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Effects on the torsional vibration behavior in the investigation of dental implant osseointegration using resonance frequency analysis: a numerical approach.

    PubMed

    Zhai, Min; Li, Bing; Li, Dehua

    2017-02-07

    Resonance frequency analysis (RFA) methods are widely used to assess implant stability, particularly the Osstell(®) device. The potential effects associated with this method have been discussed in the literature. Torsional RFA (T-RFA), mentioned in our previous study, could represent a new measurement method. The purpose of this study was to simulate T-shaped and Osstell(®) transducer-implant-bone system models; compare their vibration modes and corresponding resonance frequencies; and investigate the effects of their parameters, such as the effective implant length (EIL), bone quality, and osseointegration level, on the torsional resonance frequency (TRF) and bending resonance frequency (BRF) using three-dimensional finite element analysis. Following the finite element model validation, the TRFs and BRFs for three different EILs and four types of bone quality were obtained, and the change rates during 25 degrees of osseointegration were observed. The analysis showed that an increase in the EIL and a decrease in bone quality have less effect on the declination rate of TRFs than on that of BRFs. TRFs are highly sensitive to the stiffness of the implant-bone interface during the healing period. It was concluded that T-RFA has better sensitivity and specificity.

  3. Surface modifications to enhance the wear resistance and the osseo-integration properties of biomedical Ti-alloy

    NASA Astrophysics Data System (ADS)

    Kami, Pavani

    The current study focuses on improving the wear resistance of femoral head component and enhancing the osseo-integration properties of femoral stem component of a hip implant made of a new generation low modulus alloy, Ti-35Nb-7Zr-5Ta or TNZT. Different techniques that were adopted to improve the wear resistance of low-modulus TNZT alloy included; (a) fabrication of graded TNZT-xB (x= 0, 1, 2 wt%) samples using LENS, (b) oxidation, and (c) LASER nitriding of TNZT. TNZT-1B and TNZT-O samples have shown improved wear resistance when tested against UHMWPE ball in SBF medium. A new class of bio-ceramic coatings based on calcium phosphate (CaP), was applied on the TNZT sample surface and was further laser processed with the objective of enhancing their osseointegration properties. With optimized LASER parameters, TNZT-CaP samples have shown improved corrosion resistance, surface wettability and cellular response when compared to the base TNZT sample.

  4. The role of nanostructures and hydrophilicity in osseointegration: In-vitro protein-adsorption and blood-interaction studies.

    PubMed

    Kopf, Brigitte S; Ruch, Sylvie; Berner, Simon; Spencer, Nicholas D; Maniura-Weber, Katharina

    2015-08-01

    Protein adsorption and blood coagulation play important roles in the early stages of osseointegration and are strongly influenced by surface properties. We present a systematic investigation of the influence of different surface properties on the adsorption of the blood proteins fibrinogen and fibronectin and the degree of early blood coagulation. Experiments on custom-made and commercially available, microroughened hydrophobic titanium (Ti) surfaces (Ti SLA-Hphob ), hydrophilic (Hphil ) microroughened Ti surfaces with nanostructures (Ti SLActive-Hphil NS), and on bimetallic Ti zirconium alloy (TiZr, Roxolid®) samples were performed, to study the biological response in relation to the surface wettability and the presence of nanostructures (NS). Protein adsorption on the different substrates showed a highly significant effect of surface NS. Hydrophilicity alone did not significantly enhance protein adsorption. Overall, the combination of NS and hydrophilicity led to the highest adsorption levels; independent of whether Ti or TiZr were used. Hydrophilicity induced a strong effect on blood coagulation, whereas the effect of NS alone was weak. The combination of both surface characteristics led to early and most pronounced blood-coagulation. Therefore, nanostructured, hydrophilic Ti and TiZr surfaces may perform better in terms of osseointegration due to continuous protein adsorption and the formation of a layer of blood components on the implant surface.

  5. Influence of transfemoral amputation length on resulting loads at the osseointegrated prosthesis fixation during walking and falling.

    PubMed

    Schwarze, Michael; Hurschler, Christof; Seehaus, Frank; Correa, Tomas; Welke, Bastian

    2014-03-01

    Transfemoral amputation is a surgical measure in which the surgeon typically conserves as much tissue and bone as possible. Osseointegrated fixation of prostheses is a promising alternative to conventional socket-based fixation. However, osseointegrated prostheses pose some risk of possible bone fracture under unexpected high-impact loading scenarios, such as a fall, and this should be protected against by a safety element. The aim of the present study was to determine the effect of amputation height on the forces and moments at the bone-prosthesis interface during normal gait and three falling scenarios. Forces and moments at four amputation heights were determined from a multi-body simulation driven by data captured from an able-bodied participant. In all three falling scenarios, forces were relatively independent of amputation height, while moments generally displayed considerable increases with shorter residual limb length. Peak moments ranged from 105Nm (SD 75) (most distal amputation height) to 229Nm (SD 99) (most proximal amputation height) for a "falling during gait" scenario. Our findings reveal the dependence of interface loads on amputation height in normal gait and falling. This information may lead to improved prosthesis safety elements against bending moments. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. [A new method for prosthetisation of vascular patients with lower limb amputation: initial experiences with osseointegration technique].

    PubMed

    Ferencz, Sándor; Mangold, Viktória; Dérczy, Katalin; Takács, Ildikó; Balatonyi, Borbála; Horváth, Szabolcs; Jávor, Szaniszló; Brånemark, Rickard; Horváth, Ors Péter; Roth, Erzsébet; Wéber, György

    2009-10-01

    Prostheses use for lower limb amputees is difficult, while the socket is hard, the prosthesis is heavy. Drawbacks of conventional prosthesis are mainly associated with the socket, therefore osseointegration technique is a promising solution, since it doesn't require a socket. Our aim was to introduce this technique in Hungary and extend indication for vascular patients. The method includes two operative and one rehabilitation phases: during first operation a titanium screw is fixed into the femoral bone marrow cavity, this connects to an abutment, which also penetrates the skin, making a direct connection between the femur and the prosthesis during the second intervention. During rehabilitation the patient makes loading exercises and learns to walk with new prosthesis. This method was launched in Hungary in 2005. Two female amputees were operated on initially, their second surgery was performed in 2006 (when titanium screw was applied in the male patients, as well). Incorporation of titanium screw was exquisite, and rehabilitation was successful. One of our male patients died eight months after his first operation due to myocardial infarction. Based on our experiences, the osseointegration technique facilitates rehabilitation of vascular patients for prostheses use. Adequate follow-up and stable vascular diseases are not contraindications, although further clinical trials are needed to determine its indication.

  7. In Vivo Osseointegration Performance of Titanium Dioxide Coating Modified Polyetheretherketone Using Arc Ion Plating for Spinal Implant Application

    PubMed Central

    Tsou, Hsi-Kai; Chi, Meng-Hui; Hung, Yi-Wen; Chung, Chi-Jen; He, Ju-Liang

    2015-01-01

    Polyetheretherketone (PEEK), which has biomechanical performance similar to that of human cancellous bone, is used widely as a spinal implant material. However, its bioinertness and hydrophobic surface properties result in poor osseointegration. This study applies a novel modification method, arc ion plating (AIP), that produces a highly osteoblast compatible titanium dioxide (TiO2) coatings on a PEEK substrate. This PEEK with TiO2 coating (TiO2/PEEK) was implanted into the femurs of New Zealand white male rabbits to evaluate its in vivo performance by the push-out test and histological observation. Analytical results show that AIP can prepare TiO2 coatings on bullet-shaped PEEK substrates as implant materials. After prolonged implantation in rabbits, no signs of inflammation existed. Newly regenerated bone formed more prominently with the TiO2/PEEK implant by histological observation. The shear strength of the bone/implant interface increases as implantation period increases. Most importantly, bone bonding performance of the TiO2/PEEK implant was superior to that of bare PEEK. The rutile-TiO2 coatings achieved better osseointegration than the anatase-TiO2 coatings. Therefore, AIP-TiO2 can serve as a novel surface modification method on PEEK for spinal interbody fusion cages. PMID:26504800

  8. Load on osseointegrated fixation of a transfemoral amputee during a fall: loading, descent, impact and recovery analysis.

    PubMed

    Frossard, Laurent Alain; Tranberg, Roy; Haggstrom, Eva; Pearcy, Mark; Brånemark, Rickard

    2010-03-01

    Falling represents a health risk for lower limb amputees fitted with an osseointegrated fixation mainly because of the potential damage to the fixation. The purpose of this study was to characterize a real forward fall that occurred inadvertently to a transfemoral amputee fitted with an osseointegrated fixation while attending a gait measurement session to assess the load applied on the residuum. The objective was to analyze the load applied on the fixation with an emphasis on the sequence of events, the pattern and the magnitude of the forces and moments. The load was measured directly at 200 Hz using a six-channel transducer. Complementary video footage was also studied. The fall was divided into four phases: Loading (240 ms), descent (620 ms), impact (365 ms) and recovery (2495 ms). The main impact forces and moments occurred 870 ms and 915 ms after the heel contact, and corresponded to 133% BW and 17 % BWm, or 1.2 and 11.2 times the maximum forces and moments applied during the previous steps of the participant, respectively. This study provided key information to engineers and clinicians facing the challenge to design equipment, and rehabilitation and exercise programs to restore safely the locomotion of lower limb amputees.

  9. Osseointegration of endosseous ceramic implants after postoperative low-power laser stimulation: an in vivo comparative study.

    PubMed

    Guzzardella, Gaetano A; Torricelli, Paola; Nicoli-Aldini, Nicolò; Giardino, Roberto

    2003-04-01

    Stimulation with low-power laser (LPL) can enhance bone repair as reported in experimental studies on bone defects and fracture healing. Little data exist concerning the use of LPL postoperative stimulation to improve osseointegration of endosseous implants in orthopaedic and dental surgery. An in vivo model was used for the present study to evaluate whether Ga-Al-As (780 nm) LPL stimulation can improve biomaterial osseointegration. After drilling holes, cylindrical implants of hydroxyapatite (HA) were placed into both distal femurs of 12 rabbits. From postoperative day 1 and for 5 consecutive days, the left femurs of all rabbits were submitted to LPL treatment (LPL group) with the following parameters: 300 J/cm2, 1 W, 300 Hz, pulsating emission, 10 min. The right femurs were sham-treated (control group). Three and 6 weeks after implantation, histomorphometric and microhardness measurements were taken. A higher affinity index was observed at the HA-bone interface in the LPL group at 3 (P<0.0005) and 6 weeks (P<0.001); a significant difference in bone microhardness was seen in the LPL group vs. the control group (P<0.01). These results suggest that LPL postoperative treatment enhances the bone-implant interface.

  10. Impact of plaque accumulation on the osseointegration of titanium-zirconium alloy and titanium implants. A histological and immunohistochemical analysis.

    PubMed

    Schwarz, Frank; Mihatovic, Ilja; Golubovic, Vladimir; Bradu, Sebastian; Sager, Martin; Becker, Jürgen

    2015-11-01

    To evaluate the impact of plaque accumulation on osseointegration at surface enhanced modified hydrophilic titanium-zirconium (TiZr) alloy and titanium (Ti) implants. TiZr and Ti implants with a sand-blasted, acid etched, and chemically modified endosseous and a machined (M) transmucosal portion were bilaterally (i.e., one implant type on each side) inserted in the maxilla of six foxhounds. In a split-mouth design, experimental mucositis was induced at one randomly assigned side (NPC), while the contralateral side received mechanical plaque removal three times per week (PC). After 16 weeks, tissue biopsies were processed for histological (primary outcome: bone-to-implant contact [BIC]) and immunohistochemical (CD68) analysis. Mean BIC values varied between 81.96% (TiZrM) and 88.72% (TiM) in the NPC group, and between 87.88% (TiM) and 92.69% (TiZrM) in the PC group. Even though BIC values tended to be lower within the endosseous coronal compartment at NPC sites, within group (NPC vs. PC) comparisons failed to reach statistical significance at both types of implants. These non-BIC areas were not associated with any CD68 positive cells. Osseointegration of both TiZrM and TiM implants was not influenced by plaque accumulation in this experimental model. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  11. Establishment of a new pull-out strength testing method to quantify early osseointegration-An experimental pilot study.

    PubMed

    Nonhoff, J; Moest, T; Schmitt, Christian Martin; Weisel, T; Bauer, S; Schlegel, K A

    2015-12-01

    The animal study aims to evaluate a new experimental model for measuring sole the influence of the surface characteristics independent from implant macro-design on the level of osseointegration by registering the pull-out strength needed for removal of experimental devices with different surfaces from artificial defects. Seventy-two test bodies (36 with the FRIADENT(®) plus surface, 36 with the P15/HAp biofunctionalized surface) were inserted in six adult domestic pigs with artificial calvarial defects. The experimental devices were designed to fit in the defects leaving a gap between the test body and the local bone. After 21 days of healing, the animals were sacrificed and the test bodies were pulled out with a standardised reproducible pull-out device measuring the pull-out strength. The pull-out strength for both groups was compared. Twenty-one days after insertion a mean force of 412 ± 142 N for the P15/HAp group and 183 ± 105 N for the FRIADENT(®) plus group was measured for the removal of the specimens from the calvarial bone. The difference between the groups was statistically significant (p < 0.0001). The experimental set-up seems to be a suitable method when measuring the impact of implant surfaces on the early stage of osseointegration. Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  12. The influence of estrogen deficiency on bone around osseointegrated dental implants. An experimental study in the rat jaw model

    PubMed Central

    Giro, Gabriela; Coelho, Paulo G.; Pessoa, Roberto Sales; Pereira, Rosa Maria Rodrigues; Kawai, Toshihisa; Orrico, Silvana Regina Perez

    2011-01-01

    Purpose The aim of this study was to evaluate the influence of estrogen deficiency on bone around osseointegrated dental implants in a rat jaw model. Materials and Methods This study utilized 16 female rats, which had the first molars bilaterally extracted and allowed to heal for 30 days prior to implant placement. Sixty days after implant placement, the animals were randomly submitted to sham surgery (SHAM) or ovariectomy (OVX). The animals were euthanized 90 days post-ovariectomy. Bone to implant contact, bone area fraction occupancy between implant threads, mineral density, turnover markers and TRAP positive cells were assessed for both groups. Results The results showed that OVX group presented a decrease of systemic bone density, alterations on bone turnover markers, and an increase of TRAP positive cells relative to the SHAM group. However no difference relative to the bone to implant contact and bone area fraction occupancy was observed between groups. Conclusions The findings of this study demonstrate that estrogen deficiency may not be considered as a risk factor for osseointegrated implants failure in jaw bone. PMID:21530046

  13. Impact accelerations

    NASA Technical Reports Server (NTRS)

    Vongierke, H. E.; Brinkley, J. W.

    1975-01-01

    The degree to which impact acceleration is an important factor in space flight environments depends primarily upon the technology of capsule landing deceleration and the weight permissible for the associated hardware: parachutes or deceleration rockets, inflatable air bags, or other impact attenuation systems. The problem most specific to space medicine is the potential change of impact tolerance due to reduced bone mass and muscle strength caused by prolonged weightlessness and physical inactivity. Impact hazards, tolerance limits, and human impact tolerance related to space missions are described.

  14. Teriparatide Therapy Enhances Devitalized Femoral Allograft Osseointegration and Biomechanics in a Murine Model

    PubMed Central

    Reynolds, David G.; Takahata, Masahiko; Lerner, Amy L.; O’Keefe, Regis J.; Schwarz, Edward M.; Awad, Hani A.

    2010-01-01

    Despite the remarkable healing potential of long bone fractures, traumatic injuries that result in critical defects require challenging reconstructive limb sparing surgery. While devitalized allografts are the gold standard for these procedures, they are prone to failure due to their limited osseointegration with the host. Thus, the quest for adjuvants to enhance allograft healing remains a priority for this unmet clinical need. To address this, we investigated the effects of daily systemic injections of 40 µg/kg teriparatide (recombinant human parathyroid hormone) on the healing of devitalized allografts used to reconstruct critical femoral defects (4 mm) in C57Bl/6 mice. The femurs were evaluated at 4 and 6 weeks using micro CT, histology, and torsion testing. Our findings demonstrated that teriparatide induced prolonged cartilage formation at the graft-host junction at 4 weeks, which led to enhanced trabeculated bone callus formation and remarkable graft-host integration at 6-weeks. Moreover, we observed a significant 2-fold increase in normalized callus volume (1.04 ± 0.3 vs. 0.54 ± 0.14 mm3/mm; p<0.005), and Union Ratio (0.28 ± 0.07 vs. 0.13 ± 0.09; p<0.005), compared to saline treated controls at 6-weeks. Teriparatide treatment significantly increased the torsional rigidity (585±408 versus 1175±311 N.mm2) and yield torque (6.8±5.5 versus 10.5±4.2 N.mm) compared to controls. Interestingly, the Union Ratio correlated significantly with the yield torque and torsional rigidity (R2=0.59 and R2=0.77, p<0.001, respectively). These results illustrate the remarkable potential of teriparatide as an adjuvant therapy for allograft repair in a mouse model of massive femoral defect reconstruction, and warrant further investigation in a larger animal model at longer time intervals to justify future clinical trials for PTH therapy in limb sparing reconstructive procedures. PMID:20950720

  15. Histomorphometric and biomechanical analyses of osseointegration of four different orthodontic mini implant surfaces

    NASA Astrophysics Data System (ADS)

    Yadav, Sumit

    Objective: To evaluate the osseointegration potential of four different surfaces of mini-implants. We hypothesized that mini-implants surface roughness alters the intrinsic biomechanical properties of the bone integrated to titanium. Materials and Methods: Mini implants and circular discs were made from alloy Ti6Al4V grade 5. On the basis of surface treatment study was divided into 4 groups: Group 1: Machined: no surface treatment, Group 2: Acid etched: with hydrochloric acid, Group 3: Grit Blasted with alumina and Group 4: Grit blasted +Acid etched. Surface roughness parameters (mean surface roughness: Ra and Quadratic Average roughness: Rq) of the four discs from each group were measured by the optical profilometer. Contact angle measurement of 3 discs from each group was done with a Goniometer. Contact angle of liquids with different hydrophobicity and hydrophilicity were measured. 128 mini implants, differing in surface treatment, were placed into the tibias and femurs of 8 adult male New Zealand white rabbits. Biomechanical properties (Removal torque and hardness) measurements and histomorphometric observations were measured. Results: Ra and Rq of groups were: Machined (1.17+/-0.11, 2.59+/-0.09) Acid etched (1.82+/-0.04, 3.17+/-0.13), Grit blasted (4.83+/-0.23, 7.04+/-0.08), Grit blasted + Acid etched (3.64+/-0.03, 4.95+/-0.04) respectively. Group 4 had significantly (p=0.000) lower Ra and Rq than Group 3. The interaction between the groups and liquid was significant. Group 4 had significantly lower contact angle measurements (40.4°, 26.9°), both for blood and NaCl when compared to other three groups (p≤0.01). Group 4 had significantly higher torque than Group 3 (Tibia: 13.67>9.07N-cm; Femur: 18.21>14.12N-cm), Group 4 (Tibia: 13.67>9.78N-cm; Femur: 18.21>12.87N-cm), and machined (Tibia: 13.67>4.08N-cm; Femur: 18.21>6.49N-cm). SEM analysis reveals significantly more bone implant gap in machined implant surfaces than treated implant surfaces. Bone to implant

  16. Stiffness and ultimate load of osseointegrated prosthesis fixations in the upper and lower extremity

    PubMed Central

    2013-01-01

    Background Techniques for the skeletal attachment of amputation-prostheses have been developed over recent decades. This type of attachment has only been performed on a small number of patients. It poses various potential advantages compared to conventional treatment with a socket, but is also associated with an increased risk of bone or implant-bone interface fracture in the case of a fall. We therefore investigated the bending stiffness and ultimate bending moment of such devices implanted in human and synthetic bones. Methods Eight human specimens and 16 synthetic models of the proximal femora were implanted with lower extremity prostheses and eight human specimens and six synthetic humeri were implanted with upper extremity prostheses. They were dissected according to typical amputation levels and underwent loading in a material testing machine in a four-point bending setup. Bending stiffness, ultimate bending moment and fracture modes were determined in a load to failure experiment. Additionally, axial pull-out was performed on eight synthetic specimens of the lower extremity. Results Maximum bending moment of the synthetic femora was 160.6±27.5 Nm, the flexural rigidity of the synthetic femora was 189.0±22.6 Nm2. Maximum bending moment of the human femora was 100.4±38.5 Nm, and the flexural rigidity was 137.8±29.4 Nm2. The maximum bending moment of the six synthetic humeri was 104.9±19.0 Nm, and the flexural rigidity was 63.7±3.6 Nm2. For the human humeri the maximum bending moment was 36.7±11.0 Nm, and the flexural rigidity at was 43.7±10.5 Nm2. The maximum pull-out force for the eight synthetic femora was 3571±919 N. Conclusion Significant differences were found between human and synthetic specimens of the lower and upper extremity regarding maximum bending moment, bending displacement and flexural rigidity. The results of this study are relevant with respect to previous finding regarding the load at the interfaces of osseointegrated prosthesis

  17. [Osseointegrated implants in clinical dentistry from the point of view of prosthodontics].

    PubMed

    Kobayashi, Y

    1989-10-01

    With the life expectancy of our country reaching 80s we are encountering a society with greater proportion of the population in old ages. This social problem creates a relatively important assignment in the area of prosthodontics, especially in full denture prosthodontics. Though the most important factor that affects the success or failure of full denture prosthodontics is the condition of the residual ridge, recent studies have shown that the residual ridges continue to resorb throughout one's life span. Also our survey on the present Japanese denture patients tells us that an average person becomes edentulous at an age of 57.6, has made a full denture twice or more, has worn the denture for 8 to 10 years, and by age 65 to 67 over half of the patients have their mandibular residual ridges being even or the ridge has resorbed extremely so that the ridge is actually lower than the floor of the mouth. With the situation as it is, when we look into the future of the full denture prosthodontics it is inevitable that there will be a rapid increase in patients with extremely resorbed ridges which the present theory of full denture prosthodontics could not handle. In this sense, prosthodontic treatment of edentulous patients with implants is a relatively interesting field. In this article we will comment of the basic application technique and the prosthodontic technique which we have improved of the Brånemark's Osseointegrated implants which possess the long term basic objective clinical data and whose long term safety has been established in edentulous patients. First we will explain the basic application technique using a real case. The patient was a 56 years old female. She came to the clinic with the chief complaint of severe masticatory dysfunction due to unstable full dentures. She strongly desired fixed prosthodontics. She had worn dentures for the past 17 years. The dentures that she had on when she came in for the first visit were her 4th set of dentures. For

  18. A new adaptive method to filter terrestrial laser scanner point clouds using morphological filters and spectral information to conserve surface micro-topography

    NASA Astrophysics Data System (ADS)

    Rodríguez-Caballero, E.; Afana, A.; Chamizo, S.; Solé-Benet, A.; Canton, Y.

    2016-07-01

    Terrestrial laser scanning (TLS), widely known as light detection and ranging (LiDAR) technology, is increasingly used to provide highly detailed digital terrain models (DTM) with millimetric precision and accuracy. In order to generate a DTM, TLS data has to be filtered from undesired spurious objects, such as vegetation, artificial structures, etc., Early filtering techniques, successfully applied to airborne laser scanning (ALS), fail when applied to TLS data, as they heavily smooth the terrain surface and do not retain their real morphology. In this article, we present a new methodology for filtering TLS data based on the geometric and radiometric properties of the scanned surfaces. This methodology was built on previous morphological filters that select the minimum point height within a sliding window as the real surface. However, contrary to those methods, which use a fixed window size, the new methodology operates under different spatial scales represented by different window sizes, and can be adapted to different types and sizes of plants. This methodology has been applied to two study areas of differing vegetation type and density. The accuracy of the final DTMs was improved by ∼30% under dense canopy plants and over ∼40% on the open spaces between plants, where other methodologies drastically underestimated the real surface heights. This resulted in more accurate representation of the soil surface and microtopography than up-to-date techniques, eventually having strong implications in hydrological and geomorphological studies.

  19. Effect of low-level mechanical vibration on osteogenesis and osseointegration of porous titanium implants in the repair of long bone defects

    NASA Astrophysics Data System (ADS)

    Jing, Da; Tong, Shichao; Zhai, Mingming; Li, Xiaokang; Cai, Jing; Wu, Yan; Shen, Guanghao; Zhang, Xuhui; Xu, Qiaoling; Guo, Zheng; Luo, Erping

    2015-11-01

    Emerging evidence substantiates the potential of porous titanium alloy (pTi) as an ideal bone-graft substitute because of its excellent biocompatibility and structural properties. However, it remains a major clinical concern for promoting high-efficiency and high-quality osseointegration of pTi, which is beneficial for securing long-term implant stability. Accumulating evidence demonstrates the capacity of low-amplitude whole-body vibration (WBV) in preventing osteopenia, whereas the effects and mechanisms of WBV on osteogenesis and osseointegration of pTi remain unclear. Our present study shows that WBV enhanced cellular attachment and proliferation, and induced well-organized cytoskeleton of primary osteoblasts in pTi. WBV upregulated osteogenesis-associated gene and protein expression in primary osteoblasts, including OCN, Runx2, Wnt3a, Lrp6 and β-catenin. In vivo findings demonstrate that 6-week and 12-week WBV stimulated osseointegration, bone ingrowth and bone formation rate of pTi in rabbit femoral bone defects via μCT, histological and histomorphometric analyses. WBV induced higher ALP, OCN, Runx2, BMP2, Wnt3a, Lrp6 and β-catenin, and lower Sost and RANKL/OPG gene expression in rabbit femora. Our findings demonstrate that WBV promotes osteogenesis and osseointegration of pTi via its anabolic effect and potential anti-catabolic activity, and imply the promising potential of WBV for enhancing the repair efficiency and quality of pTi in osseous defects.

  20. Controlled Release of Naringin in Metal-Organic Framework-Loaded Mineralized Collagen Coating to Simultaneously Enhance Osseointegration and Antibacterial Activity.

    PubMed

    Yu, Mengfei; You, Dongqi; Zhuang, Junjun; Lin, Suya; Dong, Lingqing; Weng, Shengtao; Zhang, Bin; Cheng, Kui; Weng, Wenjian; Wang, Huiming

    2017-06-14

    Two important goals in orthopedic implant research are to promote osseointegration and prevent infection. However, much previous effort has been focused on the design of coatings to either enhance osseointegration while ignoring antibacterial activity or vice versa, to prevent infection while ignoring bone integration. Here, we designed a multifunctional mineralized collagen coating on titanium with the aid of metal-organic framework (MOF) nanocrystals to control the release of naringin, a Chinese herbal medicine that could promote osseointegration and prevent bacterial infection. The attachment, proliferation, osteogenic differentiation, and mineralization of mesenchymal stem cells on the coating were significantly enhanced. Meanwhile, the antibacterial abilities against Staphylococcus aureus were also promoted. Furthermore, release kinetics analysis indicated that the synergistic effect of a primary burst release stage and secondary slow release stage played a critical role in the performance and could be controlled by the relative concentrations of MOF and naringin. This work thus provides a novel strategy to engineer multifunctional orthopedic coatings that can enhance osseointegration and simultaneously inhibit microbial cell growth.

  1. Effect of low-level mechanical vibration on osteogenesis and osseointegration of porous titanium implants in the repair of long bone defects

    PubMed Central

    Jing, Da; Tong, Shichao; Zhai, Mingming; Li, Xiaokang; Cai, Jing; Wu, Yan; Shen, Guanghao; Zhang, Xuhui; Xu, Qiaoling; Guo, Zheng; Luo, Erping

    2015-01-01

    Emerging evidence substantiates the potential of porous titanium alloy (pTi) as an ideal bone-graft substitute because of its excellent biocompatibility and structural properties. However, it remains a major clinical concern for promoting high-efficiency and high-quality osseointegration of pTi, which is beneficial for securing long-term implant stability. Accumulating evidence demonstrates the capacity of low-amplitude whole-body vibration (WBV) in preventing osteopenia, whereas the effects and mechanisms of WBV on osteogenesis and osseointegration of pTi remain unclear. Our present study shows that WBV enhanced cellular attachment and proliferation, and induced well-organized cytoskeleton of primary osteoblasts in pTi. WBV upregulated osteogenesis-associated gene and protein expression in primary osteoblasts, including OCN, Runx2, Wnt3a, Lrp6 and β-catenin. In vivo findings demonstrate that 6-week and 12-week WBV stimulated osseointegration, bone ingrowth and bone formation rate of pTi in rabbit femoral bone defects via μCT, histological and histomorphometric analyses. WBV induced higher ALP, OCN, Runx2, BMP2, Wnt3a, Lrp6 and β-catenin, and lower Sost and RANKL/OPG gene expression in rabbit femora. Our findings demonstrate that WBV promotes osteogenesis and osseointegration of pTi via its anabolic effect and potential anti-catabolic activity, and imply the promising potential of WBV for enhancing the repair efficiency and quality of pTi in osseous defects. PMID:26601709

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

    PubMed

    Jin, Guodong; Qin, Hui; Cao, Huiliang; Qiao, Yuqin; Zhao, Yaochao; Peng, Xiaochun; Zhang, Xianlong; Liu, Xuanyong; Chu, Paul K

    2015-10-01

    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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Accelerator system and method of accelerating particles

    NASA Technical Reports Server (NTRS)

    Wirz, Richard E. (Inventor)

    2010-01-01

    An accelerator system and method that utilize dust as the primary mass flux for generating thrust are provided. The accelerator system can include an accelerator capable of operating in a self-neutralizing mode and having a discharge chamber and at least one ionizer capable of charging dust particles. The system can also include a dust particle feeder that is capable of introducing the dust particles into the accelerator. By applying a pulsed positive and negative charge voltage to the accelerator, the charged dust particles can be accelerated thereby generating thrust and neutralizing the accelerator system.

  4. Osseointegration of implants with dendrimers surface characteristics installed conventionally or with Piezosurgery®. A comparative study in the dog.

    PubMed

    Bengazi, Franco; Lang, Niklaus P; Canciani, Elena; Viganò, Paolo; Velez, Joaquin Urbizo; Botticelli, Daniele

    2014-01-01

    The first aim of the present experiment was to compare bone healing at implants installed in recipient sites prepared with conventional drills or a piezoelectric device. The second aim was to compare implant osseointegration onto surfaces with and without dendrimers coatings. Six Beagles dogs were used in this study. Five implants with two different surfaces, three with a ZirTi(®) surface (zirconia sand blasted, acid etched), and two with a ZirTi(®)-modified surface with dendrimers of phosphoserine and polylysine were installed in the right side of the mandible. In the most anterior region (P2, P3), two recipient sites were prepared with drills, and one implant ZirTi(®) surface and one coated with dendrimers implants were installed at random. In the posterior region (P4 and M1), three recipient sites were randomly prepared: two sites with a Piezosurgery(®) instrument and one site with drill and two ZirTi(®) surface and one coated with dendrimers implants installed. Three months after the surgery, the animals were sacrificed for histological analysis. No complications occurred during the healing period. Three implants were found not integrated and were excluded from analysis. However, n = 6 was obtained. The distance IS-B at the buccal aspect was 2.2 ± 0.8 and 1.8 ± 0.5 mm, while IS-C was 1.5 ± 0.9 and 1.4 ± 0.6 mm at the Piezosurgery(®) and drill groups, respectively. Similar values were obtained between the dendrimers-coated and ZirTi(®) surface implants. The BIC% values were higher at the drill (72%) compared to the Piezosurgery(®) (67%) sites. The BIC% were also found to be higher at the ZirTi(®) (74%) compared to the dendrimers-coated (65%) implants, the difference being statistically significant. This study has revealed that oral implants may osseointegrate equally well irrespective of whether their bed was prepared utilizing conventional drills with abundant cooling or Piezosurgery(®). Moreover, the surface coating of implants with dendrimers

  5. Crestal remodelling and osseointegration at surface-modified commercially pure titanium and titanium alloy implants in a canine model.

    PubMed

    Lee, Jaebum; Hurson, Steve; Tadros, Hatem; Schüpbach, Peter; Susin, Cristiano; Wikesjö, Ulf M E

    2012-08-01

    Ti-6Al-7Nb alloys exhibit enhanced mechanical properties and corrosion resistance and may represent an improvement to present commercially pure (CP) titanium oral implant technology. To evaluate crestal remodelling and osseointegration at CP titanium compared with Ti-6Al-7Nb alloy oral implants using a canine model. Two threaded anodized CP titanium and two Ti-6Al-7Nb alloy anodized oral implants (ø4.5 × 6.1 mm) were placed into each jaw quadrant in the edentulated posterior mandible in six adult male Hound Labrador mongrel dogs. Abutments were placed onto the implants, and the mucogingival flaps were adapted and sutured for transmucosal wound healing. Block biopsies were collected for histometric analysis following an 8-week healing interval. Healing was uneventful. Bone density outside and within the root of the threads averaged (± SE) 49.0 ± 4.5% and 38.7 ± 5.1% for CP titanium implants and 43.2 ± 3.6% and 34.2 ± 4.8% for Ti-6Al-7Nb alloy implants. Mean osseointegration reached 68.0 ± 4.4% and 62.8 ± 2.5% for CP titanium and Ti-6Al-7Nb alloy implants, respectively. Although crestal resorption at lingual sites averaged 0.2 ± 0.1 mm for both technologies, crestal resorption at buccal sites averaged 0.9 ± 0.2 and 1.0 ± 0.6 mm for CP titanium and Ti-6Al-7Nb alloy implants, respectively. There were no statistically significant differences between implant technologies for any parameter assessed. Notably, advanced/advancing buccal crestal resorption exposing the implant threads was observed in 50% of the implants (four of six animals) regardless of implant technology; osteoclastic resorption still observed at 8 weeks following implant placement. Within the limitations of study, anodized Ti-6Al-7Nb alloy implants may represent a feasible alternative to benchmark anodized CP titanium implants. Remodelling of the buccal crestal plate resulting in advanced bone loss appears a major impediment to oral implant osseointegration and possibly, in extension, implant

  6. Acceleration modules in linear induction accelerators

    NASA Astrophysics Data System (ADS)

    Wang, Shao-Heng; Deng, Jian-Jun

    2014-05-01

    The Linear Induction Accelerator (LIA) is a unique type of accelerator that is capable of accelerating kilo-Ampere charged particle current to tens of MeV energy. The present development of LIA in MHz bursting mode and the successful application into a synchrotron have broadened LIA's usage scope. Although the transformer model is widely used to explain the acceleration mechanism of LIAs, it is not appropriate to consider the induction electric field as the field which accelerates charged particles for many modern LIAs. We have examined the transition of the magnetic cores' functions during the LIA acceleration modules' evolution, distinguished transformer type and transmission line type LIA acceleration modules, and re-considered several related issues based on transmission line type LIA acceleration module. This clarified understanding should help in the further development and design of LIA acceleration modules.

  7. Synergistic effects of surface chemistry and topologic structure from modified microarc oxidation coatings on Ti implants for improving osseointegration.

    PubMed

    Zhou, Rui; Wei, Daqing; Cao, Jianyun; Feng, Wei; Cheng, Su; Du, Qing; Li, Baoqiang; Wang, Yaming; Jia, Dechang; Zhou, Yu

    2015-04-29

    Microarc oxidation (MAO) coating containing Ca, P, Si, and Na elements on a titanium (Ti) implant has been steam-hydrothermally treated and further mediated by post-heat treatment to overcome the compromised bone-implant integration. The bone regeneration, bone-implant contact, and biomechanical push-out force of the modified Ti implants are discussed thoroughly in this work. The best in vivo performances for the steam-hydrothermally treated one is attributed to the synergistic effects of surface chemistry and topologic structure. Through post-heat treatment, we can decouple the effects of surface chemistry and the nanoscale topologic structure easily. Attributed to the excellent in vivo performance of the surface-modified Ti implant, the steam-hydrothermal treatment could be a promising strategy to improve the osseointegration of the MAO coating covered Ti implant.

  8. Orthodontic Microimplants Assisted Intrusion of Supra-erupted Maxillary Molar Enabling Osseointegrated Implant Supported Mandibular Prosthesis: Case Reports.

    PubMed

    Rai, Deepak; Bhasin, Saranjeet Singh; Rai, Sheetal

    2014-12-01

    Loss of mandibular molars, when not replaced in time, are usually associated with overeruption of maxillary molars. To provide prosthetic replacement for missing lower posteriors, over erupted maxillary teeth have been intruded in past with great difficulty in adults with conventional orthodontics, along with associated problems of root resorption. Currently orthodontic microimplants provide stable intraoral anchorage, allow predictable maxillary molar intrusion enabling reestablishment of functional posterior occlusion with mandibular implant supported prosthesis, thereby reducing need for prosthetic crown reduction in maxillary arch. The added advantage of microimplant is it enables use of sectional appliance in area of concern instead of full arch bracketed appliance which an adult may not accept. The case reports demonstrates, overerupted maxillary molars were intruded using orthodontic microimplants to enable prosthetic rehabilitation of mandibular dentition by osseointegrated implant supported prosthesis. The second case report also demonstrates use of CBCT scan in planning and execution.

  9. Effect of surface roughness, porosity, and a resorbable calcium phosphate coating on osseointegration of titanium in a minipig model.

    PubMed

    Schwarz, Markus L R; Kowarsch, Markus; Rose, Steffen; Becker, Kristianna; Lenz, Tamara; Jani, Lutz

    2009-06-01

    The aim of this study was to compare the osseointegration of four different implant surfaces in the Göttingen minipig femur model. They were prepared by glasspearlblasting (A), sandblasting (B) and titaniumplasma spraying (C and D). Surface D received additionally an electrochemically deposited layer of a resorbable calcium phosphate (CaP) layer, made mainly of brushite. Sample size was n = 20 per group. Implants were placed in the intertrochanteric and intercondylar sites of both femora. After 12 weeks, implant anchorage was measured by the pull-out test and histomorphometry measurements were carried out at the bone-implant interface. Implant anchorage was 0.7 +/- 0.3 MPa for surface A, 3.2 +/- 0.6 MPa for surface B, 6.5 +/- 1.5 MPa for surface C and 7.3 +/- 1.9 MPa for surface D. The differences between surfaces were statistically significant, with exception of C and D. The stiffness of the bone-implant interface showed no statistically significant difference between surfaces. After pull-out, surface A and B showed nearly no bone spots, while on surfaces C and D bone remains were found. Bone-implant contact was 1.9 +/- 1.1% for surface A, 10.5 +/- 3.6% for surface B, 22.4 +/- 4.5% for surface C and 48.8 +/- 4.5% for surface D. The differences were statistically significant. Implant location, intertrochanteric and intercondylar, did not affect the data. In this minipig model, rougher surfaces showed better osseointegration. After 12 weeks of healing, the resorbable CaP layer enhanced significantly the bone-implant contact but not the level of anchorage. The findings also suggest that the pull-out test should be critically evaluated to determine the shear strength between bone and porous surfaces. 2008 Wiley Periodicals, Inc.

  10. The role of well-defined nanotopography of titanium implants on osseointegration: cellular and molecular events in vivo

    PubMed Central

    Karazisis, Dimitrios; Ballo, Ahmed M; Petronis, Sarunas; Agheli, Hossein; Emanuelsson, Lena; Thomsen, Peter; Omar, Omar

    2016-01-01

    Purpose Mechanisms governing the cellular interactions with well-defined nanotopography are not well described in vivo. This is partly due to the difficulty in isolating a particular effect of nanotopography from other surface properties. This study employed colloidal lithography for nanofabrication on titanium implants in combination with an in vivo sampling procedure and different analytical techniques. The aim was to elucidate the effect of well-defined nanotopography on the molecular, cellular, and structural events of osseointegration. Materials and methods Titanium implants were nanopatterned (Nano) with semispherical protrusions using colloidal lithography. Implants, with and without nanotopography, were implanted in rat tibia and retrieved after 3, 6, and 28 days. Retrieved implants were evaluated using quantitative polymerase chain reaction, histology, immunohistochemistry, and energy dispersive X-ray spectroscopy (EDS). Results Surface characterization showed that the nanotopography was well defined in terms of shape (semispherical), size (79±6 nm), and distribution (31±2 particles/µm2). EDS showed similar levels of titanium, oxygen, and carbon for test and control implants, confirming similar chemistry. The molecular analysis of the retrieved implants revealed that the expression levels of the inflammatory cytokine, TNF-α, and the osteoclastic marker, CatK, were reduced in cells adherent to the Nano implants. This was consistent with the observation of less CD163-positive macrophages in the tissue surrounding the Nano implant. Furthermore, periostin immunostaining was frequently detected around the Nano implant, indicating higher osteogenic activity. This was supported by the EDS analysis of the retrieved implants showing higher content of calcium and phosphate on the Nano implants. Conclusion The results show that Nano implants elicit less periimplant macrophage infiltration and downregulate the early expression of inflammatory (TNF-α) and

  11. Effect of immediate functional loading on osseointegration of implants used for single tooth replacement. A human histological study.

    PubMed

    Donati, Mauro; Botticelli, Daniele; La Scala, Vincenzo; Tomasi, Cristiano; Berglundh, Tord

    2013-07-01

    To analyze hard tissue reactions to immediate functionally loaded single implants that were installed either with a conventional drill preparation procedure or with an osteotome preparation technique. Thirteen subjects with two sites requiring single tooth rehabilitation by means of implants volunteered for the study. Each subject received one test (immediate functionally loaded) and one control (non-loaded) implant. In six subjects (group 1) the implants were placed using a conventional drilling procedure, whereas in the remaining seven subjects (group 2) an osteotome preparation procedure was performed. Block biopsies containing test and control implants and peri-implant bone tissues were collected at 1 month in four of the subjects in group 1 and in five subjects of group 2. The remaining implant sites were sampled at 3 months after implant placement. The biopsies were prepared for histological examination. Two implants of the test-2 group (osteotome preparation) representing 1 month of healing and another test-2 implant representing 3 months of healing failed to integrate. A multilevel multivariate statistical analysis demonstrated that no differences in bone-to-implant contact (BIC)% were found in between test and control implants, the density of newly formed peri-implant bone was significantly higher around test than control implants at 1 and 3 months of healing. Sections representing osteotome technique sites showed fractured trabeculae and large amounts of bone particles. It is suggested that immediate loading of implants does not influence the osseointegration process, whereas the density of newly formed peri-implant bone at such sites appears to be increased in relation to unloaded control implants. The use of an osteotome preparation technique during installation results in damage of peri-implant bone and enhances the risk for failure in osseointegration. © 2012 John Wiley & Sons A/S.

  12. Effect of a local, one time, low-dose injection of zoledronic acid on titanium implant osseointegration in ovariectomized rats

    PubMed Central

    Ying, Gao; Bo, Lian; Yanjun, Jiao; Lina, Wu

    2016-01-01

    Introduction Local application of bisphosphonates has been proven to be safer than systemic administration to promote implant fixation. The objective of this study was to introduce such a simple, convenient and efficient method to enhance titanium (Ti) implant osseointegration in ovariectomized (OVX) rats. Material and methods Twenty female Sprague-Dawley rats sequentially underwent bilateral ovariectomy and tibia implantation, and injection of 30 µg/implant zoledronic acid (ZOL) at the site of implantation was performed. At the end of the study, the tibiae, mandibles, femurs and vertebrae were harvested for dual energy X-ray absorptiometry, histology and micro-computed tomography examination. Results Ovariectomized rats showed poor bone density, bone mass and trabecular microstructure. OVX + ZOL rats were characterized by significantly improved peri-implant bone area (1.72-fold), bone contact (2.30-fold), bone mineral density (1.57-fold) and bone mineral content (1.67-fold), as well as moderately increased bone volume to total volume ratio (1.34-fold), percentage osteointegration (1.54-fold), connectivity density (1.45-fold), and trabecular number (1.43-fold), but decreased trabecular separation (57.69%) when compared with the control levels (p < 0.05). No histological signs of jaw osteonecrosis were observed in the rats treated with ZOL, and there was no significant difference between the OVX group and OVX + ZOL group in the bone mass of the mandible, femur and 5th lumbar vertebra (p > 0.05). In addition, the overproduction of osteoporosis-induced advanced glycation end-products (AGEs) was completely prevented by local treatment with 30 µg/implant ZOL. Conclusions A local, one time, low-dose injection of ZOL at the site of implantation is able to promote the osseointegration of Ti implants following postmenopausal osteoporosis, and this action may be partly mediated by inhibition of the osteoporosis-induced AGE overproduction in the bone marrow. PMID:27695483

  13. Influence of Age on Factors associated with Peri-implant Bone Loss after Prosthetic Rehabilitation over Osseointegrated Implants.

    PubMed

    Pedro, Rejane El; De Carli, João P; Linden, Maria Ss; Lima, Igor Fp; Paranhos, Luiz R; Costa, Max D; Bós, Ângelo Jg

    2017-01-01

    To verify the influence of age on factors associated with peri-implant bone loss after prosthetic rehabilitation over osseointegrated implants. This is an analytical, observational, and longitudinal study with initial 23 participants. Patients presenting with osseointegrated implants with their respective prostheses installed were included, and they could be carriers of chronic and degenerative diseases, such as diabetes, osteoporosis, hypothyroidism, cardiovascular disease (CVD), and systemic arterial hypertension. Thus, 18 participants with 57 implants were selected and followed up from 2009 to 2013. For statistical analysis, chi-square or Fisher's exact test was used for the association of systemic conditions and bone loss. Student's t-test was used for mean comparisons of age and number of total upper and lower implants. The average age of the sample studied was 71.05 years (65-80). The average implant per person was 3.2. Smoking had an influence on both mesial and distal bone loss, and the latter was significant (p = 0.0370). The association between bone loss and gender was also significant (p < 0.05). Moreover, male gender and upper implants were factors significantly associated with bone loss. The systemic conditions, when isolated, did not have significant influence on implant survival. Age is not a factor that, alone, contraindicates implant-rehabilitating therapy. On the contrary, smoking has a significant influence on dental implant survival. Systemic diseases, such as osteoporosis, hypothyroidism, diabetes, hypertension, and heart diseases, when controlled, are not contraindication factors. This study is relevant for assessing peri-implant bone loss in elderly patients, right after implant installation and over time. Therefore, it was possible to verify that age is not a limiting factor for this procedure. Controlled systemic diseases do not contraindicate implant installation, but smoking is a factor that affects implant survival.

  14. Low-level laser therapy affects osseointegration in titanium implants: resonance frequency, removal torque, and histomorphometric analysis in rabbits

    PubMed Central

    2016-01-01

    Objectives The purpose of this study was to investigate the effects of low-level laser therapy (LLLT) with a diode gallium-aluminum-arsenide (Ga-Al-As) low-level laser device on the healing and attachment of titanium implants in bone. Materials and Methods Thirteen New Zealand white male rabbits weighing 3.0±0.5 kg were used for this study. Dental titanium implants (3.75 mm in diameter and 8.5 mm in length, US II RBM plus fixture; Osstem, Seoul, Korea) were implanted into both femurs of each rabbit. The rabbits were randomly divided into a LLLT group and a control group. The LLLT was initiated immediately after surgery and then repeated daily for 7 consecutive days in the LLLT group. Six weeks and 12 weeks after implantation, we evaluated and compared the osseointegration of the LLLT group and control group, using histomorphometric analysis, removal torque testing, and resonance frequency analysis (RFA). The results were statistically significant when the level of probability was 0.05 or less based on a non-parametric Mann-Whitney U-test. Results The implant survival rate was about 96%. Histologically and histomorphometrically, we observed that the titanium implants were more strongly attached in LLLT group than in control group. However, there was no significant difference between the LLLT group and control group in removal torque or RFA. Conclusion Histologically, LLLT might promote cell-level osseointegration of titanium implants, but there was no statistically significant effects. PMID:26904488

  15. Progress on plasma accelerators

    SciTech Connect

    Chen, P.

    1986-05-01

    Several plasma accelerator concepts are reviewed, with emphasis on the Plasma Beat Wave Accelerator (PBWA) and the Plasma Wake Field Accelerator (PWFA). Various accelerator physics issues regarding these schemes are discussed, and numerical examples on laboratory scale experiments are given. The efficiency of plasma accelerators is then revealed with suggestions on improvements. Sources that cause emittance growth are discussed briefly.

  16. Composite coating of 58S bioglass and hydroxyapatite on a poly (ethylene terepthalate) artificial ligament graft for the graft osseointegration in a bone tunnel

    NASA Astrophysics Data System (ADS)

    Li, Hong; Wu, Yang; Ge, Yunsheng; Jiang, Jia; Gao, Kai; Zhang, Pengyun; Wu, Lingxiang; Chen, Shiyi

    2011-09-01

    The purpose of this study was to determine the effect of the combination of hydroxyapatite (HA) and bioglass (BG) on polyethylene terephthalate (PET) artificial ligament graft osseointegration within the bone tunnel. The results of in vitro culturing of MC3T3-E1 mouse osteoblastic cells proved that this HA/BG composite coating can promote the cell compatibility of grafts. A rabbit extraarticular tendon-to-bone healing model was used to evaluate the effect of this composite coating on PET artificial ligaments in vivo. The final results demonstrated that HA/BG coating improved new bone formation at the graft-bone interface and increased the load-to-failure property of graft in bone tunnel compared to the control group at early time. The study has shown that HA/BG composite coating on the PET artificial ligament surface has a positive effect in the induction of artificial ligament osseointegration within the bone tunnel.

  17. Fabrication of an rhBMP-2 loaded porous β-TCP microsphere-hyaluronic acid-based powder gel composite and evaluation of implant osseointegration.

    PubMed

    Lee, Jae Hyup; Kim, Jungju; Baek, Hae-Ri; Lee, Kyung Mee; Seo, Jun-Hyuk; Lee, Hyun-Kyung; Lee, A-Young; Zheng, Guang Bin; Chang, Bong-Soon; Lee, Choon-Ki

    2014-09-01

    Methods to improve osseointegration that include implantation of rhBMP-2 with various kinds of carriers are currently of considerable interest. The present study was conducted to evaluate if the rhBMP-2 loaded β-TCP microsphere-hyaluronic acid-based powder-like hydrogel composite (powder gel) can act as an effective rhBMP-2 carrier for implantation in host bone with a bone defect or poor bone quality. The release pattern for rhBMP-2 was then evaluated against an rhBMP-2-loaded collagen sponge as a control group. Dental implants were also inserted into the tibias of three groups of rabbits: an rhBMP-2 (200 µg) loaded powder gel composite implanted group, an implant only group, and a powder gel implanted group. Micro-CT and histology of the implanted areas were carried out four weeks later. The rhBMP-2 powder gel released less rhBMP-2 than the collagen sponge, but it continued a slow release for more than 7 days. The rhBMP-2 powder gel composite improved osseointegration of the dental implant by increasing the amount of new bone formation in the implant pitch and it improved the bone quality and bone quantity of new bone. The histology results indicated that the rhBMP-2 powder gel composite improved the osseointegration in the cortical bone as well as the marrow space along the fixture. The bone-to-implant contact ratio of the rhBMP-2 (200 µg) loaded powder gel composite implanted group was significantly higher than those of the implant only group and the powder gel implanted group. The powder gel appeared to be a good carrier and could release rhBMP-2 slowly to promote the formation of new bone following implantation in a bone defect, thereby improving implant osseointegration.

  18. ACCELERATION AND THE GIFTED.

    ERIC Educational Resources Information Center

    GIBSON, ARTHUR R.; STEPHANS, THOMAS M.

    ACCELERATION OF PUPILS AND SUBJECTS IS CONSIDERED A MEANS OF EDUCATING THE ACADEMICALLY GIFTED STUDENT. FIVE INTRODUCTORY ARTICLES PROVIDE A FRAMEWORK FOR THINKING ABOUT ACCELERATION. FIVE PROJECT REPORTS OF ACCELERATED PROGRAMS IN OHIO ARE INCLUDED. ACCELERATION IS NOW BEING REGARDED MORE FAVORABLY THAN FORMERLY, BECAUSE METHODS HAVE BEEN…

  19. Future accelerator technology

    SciTech Connect

    Sessler, A.M.

    1986-05-01

    A general discussion is presented of the acceleration of particles. Upon this foundation is built a categorization scheme into which all accelerators can be placed. Special attention is devoted to accelerators which employ a wake-field mechanism and a restricting theorem is examined. It is shown how the theorem may be circumvented. Comments are made on various acceleration schemes.

  20. ACCELERATION AND THE GIFTED.

    ERIC Educational Resources Information Center

    GIBSON, ARTHUR R.; STEPHANS, THOMAS M.

    ACCELERATION OF PUPILS AND SUBJECTS IS CONSIDERED A MEANS OF EDUCATING THE ACADEMICALLY GIFTED STUDENT. FIVE INTRODUCTORY ARTICLES PROVIDE A FRAMEWORK FOR THINKING ABOUT ACCELERATION. FIVE PROJECT REPORTS OF ACCELERATED PROGRAMS IN OHIO ARE INCLUDED. ACCELERATION IS NOW BEING REGARDED MORE FAVORABLY THAN FORMERLY, BECAUSE METHODS HAVE BEEN…

  1. Laser driven ion accelerator

    DOEpatents

    Tajima, Toshiki

    2005-06-14

    A system and method of accelerating ions in an accelerator to optimize the energy produced by a light source. Several parameters may be controlled in constructing a target used in the accelerator system to adjust performance of the accelerator system. These parameters include the material, thickness, geometry and surface of the target.

  2. Laser driven ion accelerator

    DOEpatents

    Tajima, Toshiki

    2006-04-18

    A system and method of accelerating ions in an accelerator to optimize the energy produced by a light source. Several parameters may be controlled in constructing a target used in the accelerator system to adjust performance of the accelerator system. These parameters include the material, thickness, geometry and surface of the target.

  3. Developing a Quantitative Measurement System for Assessing Heterotopic Ossification and Monitoring the Bioelectric Metrics from Electrically Induced Osseointegration in the Residual Limb of Service Members

    PubMed Central

    Isaacson, Brad M.; Stinstra, Jeroen G.; MacLeod, Rob S.; Pasquina, Paul F.; Bloebaum, Roy D.

    2011-01-01

    Poor prosthetic fit is often the result of heterotopic ossification (HO), a frequent problem following blast injuries for returning service members. Osseointegration technology offers an advantage for individuals with significant HO and poor socket tolerance by using direct skeletal attachment of a prosthesis to the distal residual limb, but remains limited due to prolonged post-operative rehabilitation regimens. Therefore, electrical stimulation has been proposed as a catalyst for expediting skeletal attachment and the bioelectric effects of HO were evaluated using finite element analysis in 11 servicemen with transfemoral amputations. Retrospective computed tomography (CT) scans provided accurate reconstructions, and volume conductor models demonstrated the variability in residual limb anatomy and necessity for patient-specific modeling to characterize electrical field variance if patients were to undergo a theoretical osseointegration of a prosthesis. In this investigation, the volume of HO was statistically significant when selecting the optimal potential difference for enhanced skeletal fixation, since higher HO volumes required increased voltages at the periprosthetic bone (p = 0.024, r = 0.670). Results from Spearman’s rho correlations also indicated that the age of the subject and volume of HO were statistically significant and inversely proportional, in which younger service members had a higher frequency of HO (p = 0.041, r = −0.622). This study demonstrates that the volume of HO and age may affect the voltage threshold necessary to improve current osseointegration procedures. PMID:20458630

  4. Semaphorin 3A-modified adipose-derived stem cell sheet may improve osseointegration in a type 2 diabetes mellitus rat model.

    PubMed

    Fang, Kaixiu; Song, Wen; Wang, Lifeng; Xu, Xiaoru; Tan, Naiwen; Zhang, Sijia; Wei, Hongbo; Song, Yingliang

    2016-09-01

    Although titanium (Ti) implants are considered to be an optimal choice for the replacement of missing teeth, it remains difficult to obtain sufficient osseointegration in patients with type 2 diabetes mellitus (T2DM). The present study aimed to investigate whether adipose-derived stem cells (ASCs) may be used to improve Ti implant osseointegration in T2DM conditions with the addition of semaphorin 3A (Sema3A), a recently identified osteoprotective protein. Cell morphology was observed using a scanning electron microscope. Cell proliferation was determined using Cell Counting Kit‑8. Osteogenic differentiation was confirmed by the staining of alkaline phosphatase, collagen secretion and calcium deposition. An in vivo evaluation was performed in the T2DM rat model, which was induced by a high‑fat diet and a low‑dose streptozoto