JOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 5 2005
Saj Jivraj DDS
The predictability of dental implants using the traditional Branemark protocol has been well documented. Since its inception, this protocol has been progressively challenged to decrease treatment time, minimize the number of surgical procedures, and maximize esthetic outcomes. Today, in specific clinical situations, implants may be placed and immediately loaded with provisional restorations. Immediate loading in the edentulous mandible has been well documented. There are also good data to show that immediate loading of the edentulous maxilla is also feasible if bone quality is suitable. The focus now has shifted toward immediate loading of implants placed in the esthetic zone. Clinicians have recognized that the challenge of providing anterior tooth replacements is in preserving the hard and soft tissue components that exist around natural teeth. The advantages of immediate restoration are obvious; however, the application of immediate or early load may pose an increased risk of implant failure in single-tooth situations. The prerequisites for achieving and maintaining acceptable results are not fully known. This review examines some of the literature concerning the reliability of early or immediate loading of implants placed in the esthetic zone. [source]

Complication of a Polyalkylimide Implant in a Patient with Facial Trauma

DERMATOLOGIC SURGERY, Issue 9 2008
JORGE OCAMPO-CANDIANI MD
No abstract is available for this article. [source]

Injectable Hyaluronic Acid Implant for Malar and Mental Enhancement

DERMATOLOGIC SURGERY, Issue 7 2006
FRCP, NICHOLAS J. LOWE MD
BACKGROUND The use of a thicker injectable implant version of one of the hyaluronic acid dermal fillers (Restylane SubQ, Q-Med, Uppsala, Sweden) is described. OBJECTIVE A group of treated patients has been studied for more than 1 year. Restylane SubQ was injected to the submuscular plane of the upper cheeks and chin to observe efficacy of augmentation and side effect profile, and further observations were made of the duration of benefit. METHODS Patient details,72 patients were treated, 68 for upper cheek augmentation, 2 for chin augmentation, and 2 for both areas. Four patients received second injections 8 weeks after the first to increase augmentation. RESULTS Patients all showed a persistence of benefit during the posttreatment observation period of up to 64 weeks. Four patients had minor side effects that resolved with local treatment and time. Four patients had second injections to complete augmentation without complications. CONCLUSIONS Restylane SubQ is a useful injectable agent to augment and lift upper cheeks and recontour chins. Further efficacy studies seem justified. [source]

Complications of Expanded Polytetrafluoroethylene (e-PTFE) Facial Implant

DERMATOLOGIC SURGERY, Issue 9 2001
Harold J. Brody MD
Implantation of the expanded polytetrafluoroethylene (e-PTFE) implant to achieve correction of nasolabial folds or thinning lip has been fraught with complications in spite of patient acceptance since its introduction in 1997. The four most frequent postoperative complications are extrusion, movement, infection, and swelling. In examination of 86 insertions of the 3.2 mm tubular implants, these sequelae are generally manageable for the physician and patient. If the patient understands possible courses of healing, both physician and patient satisfaction may be achieved. [source]

Cement Selection for Cement-Retained Crown Technique with Dental Implants

JOURNAL OF PROSTHODONTICS, Issue 2 2008
James L. Sheets DDS
Abstract Purpose: The purpose of this study was to assess and compare the retentive nature of common dental cements that have been adapted for use in the implant abutment cement-retained crown (CRC) technique with those specifically formulated for this purpose. Materials and Methods: Ten regular diameter implant analogs were embedded in stainless steel disks. Unmodified CRC abutments were attached and torqued to 30 Ncm. Test crowns were waxed and cast with base metal alloy. Castings were fitted, cleaned with aluminum oxide, and steam cleaned prior to application of the cement. The cements used were: (1) Temp Bond, (2) UltraTemp, regular, (3) UltraTemp firm, (4) ImProv with petroleum jelly coating of crown, (5) ImProv without petroleum jelly, (6) Premier Implant with KY Jelly coating of abutment, (7) Premier Implant without KY jelly, (8) TR-2, (9) Fleck's, (10) Ketac Cem Aplicap, and (11) Fuji Plus Capsule. After cementation, assemblies were stored for 24 hours. Each sample was subjected to a pull-out test using an Instron universal testing machine at a crosshead speed of 5.0 mm/min. Loads required to remove the crowns were recorded, and mean values for each group determined. A one-way ANOVA and a post hoc least square difference (LSD) test were done for pairwise comparison at a confidence interval of 95%. Results: The mean values (±SD) of loads at failure (n = 10) for various cements were as follows (N): Ultratemp, regular 358.6 (±38.2) (Group A), ImProv without petroleum jelly 172.4 (±59.6) (Group B), Fleck's 171.8 (±62.2) (Group B), Ketac Cem 167.8 (±69.1) (Group B), UltraTemp firm 158.8 (±62.7) (Group BC), Fuji Plus 147.5 (±69.7) (Group BC), Premier without KY jelly 131.6 (±31.8) (Group BC), ImProv using petroleum jelly 130.8 (±42.5) (Group BC), Temp Bond 117.8 (±48.3) (Group C), TR-2 41.2 (±16.6) (Group D), and Premier with KY jelly 31.6 (±24.8) (Group D). Groups with the same letter were not significantly different. Conclusions: Within the limitations of this in vitro study, it is not suggested that any one cement is better than another at retaining cement-retained crowns (CRCs) to implant abutments or that a threshold value must be accomplished to ensure retention. The ranking of cements presented is meant to be a discretionary guide for the clinician in deciding the amount of desired retention between castings and implant abutments. [source]

Implant of a Biventricular Pacemaker in a Patient with Dextrocardia and Persistent Left Superior Vena Cava

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 8 2006
CHRISTIAN POTT
Congenital anomalies of the heart can pose challenges to cardiac invasive procedures. Here, we present the case of a 40-year-old man with the combination of dextrocardia, a persistent left superior vena cava, and idiopathic dilated cardiomyopathy. We describe the successful implantation of a biventricular pacemaker,defibrillator under this complex anatomic condition. [source]

An Ill Wind-Iatrogenic Air Embolus Around Pacing Leads During Defibrillator Implant with Coexisting Pulmonary Fibrosis

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2 2006
DANIEL M. NINIO
We present a case of air embolism during biventricular defibrillator implantation in a 58-year-old man with pulmonary fibrosis. To prevent air entry after the dilator was removed, the subclavian venous sheath was covered before the lead was introduced. Air embolism occurred during inspiration around the lead body in the appropriate sized sheath but without a hemostatic valve. Extraordinary swings in intrathoracic pressure due to noncompliant lungs may have contributed to this unusual complication. [source]

Repair of mandible defect with tissue engineering bone in rabbits

ANZ JOURNAL OF SURGERY, Issue 11 2005
Zhi Li
Background: The aim of the present study was to investigate the effect of tissue engineering bone composed of bone marrow-derived osteoblasts and demineralized bone in repairing mandible defect. Methods: Bone marrow-derived osteoblasts of 20 rabbits were cultured and seeded into scaffold of allogeneic demineralized bone to construct tissue engineering bone graft in vitro, which was used to repair the 10 × 5-mm bone defect made in the same rabbit mandible edge. Implant of demineralized bone alone was as the control. Rabbits were killed according to the schedule: five after 2 weeks, five after 4 weeks, five after 8 weeks, five after 12 weeks, and the implants were harvested for gross, radiographic, and histological observation. Results: New bone formation at the margin region of defect and osteogenesis at the centre were observed in the implant of tissue engineering bone, and the bone formation pattern included osteogenesis, osteoconduction, and osteoinduction. In the implant of demineralized bone alone, the major bone formation pattern was ,creeping substitute'. Conclusions: The tissue engineering bone graft constructed by autogenous bone marrow-derived osteoblasts and allogeneic demineralized bone was better than demineralized bone alone in bone formation capability, which might be an ideal graft for bone defect repair. [source]

A Power Efficient Electronic Implant for a Visual Cortical Neuroprosthesis

ARTIFICIAL ORGANS, Issue 3 2005
Jonathan Coulombe
Abstract:, An integrated microstimulator designed for a cortical visual prosthesis is presented, along with a pixel reordering algorithm, together minimizing the peak total current and voltage required for stimulation of large numbers of electrodes at a high rate. In order to maximize the available voltage for stimulation at a given supply voltage for generating biphasic pulses, the device uses monopolar stimulation, where the return electrode voltage is dynamically varied. Thus, the voltage available for stimulation is maximized, as opposed to the conventional fixed return voltage monopolar approach, and impedance is significantly lower than can be achieved using bipolar stimulation with microelectrodes. This enables the use of a low voltage power supply, minimizing power consumption of the device. An important constraint resulting from this stimulation strategy, however, is that current generation needs to be simultaneous and in-phase for all active parallel channels, imposing heavy stress on the wireless power recovery and regulation circuitry in large electrode count systems such as a visual prosthesis. An ordering algorithm to be implemented in the external controller of the prosthesis is then proposed. Based on the data for each frame of the video signal to be transmitted to the implant, the algorithm minimizes the total generated current standard deviation between time multiplexed stimulations by determining the most appropriate combination of parallel stimulation channels to be activated simultaneously. A stimulator prototype has been implemented in CMOS technology and successfully tested. Execution of the external controller reordering algorithm on an application specific hardware architecture has been verified using a System-On-Chip development platform. A near 75% decrease in the total stimulation current standard deviation was observed with a one-pass algorithm, whereas a recursive variation of the algorithm resulted in a greater than 95% decrease of the same variable. [source]

First experience with The IRIS retinal implant system

ACTA OPHTHALMOLOGICA, Issue 2009
M VELIKAY-PAREL
Purpose To report on the first 4 months experience of a patient with the active IRIS- Implant. Methods 4 weeks after implantation the training with the active implant started. Thresholds were measured at each training day. Light perception, light localisation, point to point discrimination and motion detection were measured with special test procedures. Visual function training was performed. Results Visual perception was achieved, when the stimuli were generated by the computer and with the camera mode. All tests were successful. Conclusion Successful stimulation and major improvements during the training demonstrates that with the Iris Implant System a visual perception can be achieved, which is relevant for daily life. [source]

Usefulness of Brain Natriuretic Peptide Level at Implant in Predicting Mortality in Patients with Advanced But Stable Heart Failure Receiving Cardiac Resynchronization Therapy

CLINICAL CARDIOLOGY, Issue 11 2009
Aiman El-Saed MD
Abstract Background Brain natriuretic peptide (BNP) level has emerged as a predictor of death and hospital readmission in patients with heart failure (HF). The value of baseline BNP assessment in advanced HF patients receiving cardiac resynchronization defibrillator therapy (CRT-D) has not been firmly established. Hypothesis We hypothesized that a baseline BNP level would predict all cause mortality and HF hospitalization in HF patients receiving cardiac resynchronization therapy. Methods A retrospective chart review of all patients having BNP assessment prior to implantation of a CRT-D for standard indications during 2004 and 2005 was conducted at the Veterans Affairs Pittsburgh Healthcare System. The primary endpoint was all-cause mortality and the secondary endpoint was HF-related hospitalization. We used findings from the receiver operating characteristic (ROC) curve to define low (<492 pg/mL) and high (,492 pg/mL) BNP groups. Results Out of 173 CRT-D recipients, 115 patients (mean age 67.0 ± 10.7 years, New York Heart Association [NYHA] class 2.9 ± 0.3, left ventricular ejection fraction [LVEF] 22.5% ± 9.6%, QRS 148.3 ± 30.4 ms) had preimplantation BNP measured (mean 559 ± 761 pg/mL and median 315 pg/mL). During a mean follow-up time of 17.5 ± 6.5 mo, 27 deaths (23.5%) and 31 HF hospitalizations (27.0%) were recorded. Compared to those with low BNP (n = 74), those of high BNP (n = 41) were older, had lower LVEF, higher creatinine levels, suffered more deaths, and HF hospitalizations. In multivariate regression models, higher BNP remained a significant predictor of both the primary endpoint (hazard ratio [HR]: 2.89, 95% confidence interval [CI] 1.06,7.88, p = 0.038) and secondary endpoint (HR: 4.23, 95% CI: 1.68,10.60, p = 0.002). Conclusions Baseline BNP independently predicted mortality and HF hospitalization in a predominantly older white male population of advanced HF patients receiving CRT-D. Elevated BNP levels may identify a vulnerable HF population with a particularly poor prognosis despite CRT-D. Copyright © 2009 Wiley Periodicals, Inc. [source]

Marginal Bone Loss at Implants: A Retrospective, Long-Term Follow-Up of Turned Brånemark System® Implants

CLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 1 2009
Odont Lic, Solweig Sundén Pikner DDS
ABSTRACT Background: Lately, presence of progressive bone loss around oral implants has been discussed. Purpose: The aim of this study was to report in a large patient group with different prosthetic restorations marginal bone level and its change as measured in radiographs obtained from prosthesis insertion up to a maximum 20 years in service. Further, it also aimed to study the impact of gender, age, jaw, prosthetic restoration, and calendar year of surgery. Materials and Methods: Out of 1,716 patients recorded for clinical examination during 1999, 1,346 patients (78.4%) could be identified. A total of 640 patients (3,462 originally installed Brånemark System® implants, Nobel Biocare, Göteborg, Sweden) with a follow-up of ,5 years were included in the study, while patients with continuous overdentures and augmentation procedures were not. Distance between the fixture/abutment junction (FAJ) and the marginal bone level was recorded. Results: The number of implants with a mean bone level of ,3 mm below FAJ increased from 2.8% at prosthesis insertion to 5.6% at year 1, and 10.8% after 5 years. Corresponding values after 10, 15, and 20 years were 15.2, 17.2, and 23.5%, respectively. Implant-based bone loss was as a mean 0.8 mm (SD 0.8) after 5 years, followed by only minor average changes. Mean bone loss on patient level followed a similar pattern. Disregarding follow-up time, altogether 183 implants (107 patients) showed a bone loss ,3 mm from prosthesis insertion to last examination. Significantly larger bone loss was found the older the patient was at surgery and for lower jaw implants. Conclusions: Marginal bone support at Brånemark implants was with few exceptions stable over years. [source]

One-Year Prospective Three-Center Study Comparing the Outcome of a "Soft Bone Implant" (Prototype Mk IV) and the Standard Brånemark Implant

CLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 2 2003
Bertil Friberg DDS
ABSTRACT Background: Oral implant treatment ad modum Brånemark has been used for decades in the rehabilitation of edentate and partially dentate patients. Posterior jaw regions frequently exhibit bone of poor texture, and it is often difficult to obtain primary stability. Thus, it may prove beneficial to deviate from the original protocol and to use implants with a modified design, for example, with a slightly tapered geometry. Purpose: The purpose of the investigation was to compare the early behavior of a modified (prototype Mk IV, Branemark System, Nobel Biocare AB, Gothenburg, Sweden; test) implant with that of the standard Brånemark implant (control) in regions of mainly type 4 bone. Materials and Methods: Three Swedish centers participated, and a total of 44 patients were treated with oral implants for 39 maxillas and 5 mandibles. The study focused on the most distal right and left implant sites (88 implants), which were randomized to receive either a test or a control implant. Various parameters were recorded, such as registered insertion torque (OsseoCare, Nobel Biocare AB), wobbling during insertion, primary and secondary stability (as measured with resonance frequency), and marginal bone loss. The implants were followed up for 1 year. Results.: The test implant more frequently required a higher insertion torque and showed a significantly higher primary stability than the control implant. This difference in stability leveled out over time, and test and control implants exhibited similar secondary stability at abutment operation and at the 1-year visit. Wobbling during insertion was rarely recorded for either of the implant designs. The 1-year cumulative success rate was 93.1% for test implants and 88.4% for control implants. Conclusions: The modified implant design resulted in an increased primary stability, which may be important when placing implants in jaw regions of type 4 bone. However, independent of the achieved primary stability, successful implants tended to approach similar secondary stability in the two designs tested. [source]

Effects of a Mechanical Barrier on the Integration of Cortical Onlay Bone Grafts Placed Simultaneously with Endosseous Implant

CLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 2 2002
Luiz Z. Salata DDS
ABSTRACT Background: Previous experimental studies on onlay bone graft integration have shown either advantages or disadvantages to the use of mechanical barriers. This indicates that the role played by the biologic properties of transplanted bone and membrane in graft revascularization and bone remodeling has not yet been established. The outcomes regarding osseointegration of titanium dental implants applied in such a condition are still contradictory. Purpose: The rabbit's radius model that is grafted onto the mandibular lower border and covered by membrane can reproduce a challenging experimental situation to preliminarily study the factors involved in osseointegration under deprived blood vessels source. Materials and Methods: Fourteen New Zealand White rabbits had a 2.5-cm segment of the right radius osteoectomized and fixed onto the right mandibular lower border using titanium screws. Two screw-shaped titanium implants (2.5 mm wide 2.5 mm long) were installed 7 mm apart in the mid length of the grafted bone. In experimental sites, the graft with the implants and graft-host bone junction were covered by expanded polytetrafluoroethylene (e-PTFE) membrane; control sites were left uncovered. Eight animals from the experimental group and six animals from the control group were sacrificed at 6 and 24 weeks after surgery. Ground sections obtained from en bloc tissues containing graft, implants, and recipient bone were subjected to histologic evaluation and histomorphometric analysis (area occupied by the graft and bone-to-implant contact). Results: The graft showed significantly more resorption after 24 weeks than at 6 weeks (p .05) irrespective of the treatment (with or without membrane), although the amount of new bone was greater at 24 weeks in sites where a membrane was covering the graft. Compared with 6 weeks postoperatively, the bone-to-implant contact was considerably improved at 24 weeks (p .05), and the membrane seemed beneficial for implant osseointegration when compared with unprotected sites (p .05). As a result of graft resorption, the amount of soft tissue was considerably expanded in sites beneath membrane, accompanied by a sustained process of trabecular bone deposition close to the barrier. Conclusions: Cortical onlay grafts covered by membrane demonstrated delayed remodeling, probably as a consequence of a hindered process of graft revascularization. Grafts covered by membrane might rely on previous host bone resorption both to become revascularized and to remodel. The findings that the membrane-protected grafts were most resorbed at 24 weeks might be attributable to better implant osseointegration, because the fixtures were exposed to greater mechanical stimulation in these sites. [source]

An In Vivo Study of the Host Response to Starch-Based Polymers and Composites Subcutaneously Implanted in Rats

MACROMOLECULAR BIOSCIENCE, Issue 8 2005
Alexandra P. Marques
Abstract Summary: Implant failure is one of the major concerns in the biomaterials field. Several factors have been related to the fail but in general these biomaterials do not exhibit comparable physical, chemical or biological properties to natural tissues and ultimately, these devices can lead to chronic inflammation and foreign-body reactions. Starch-based biodegradable materials and composites have shown promising properties for a wide range of biomedical applications as well as a reduced capacity to elicit a strong reaction from immune system cells in vitro. In this work, blends of corn starch with ethylene vinyl alcohol (SEVA-C), cellulose acetate (SCA) and polycaprolactone (SPCL), as well as hydroxyapatite (HA) reinforced starch-based composites, were investigated in vivo. The aim of the work was to assess the host response evoked for starch-based biomaterials, identifying the presence of key cell types. The tissues surrounding the implant were harvested together with the material and processed histologically for evaluation using immunohistochemistry. At implant retrieval there was no cellular exudate around the implants and no macroscopic signs of an inflammatory reaction in any of the animals. The histological analysis of the sectioned interface tissue after immunohistochemical staining using ED1, ED2, CD54, MHC class II and ,/, antibodies showed positively stained cells for all antibodies, except for ,/, for all the implantation periods, where it was different for the various polymers and for the period of implantation. SPCL and SCA composites were the materials that stimulated the greatest cellular tissue responses, but generally biodegradable starch-based materials did not induce a severe reaction for the studied implantation times, which contrasts with other types of degradable polymeric biomaterials. [source]

Lexicon for Soft Tissue Implants

DERMATOLOGIC SURGERY, Issue 2009
ROD J. ROHRICH MD
First page of article [source]

Low Temperature Fabrication of ,-TCP,PCL Nanocomposites for Bone Implants,

ADVANCED ENGINEERING MATERIALS, Issue 8 2010
Michael Bernstein
Abstract A method to fabricate strong bioresorbable calcium phosphate,polymer nanocomposites with low polymer content without exposing the material to excessively high-processing temperatures is reported. Dense ,-TCP-based nanocomposites containing 5 or 15,vol% of uniformly distributed polycaprolactone (PCL) polymer were obtained by mixing ,-TCP nanopowder with PCL dissolved in chloroform followed by room temperature consolidation at the high pressure of 2.5,GPa (cold sintering). The composites had an attractive combination of compressive strength and ductility, and their dissolution behavior was similar to that of pure cold sintered ,-TCP. The immersion of ,-TCP,PCL composites in simulated body fluid (SBF) yielded in vitro deposition of a bone-like apatite layer suggesting the ability of these materials to bind to native bone tissue upon implantation. [source]

Apatite Deposition on NaOH-Treated PEEK and UHMWPE Films for Sclera Materials in Artificial Cornea Implants,

ADVANCED ENGINEERING MATERIALS, Issue 7 2010
Monica Pino
Abstract Cornea implants consist of a clear optic portion with a surrounding ring known as the skirt, which needs to integrate with the sclera. However, currently used skirt materials lead to poor tissue integration. Improvements in this respect may be achieved by using a bioactive skirt material that adapts to the metabolic activity of the cornea. Polyether etherketone (PEEK) and ultra-high molecular weight polyethylene (UHMWPE) might provide interesting alternatives, if they can be rendered bioactive. We, therefore, investigated the potential of surface-modifying PEEK and UHMWPE films through the use of a two-step treatment. This process involved a suitable chemical surface modification (via immersion in NaOH), with subsequent formation of apatite layers on the polymers' surfaces through exposure to supersaturated simulated body fluid (1.5 SBF). In the present work the effect of 5 and 10,M NaOH on formation of the apatite layer has been investigated with regard to wettability and topography features. In addition, the chemical stability of the apatite layer formed has been analyzed. Our data demonstrate that with an increase in NaOH concentration the wettability of the polymer increased, whilst some changes to the polymer film topography (increase/decrease in roughness) were observed. Most beneficially, the apatite layer that subsequently was grown on pre-treated PEEK and UHMWPE films through immersion in 1.5 SBF contained phosphate and carbonate ions, in similar ratios to those found in the apatite in dentine, thus, promising good in vivo bioactivity of these polymer films,a necessity if they are to be integrated into artificial cornea. [source]

Biphasic Resorbable Calcium Phosphate Ceramic for Bone Implants and Local Alendronate Delivery,

ADVANCED ENGINEERING MATERIALS, Issue 5 2010
Shashwat S. Banerjee
A novel biphasic calcium phosphate ceramic composed of tricalcium phosphate (TCP) and calcium pyrophosphate (CP) is synthesized in order to tailor the biodegradation behavior of the ceramic. The results show that biphasic TCP/CP ceramic has a strength of 62.2,±,2.1 MPa, which is superior to single-phase TCP and CP ceramics, which show strengths of 44.3,±,3.0 and 53.0,±,4.8 MPa, respectively. In addition, biphasic TCP/CP ceramic displays a controlled strength degradation from 62.2,±,2.1 to 40.5,±,1.0 MPa in stimulated body fluid over a period of 28 d. An in vitro cell materials interaction study using human fetal osteoblast cells indicates that TCP/CP ceramic is cytocompatible. TCP/CP ceramic also show a good loading capacity for alendronate. Adsorption of alendronate (AD) on the TCP/CP surface is found to proceed via ligand exchange mechanism and the in vitro release profile of AD from TCP/CP surface is characterized by an initial fast release followed by a slow and sustained release. Strong electrostatic interactions between AD groups and surface Ca2+ ions enable the slow and sustained release of AD. These results demonstrate that the newly developed biphasic ceramic, with its controlled strength degradation and drug release, shows promise for use in orthopedic and tissue engineering applications. [source]

Powder Metallurgical Near-Net-Shape Fabrication of Porous NiTi Shape Memory Alloys for Use as Long-Term Implants by the Combination of the Metal Injection Molding Process with the Space-Holder Technique,

ADVANCED ENGINEERING MATERIALS, Issue 12 2009
Manuel Köhl
Abstract A new method was developed for producing highly porous NiTi for use as an implant material. The combination of the space-holder technique with the metal injection molding process allows a net-shape fabrication of geometrically complex samples and the possibility of mass production for porous NiTi. Further, the porosity can be easily adjusted with respect to pore size, pore shape, and total porosity. The influence of the surface properties of powder metallurgical NiTi on the biocompatibility was first examined using human mesenchymal stem cells (hMSCs). It was found that pre-alloyed NiTi powders with an average particle size smaller than 45,,m led to the surface properties most suitable for the adhesion and proliferation of hMSCs. For the production of highly porous NiTi, different space-holder materials were investigated regarding low C- and O-impurity contents and the reproducibility of the process. NaCl was the most promising space-holder material compared to PMMA and saccharose and was used in subsequent studies. In these studies, the influence of the total porosity on the mechanical properties of NiTi is investigated in detail. As a result, bone-like mechanical properties were achieved by the choice of Ni-rich NiTi powder and a space-holder content of 50,vol% with a particle size fraction of 355,500,,m. Pseudoelasticity of up to 6% was achieved in compression tests at 37,°C as well as a bone-like loading stiffness of 6.5,GPa, a sufficient plateau stress ,25 of 261,MPa and a value for ,50 of 415,MPa. The first biological tests of the porous NiTi samples produced by this method showed promising results regarding proliferation and ingrowth of mesenchymal stem cells, also in the pores of the implant material. [source]

PE-UHMW in Hip Implants: Properties of Conventional and Crosslinked Prosthetic Components

ADVANCED ENGINEERING MATERIALS, Issue 10 2009
Ruth Markut-Kohl
Hip implants made of crosslinked ultra high molecular weight polyethylene,PE-UHMW,(different as-received conditions) are compared with a retrieval made from non-crosslinked PE-UHMW and a control PE-UHMW. Oxidation leads to recrystallization and the enhanced crystallinity corresponds to higher hardness values. These structure-property relations are discussed for conventional PE-UHMW and also for crosslinked material. [source]

Influence of Different Surface Machining Treatments of Magnesium-based Resorbable Implants on the Degradation Behavior in Rabbits,

ADVANCED ENGINEERING MATERIALS, Issue 5 2009
Nina Von Der Höh
The surface of magnesium,calcium implants (MgCa0.8) was differently treated which resulted in cylinders with smooth, sand-blasted, or threaded surface. These cylinders were implanted into the medial femoral condyle of New Zealand White rabbits. The degradation behavior and the reaction of the organism were assessed by clinical compatibility, radiographs, and µ -computed tomography. [source]

Multi-walled Carbon Nanotube-Reinforced Hydroxyapatite Layers on Ti6Al4V Medical Implants by Electrophoretic Deposition (EPD),

ADVANCED ENGINEERING MATERIALS, Issue 1-2 2008
C. Kaya
Sol-gel synthesised nano-size hydroxyapatite (HA) powders were dispersed in water-based suspensions with the addition of multi-walled carbon nanotubes. Ti6Al4V medical alloys were coated with monolithic and carbon nanotube-reinforced HA using electrophoretic deposition (EPD) in an attempt to control deposit structure and thickness. It was shown that the sintering temperature of the deposited HA layers was significantly lowered by the use of sinter active nano-powders. Moreover the addition of carbon nanotubes increased the bonding strength of the EPD-formed layers to the metallic substrate. The cost-effective EPD technique used in the present work has high industrial potential for coating metallic medical implants with composite bioactive layers. [source]

Bone Implants: (Osteoconductive and Osteoinductive Properties of Zeolite MFI Coatings on Titanium Alloys) Adv.

ADVANCED FUNCTIONAL MATERIALS, Issue 24 2009
Funct.
Biocompatible zeolite anti-corrosion coatings have potential for success as bone scaffolding materials. In this work, reported by Y. Yan and co-workers, titanium-based dental implants are covered with zeolite MFI coatings to prevent against corrosion within the dental cavity. Zeolite coatings are non-toxic, and prevent the release of toxic ions from metals into tissue. The 3D micro-topology of the zeolites also enhances cell proliferation, differentiation, and surface adhesion. [source]

A Computational Approach on the Osseointegration of Bone Implants Based on a Bio-Active Interface Theory

GAMM - MITTEILUNGEN, Issue 2 2009
André Lutz
Abstract In this presentation an integrated approach on the simulation of osseointegration in the boneimplant interface is outlined. Besides the consistent combination of computational bone remodelling simulation and established medical imaging techniques, a new model refinement in terms of a bioactive interface theory is introduced, which enables the simulation of bone ingrowth in rough coated uncemented implants. Under consideration of seven physiological loads of daily motion the bone-implant relative micromotion in a soft tissue region around the endoprosthesis is investigated. As the micromotions are an important factor for osseointegration, because excessive micromotion leads to apposition of fibrous tissue, they are considered for the simulation of osseointegration. Results for different parameter constellations, regarding thickness and stiffness of bone-implant interface layer, are compared and the ingrowth for different configurations is predicted. With these results conclusions can be made about the stability of prosthesis in the host bone, which is an important factor for the clinical success of the treatment (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Electrosprayed Enzyme Coatings as Bioinspired Alternatives to Bioceramic Coatings for Orthopedic and Oral Implants

ADVANCED FUNCTIONAL MATERIALS, Issue 5 2009
Lise T. de Jonge
Abstract The biological performance of orthopedic and oral implants can be significantly improved by functionalizing the non-physiological metallic implant surface through the application of biologically active coatings. In this paper, a cost-effective alternative to traditional biomedical coatings for bone substitution through exploitation of the specific advantages of the electrospray deposition technique for the immobilization of the enzyme alkaline phosphatase (ALP) onto the implant surface is presented. Since ALP increases the local inorganic phosphate concentration required for physiological mineralization of hard tissues, ALP coatings will enable enzyme-mediated mineralization onto titanium surfaces. To evaluate the bone-bioactive capacity of the ALP-coated titanium surface, soaking experiments are performed. Although the purely inorganic so-called simulated body fluid is the standard in vitro procedure for predictive studies on potential bone bonding in vivo, an alternative testing solution is proposed that also contains organic phosphates (cell culture medium supplemented with the organic ,-b; -glycerophosphate (,-b; -GP) and serum proteins), thereby resembling the in vivo conditions more closely. Under these physiological conditions, the electrosprayed ALP coatings accelerated mineralization onto the titanium surface as compared to noncoated implant material by means of enzymatic pathways. Therefore, this novel approach toward implant fixation holds significant promise. [source]

Transplants and Implants: The Economics of Self-Improvement

INTERNATIONAL ECONOMIC REVIEW, Issue 3 2001
Ken Burdett
This article examines equilibrium self-improvement and marriage proposal strategies in a two-sided search model with nontransferable utility. Singles are vertically differentiated,some make better marriage partners than others. A complete characterization of equilibrium is provided. It is shown there are two externalities to self-improvement decisions. Further, these externalities may support multiple Pareto rankable equilibria. By encouraging everybody to self-improve, society can create a situation where everybody is forced to improve to remain "acceptable." But a preferred equilibrium may exist where there is less (costly) self-improvement. [source]

Evaluation of the cost-effectiveness of root canal treatment using conventional approaches versus replacement with an implant

INTERNATIONAL ENDODONTIC JOURNAL, Issue 10 2009
M. W. Pennington
Abstract Aim, To evaluate the cost-effectiveness of root canal treatment for a maxillary incisor tooth with a pulp infection, in comparison with extraction and replacement with a bridge, denture or implant supported restoration. Methodology, A Markov model was built to simulate the lifetime path of restorations placed on the maxillary incisor following the initial treatment decision. It was assumed that the goal of treatment was the preservation of a fixed platform support for a crown without involving the adjacent teeth. Consequently, the model estimates the lifetime costs and the total longevity of tooth and implant supported crowns at the maxillary incisor site. The model considers the initial treatment decisions, and the various subsequent treatment decisions that might be taken if initial restorations fail. Results, Root canal treatment extended the life of the tooth at an additional cost of £5,8 per year of tooth life. Provision of orthograde re-treatment, if the root canal treatment fails returns further extension of the expected life of the tooth at a cost of £12,15 per year. Surgical re-treatment is not cost-effective; it is cheaper, per year, to extend the life of the crown by replacement with a single implant restoration if orthograde endodontic treatment fails. Conclusion, Modelling the available clinical and cost data indicates that, root canal treatment is highly cost-effective as a first line intervention. Orthograde re-treatment is also cost-effective, if a root treatment subsequently fails, but surgical re-treatment is not. Implants may have a role as a third line intervention if re-treatment fails. [source]

Histological biocompatibility of new, non-absorbable glaucoma deep sclerectomy implant

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 2 2007
Jakub J. Ka
Abstract We performed this study to compare the intrascleral biocompatibility of three materials: non-absorbable hydrogel contact lens polymer, non-absorbable silicone rubber, and absorbable cross-linked sodium hyaluronate. Intrascleral implantation of three different materials was performed in 13 healthy, pigmented rabbits. Implants of methacrylic hydrogel, silicone rubber, and cross-linked sodium hyaluronate were implanted in 10, 8, and 8 eyes, respectively. The animals were euthanized at 7, 30, 180, and 360 days post implantation. The eyes were enucleated and immediately fixed in 10% buffered formalin. Semithin sections were cut and stained with hematoxylin-eosin. Light microscope analysis of the specimens was performed. The least severe inflammatory reaction was observed with cross-linked sodium hyaluronate implants. The number of inflammatory cells in proximity to methacrylic hydrogel and silicone implants at all periods of follow up was similar. The thickest fibrous capsule was observed with silicone implants (average, 28.38 ± 11.17 ,m). This area was thinner with methacrylic hydrogel implants (average, 14.90 ± 5.57 ,m) and was thinnest around sodium hyaluronate implants (average, 7.21 ± 2.33 ,m). For each type of implant, the wall on the conjunctival side of the fibrous capsule was significantly thicker than the wall on the choiroidal side. The space between the implant, scleral flap, and bed was filled soon after surgery with connective tissue rich in vessels. In our study, cross-linked sodium hyaluronate had the highest intrascleral biocompatibility. Although the inflammatory responses of the sclera to methacrylic hydrogel and silicone rubber were similar in nature, a thicker fibrous capsule was generated around silicone implants. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006 [source]