Imaging of common breast implants and implant-related complications: A pictorial essay

PubMed Central

Shah, Amisha T; Jankharia, Bijal B

2016-01-01

The number of women undergoing breast implant procedures is increasing exponentially. It is, therefore, imperative for a radiologist to be familiar with the normal and abnormal imaging appearances of common breast implants. Diagnostic imaging studies such as mammography, ultrasonography, and magnetic resonance imaging are used to evaluate implant integrity, detect abnormalities of the implant and its surrounding capsule, and detect breast conditions unrelated to implants. Magnetic resonance imaging of silicone breast implants, with its high sensitivity and specificity for detecting implant rupture, is the most reliable modality to asses implant integrity. Whichever imaging modality is used, the overall aim of imaging breast implants is to provide the pertinent information about implant integrity, detect implant failures, and to detect breast conditions unrelated to the implants, such as cancer. PMID:27413269

In vivo ultrasonic detection of polyurea crosslinked silica aerogel implants.

PubMed

Sabri, Firouzeh; Sebelik, Merry E; Meacham, Ryan; Boughter, John D; Challis, Mitchell J; Leventis, Nicholas

2013-01-01

Polyurea crosslinked silica aerogels are highly porous, lightweight, and mechanically strong materials with great potential for in vivo applications. Recent in vivo and in vitro studies have demonstrated the biocompatibility of this type of aerogel. The highly porous nature of aerogels allows for exceptional thermal, electric, and acoustic insulating capabilities that can be taken advantage of for non-invasive external imaging techniques. Sound-based detection of implants is a low cost, non-invasive, portable, and rapid technique that is routinely used and readily available in major clinics and hospitals. In this study the first in vivo ultrasound response of polyurea crosslinked silica aerogel implants was investigated by means of a GE Medical Systems LogiQe diagnostic ultrasound machine with a linear array probe. Aerogel samples were inserted subcutaneously and sub-muscularly in a) fresh animal model and b) cadaveric human model for analysis. For comparison, samples of polydimethylsiloxane (PDMS) were also imaged under similar conditions as the aerogel samples. Polyurea crosslinked silica aerogel (X-Si aerogel) implants were easily identified when inserted in either of the regions in both fresh animal model and cadaveric model. The implant dimensions inferred from the images matched the actual size of the implants and no apparent damage was sustained by the X-Si aerogel implants as a result of the ultrasonic imaging process. The aerogel implants demonstrated hyperechoic behavior and significant posterior shadowing. Results obtained were compared with images acquired from the PDMS implants inserted at the same location.

[Tachycardia detection in implantable cardioverter-defibrillators by Sorin/LivaNova : Algorithms, pearls and pitfalls].

PubMed

Kolb, Christof; Ocklenburg, Rolf

2016-09-01

For physicians involved in the treatment of patients with implantable cardioverter-defibrillators (ICDs) the knowledge of tachycardia detection algorithms is of paramount importance. This knowledge is essential for adequate device selection during de-novo implantation, ICD replacement, and for troubleshooting during follow-up. This review describes tachycardia detection algorithms incorporated in ICDs by Sorin/LivaNova and analyses their strengths and weaknesses.

A hardware-algorithm co-design approach to optimize seizure detection algorithms for implantable applications.

PubMed

Raghunathan, Shriram; Gupta, Sumeet K; Markandeya, Himanshu S; Roy, Kaushik; Irazoqui, Pedro P

2010-10-30

Implantable neural prostheses that deliver focal electrical stimulation upon demand are rapidly emerging as an alternate therapy for roughly a third of the epileptic patient population that is medically refractory. Seizure detection algorithms enable feedback mechanisms to provide focally and temporally specific intervention. Real-time feasibility and computational complexity often limit most reported detection algorithms to implementations using computers for bedside monitoring or external devices communicating with the implanted electrodes. A comparison of algorithms based on detection efficacy does not present a complete picture of the feasibility of the algorithm with limited computational power, as is the case with most battery-powered applications. We present a two-dimensional design optimization approach that takes into account both detection efficacy and hardware cost in evaluating algorithms for their feasibility in an implantable application. Detection features are first compared for their ability to detect electrographic seizures from micro-electrode data recorded from kainate-treated rats. Circuit models are then used to estimate the dynamic and leakage power consumption of the compared features. A score is assigned based on detection efficacy and the hardware cost for each of the features, then plotted on a two-dimensional design space. An optimal combination of compared features is used to construct an algorithm that provides maximal detection efficacy per unit hardware cost. The methods presented in this paper would facilitate the development of a common platform to benchmark seizure detection algorithms for comparison and feasibility analysis in the next generation of implantable neuroprosthetic devices to treat epilepsy. Copyright © 2010 Elsevier B.V. All rights reserved.

Polyimide-based intracortical neural implant with improved structural stiffness

NASA Astrophysics Data System (ADS)

Lee, Kee-Keun; He, Jiping; Singh, Amarjit; Massia, Stephen; Ehteshami, Gholamreza; Kim, Bruce; Raupp, Gregory

2004-01-01

A novel structure for chronically implantable cortical electrodes using polyimide bio-polymer was devised, which provides both flexibility for micro-motion compliance between brain tissues and the skull and at the brain/implant interface and stiffness for better surgical handling. A 5-10 µm thick silicon backbone layer was attached to the tip of the electrode to enhance the structural stiffness. This stiff segment was then followed by a 1 mm flexible segment without a silicon backbone layer. The fabricated implants have tri-shanks with five recording sites (20 µm × 20 µm) and two vias of 40 µm × 40 µm on each shank. In vitro cytotoxicity tests of prototype implants revealed no adverse toxic effects on cells. Bench test impedance values were assessed, resulting in an average impedance value of ~2 MOmega at 1 KHz. For a 5 µm thick silicon backbone electrode, the stiffness of polyimide-based electrodes was increased ten times over that of electrodes without the silicon backbone layer. Furthermore, polyimide-based electrodes with 5 µm and 10 µm thick silicon backbone layer penetrated pia of rat brain without buckling that has been observed in implants without silicon reinforcement.

Frequency modulation detection in cochlear implant subjects

NASA Astrophysics Data System (ADS)

Chen, Hongbin; Zeng, Fan-Gang

2004-10-01

Frequency modulation (FM) detection was investigated in acoustic and electric hearing to characterize cochlear-implant subjects' ability to detect dynamic frequency changes and to assess the relative contributions of temporal and spectral cues to frequency processing. Difference limens were measured for frequency upward sweeps, downward sweeps, and sinusoidal FM as a function of standard frequency and modulation rate. In electric hearing, factors including electrode position and stimulation level were also studied. Electric hearing data showed that the difference limen increased monotonically as a function of standard frequency regardless of the modulation type, the modulation rate, the electrode position, and the stimulation level. In contrast, acoustic hearing data showed that the difference limen was nearly a constant as a function of standard frequency. This difference was interpreted to mean that temporal cues are used only at low standard frequencies and at low modulation rates. At higher standard frequencies and modulation rates, the reliance on the place cue is increased, accounting for the better performance in acoustic hearing than for electric hearing with single-electrode stimulation. The present data suggest a speech processing strategy that encodes slow frequency changes using lower stimulation rates than those typically employed by contemporary cochlear-implant speech processors. .

In Vivo Ultrasonic Detection of Polyurea Crosslinked Silica Aerogel Implants

PubMed Central

Sabri, Firouzeh; Sebelik, Merry E.; Meacham, Ryan; Boughter, John D.; Challis, Mitchell J.; Leventis, Nicholas

2013-01-01

Background Polyurea crosslinked silica aerogels are highly porous, lightweight, and mechanically strong materials with great potential for in vivo applications. Recent in vivo and in vitro studies have demonstrated the biocompatibility of this type of aerogel. The highly porous nature of aerogels allows for exceptional thermal, electric, and acoustic insulating capabilities that can be taken advantage of for non-invasive external imaging techniques. Sound-based detection of implants is a low cost, non-invasive, portable, and rapid technique that is routinely used and readily available in major clinics and hospitals. Methodology In this study the first in vivo ultrasound response of polyurea crosslinked silica aerogel implants was investigated by means of a GE Medical Systems LogiQe diagnostic ultrasound machine with a linear array probe. Aerogel samples were inserted subcutaneously and sub-muscularly in a) fresh animal model and b) cadaveric human model for analysis. For comparison, samples of polydimethylsiloxane (PDMS) were also imaged under similar conditions as the aerogel samples. Conclusion/significance Polyurea crosslinked silica aerogel (X-Si aerogel) implants were easily identified when inserted in either of the regions in both fresh animal model and cadaveric model. The implant dimensions inferred from the images matched the actual size of the implants and no apparent damage was sustained by the X-Si aerogel implants as a result of the ultrasonic imaging process. The aerogel implants demonstrated hyperechoic behavior and significant posterior shadowing. Results obtained were compared with images acquired from the PDMS implants inserted at the same location. PMID:23799093

Breast implants and breast cancer: a review of incidence, detection, mortality, and survival.

PubMed

Deapen, Dennis

2007-12-01

Soon after breast implants were commercially introduced over 30 years ago, questions about potential carcinogenicity were raised. Animal experiments dating back to the mid-twentieth century demonstrated that foreign body implantation of many materials, including silicone, can induce sarcomas. Indeed, female breast cancer incidence rates in the United States have increased substantially over that period. Of the several published studies from various countries that have formally investigated the risk of breast cancer among augmentation mammaplasty patients, none show any evidence of increased risk. In fact, most find lower than expected risk, some with statistically significant reductions. Similarly, breast cancer mortality among these patients is generally found to be below that expected of other similar women. Delayed detection of breast cancer is a concern for these patients because implants can interfere with mammography. However, using indicators such as stage at diagnosis and tumor size, current research shows that augmentation patients do not experience delayed detection. Furthermore, several comparisons of post-breast cancer survival of augmented versus nonaugmented patients have found no significant differences. In summary, breast implants are not associated with an increased risk of breast cancer incidence or death, and these patients do not experience delayed detection or poorer post-breast cancer survival.

Biomimetic structured surfaces increase primary adhesion capacity of cartilage implants.

PubMed

Lahner, Matthias; Kalwa, Lukas; Olbring, Roxana; Mohr, Charlotte; Göpfert, Lena; Seidl, Tobias

2015-01-01

In cartilage repair, scaffold-assisted single-step techniques are used to improve the cartilage regeneration. Nevertheless, the fixation of cartilage implants represents a challenge in orthopaedics, particularly in the moist conditions that pertain during arthroscopic surgery. Within the animal kingdom a broad range of species has developed working solutions to intermittent adhesion under challenging conditions. Using a top-down approach we identified promising mechanisms for biomimetic transfer The tree-frog adhesive system served as a test case to analyze the adhesion capacity of a polyglycolic acid (PGA) scaffold with and without a structural modification in a bovine articular cartilage defect model. To this end, PGA implants were modified with a simplified foot-pad structure and evaluated on femoral articular bovine cartilage lesions. Non-structured PGA scaffolds were used as control. Both implants were pressed on 20 mm × 20 mm full-thickness femoral cartilage defects using a dynamometer. The structured scaffolds showed a higher adhesion capacity on the cartilage defect than the non-structured original scaffolds. The results suggest that the adhesion ability can be increased by means of biomimetic structured surfaces without the need of additional chemical treatment and thus significantly facilitate primary fixation procedures.

Brief ultrasonication improves detection of biofilm-formative bacteria around a metal implant.

PubMed

Kobayashi, Naomi; Bauer, Thomas W; Tuohy, Marion J; Fujishiro, Takaaki; Procop, Gary W

2007-04-01

Biofilms are complex microenvironments produced by microorganisms on surfaces. Ultrasonication disrupts biofilms and may make the microorganism or its DNA available for detection. We determined whether ultrasonication could affect our ability to detect bacteria adherent to a metal substrate. A biofilm-formative Staphylococcus aureus strain was used for an in vitro implant infection model (biofilm-formative condition). We used quantitative culture and real time-polymerase chain reaction to determine the influence of different durations of ultrasound on bacterial adherence and viability. Sonication for 1 minute increased the yield of bacteria. Sonication longer than 5 minutes led to fewer bacterial colonies by conventional culture but not by polymerase chain reaction. This suggests short periods of sonication help release bacteria from the metal substrate by disrupting the biofilm, but longer periods of sonication lyse bacteria prohibiting their detection in microbiologic cultures. A relatively short duration of sonication may be desirable for maximizing detection of biofilm-formative bacteria around implants by culture or polymerase chain reaction.

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

PubMed

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

2008-11-06

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. 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. 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. The results of this study indicate similar osseointegration of zirconia and titanium implants at the ultrastructural level.

Structural and optical properties of vanadium ion-implanted GaN

NASA Astrophysics Data System (ADS)

Macková, A.; Malinský, P.; Jagerová, A.; Sofer, Z.; Klímová, K.; Sedmidubský, D.; Mikulics, M.; Lorinčík, J.; Veselá, D.; Böttger, R.; Akhmadaliev, S.

2017-09-01

The field of advanced electronic and optical devices searches for a new generation of transistors and lasers. The practical development of these novel devices depends on the availability of materials with the appropriate magnetic and optical properties, which is strongly connected to the internal morphology and the structural properties of the prepared doped structures. In this contribution, we present the characterisation of V ion-doped GaN epitaxial layers. GaN layers, oriented along the (0 0 0 1) crystallographic direction, grown by low-pressure metal-organic vapour-phase epitaxy (MOVPE) on c-plane sapphire substrates were implanted with 400 keV V+ ions at fluences of 5 × 1015 and 5 × 1016 cm-2. Elemental depth profiling was accomplished by Rutherford Backscattering Spectrometry (RBS) and Secondary Ion Mass Spectrometry (SIMS) to obtain precise information about the dopant distribution. Structural investigations are needed to understand the influence of defect distribution on the crystal-matrix recovery and the desired structural and optical properties. The structural properties of the ion-implanted layers were characterised by RBS-channelling and Raman spectroscopy to get a comprehensive insight into the structural modification of implanted GaN and to study the influence of subsequent annealing on the crystalline matrix reconstruction. Photoluminescence measurement was carried out to check the optical properties of the prepared structures.

Metallic orthopaedic implants and airport metal detectors.

PubMed

Kamineni, S; Legge, S; Ware, H

2002-01-01

Airport security can detect in vivo metallic implants. We hypothesized that a soft tissue shield and fast transit through archway detectors would decrease implant detectability, whereas greater implant mass would increase detectability. Twelve patients with 8 orthopaedic implants in vivo and 60 trauma and arthroplasty implants in vitro were subjected to standard airport security measures at Stanstead Airport (British Airports Authority), including arch and standard and nonstandard hand-held detectors. Archway detectors failed to detect some implants; hand-held detectors detected almost all implants except an ankle arthroplasty. Positive archway detection was related to implant transit speed through the detection field. The implant mass consistently affected detection in stainless steel and titanium implants, and a 1-inch wax shield had no effect. Patients with metallic implants should prepare routinely with documentation of their implant before traveling through security ports.

Etching and structure changes in PMMA coating under argon plasma immersion ion implantation

NASA Astrophysics Data System (ADS)

Kondyurin, Alexey; Bilek, Marcela

2011-06-01

A thin (120 nm) polymethylmethacrylate coating was treated by plasma immersion ion implantation with Ar using pulsed bias at 20 kV. Ellipsometry and FTIR spectroscopy and gel-fraction formation were used to detect the structure transformations as a function of ion fluence. The kinetics of etching, variations in refractive index and extinction coefficient in 400-1000 nm of wavelength, concentration changes in carbonyl, ether, methyl and methylene groups all as a function of ion fluence were analyzed. A critical ion fluence of 10 15 ions/cm 2 was observed to be a border between competing depolymerization and carbonization processes. Chemical reactions responsible for reorganization of the PMMA chemical structure under ion beam treatment are proposed.

[Study on Microbial Diversity of Peri-implantitis Subgingival by High-throughput Sequencing].

PubMed

Li, Zhi-jie; Wang, Shao-guo; Li, Yue-hong; Tu, Dong-xiang; Liu, Shi-yun; Nie, Hong-bing; Li, Zhi-qiang; Zhang, Ju-mei

2015-07-01

To study microbial diversity of peri-implantitis subgingival with high-throughput sequencing, and investigate microbiological etiology of peri-implantitis. Subgingival plaques were sampled from the patients with peri-implantitis (D group) and non-peri-implantitis subjects (N group). The microbiological diversity of the subgingival plaques was detected by sequencing V4 region of 16S rRNA with Illumina Miseq platform. The diversity of the community structure was analyzed using Mothur software. A total of 156 507 gene sequences were detected in nine samples and 4 402 operational taxonomic units (OTUs) were found. Selenomonas, Pseudomonas, and Fusobacterium were dominant bacteria in D group, while Fusobacterium, Veillonella and Streptococcus were dominant bacteria in N group. Differences between peri-implantitis and non-peri-implantitis bacterial communities were observed at all phylogenetic levels by LEfSe, which was also found in PcoA test. The occurrence of peri-implantitis is not only related to periodontitis pathogenic microbe, but also related with the changes of oral microbial community structure. Treponema, Herbaspirillum, Butyricimonas and Phaeobacte may be closely related to the occurrence and development of peri-implantitis.

Self-Powered Implantable Skin-Like Glucometer for Real-Time Detection of Blood Glucose Level In Vivo

NASA Astrophysics Data System (ADS)

Zhang, Wanglinhan; Zhang, Linlin; Gao, Huiling; Yang, Wenyan; Wang, Shuai; Xing, Lili; Xue, Xinyu

2018-06-01

Implantable bioelectronics for analyzing physiological biomarkers has recently been recognized as a promising technique in medical treatment or diagnostics. In this study, we developed a self-powered implantable skin-like glucometer for real-time detection of blood glucose level in vivo. Based on the piezo-enzymatic-reaction coupling effect of GOx@ZnO nanowire, the device under an applied deformation can actively output piezoelectric signal containing the glucose-detecting information. No external electricity power source or battery is needed for this device, and the outputting piezoelectric voltage acts as both the biosensing signal and electricity power. A practical application of the skin-like glucometer implanted in mouse body for detecting blood glucose level has been simply demonstrated. These results provide a new technique path for diabetes prophylaxis and treatment.

Formation of SIMOX-SOI structure by high-temperature oxygen implantation

NASA Astrophysics Data System (ADS)

Hoshino, Yasushi; Kamikawa, Tomohiro; Nakata, Jyoji

2015-12-01

We have performed oxygen ion implantation in silicon at very high substrate-temperatures (⩽1000 °C) for the purpose of forming silicon-on-insulator (SOI) structure. We have expected that the high-temperature implantation can effectively avoids ion-beam-induced damages in the SOI layer and simultaneously stabilizes the buried oxide (BOX) and SOI-Si layer. Such a high-temperature implantation makes it possible to reduce the post-implantation annealing temperature. In the present study, oxygen ions with 180 keV are incident on Si(0 0 1) substrates at various temperatures from room temperature (RT) up to 1000 °C. The ion-fluencies are in order of 1017-1018 ions/cm2. Samples have been analyzed by atomic force microscope, Rutherford backscattering, and micro-Raman spectroscopy. It is found in the AFM analysis that the surface roughness of the samples implanted at 500 °C or below are significantly small with mean roughness of less than 1 nm, and gradually increased for the 800 °C-implanted sample. On the other hand, a lot of dents are observed for the 1000 °C-implanted sample. RBS analysis has revealed that stoichiometric SOI-Si and BOX-SiO2 layers are formed by oxygen implantation at the substrate temperatures of RT, 500, and 800 °C. However, SiO2-BOX layer has been desorbed during the implantation. Raman spectra shows that the ion-beam-induced damages are fairly suppressed by such a high-temperatures implantation.

Structural Transformations in Austenitic Stainless Steel Induced by Deuterium Implantation: Irradiation at 295 K

NASA Astrophysics Data System (ADS)

Morozov, Oleksandr; Zhurba, Volodymir; Neklyudov, Ivan; Mats, Oleksandr; Progolaieva, Viktoria; Boshko, Valerian

2016-02-01

Deuterium thermal desorption spectra were investigated on the samples of austenitic steel 18Cr10NiTi pre-implanted at 295 K with deuterium ions in the dose range from 8 × 1014 to 2.7 × 1018 D/cm2. The kinetics of structural transformation development in the steel layer was traced from deuterium thermodesorption spectra as a function of deuterium concentration. Three characteristic regions with different low rates of deuterium amount desorption as the implantation dose increases were revealed: I—the linear region of low implantation doses (up to 1 × 1017 D/cm2); II—the nonlinear region of medium implantation doses (1 × 1017 to 8 × 1017 D/cm2); III—the linear region of high implantation doses (8 × 1017 to 2.7 × 1018 D/cm2). During the process of deuterium ion irradiation, the coefficient of deuterium retention in steel varies in discrete steps. Each of the discrete regions of deuterium retention coefficient variation corresponds to different implanted-matter states formed during deuterium ion implantation. The low-dose region is characterized by formation of deuterium-vacancy complexes and solid-solution phase state of deuterium in the steel. The total concentration of the accumulated deuterium in this region varies between 2.5 and 3 at.%. The medium-dose region is characterized by the radiation-induced action on the steel in the presence of deuterium with the resulting formation of the energy-stable nanosized crystalline structure of steel, having a developed network of intercrystalline boundaries. The basis for this developed network of intercrystalline boundaries is provided by the amorphous state, which manifests itself in the thermodesorption spectra as a widely temperature-scale extended region of deuterium desorption (structure formation with a varying activation energy). The total concentration of the accumulated deuterium in the region of medium implantation doses makes 7 to 8 at.%. The resulting structure shows stability against the action of

Reliability of scanning laser acoustic microscopy for detecting internal voids in structural ceramics

NASA Technical Reports Server (NTRS)

Roth, D. J.; Baaklini, G. Y.

1986-01-01

The reliability of 100 MHz scanning laser acoustic microscopy (SLAM) for detecting internal voids in sintered specimens of silicon nitride and silicon carbide was evaluated. The specimens contained artificially implanted voids and were positioned at depths ranging up to 2 mm below the specimen surface. Detection probability of 0.90 at a 0.95 confidence level was determined as a function of material, void diameter, and void depth. The statistical results presented for void detectability indicate some of the strengths and limitations of SLAM as a nondestructive evaluation technique for structural ceramics.

Microstructure and mechanical properties of porous titanium structures fabricated by electron beam melting for cranial implants.

PubMed

Moiduddin, Khaja

2018-02-01

The traditional methods of metallic bone implants are often dense and suffer from adverse reactions, biomechanical mismatch and lack of adequate space for new bone tissue to grow into the implant. The objective of this study is to evaluate the customized porous cranial implant with mechanical properties closer to that of bone and to improve the aesthetic outcome in cranial surgery with precision fitting for a better quality of life. Two custom cranial implants (bulk and porous) are digitally designed based on the Digital Imaging and Communications in Medicine files and fabricated using additive manufacturing. Initially, the defective skull model and the implant were fabricated using fused deposition modeling for the purpose of dimensional validation. Subsequently, the implant was fabricated using titanium alloy (Ti6Al4V extra low interstitial) by electron beam melting technology. The electron beam melting-produced body diagonal node structure incorporated in cranial implant was evaluated based on its mechanical strength and structural characterization. The results show that the electron beam melting-produced porous cranial implants provide the necessary framework for the bone cells to grow into the pores and mimic the architecture and mechanical properties closer to the region of implantation. Scanning electron microscope and micro-computed tomography scanning confirm that the produced porous implants have a highly regular pattern of porous structure with a fully interconnected network channel without any internal defect and voids. The physical properties of the titanium porous structure, containing the compressive strength of 61.5 MPa and modulus of elasticity being 1.20 GPa, represent a promising means of reducing stiffness and stress-shielding effect on the surrounding bone. This study reveals that the use of porous structure in cranial reconstruction satisfies the need of lighter implants with an adequate mechanical strength and structural characteristics

Implantable self-reset CMOS image sensor and its application to hemodynamic response detection in living mouse brain

NASA Astrophysics Data System (ADS)

Yamaguchi, Takahiro; Takehara, Hiroaki; Sunaga, Yoshinori; Haruta, Makito; Motoyama, Mayumi; Ohta, Yasumi; Noda, Toshihiko; Sasagawa, Kiyotaka; Tokuda, Takashi; Ohta, Jun

2016-04-01

A self-reset pixel of 15 × 15 µm2 with high signal-to-noise ratio (effective peak SNR ≃64 dB) for an implantable image sensor has been developed for intrinsic signal detection arising from hemodynamic responses in a living mouse brain. For detecting local conversion between oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) in brain tissues, an implantable imaging device was fabricated with our newly designed self-reset image sensor and orange light-emitting diodes (LEDs; λ = 605 nm). We demonstrated imaging of hemodynamic responses in the sensory cortical area accompanied by forelimb stimulation of a living mouse. The implantable imaging device for intrinsic signal detection is expected to be a powerful tool to measure brain activities in living animals used in behavioral analysis.

Structural investigations in helium implanted cubic zirconia using grazing incidence XRD and EXAFS spectroscopy

NASA Astrophysics Data System (ADS)

Kuri, G.; Degueldre, C.; Bertsch, J.; Döbeli, M.

2010-06-01

The crystal structure and local atom arrangements surrounding Zr atoms were determined for a helium implanted cubic stabilized zirconia (CSZ) using X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy, respectively, measured at glancing angles. The implanted specimen was prepared at a helium fluence of 2 × 10 16 cm -2 using He + beams at two energies (2.54 and 2.74 MeV) passing through a 8.0 μm Al absorber foil. XRD results identified the formation of a new rhombohedral phase in the helium embedded layer, attributed to internal stress as a result of expansion of the CSZ-lattice. Zr K-edge EXAFS data suggested loss of crystallinity in the implanted lattice and disorder of the Zr atoms environment. EXAFS Fourier transforms analysis showed that the average first-shell radius of the Zr sbnd O pair in the implanted sample was slightly larger than that of the CSZ standard. Common general disorder features were explained by rhombohedral type short-range ordered clusters. The average structural parameters estimated from the EXAFS data of unimplanted and implanted CSZ are compared and discussed. Potential of EXAFS as a local probe of atomic-scale structural modifications induced by helium implantation in CSZ is demonstrated.

Speech detection in noise and spatial unmasking in children with simultaneous versus sequential bilateral cochlear implants.

PubMed

Chadha, Neil K; Papsin, Blake C; Jiwani, Salima; Gordon, Karen A

2011-09-01

To measure speech detection in noise performance for children with bilateral cochlear implants (BiCI), to compare performance in children with simultaneous implant versus those with sequential implant, and to compare performance to normal-hearing children. Prospective cohort study. Tertiary academic pediatric center. Children with early-onset bilateral deafness and 2-year BiCI experience, comprising the "sequential" group (>2 yr interimplantation delay, n = 12) and "simultaneous group" (no interimplantation delay, n = 10) and normal-hearing controls (n = 8). Thresholds to speech detection (at 0-degree azimuth) were measured with noise at 0-degree azimuth or ± 90-degree azimuth. Spatial unmasking (SU) as the noise condition changed from 0-degree azimuth to ± 90-degree azimuth and binaural summation advantage (BSA) of 2 over 1 CI. Speech detection in noise was significantly poorer than controls for both BiCI groups (p < 0.0001). However, the SU in the simultaneous group approached levels found in normal controls (7.2 ± 0.6 versus 8.6 ± 0.6 dB, p > 0.05) and was significantly better than that in the sequential group (3.9 ± 0.4 dB, p < 0.05). Spatial unmasking was unaffected by the side of noise presentation in the simultaneous group but, in the sequential group, was significantly better when noise was moved to the second rather than the first implanted ear (4.8 ± 0.5 versus 3.0 ± 0.4 dB, p < 0.05). This was consistent with a larger BSA from the sequential group's second rather than first CI. Children with simultaneously implanted BiCI demonstrated an advantage over children with sequential implant by using spatial cues to improve speech detection in noise.

Structural transformations in austenitic stainless steel induced by deuterium implantation: irradiation at 100 K

NASA Astrophysics Data System (ADS)

Morozov, Oleksandr; Zhurba, Volodymyr; Neklyudov, Ivan; Mats, Oleksandr; Rud, Aleksandr; Chernyak, Nikolay; Progolaieva, Viktoria

2015-03-01

Deuterium thermal desorption spectra were investigated on the samples of austenitic stainless steel 18Cr10NiTi preimplanted at 100 K with deuterium ions in the dose range from 3 × 1015 to 5 × 1018 D/cm2. The kinetics of structural transformation development in the implantation steel layer was traced from deuterium thermodesorption spectra as a function of implanted deuterium concentration. At saturation of austenitic stainless steel 18Cr10NiTi with deuterium by means of ion implantation, structural-phase changes take place, depending on the dose of implanted deuterium. The maximum attainable concentration of deuterium in steel is C = 1 (at.D/at.met. = 1/1). The increase in the implanted dose of deuterium is accompanied by the increase in the retained deuterium content, and as soon as the deuterium concentration attains C ≈ 0.5 the process of shear martensitic structural transformation in steel takes place. It includes the formation of bands, body-centered cubic (bcc) crystal structure, and the ferromagnetic phase. Upon reaching the deuterium concentration C > 0.5, the presence of these molecules causes shear martensitic structural transformations in the steel, which include the formation of characteristic bands, bcc crystal structure, and the ferromagnetic phase. At C ≥ 0.5, two hydride phases are formed in the steel, the decay temperatures of which are 240 and 275 K. The hydride phases are formed in the bcc structure resulting from the martensitic structural transformation in steel.

Optimization of single keV ion implantation for the construction of single P-donor devices

NASA Astrophysics Data System (ADS)

Yang, Changyi; Jamieson, David N.; Hopf, Toby; Andresen, Soren E.; Hearne, Sean M.; Hudson, Fay E.; Pakes, Christopher I.; Mitic, Mladen; Gauja, Eric; Tamanyan, Grigori; Dzurak, Andrew S.; Prawer, Steven; Clark, Robert G.

2005-02-01

We report recent progress in single keV ion implantation and online detection for the controlled implantation of single donors in silicon. When integrated with silicon nanofabrication technology this forms the "top down" strategy for the construction of prototype solid state quantum computer devices based on phosphorus donors in silicon. We have developed a method of single ion implantation and online registration that employs detector electrodes adjacent to the area into which the donors are to be implanted. The implantation sites are positioned with nanometer accuracy using an electron beam lithography patterned PMMA mask. Control of the implantation depth of 20 nm is achieved by tuning the phosphorus ion energy to 14 keV. The counting of single ion implantation in each site is achieved by the detection of e-/h+ pairs produced by the implanted phosphorus ion in the substrate. The system is calibrated by use of Mn K-line x-rays (5.9 and 6.4 keV) and we find the ionization energy of the 14 keV phosphorus ions in silicon to be about 3.5-4.0 keV for implants through a 5 nm SiO2 surface layer. This paper describes the development of an improved PIN detector structure that provides more reliable performance of the earlier MOS structure. With the new structure, the energy noise threshold has been minimized to 1 keV or less. Unambiguous detection/counting of single keV ion implantation events were achieved with a confidence level greater than 98% with a reliable and reproducible fabrication process.

Surface and local electronic structure modification of MgO film using Zn and Fe ion implantation

NASA Astrophysics Data System (ADS)

Singh, Jitendra Pal; Lim, Weon Cheol; Lee, Jihye; Song, Jonghan; Lee, Ik-Jae; Chae, Keun Hwa

2018-02-01

Present work is motivated to investigate the surface and local electronic structure modifications of MgO films implanted with Zn and Fe ions. MgO film was deposited using radio frequency sputtering method. Atomic force microscopy measurements exhibit morphological changes associated with implantation. Implantation of Fe and Zn ions leads to the reduction of co-ordination geometry of Mg2+ ions in host lattice. The effect is dominant at bulk of film rather than surface as the large concentration of implanted ions resides inside bulk. Moreover, the evidences of interaction among implanted ions and oxygen are not being observed using near edge fine structure measurements.

Structural Transformations in Austenitic Stainless Steel Induced by Deuterium Implantation: Irradiation at 295 K.

PubMed

Morozov, Oleksandr; Zhurba, Volodymir; Neklyudov, Ivan; Mats, Oleksandr; Progolaieva, Viktoria; Boshko, Valerian

2016-12-01

Deuterium thermal desorption spectra were investigated on the samples of austenitic steel 18Cr10NiTi pre-implanted at 295 K with deuterium ions in the dose range from 8 × 10(14) to 2.7 × 10(18) D/cm(2). The kinetics of structural transformation development in the steel layer was traced from deuterium thermodesorption spectra as a function of deuterium concentration. Three characteristic regions with different low rates of deuterium amount desorption as the implantation dose increases were revealed: I-the linear region of low implantation doses (up to 1 × 10(17) D/cm(2)); II-the nonlinear region of medium implantation doses (1 × 10(17) to 8 × 10(17) D/cm(2)); III-the linear region of high implantation doses (8 × 10(17) to 2.7 × 10(18) D/cm(2)). During the process of deuterium ion irradiation, the coefficient of deuterium retention in steel varies in discrete steps. Each of the discrete regions of deuterium retention coefficient variation corresponds to different implanted-matter states formed during deuterium ion implantation. The low-dose region is characterized by formation of deuterium-vacancy complexes and solid-solution phase state of deuterium in the steel. The total concentration of the accumulated deuterium in this region varies between 2.5 and 3 at.%. The medium-dose region is characterized by the radiation-induced action on the steel in the presence of deuterium with the resulting formation of the energy-stable nanosized crystalline structure of steel, having a developed network of intercrystalline boundaries. The basis for this developed network of intercrystalline boundaries is provided by the amorphous state, which manifests itself in the thermodesorption spectra as a widely temperature-scale extended region of deuterium desorption (structure formation with a varying activation energy). The total concentration of the accumulated deuterium in the region of medium implantation doses makes 7 to 8 at.%. The

The unsuitability of implantable Doppler probes for the early detection of renal vascular complications – a porcine model for prevention of renal transplant loss

PubMed Central

Jespersen, Bente; Møldrup, Ulla; Keller, Anna K.

2017-01-01

Background Vascular occlusion is a rare, but serious complication after kidney transplantation often resulting in graft loss. We therefore aimed to develop an experimental porcine model for stepwise reduction of the renal venous blood flow and to compare an implantable Doppler probe and microdialysis for fast detection of vascular occlusion. Methods In 20 pigs, implantable Doppler probes were placed on the renal artery and vein and a microdialysis catheter was placed in the renal cortex. An arterial flowprobe served as gold standard. Following two-hour baseline measurements, the pigs were randomised to stepwise venous occlusion, complete venous occlusion, complete arterial occlusion or controls. Results All parameters were stable through baseline measurements. Glutamate and lactate measured by microdialysis increased significantly (p = 0.02 and p = 0.03 respectively) 30 minutes after a 2/3 (66%) reduction in renal blood flow. The implantable Doppler probe was not able to detect flow changes until there was total venous occlusion. Microdialysis detected changes in local metabolism after both arterial and venous occlusion; the implantable Doppler probe could only detect vascular occlusions on the vessel it was placed. Conclusions We developed a new model for stepwise renal venous blood flow occlusion. Furthermore, the first comparison of the implantable Doppler probe and microdialysis for detection of renal vascular occlusions was made. The implantable Doppler probe could only detect flow changes after a complete occlusion, whereas microdialysis detected changes earlier, and could detect both arterial and venous occlusion. Based on these results, the implantable Doppler probe for early detection of vascular occlusions cannot be recommended. PMID:28542429

NMR detection of short-lived β-emitter 12N implanted in water

NASA Astrophysics Data System (ADS)

Sugihara, T.; Mihara, M.; Shimaya, J.; Matsuta, K.; Fukuda, M.; Ohno, J.; Tanaka, M.; Yamaoka, S.; Watanabe, K.; Iwakiri, S.; Yanagihara, R.; Tanaka, Y.; Du, H.; Onishi, K.; Kambayashi, S.; Minamisono, T.; Nishimura, D.; Izumikawa, T.; Ozawa, A.; Ishibashi, Y.; Kitagawa, A.; Sato, S.; Torikoshi, M.; Momota, S.

2017-11-01

The beta-detected nuclear magnetic resonance ( β-NMR) in liquid H2O has been observed for the first time using a short-lived β-ray emitter 12N ( I π = 1+, T 1/2=11 ms). A nuclear spin polarized 12N beam with an energy of about 20 MeV/nucleon was implanted into an enclosed water sample. About 50 % of implanted 12N ions maintained nuclear polarization and exhibited a β-NMR spectrum. The chemical shift of 12N in H2O relative to 12N in Pt was deduced to be -(3.6±0.5) × 102 ppm.

Structural transformations in austenitic stainless steel induced by deuterium implantation: irradiation at 100 K.

PubMed

Morozov, Oleksandr; Zhurba, Volodymyr; Neklyudov, Ivan; Mats, Oleksandr; Rud, Aleksandr; Chernyak, Nikolay; Progolaieva, Viktoria

2015-01-01

Deuterium thermal desorption spectra were investigated on the samples of austenitic stainless steel 18Cr10NiTi preimplanted at 100 K with deuterium ions in the dose range from 3 × 10(15) to 5 × 10(18) D/cm(2). The kinetics of structural transformation development in the implantation steel layer was traced from deuterium thermodesorption spectra as a function of implanted deuterium concentration. At saturation of austenitic stainless steel 18Cr10NiTi with deuterium by means of ion implantation, structural-phase changes take place, depending on the dose of implanted deuterium. The maximum attainable concentration of deuterium in steel is C = 1 (at.D/at.met. = 1/1). The increase in the implanted dose of deuterium is accompanied by the increase in the retained deuterium content, and as soon as the deuterium concentration attains C ≈ 0.5 the process of shear martensitic structural transformation in steel takes place. It includes the formation of bands, body-centered cubic (bcc) crystal structure, and the ferromagnetic phase. Upon reaching the deuterium concentration C > 0.5, the presence of these molecules causes shear martensitic structural transformations in the steel, which include the formation of characteristic bands, bcc crystal structure, and the ferromagnetic phase. At C ≥ 0.5, two hydride phases are formed in the steel, the decay temperatures of which are 240 and 275 K. The hydride phases are formed in the bcc structure resulting from the martensitic structural transformation in steel.

Impact of nucleation of carbonaceous clusters on structural, electrical and optical properties of Cr+-implanted PMMA

NASA Astrophysics Data System (ADS)

Arif, Shafaq; Rafique, M. Shahid; Saleemi, Farhat; Naab, Fabian; Toader, Ovidiu; Mahmood, Arshad; Aziz, Uzma

2016-09-01

Specimens of polymethylmethacrylate (PMMA) have been implanted with 400 keV Cr+ ions at different ion fluences ranging from 5 × 1013 to 5 × 1015 ions/cm2. The possible chemical reactions involved in the nucleation of conjugated carbonaceous clusters in implanted PMMA are discussed. Furthermore, impact of formation of carbonaceous clusters on structural, optical, electrical and morphological properties of implanted PMMA has been examined. The structural modifications in implanted PMMA are observed by Raman spectroscopy. The variation in optical band gap and Urbach energy is measured using UV-visible spectroscopic analysis. The effects of Cr+ ion implantation on electrical and morphological properties are investigated by four-probe apparatus and atomic force microscopy, respectively. The Raman spectroscopic analysis confirmed the formation of carbonaceous clusters with the transformation of implanted layer of PMMA into amorphous carbon. Simultaneously, the optical band gap of implanted PMMA has reduced from 3.13 to 0.85 eV. The increase in Urbach energy favors the decline in band gap together with the structural modification in implanted PMMA. As a result of Cr+ ion implantation, the electrical conductivity of PMMA has improved from 2.14 ± 0.06 × 10-10 S/cm (pristine) to 7.20 ± 0.36 × 10-6 S/cm. The AFM images revealed a decrease in surface roughness with an increment in ion fluence up to 5 × 1014 ions/cm2. The modification in the electrical, optical and structural properties makes the PMMA a promising candidate for its future utilization, as a semiconducting and optically active material, in various fields like plastic electronics and optoelectronic devices.

Bone bonding strength of diamond-structured porous titanium-alloy implants manufactured using the electron beam-melting technique.

PubMed

Hara, Daisuke; Nakashima, Yasuharu; Sato, Taishi; Hirata, Masanobu; Kanazawa, Masayuki; Kohno, Yusuke; Yoshimoto, Kensei; Yoshihara, Yusuke; Nakamura, Akihiro; Nakao, Yumiko; Iwamoto, Yukihide

2016-02-01

The present study examined the bone bonding strength of diamond-structured porous titanium-alloy (Porous-Ti-alloy) manufactured using the electron beam-melting technique in comparison with fiber mesh-coated or rough-surfaced implants. Cylindrical implants with four different pore sizes (500, 640, 800, and 1000μm) of Porous-Ti-alloy, titanium fiber mesh (FM), and surfaces roughened by titanium arc spray (Ti-spray) were implanted into the distal femur of rabbits. Bone bonding strength and histological bone ingrowth were evaluated at 4 and 12weeks after implantation. The bone bonding strength of Porous-Ti-alloy implants (640μm pore size) increased over time from 541.4N at 4weeks to 704.6N at 12weeks and was comparable to that of FM and Ti-spray implants at both weeks. No breakage of the porous structure after mechanical testing was found with Porous-Ti-alloy implants. Histological bone ingrowth that increased with implantation time occurred along the inner structure of Porous-Ti-alloy implants. There was no difference in bone ingrowth in Porous-Ti-alloy implants with pore sizes among 500, 640, and 800μm; however, less bone ingrowth was observed with the 1000μm pore size. These results indicated Porous-Ti-alloy implants with pore size under 800μm provided biologically active and mechanically stable surface for implant fixation to bone, and had potential advantages for weight bearing orthopedic implants such as acetabular cups. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparative silicone breast implant evaluation using mammography, sonography, and magnetic resonance imaging: experience with 59 implants.

PubMed

Ahn, C Y; DeBruhl, N D; Gorczyca, D P; Shaw, W W; Bassett, L W

1994-10-01

With the current controversy regarding the safety of silicone implants, the detection and evaluation of implant rupture are causing concern for both plastic surgeons and patients. Our study obtained comparative value analysis of mammography, sonography, and magnetic resonance imaging (MRI) in the detection of silicone implant rupture. Twenty-nine symptomatic patients (total of 59 silicone implants) were entered into the study. Intraoperative findings revealed 21 ruptured implants (36 percent). During physical examination, a positive "squeeze test" was highly suggestive of implant rupture. Mammograms were obtained of 51 implants (sensitivity 11 percent, specificity 89 percent). Sonography was performed on 57 implants (sensitivity 70 percent, specificity 92 percent). MRI was performed on 55 implants (sensitivity 81 percent, specificity 92 percent). Sonographically, implant rupture is demonstrated by the "stepladder sign." Double-lumen implants may appear as false-positive results for rupture on sonography. On MRI, the "linguine sign" represents disrupted fragments of a ruptured implant. The most reliable imaging modality for implant rupture detection is MRI, followed by sonogram. Mammogram is the least reliable. Our study supports the clinical indication and diagnostic value of sonogram and MRI in the evaluation of symptomatic breast implant patients.

The local structure and ferromagnetism in Fe-implanted SrTiO3 single crystals

NASA Astrophysics Data System (ADS)

Lobacheva, O.; Chavarha, M.; Yiu, Y. M.; Sham, T. K.; Goncharova, L. V.

2014-07-01

We report a connection between the local structure of low-level Fe impurities and vacancies as the cause of ferromagnetic behavior observed in strontium titanate single crystals (STO), which were implanted with Fe and Si ions at different doses then annealed in oxygen. The effects of Fe doping and post-implantation annealing of STO were studied by X-ray Absorption Near Edge Structure (XANES) spectroscopy and Superconducting Quantum Interference Device magnetometry. XANES spectra for Fe and Ti K- and L-edge reveal the changes in the local environment of Fe and Ti following the implantation and annealing steps. The annealing in oxygen atmosphere partially healed implantation damages and changed the oxidation state of the implanted iron from metallic Fe0 to Fe2+/Fe3+ oxide. The STO single crystals were weak ferromagnets prior to implantation. The maximum saturation moment was obtained after our highest implantation dose of 2 × 1016 Fe atom/cm2, which could be correlated with the metallic Fe0 phases in addition to the presence of O/Ti vacancies. After recrystallization annealing, the ferromagnetic response disappears. Iron oxide phases with Fe2+ and Fe3+ corresponding to this regime were identified and confirmed by calculations using Real Space Multiple Scattering program (FEFF9).

Insights from imaging the implanting embryo and the uterine environment in three dimensions

PubMed Central

Arora, Ripla; Fries, Adam; Oelerich, Karina; Marchuk, Kyle; Sabeur, Khalida; Giudice, Linda C.

2016-01-01

Although much is known about the embryo during implantation, the architecture of the uterine environment in which the early embryo develops is not well understood. We employed confocal imaging in combination with 3D analysis to identify and quantify dynamic changes to the luminal structure of murine uterus in preparation for implantation. When applied to mouse mutants with known implantation defects, this method detected striking peri-implantation abnormalities in uterine morphology that cannot be visualized by histology. We revealed 3D organization of uterine glands and found that they undergo a stereotypical reorientation concurrent with implantation. Furthermore, we extended this technique to generate a 3D rendering of the cycling human endometrium. Analyzing the uterine and embryo structure in 3D for different genetic mutants and pathological conditions will help uncover novel molecular pathways and global structural changes that contribute to successful implantation of an embryo. PMID:27836961

Composite fibrous glaucoma drainage implant

NASA Astrophysics Data System (ADS)

Klapstova, A.; Horakova, J.; Shynkarenko, A.; Lukas, D.

2017-10-01

Glaucoma is a frequent reason of loss vision. It is usually caused by increased intraocular pressure leading to damage of optic nerve head. This work deals with the development of fibrous structure suitable for glaucoma drainage implants (GDI). Commercially produced metallic glaucoma implants are very effective in lowering intraocular pressure. However, these implants may cause adverse events such as damage to adjacent tissue, fibrosis, hypotony or many others [1]. The aim of this study is to reduce undesirable properties of currently produced drains and improve their properties by creating of the composite fibrous drain for achieve a normal intraocular pressure. Two types of electrospinning technologies were used for the production of very small tubular implants. First type was focused for production of outer part of tubular drain and the second type of electrospinning method made the inner part of shape follows the connections of both parts. Complete implant had a special properties suitable for drainage of fluid. Morphological parameters, liquid transport tests and in-vitro cell adhesion tests were detected.

Structural and electrical properties of In-implanted Ge

DOE PAGES

Feng, R.; Kremer, F.; Sprouster, D. J.; ...

2015-10-22

Here, we report on the effects of dopant concentration on the structural and electrical properties of In-implanted Ge. For In concentrations of ≤ 0.2 at. %, extended x-ray absorption fine structure and x-ray absorption near-edge structure measurements demonstrate that all In atoms occupy a substitutional lattice site while metallic In precipitates are apparent in transmission electron micrographs for In concentrations ≥0.6 at. %. Evidence of the formation of In-vacancy complexes deduced from extended x-ray absorption fine structure measurements is complimented by density functional theory simulations. Hall effect measurements of the conductivity, carrier density, and carrier mobility are then correlated withmore » the substitutional In fraction.« less

Detection of crestal radiolucencies around dental implants: an in vitro experimental study.

PubMed

Sirin, Yigit; Horasan, Sinan; Yaman, Duygu; Basegmez, Cansu; Tanyel, Cem; Aral, Ali; Guven, Koray

2012-07-01

The aim of this study was to compare the diagnostic potentials and practical advantages of different imaging modalities in detecting bone defects around dental implants. Crestal bone defects with sequentially larger diameters were randomly prepared around 100 implants that were inserted in bovine bone blocks. Conventional periapical radiography (PR), direct digital radiography (DDR), panoramic radiography (PANO), cone-beam computed tomography (CBCT), and multislice computed tomography (MSCT) were performed for all specimens. The diagnostic accuracies of the devices, confidence of the answers, subjective image quality, defect visibility in planar orientations, and duration of diagnosis were analyzed based on the interpretations of 7 calibrated observers. The agreement levels of intra- and interobserver scores were rated good. PR, DDR, and CBCT were mostly more accurate than PANO and MSCT (P < .05). Confidence levels were positively correlated with the defect size (ρ = 0.20, P < .01), and that of DDR was the highest (P < .05). The subjective image quality of PR and DDR was higher than that of CBCT, PANO, and MSCT (P < .05 for all comparisons). Axial-coronal-sagittal visibilities of the defects were higher for CBCT compared with MSCT (P < .05). The diagnostic time was shorter for DDR (P < .05) and longer for the tomographic systems (P < .05) than for the other devices. DDR may provide a faster and more confident diagnostic option that is as accurate as PR in detecting peri-implant radiolucencies. CBCT has a comparable potential to these intraoral systems but with slower decision making and lower image quality, whereas PANO and MSCT become more reliable when bone defects have a diameter that is at least 1.5 mm larger than that of the implant. Copyright © 2012 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Critical analysis of dual-chamber implantable cardioverter-defibrillator arrhythmia detection : results and technical considerations.

PubMed

Wilkoff, B L; Kühlkamp, V; Volosin, K; Ellenbogen, K; Waldecker, B; Kacet, S; Gillberg, J M; DeSouza, C M

2001-01-23

One of the perceived benefits of dual-chamber implantable cardioverter-defibrillators (ICDs) is the reduction in inappropriate therapy due to new detection algorithms. It was the purpose of the present investigation to propose methods to minimize bias during such comparisons and to report the arrhythmia detection clinical results of the PR Logic dual-chamber detection algorithm in the GEM DR ICD in the context of these methods. Between November 1997 and October 1998, 933 patients received the GEM DR ICD in this prospective multicenter study. A total of 4856 sustained arrhythmia episodes (n=311) with stored electrogram and marker channel were classified by the investigators; 3488 episodes (n=232) were ventricular tachycardia (VT)/ventricular fibrillation (VF), and 1368 episodes (n=149) were supraventricular tachycardia (SVT). The overall detection results were corrected for multiple episodes within a patient with the generalized estimating equations (GEE) method with an exchangeable correlation structure between episodes. The relative sensitivity for detection of sustained VT and/or VF was 100.0% (3488 of 3488, n=232; 95% CI 98.3% to 100%), the VT/VF positive predictivity was 88.4% uncorrected (3488 of 3945, n=278) and 78.1% corrected (95% CI 73.3% to 82.3%) with the GEE method, and the SVT positive predictivity was 100.0% (911 of 911, n=101; 95% CI 96% to 100%). A structured approach to analysis limits the bias inherent in the evaluation of tachycardia discrimination algorithms through the use of relative VT/VF sensitivity, VT/VF positive predictivity, and SVT positive predictivity along with corrections for multiple tachycardia episodes in a single patient.

Multimodality Imaging-based Evaluation of Single-Lumen Silicone Breast Implants for Rupture.

PubMed

Seiler, Stephen J; Sharma, Pooja B; Hayes, Jody C; Ganti, Ramapriya; Mootz, Ann R; Eads, Emily D; Teotia, Sumeet S; Evans, W Phil

2017-01-01

Breast implants are frequently encountered on breast imaging studies, and it is essential for any radiologist interpreting these studies to be able to correctly assess implant integrity. Ruptures of silicone gel-filled implants often occur without becoming clinically obvious and are incidentally detected at imaging. Early diagnosis of implant rupture is important because surgical removal of extracapsular silicone in the breast parenchyma and lymphatics is difficult. Conversely, misdiagnosis of rupture may prompt a patient to undergo unnecessary additional surgery to remove the implant. Mammography is the most common breast imaging examination performed and can readily depict extracapsular free silicone, although it is insensitive for detection of intracapsular implant rupture. Ultrasonography (US) can be used to assess the internal structure of the implant and may provide an economical method for initial implant assessment. Common US signs of intracapsular rupture include the "keyhole" or "noose" sign, subcapsular line sign, and "stepladder" sign; extracapsular silicone has a distinctive "snowstorm" or echogenic noise appearance. Magnetic resonance (MR) imaging is the most accurate and reliable means for assessment of implant rupture and is highly sensitive for detection of both intracapsular and extracapsular rupture. MR imaging findings of intracapsular rupture include the keyhole or noose sign, subcapsular line sign, and "linguine" sign, and silicone-selective MR imaging sequences are highly sensitive to small amounts of extracapsular silicone. © RSNA, 2017.

Reliability of implant placement after virtual planning of implant positions using cone beam CT data and surgical (guide) templates.

PubMed

Nickenig, Hans-Joachim; Eitner, Stephan

2007-01-01

We assessed the reliability of implant placement after virtual planning of implant positions using cone-beam CT data and surgical guide templates. A total of 102 patients (250 implants, 55.4% mandibular; mean patient age, 40.4 years) who had undergone implant treatment therapy in an armed forces dental clinic (Cologne, Germany) between July 1, 2005 and December 1, 2005. They were treated with a system that allows transfer of virtual planning to surgical guide templates. Only in eight cases the surgical guides were not used because a delayed implant placement was necessary. In four posterior mandibular cases, handling was limited because of reduced interocclusal distance, requiring 50% shortening of the drill guides. The predictability of implant size was high: only one implant was changed to a smaller diameter (because of insufficient bone). In all cases, critical anatomical structures were protected and no complications were detected in postoperative panoramic radiographs. In 58.1% (147) of the 250 implants, a flapless surgery plan was realized. Implant placement after virtual planning of implant positions using cone beam CT data and surgical templates can be reliable for preoperative assessment of implant size, position, and anatomical complications. It is also indicative of cases amenable to flapless surgery.

Erbium ion implantation into diamond - measurement and modelling of the crystal structure.

PubMed

Cajzl, Jakub; Nekvindová, Pavla; Macková, Anna; Malinský, Petr; Sedmidubský, David; Hušák, Michal; Remeš, Zdeněk; Varga, Marián; Kromka, Alexander; Böttger, Roman; Oswald, Jiří

2017-02-22

Diamond is proposed as an extraordinary material usable in interdisciplinary fields, especially in optics and photonics. In this contribution we focus on the doping of diamond with erbium as an optically active centre. In the theoretical part of the study based on DFT simulations we have developed two Er-doped diamond structural models with 0 to 4 carbon vacancies in the vicinity of the Er atom and performed geometry optimizations by the calculation of cohesive energies and defect formation energies. The theoretical results showed an excellent agreement between the calculated and experimental cohesive energies for the parent diamond. The highest values of cohesive energies and the lowest values of defect formation energies were obtained for models with erbium in the substitutional carbon position with 1 or 3 vacancies in the vicinity of the erbium atom. From the geometry optimization the structural model with 1 vacancy had an octahedral symmetry whereas the model with 3 vacancies had a coordination of 10 forming a trigonal structure with a hexagonal ring. In the experimental part, erbium doped diamond crystal samples were prepared by ion implantation of Er + ions using ion implantation fluences ranging from 1 × 10 14 ions per cm 2 to 5 × 10 15 ions per cm 2 . The experimental results revealed a high degree of diamond structural damage after the ion implantation process reaching up to 69% of disordered atoms in the samples. The prepared Er-doped diamond samples annealed at the temperatures of 400, 600 and 800 °C in a vacuum revealed clear luminescence, where the 〈110〉 cut sample has approximately 6-7 times higher luminescence intensity than the 〈001〉 cut sample with the same ion implantation fluence. The reported results are the first demonstration of the Er luminescence in the single crystal diamond structure for the near-infrared spectral region.

Airport detectors and orthopaedic implants.

PubMed

van der Wal, Bart C H; Grimm, Bernd; Heyligers, Ide C

2005-08-01

As a result of the rising threats of terrorism, airport security has become a major issue. Patients with orthopaedic implants are concerned that they may activate alarms at airport security gates. A literature overview showed that the activation rate of the alarm by hand-held detectors is higher than for arch detectors (100% versus 56%). Arch detection rate has significantly increased from 0% before 1995 up to 83.3% after 1994. Reported factors which influence detection rates are implant mass, implant combinations, implant volume, transfer speed, side of implant, detector model, sensitivity settings, material and tissue masking. Detection rate has been improved by more sensitive devices and improved filter software. Doctors should be able to objectively inform patients. A form is presented which will easily inform the airport security staff.

Structural properties of H-implanted InP crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bocchi, C.; Franzosi, P.; Lazzarini, L.

1993-07-01

H has been implanted in InP crystals at the energy E [equals] 100 keV and at different doses ranging from [sigma] [equals] 1 x 10[sup 13] to [sigma] [equals] 5 x 10[sup 16] cm[sup [minus]2]. The depth dependence of the elastic lattice strain has been investigated by high resolution X-ray diffractometry. The implantation produces a lattice dilation. The strain increases with increasing depth, reaches the maximum at about 0.75 [mu]m, and then decreases rapidly; moreover the maximum strain is proportional to the dose. No extended crystal defects have been detected by transmission electron microscopy up to [sigma] <1 x 10[supmore » 16] cm[sup [minus]2] a buried amorphous layer 28 nm in thickness has been observed at the same depth where the strain is maximum. The thickness of the amorphous layer increases by further increasing the dose and reaches a value of about 0.18 [mu]m for [sigma] [equals] 5 x 10[sup 16] cm[sup [minus]2].« less

Offline impedance measurements for detection and mitigation of dangerous implant interactions: an RF safety prescreen.

PubMed

Ellenor, Christopher W; Stang, Pascal P; Etezadi-Amoli, Maryam; Pauly, John M; Scott, Greig C

2015-03-01

The concept of a "radiofrequency safety prescreen" is investigated, wherein dangerous interactions between radiofrequency fields used in MRI, and conductive implants in patients are detected through impedance changes in the radiofrequency coil. The behavior of coupled oscillators is reviewed, and the resulting, observable impedance changes are discussed. A birdcage coil is loaded with a static head phantom and a wire phantom with a wire close to its resonant length, the shape, position, and orientation of which can be changed. Interactions are probed with a current sensor and network analyzer. Impedance spectra show dramatic, unmistakable splitting in cases of strong coupling, and strong correlation is observed between induced current and scattering parameters. The feasibility of a new, low-power prescreening technique has been demonstrated in a simple phantom experiment, which can unambiguously detect resonant interactions between an implanted wire and an imaging coil. A new technique has also been presented which can detect parallel transmit null modes for the wire. © 2014 Wiley Periodicals, Inc.

Biomechanical effects of two different collar implant structures on stress distribution under cantilever fixed partial dentures.

PubMed

Merıç, Gökçe; Erkmen, Erkan; Kurt, Ahmet; Eser, Atilim; özden, Ahmet Utku

2011-11-01

The purpose of the study was to compare the effects of two distinct collar geometries of implants on stress distribution in the bone around the implants supporting cantilever fixed partial dentures (CFPDs) as well as in the implant-abutment complex and superstructures. The three-dimensional finite element method was selected to evaluate the stress distribution. CFPDs which was supported by microthread collar structured (MCS) and non-microthread collar structured (NMCS) implants was modeled; 300 N vertical, 150 N oblique and 60 N horizontal forces were applied to the models separately. The stress values in the bone, implant-abutment complex and superstructures were calculated. In the MCS model, higher stresses were located in the cortical bone and implant-abutment complex in the case of vertical load while decreased stresses in cortical bone and implant-abutment complex were noted within horizontal and oblique loading. In the case of vertical load, decreased stresses have been noted in cancellous bone and framework. Upon horizontal and oblique loading, a MCS model had higher stress in cancellous bone and framework than the NMCS model. Higher von Mises stresses have been noted in veneering material for NMCS models. It has been concluded that stress distribution in implant-supported CFPDs correlated with the macro design of the implant collar and the direction of applied force.

Investigation of Ion-Implanted Photosensitive Silicon Structures by Electrochemical Capacitance–Voltage Profiling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yakovlev, G. E., E-mail: geyakovlev@etu.ru; Frolov, D. S.; Zubkova, A. V.

2016-03-15

The method of electrochemical capacitance–voltage profiling is used to study boron-implanted silicon structures for CCD matrices with backside illumination. A series of specially prepared structures with different energies and doses of ion implantation and also with various materials used for the coating layers (aluminum, silicon oxide, and their combinations) is studied. The profiles of the depth distribution of majority charge carriers of the studied structures are obtained experimentally. Also, using the Poisson equation and the Fredholm equation of the first kind, the distributions of the charge-carrier concentration and of the electric field in the structures are calculated. On the basismore » of the analysis and comparison of theoretical and experimental concentration profiles, recommendations concerning optimization of the structures’ parameters in order to increase the value of the pulling field and decrease the effect of the surface potential on the transport of charge carriers are suggested.« less

Tribological properties and surface structures of ion implanted 9Cr18Mo stainless steels

NASA Astrophysics Data System (ADS)

Fengbin, Liu; Guohao, Fu; Yan, Cui; Qiguo, Sun; Min, Qu; Yi, Sun

2013-07-01

The polished quenched-and-tempered 9Cr18Mo steels were implanted with N ions and Ti ions respectively at a fluence of 2 × 1017 ions/cm2. The mechanical properties of the samples were investigated by using nanoindenter and tribometer. The results showed that the ion implantations would improve the nanohardness and tribological property, especially N ion implantation. The surface analysis of the implanted samples was carried out by using XRD, XPS and AES. It indicated that the surface exhibits graded layers after ion implantation. For N ion implantation, the surface about 20 nm thickness is mainly composed of supersaturated interstitial N solid solution, oxynitrides, CrxCy phase and metal nitrides. In the subsurface region, the metal nitrides dominate and the other phases disappear. For Ti ion implantation, the surface of about 20 nm thickness is mainly composed of titanium oxides and carbon amorphous phase, the interstitial solid solution of Ti in Fe is abundant in the subsurface region. The surface components and structures have significant contributions to the improved mechanical properties.

Effects of immediate and delayed loading on peri-implant trabecular structures: a cone beam CT evaluation.

PubMed

Huang, Yan; Van Dessel, Jeroen; Liang, Xin; Depypere, Maarten; Zhong, Weijian; Ma, Guowu; Lambrichts, Ivo; Maes, Frederik; Jacobs, Reinhilde

2014-12-01

To develop a method for characterizing trabecular bone microarchitecture using cone beam computed tomography (CBCT) and to evaluate trabecular bone changes after rehabilitation using immediate versus delayed implant protocols. Six mongrel dogs randomly received 27 titanium implants in the maxillary incisor or mandibular premolar areas, following one of four protocols: (1) normal extraction socket healing; (2) immediate implant placement and immediate loading; (3) delayed implant placement and delayed loading; (4) delayed implant placement and immediate loading. The animals were euthanized at 8 weeks, and block biopsies were scanned using high resolution CBCT. Standard bone structural variables were assessed in coronal, middle, and apical levels. Coronal and middle regions had more compact, more platelike, and thicker trabeculae. Protocols (2), (3), and (4) had significantly higher values (p < 0.001) than protocol (1) for bone surface density, bone surface volume ratio, and connectivity density, while significantly lower values (p < 0.001) were found for trabecular separation and fractal dimension. However, protocols (2), (3), and (4) did not show significantly different bone remodeling. Compared with normal extraction healing, the implant protocols have an improved bone structural integration. Results do not suggest a different bone remodeling pattern when a delayed versus an immediate implant protocol is used. © 2013 Wiley Periodicals, Inc.

The relationship between dental implant stability and trabecular bone structure using cone-beam computed tomography

PubMed Central

2016-01-01

Purpose The objective of this study was to investigate the relationships between primary implant stability as measured by impact response frequency and the structural parameters of trabecular bone using cone-beam computed tomography(CBCT), excluding the effect of cortical bone thickness. Methods We measured the impact response of a dental implant placed into swine bone specimens composed of only trabecular bone without the cortical bone layer using an inductive sensor. The peak frequency of the impact response spectrum was determined as an implant stability criterion (SPF). The 3D microstructural parameters were calculated from CT images of the bone specimens obtained using both micro-CT and CBCT. Results SPF had significant positive correlations with trabecular bone structural parameters (BV/TV, BV, BS, BSD, Tb.Th, Tb.N, FD, and BS/BV) (P<0.01) while SPF demonstrated significant negative correlations with other microstructural parameters (Tb.Sp, Tb.Pf, and SMI) using micro-CT and CBCT (P<0.01). Conclusions There was an increase in implant stability prediction by combining BV/TV and SMI in the stepwise forward regression analysis. Bone with high volume density and low surface density shows high implant stability. Well-connected thick bone with small marrow spaces also shows high implant stability. The combination of bone density and architectural parameters measured using CBCT can predict the implant stability more accurately than the density alone in clinical diagnoses. PMID:27127692

Dual chamber arrhythmia detection in the implantable cardioverter defibrillator.

PubMed

Dijkman, B; Wellens, H J

2000-10-01

Dual chamber implantable cardioverter defibrillator (ICD) technology extended ICD therapy to more than termination of hemodynamically unstable ventricular tachyarrhythmias. It created the basis for dual chamber arrhythmia management in which dependable detection is important for treatment and prevention of both ventricular and atrial arrhythmias. Dual chamber detection algorithms were investigated in two Medtronic dual chamber ICDs: the 7250 Jewel AF (33 patients) and the 7271 Gem DR (31 patients). Both ICDs use the same PR Logic algorithm to interpret tachycardia as ventricular tachycardia (VT), supraventricular tachycardia (SVT), or dual (VT+ SVT). The accuracy of dual chamber detection was studied in 310 of 1,367 spontaneously occurring tachycardias in which rate criterion only was not sufficient for arrhythmia diagnosis. In 78 episodes there was a double tachycardia, in 223 episodes SVT was detected in the VT or ventricular fibrillation zone, and in 9 episodes arrhythmia was detected outside the boundaries of the PR Logic functioning. In 100% of double tachycardias the VT was correctly diagnosed and received priority treatment. SVT was seen in 59 (19%) episodes diagnosed as VT. The causes of inappropriate detection were (1) algorithm failure (inability to fulfill the PRdetection ability in 13 of 59 of inappropriately detected arrhythmias. Dual chamber detection algorithms evaluated in a subset of diagnostically difficult arrhythmias allow safe detection of double tachycardias but require further extension and programmability to

Offline Impedance Measurements for Detection and Mitigation of Dangerous Implant Interactions: An RF Safety Prescreen

PubMed Central

Ellenor, Christopher W; Stang, Pascal P; Etezadi-Amoli, Maryam; Pauly, John M; Scott, Greig C

2015-01-01

Purpose The concept of a “radiofrequency safety prescreen” is investigated, wherein dangerous interactions between radiofrequency fields used in MRI, and conductive implants in patients are detected through impedance changes in the radiofrequency coil. Theory The behavior of coupled oscillators is reviewed, and the resulting, observable impedance changes are discussed. Methods A birdcage coil is loaded with a static head phantom and a wire phantom with a wire close to its resonant length, the shape, position, and orientation of which can be changed. Interactions are probed with a current sensor and network analyzer. Results Impedance spectra show dramatic, unmistakable splitting in cases of strong coupling, and strong correlation is observed between induced current and scattering parameters. Conclusions The feasibility of a new, low-power prescreening technique has been demonstrated in a simple phantom experiment, which can unambiguously detect resonant interactions between an implanted wire and an imaging coil. A new technique has also been presented which can detect parallel transmit null modes for the wire. Magn Reson Med 73:1328–1339, 2015. © 2014 Wiley Periodicals, Inc. PMID:24623586

Short Implants: New Horizon in Implant Dentistry.

PubMed

Jain, Neha; Gulati, Manisha; Garg, Meenu; Pathak, Chetan

2016-09-01

The choice of implant length is an essential factor in deciding the survival rates of these implants and the overall success of the prosthesis. Placing an implant in the posterior part of the maxilla and mandible has always been very critical due to poor bone quality and quantity. Long implants can be placed in association with complex surgical procedures such as sinus lift and bone augmentation. These techniques are associated with higher cost, increased treatment time and greater morbidity. Hence, there is need for a less invasive treatment option in areas of poor bone quantity and quality. Data related to survival rates of short implants, their design and prosthetic considerations has been compiled and structured in this manuscript with emphasis on the indications, advantages of short implants and critical biomechanical factors to be taken into consideration when choosing to place them. Studies have shown that comparable success rates can be achieved with short implants as those with long implants by decreasing the lateral forces to the prosthesis, eliminating cantilevers, increasing implant surface area and improving implant to abutment connection. Short implants can be considered as an effective treatment alternative in resorbed ridges. Short implants can be considered as a viable treatment option in atrophic ridge cases in order to avoid complex surgical procedures required to place long implants. With improvement in the implant surface geometry and surface texture, there is an increase in the bone implant contact area which provides a good primary stability during osseo-integration.

The Relationship Between Spectral Modulation Detection and Speech Recognition: Adult Versus Pediatric Cochlear Implant Recipients

PubMed Central

Noble, Jack H.; Camarata, Stephen M.; Sunderhaus, Linsey W.; Dwyer, Robert T.; Dawant, Benoit M.; Dietrich, Mary S.; Labadie, Robert F.

2018-01-01

Adult cochlear implant (CI) recipients demonstrate a reliable relationship between spectral modulation detection and speech understanding. Prior studies documenting this relationship have focused on postlingually deafened adult CI recipients—leaving an open question regarding the relationship between spectral resolution and speech understanding for adults and children with prelingual onset of deafness. Here, we report CI performance on the measures of speech recognition and spectral modulation detection for 578 CI recipients including 477 postlingual adults, 65 prelingual adults, and 36 prelingual pediatric CI users. The results demonstrated a significant correlation between spectral modulation detection and various measures of speech understanding for 542 adult CI recipients. For 36 pediatric CI recipients, however, there was no significant correlation between spectral modulation detection and speech understanding in quiet or in noise nor was spectral modulation detection significantly correlated with listener age or age at implantation. These findings suggest that pediatric CI recipients might not depend upon spectral resolution for speech understanding in the same manner as adult CI recipients. It is possible that pediatric CI users are making use of different cues, such as those contained within the temporal envelope, to achieve high levels of speech understanding. Further investigation is warranted to investigate the relationship between spectral and temporal resolution and speech recognition to describe the underlying mechanisms driving peripheral auditory processing in pediatric CI users. PMID:29716437

Towards deployable meta-implants.

PubMed

Bobbert, F S L; Janbaz, S; Zadpoor, A A

2018-06-07

Meta-biomaterials exhibit unprecedented or rare combinations of properties not usually found in nature. Such unusual mechanical, mass transport, and biological properties could be used to develop novel categories of orthopedic implants with superior performance, otherwise known as meta-implants. Here, we use bi-stable elements working on the basis of snap-through instability to design deployable meta-implants. Deployable meta-implants are compact in their retracted state, allowing them to be brought to the surgical site with minimum invasiveness. Once in place, they are deployed to take their full-size load-bearing shape. We designed five types of meta-implants by arranging bi-stable elements in such a way to obtain a radially-deployable structure, three types of auxetic structures, and an axially-deployable structure. The intermediate stable conditions ( i.e. multi-stability features), deployment force, and stiffness of the meta-implants were found to be strongly dependent on the geometrical parameters of the bi-stable elements as well as on their arrangement.

Comparisons between detection threshold and loudness perception for individual cochlear implant channels

PubMed Central

Bierer, Julie Arenberg; Nye, Amberly D

2014-01-01

Objective The objective of the present study, performed in cochlear implant listeners, was to examine how the level of current required to detect single-channel electrical pulse trains relates to loudness perception on the same channel. The working hypothesis was that channels with relatively high thresholds, when measured with a focused current pattern, interface poorly to the auditory nerve. For such channels a smaller dynamic range between perceptual threshold and the most comfortable loudness would result, in part, from a greater sensitivity to changes in electrical field spread compared to low-threshold channels. The narrower range of comfortable listening levels may have important implications for speech perception. Design Data were collected from eight, adult cochlear implant listeners implanted with the HiRes90k cochlear implant (Advanced Bionics Corp.). The partial tripolar (pTP) electrode configuration, consisting of one intracochlear active electrode, two flanking electrodes carrying a fraction (σ) of the return current, and an extracochlear ground, was used for stimulation. Single-channel detection thresholds and most comfortable listening levels were acquired using the most focused pTP configuration possible (σ ≥ 0.8) to identify three channels for further testing – those with the highest, median, and lowest thresholds – for each subject. Threshold, equal-loudness contours (at 50% of the monopolar dynamic range), and loudness growth functions were measured for each of these three test channels using various partial tripolar fractions. Results For all test channels, thresholds increased as the electrode configuration became more focused. The rate of increase with the focusing parameter σ was greatest for the high-threshold channel compared to the median- and low-threshold channels. The 50% equal-loudness contours exhibited similar rates of increase in level across test channels and subjects. Additionally, test channels with the highest

Short Implants: New Horizon in Implant Dentistry

PubMed Central

Gulati, Manisha; Garg, Meenu; Pathak, Chetan

2016-01-01

The choice of implant length is an essential factor in deciding the survival rates of these implants and the overall success of the prosthesis. Placing an implant in the posterior part of the maxilla and mandible has always been very critical due to poor bone quality and quantity. Long implants can be placed in association with complex surgical procedures such as sinus lift and bone augmentation. These techniques are associated with higher cost, increased treatment time and greater morbidity. Hence, there is need for a less invasive treatment option in areas of poor bone quantity and quality. Data related to survival rates of short implants, their design and prosthetic considerations has been compiled and structured in this manuscript with emphasis on the indications, advantages of short implants and critical biomechanical factors to be taken into consideration when choosing to place them. Studies have shown that comparable success rates can be achieved with short implants as those with long implants by decreasing the lateral forces to the prosthesis, eliminating cantilevers, increasing implant surface area and improving implant to abutment connection. Short implants can be considered as an effective treatment alternative in resorbed ridges. Short implants can be considered as a viable treatment option in atrophic ridge cases in order to avoid complex surgical procedures required to place long implants. With improvement in the implant surface geometry and surface texture, there is an increase in the bone implant contact area which provides a good primary stability during osseo-integration. PMID:27790598

Structural and electrical properties of Se-hyperdoped Si via ion implantation and flash lamp annealing

NASA Astrophysics Data System (ADS)

Liu, Fang; Prucnal, S.; Yuan, Ye; Heller, R.; Berencén, Y.; Böttger, R.; Rebohle, L.; Skorupa, W.; Helm, M.; Zhou, S.

2018-06-01

We report on the hyperdoping of silicon with selenium obtained by ion implantation followed by flash lamp annealing. It is shown that the degree of crystalline lattice recovery of the implanted layers and the Se substitutional fraction depend on the pulse duration and energy density of the flash. While the annealing at low energy densities leads to an incomplete recrystallization, annealing at high energy densities results in a decrease of the substitutional fraction of impurities. The electrical properties of the implanted layers are well-correlated with the structural properties resulting from different annealing processing.

Perception of Interaural Phase Differences With Envelope and Fine Structure Coding Strategies in Bilateral Cochlear Implant Users

PubMed Central

Arndt, Susan; Aschendorff, Antje; Laszig, Roland; Wesarg, Thomas

2016-01-01

The ability to detect a target signal masked by noise is improved in normal-hearing listeners when interaural phase differences (IPDs) between the ear signals exist either in the masker or in the signal. To improve binaural hearing in bilaterally implanted cochlear implant (BiCI) users, a coding strategy providing the best possible access to IPD is highly desirable. In this study, we compared two coding strategies in BiCI users provided with CI systems from MED-EL (Innsbruck, Austria). The CI systems were bilaterally programmed either with the fine structure processing strategy FS4 or with the constant rate strategy high definition continuous interleaved sampling (HDCIS). Familiarization periods between 6 and 12 weeks were considered. The effect of IPD was measured in two types of experiments: (a) IPD detection thresholds with tonal signals addressing mainly one apical interaural electrode pair and (b) with speech in noise in terms of binaural speech intelligibility level differences (BILD) addressing multiple electrodes bilaterally. The results in (a) showed improved IPD detection thresholds with FS4 compared with HDCIS in four out of the seven BiCI users. In contrast, 12 BiCI users in (b) showed similar BILD with FS4 (0.6 ± 1.9 dB) and HDCIS (0.5 ± 2.0 dB). However, no correlation between results in (a) and (b) both obtained with FS4 was found. In conclusion, the degree of IPD sensitivity determined on an apical interaural electrode pair was not an indicator for BILD based on bilateral multielectrode stimulation. PMID:27659487

Spectrotemporal Modulation Detection and Speech Perception by Cochlear Implant Users

PubMed Central

Won, Jong Ho; Moon, Il Joon; Jin, Sunhwa; Park, Heesung; Woo, Jihwan; Cho, Yang-Sun; Chung, Won-Ho; Hong, Sung Hwa

2015-01-01

Spectrotemporal modulation (STM) detection performance was examined for cochlear implant (CI) users. The test involved discriminating between an unmodulated steady noise and a modulated stimulus. The modulated stimulus presents frequency modulation patterns that change in frequency over time. In order to examine STM detection performance for different modulation conditions, two different temporal modulation rates (5 and 10 Hz) and three different spectral modulation densities (0.5, 1.0, and 2.0 cycles/octave) were employed, producing a total 6 different STM stimulus conditions. In order to explore how electric hearing constrains STM sensitivity for CI users differently from acoustic hearing, normal-hearing (NH) and hearing-impaired (HI) listeners were also tested on the same tasks. STM detection performance was best in NH subjects, followed by HI subjects. On average, CI subjects showed poorest performance, but some CI subjects showed high levels of STM detection performance that was comparable to acoustic hearing. Significant correlations were found between STM detection performance and speech identification performance in quiet and in noise. In order to understand the relative contribution of spectral and temporal modulation cues to speech perception abilities for CI users, spectral and temporal modulation detection was performed separately and related to STM detection and speech perception performance. The results suggest that that slow spectral modulation rather than slow temporal modulation may be important for determining speech perception capabilities for CI users. Lastly, test–retest reliability for STM detection was good with no learning. The present study demonstrates that STM detection may be a useful tool to evaluate the ability of CI sound processing strategies to deliver clinically pertinent acoustic modulation information. PMID:26485715

Optimal wireless receiver structure for omnidirectional inductive power transmission to biomedical implants.

PubMed

Gougheri, Hesam Sadeghi; Kiani, Mehdi

2016-08-01

In order to achieve omnidirectional inductive power transmission to biomedical implants, the use of several orthogonal coils in the receiver side (Rx) has been proposed in the past. In this paper, the optimal Rx structure for connecting three orthogonal Rx coils and the power management is found to achieve the maximum power delivered to the load (PDL) in the presence of any Rx coil tilting. Unlike previous works, in which a separate power management has been used for each coil to deliver power to the load, different resonant Rx structures for connecting three Rx coils to a single power management are studied. In simulations, connecting three Rx coils with the diameters of 3 mm, 3.3 mm, and 3.6 mm in series and resonating them with a single capacitor at the operation frequency of 100 MHz led to the maximum PDL for large loads when the implant was tilted for 45o. This optimal Rx structure achieves higher PDL in worst-case scenarios as well as reduces the number of power managements to only one.

High-dose MeV electron irradiation of Si-SiO2 structures implanted with high doses Si+

NASA Astrophysics Data System (ADS)

Kaschieva, S.; Angelov, Ch; Dmitriev, S. N.

2018-03-01

The influence was studied of 22-MeV electron irradiation on Si-SiO2 structures implanted with high-fluence Si+ ions. Our earlier works demonstrated that Si redistribution is observed in Si+-ion-implanted Si-SiO2 structures (after MeV electron irradiation) only in the case when ion implantation is carried out with a higher fluence (1016 cm-2). We focused our attention on the interaction of high-dose MeV electron irradiation (6.0×1016 cm-2) with n-Si-SiO2 structures implanted with Si+ ions (fluence 5.4×1016 cm-2 of the same order magnitude). The redistribution of both oxygen and silicon atoms in the implanted Si-SiO2 samples after MeV electron irradiation was studied by Rutherford back-scattering (RBS) spectroscopy in combination with a channeling technique (RBS/C). Our results demonstrated that the redistribution of oxygen and silicon atoms in the implanted samples reaches saturation after these high doses of MeV electron irradiation. The transformation of amorphous SiO2 surface into crystalline Si nanostructures (after MeV electron irradiation) was evidenced by atomic force microscopy (AFM). Silicon nanocrystals are formed on the SiO2 surface after MeV electron irradiation. The shape and number of the Si nanocrystals on the SiO2 surface depend on the MeV electron irradiation, while their size increases with the dose. The mean Si nanocrystals height is 16-20 nm after irradiation with MeV electrons at the dose of 6.0×1016 cm-2.

Helium Irradiation and Implantation Effects on the Structure of Amorphous Silicon Oxycarbide

DOE PAGES

Su, Qing; Inoue, Shinsuke; Ishimaru, Manabu; ...

2017-06-20

Despite recent interest in amorphous ceramics for a variety of nuclear applications, many details of their structure before and after irradiation/implantation remain unknown. Here we investigated the short-range order of amorphous silicon oxycarbide (SiOC) alloys by using the atomic pair-distribution function (PDF) obtained from electron diffraction. The PDF results show that the structure of SiOC alloys are nearly unchanged after both irradiation up to 30 dpa and He implantation up to 113 at%. TEM characterization shows no sign of crystallization, He bubble or void formation, or segregation in all irradiated samples. Irradiation results in a decreased number of Si-O bondsmore » and an increased number of Si-C and C-O bonds. This study sheds light on the design of radiation-tolerant materials that do not experience helium swelling for advanced nuclear reactor applications.« less

Helium Irradiation and Implantation Effects on the Structure of Amorphous Silicon Oxycarbide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, Qing; Inoue, Shinsuke; Ishimaru, Manabu

Despite recent interest in amorphous ceramics for a variety of nuclear applications, many details of their structure before and after irradiation/implantation remain unknown. Here we investigated the short-range order of amorphous silicon oxycarbide (SiOC) alloys by using the atomic pair-distribution function (PDF) obtained from electron diffraction. The PDF results show that the structure of SiOC alloys are nearly unchanged after both irradiation up to 30 dpa and He implantation up to 113 at%. TEM characterization shows no sign of crystallization, He bubble or void formation, or segregation in all irradiated samples. Irradiation results in a decreased number of Si-O bondsmore » and an increased number of Si-C and C-O bonds. This study sheds light on the design of radiation-tolerant materials that do not experience helium swelling for advanced nuclear reactor applications.« less

In vivo XCT bone characterization of lattice structured implants fabricated by additive manufacturing.

PubMed

Obaton, A-F; Fain, J; Djemaï, M; Meinel, D; Léonard, F; Mahé, E; Lécuelle, B; Fouchet, J-J; Bruno, G

2017-08-01

Several cylindrical specimens and dental implants, presenting diagonal lattice structures with different cell sizes (600, 900 and 1200 μm) were additively manufactured by selective laser melting process. Then they were implanted for two months in a sheep. After removal, they were studied by Archimedes' method as well as X-ray computed tomography in order to assess the penetration of bone into the lattice. We observed that the additive manufactured parts were geometrically conformed to the theoretical specifications. However, several particles were left adhering to the surface of the lattice, thereby partly or entirely obstructing the cells. Nevertheless, bone penetration was clearly visible. We conclude that the 900 μm lattice cell size is more favourable to bone penetration than the 1200 μm lattice cell size, as the bone penetration is 84% for 900 μm against 54% for 1200 μm cell structures. The lower bone penetration value for the 1200 μm lattice cell could possibly be attributed to the short residence time in the sheep. Our results lead to the conclusion that lattice implants additively manufactured by selective laser melting enable better bone integration.

Interactions between pacing and arrhythmia detection algorithms in the dual chamber implantable cardioverter defibrillator.

PubMed

Dijkman, B; Wellens, H J

2001-09-01

Dual chamber implantable cardioverter defibrillator (ICD) combines the possibility to detect and treat ventricular and atrial arrhythmias with the possibility of modern heart stimulation techniques. Advanced pacing algorithms together with extended arrhythmia detection capabilities can give rise to new types of device-device interactions. Some of the possible interactions are illustrated by four cases documented in four models of dual chamber ICDs. Functioning of new features in dual chamber devices is influenced by the fact that the pacemaker is not a separate device but a part of the ICD system and that both are being used in a patient with arrhythmia. Programming measures are suggested to optimize use of new pacing algorithms while maintaining correct arrhythmia detection.

Au5+ ion implantation induced structural phase transitions probed through structural, microstructural and phonon properties in BiFeO3 ceramics, using synergistic ion beam energy

NASA Astrophysics Data System (ADS)

Dey, Ranajit; Bajpai, P. K.

2018-04-01

Implanted Au5+-ion-induced modification in structural and phonon properties of phase pure BiFeO3 (BFO) ceramics prepared by sol-gel method was investigated. These BFO samples were implanted by 15.8 MeV ions of Au5+ at various ion fluence ranging from 1 × 1014 to 5 × 1015 ions/cm2. Effect of Au5+ ions' implantation is explained in terms of structural phase transition coupled with amorphization/recrystallization due to ion implantation probed through XRD, SEM, EDX and Raman spectroscopy. XRD patterns show broad diffuse contributions due to amorphization in implanted samples. SEM images show grains collapsing and mounds' formation over the surface due to mass transport. The peaks of the Raman spectra were broadened and also the peak intensities were decreased for the samples irradiated with 15.8 MeV Au5+ ions at a fluence of 5 × 1015 ion/cm2. The percentage increase/decrease in amorphization and recrystallization has been estimated from Raman and XRD data, which support the synergistic effects being operative due to comparable nuclear and electronic energy losses at 15.8 MeV Au5+ ion implantation. Effect of thermal treatment on implanted samples is also probed and discussed.

Perception of Interaural Phase Differences With Envelope and Fine Structure Coding Strategies in Bilateral Cochlear Implant Users.

PubMed

Zirn, Stefan; Arndt, Susan; Aschendorff, Antje; Laszig, Roland; Wesarg, Thomas

2016-09-22

The ability to detect a target signal masked by noise is improved in normal-hearing listeners when interaural phase differences (IPDs) between the ear signals exist either in the masker or in the signal. To improve binaural hearing in bilaterally implanted cochlear implant (BiCI) users, a coding strategy providing the best possible access to IPD is highly desirable. In this study, we compared two coding strategies in BiCI users provided with CI systems from MED-EL (Innsbruck, Austria). The CI systems were bilaterally programmed either with the fine structure processing strategy FS4 or with the constant rate strategy high definition continuous interleaved sampling (HDCIS). Familiarization periods between 6 and 12 weeks were considered. The effect of IPD was measured in two types of experiments: (a) IPD detection thresholds with tonal signals addressing mainly one apical interaural electrode pair and (b) with speech in noise in terms of binaural speech intelligibility level differences (BILD) addressing multiple electrodes bilaterally. The results in (a) showed improved IPD detection thresholds with FS4 compared with HDCIS in four out of the seven BiCI users. In contrast, 12 BiCI users in (b) showed similar BILD with FS4 (0.6 ± 1.9 dB) and HDCIS (0.5 ± 2.0 dB). However, no correlation between results in (a) and (b) both obtained with FS4 was found. In conclusion, the degree of IPD sensitivity determined on an apical interaural electrode pair was not an indicator for BILD based on bilateral multielectrode stimulation. © The Author(s) 2016.

Airport and superficial femoral artery obstruction due to a wandering coronary stent: the possibility of airport detection of modern implant metals.

PubMed

Teijink, J A W; van Herwaarden, J A; van den Berg, J C; Overtoom, T C; Moll, F L

2004-06-01

In the treatment of coronary artery disease, peripheral loss of a coronary stent is an unusual complication. We present the case of a patient who suggested that his right leg claudication was caused by a slipped coronary stent 2 years previously. The patient was convinced about this unusual finding based on an airport security check. Examination proved him to be right. However, the ability to detect an object using eddy currents is dependent on the object's permeability and its conductivity. Ferrous (iron) content is not the critical factor. Modern implant materials and processing techniques result in implants that are difficult to magnetize i.e. their permeability is very low. In addition their conductivity is very low. This enables modern implants to escape detection at airports. For this reason the event at the airport, as described by our patient, is considered coincidental.

Tailoring the structural and magnetic properties of masked CoPt thin films using ion implantation

NASA Astrophysics Data System (ADS)

Kumar, Durgesh; Gupta, Surbhi; Jin, Tianli; Nongjai, R.; Asokan, K.; Piramanayagam, S. N.

2018-05-01

The effects of ion implantations through a mask on the structural and magnetic properties of Co80Pt20 films were investigated. The mask was patterned using the self-assembly of diblock copolymers. For implantation, high (40 keV for 14N+ and 100 keV for 40Ar+) and low (7.5 keV for 14N+ and 4.5 keV for 40Ar+) energy 14N+ and 40Ar+ ions were used to modify the structural and magnetic properties of these films. X-ray diffraction and TRIM simulations were performed for understanding the structural changes due to ion implantations. These results revealed the intermixing of Co atoms in lower layers and lattice expansion in Co80Pt20 magnetic and Ru layers. A lateral straggling of Co caused an increase in the exchange coupling in the masked region. Depletion of Co atoms in Co80Pt20 layer caused a decrease in the anisotropy constant, which were further confirmed by the alternating gradient force magnetometer and magnetic force microscopy results. The magnetic force microscopy images showed an increase in domain width and domain wall width confirming the above-mentioned effects.

[Principles of bone tissue structures interaction with full removable dentures fixed on intraosseous implantates modelling].

PubMed

Shashmurina, V R; Chumachenko, E N; Olesova, V N; Volozhin, A I

2008-01-01

Math modelling "removable dentures-implantate-bone" with size and density of bone tissue as variables was created. It allowed to study biomechanical bases of mandibular bone tissue structures interaction with full removable dentures of different constructions and fixed on intraosseous implantates. Analysis of the received data showed that in the majority of cases it was expedient to recommend 3 bearing (abutments) system of denture making. Rest on 4 and more implantates was appropriate for patients with reduced density of spongy bone and significant mandibular bone atrophy. 2 abutment system can be used in patients with high density of spongy bone and absence of mandibular bone atrophy.

Autonomous assembly of epithelial structures by subrenal implantation of dissociated embryonic inner-ear cells.

PubMed

Wang, Li; Zhang, Kaiqing; Zhu, Helen He; Gao, Wei-Qiang

2015-05-27

Microenvironment and cell-cell interactions play an important role during embryogenesis and are required for the stemness and differentiation of stem cells. The inner-ear sensory epithelium, containing hair cells and supporting cells, is derived from the stem cells within the otic vesicle at early embryonic stages. However, whether or not such microenvironment or cell-cell interactions within the embryonic otic tissue have the capacity to regulate the proliferation and differentiation of stem cells and to autonomously reassemble the cells into epithelial structures is unknown. Here, we report that on enzymatic digestion and dissociation to harvest all the single cells from 13.5-day-old rat embryonic (E13.5) inner-ear tissue as well as on implantation of these cells under renal capsules; the dissociated cells are able to reassemble themselves to form epithelial structures as early as 7 days after implantation. By 25 days after implantation, more mature epithelial structures are formed. Immunostaining with cell-type-specific markers reveals that hair cells and supporting cells are not only formed, but are also well aligned with the hair cells located in the apical layer surrounded by the supporting cells. These findings suggest that microenvironment and cell-cell interactions within the embryonic inner-ear tissue have the autonomous signals to induce the formation of sensory epithelial structures. This method may also provide a useful system to study the potential of stem cells to differentiate into hair cells in vivo.

Bio-mimicking nano and micro-structured surface fabrication for antibacterial properties in medical implants.

PubMed

Jaggessar, Alka; Shahali, Hesam; Mathew, Asha; Yarlagadda, Prasad K D V

2017-10-02

Orthopaedic and dental implants have become a staple of the medical industry and with an ageing population and growing culture for active lifestyles, this trend is forecast to continue. In accordance with the increased demand for implants, failure rates, particularly those caused by bacterial infection, need to be reduced. The past two decades have led to developments in antibiotics and antibacterial coatings to reduce revision surgery and death rates caused by infection. The limited effectiveness of these approaches has spurred research into nano-textured surfaces, designed to mimic the bactericidal properties of some animal, plant and insect species, and their topographical features. This review discusses the surface structures of cicada, dragonfly and butterfly wings, shark skin, gecko feet, taro and lotus leaves, emphasising the relationship between nano-structures and high surface contact angles on self-cleaning and bactericidal properties. Comparison of these surfaces shows large variations in structure dimension and configuration, indicating that there is no one particular surface structure that exhibits bactericidal behaviour against all types of microorganisms. Recent bio-mimicking fabrication methods are explored, finding hydrothermal synthesis to be the most commonly used technique, due to its environmentally friendly nature and relative simplicity compared to other methods. In addition, current proposed bactericidal mechanisms between bacteria cells and nano-textured surfaces are presented and discussed. These models could be improved by including additional parameters such as biological cell membrane properties, adhesion forces, bacteria dynamics and nano-structure mechanical properties. This paper lastly reviews the mechanical stability and cytotoxicity of micro and nano-structures and materials. While the future of nano-biomaterials is promising, long-term effects of micro and nano-structures in the body must be established before nano-textures can

Detection of five potentially periodontal pathogenic bacteria in peri-implant disease: A comparison of PCR and real-time PCR.

PubMed

Schmalz, Gerhard; Tsigaras, Sandra; Rinke, Sven; Kottmann, Tanja; Haak, Rainer; Ziebolz, Dirk

2016-07-01

The aim of this study was to compare the microbial analysis methods of polymerase chain reaction (PCR) and real-time PCR (RT-PCR) in terms of detection of five selected potentially periodontal pathogenic bacteria in peri-implant disease. Therefore 45 samples of healthy, mucositis and peri-implantitis (n = 15 each) were assessed according to presence of the following bacteria using PCR (DNA-strip technology) and RT-PCR (fluorescent dye SYBR green-system): Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Treponema denticola (Td), Tanerella forsythia (Tf), and Fusobacterium nucleatum (Fn). There were no significant correlations between the bacterial and disease patterns, so the benefit of using microbiological tests for the diagnosis of peri-implant diseases is questionable. Correlations between the methods were highest for Tf (Kendall's Tau: 0.65, Spearman: 0.78), Fn (0.49, 0.61) and Td (0.49, 0.59). For Aa (0.38, 0.42) and Pg (0.04, 0.04), lower correlation values were detected. Accordingly, conventional semi-quantitative PCR seems to be sufficient for analyzing potentially periodontal pathogenic bacterial species. Copyright © 2016 Elsevier Inc. All rights reserved.

A novel self-aligned oxygen (SALOX) implanted SOI MOSFET device structure

NASA Astrophysics Data System (ADS)

Tzeng, J. C.; Baerg, W.; Ting, C.; Siu, B.

The morphology of the novel self-aligned oxygen implanted SOI (SALOX SOI) [1] MOSFET was studied. The channel silicon of SALOX SOI was confirmed to be undamaged single crystal silicon and was connected with the substrate. Buried oxide formed by oxygen implantation in this SALOX SOI structure was shown by a cross section transmission electron micrograph (X-TEM) to be amorphous. The source/drain silicon on top of the buried oxide was single crystal, as shown by the transmission electron diffraction (TED) pattern. The source/drain regions were elevated due to the buried oxide volume expansion. A sharp silicon—silicon dioxide interface between the source/drain silicon and buried oxide was observed by Auger electron spectroscopy (AES). Well behaved n-MOS transistor current voltage characteristics were obtained and showed no I-V kink.

Growth of surface structures correlated with structural and mechanical modifications of brass by laser-induced Si plasma ions implantation

NASA Astrophysics Data System (ADS)

Ahmad, Shahbaz; Bashir, Shazia; Rafique, M. Shahid; Yousaf, Daniel

2017-04-01

Laser-produced Si plasma is employed as an ion source for implantation on the brass substrate for its surface, structural, and mechanical modifications. Thomson parabola technique is employed for the measurement of energy and flux of Si ions using CR-39. In response to stepwise increase in number of laser pulses from 3000 to 12000, four brass substrates were implanted by laser-induced Si plasma ions of energy 290 keV at different fluxes ranging from 45 × 1012 to 75 × 1015 ions/cm2. SEM analysis reveals the formation of nano/micro-sized irregular shaped cavities and pores for the various ion fluxes for varying numbers of laser pulses from 3000 to 9000. At the maximum ion flux for 12,000 pulses, distinct and organized grains with hexagonal and irregular shaped morphology are revealed. X-ray diffractometer (XRD) analysis exhibits that a new phase of CuSi (311) is identified which confirms the implantation of Si ions in brass substrate. A significant decrease in mechanical properties of implanted brass, such as Yield Stress (YS), Ultimate Tensile Strength (UTS), and hardness, with increasing laser pulses from 3000 to 6000 is observed. However, with increasing laser pulses from 9000 to a maximum value of 12,000, an increase in mechanical properties like hardness, YS, and UTS is observed. The generation as well as annihilation of defects, recrystallization, and intermixing of Si precipitates with brass matrix is considered to be responsible for variations in surface, structural, and mechanical modifications of brass.

A Structural Equation Modeling Approach to Examining Factors Influencing Outcomes with Cochlear Implant in Mandarin-Speaking Children

PubMed Central

Chen, Yuan; Wong, Lena L. N.; Zhu, Shufeng; Xi, Xin

2015-01-01

Objective To examine the direct and indirect effects of demographical factors on speech perception and vocabulary outcomes of Mandarin-speaking children with cochlear implants (CIs). Methods 115 participants implanted before the age of 5 and who had used CI before 1 to 3 years were evaluated using a battery of speech perception and vocabulary tests. Structural equation modeling was used to test the hypotheses proposed. Results Early implantation significantly contributed to speech perception outcomes while having undergone a hearing aid trial (HAT) before implantation, maternal educational level (MEL), and having undergone universal newborn hearing screening (UNHS) before implantation had indirect effects on speech perception outcomes via their effects on age at implantation. In addition, both age at implantation and MEL had direct and indirect effects on vocabulary skills, while UNHS and HAT had indirect effects on vocabulary outcomes via their effects on age at implantation. Conclusion A number of factors had indirect and direct effects on speech perception and vocabulary outcomes in Mandarin-speaking children with CIs and these factors were not necessarily identical to those reported among their English-speaking counterparts. PMID:26348360

Early diagnosis of orthopedic implant failure using macromolecular imaging agents.

PubMed

Ren, Ke; Dusad, Anand; Zhang, Yijia; Purdue, P Edward; Fehringer, Edward V; Garvin, Kevin L; Goldring, Steven R; Wang, Dong

2014-08-01

To develop and evaluate diagnostic tools for early detection of wear particle-induced orthopaedic implant loosening. N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymer was tagged with a near infrared dye and used to detect the inflammation induced by polymethylmethacrylate (PMMA) particles in a murine peri-implant osteolysis model. It was established by inserting an implant into the distal femur and challenging with routine PMMA particles infusion. The osteolysis was evaluated by micro-CT and histological analysis at different time points. Significant peri-implant osteolysis was found 3-month post PMMA particle challenge by micro-CT and histological analysis. At 1-month post challenge, when there was no significant peri-implant bone loss, the HPMA copolymer-near infrared dye conjugate was found to specifically target the femur with PMMA particles deposition, but not the contralateral control femur with phosphate buffered saline (PBS) infusion. The results from this study demonstrate the feasibility of utilizing the macromolecular diagnostic agent to detect particle-induced peri-implant inflammation prior to the development of detectable osteolysis. Recognition of this early pathological event would provide the window of opportunity for prevention of peri-implant osteolysis and subsequent orthopaedic implant failure.

Alloplastic implants for orbital wall reconstruction.

PubMed

Jacono, A A; Moskowitz, B

2000-01-01

Nonabsorbable alloplastic implants for orbital wall reconstruction have been widely accepted by surgeons because of their ready availability, stability, and biocompatability. Many complications have arisen with this class of implants because the lack of host tissue integration allows for implant migration, implant extrusion, recurrent hemorrhage, and infection. Porous polyethylene implants provide a welcome alternative as they have the unique properly of supporting tissue ingrowth in vivo. Their semirigid structure provides structural stability when used around the orbit, and their malleability allows for easy contouring. This paper presents our surgical approach to reconstructing orbital defects with porous polyethylene implants, including orbital floor, and superior, medial, and lateral wall defects, and discusses the advantages/disadvantages of other nonabsorbable alloplasts.

The Effect of Breast Implants on Mammogram Outcomes.

PubMed

Kam, Kelli; Lee, Esther; Pairawan, Seyed; Anderson, Kendra; Cora, Cherie; Bae, Won; Senthil, Maheswari; Solomon, Naveenraj; Lum, Sharon

2015-10-01

Breast cancer detection in women with implants has been questioned. We sought to evaluate the impact of breast implants on mammographic outcomes. A retrospective review of women undergoing mammography between March 1 and October 30, 2013 was performed. Demographic characteristics and mammogram results were compared between women with and without breast implants. Overall, 4.8 per cent of 1863 women identified during the study period had breast implants. Median age was 59 years (26-93). Women with implants were younger (53.9 vs 59.2 years, P < 0.0001), had lower body mass index (25.4 vs 28.9, P < 0.0001), and were more likely to have dense breast tissue (72.1% vs 56.4%, P = 0.004) than those without. There were no statistically significant differences with regards to Breast Imaging Recording and Data System 0 score (13.3% with implants vs 21.4% without), call back exam (18.9% with vs 24.1% without), time to resolution of abnormal imaging (58.6 days with vs 43.3 without), or cancer detection rate (0% with implants vs 1.0% without). Because implants did not significantly affect mammogram results, women with implants should be reassured that mammography remains useful in detecting cancer. However, future research is required to determine whether lower call back rates and longer time to resolution of imaging findings contribute to delays in diagnosis in patients with implants.

Laser beam melting 3D printing of Ti6Al4V based porous structured dental implants: fabrication, biocompatibility analysis and photoelastic study

NASA Astrophysics Data System (ADS)

Yang, Fei; Chen, Chen; Zhou, Qianrong; Gong, Yiming; Li, Ruixue; Li, Chichi; Klämpfl, Florian; Freund, Sebastian; Wu, Xingwen; Sun, Yang; Li, Xiang; Schmidt, Michael; Ma, Duan; Yu, Youcheng

2017-03-01

Fabricating Ti alloy based dental implants with defined porous scaffold structure is a promising strategy for improving the osteoinduction of implants. In this study, we use Laser Beam Melting (LBM) 3D printing technique to fabricate porous Ti6Al4V dental implant prototypes with three controlled pore sizes (200, 350 and 500 μm). The mechanical stress distribution in the surrounding bone tissue is characterized by photoelastography and associated finite element simulation. For in-vitro studies, experiments on implants’ biocompatibility and osteogenic capability are conducted to evaluate the cellular response correlated to the porous structure. As the preliminary results, porous structured implants show a lower stress-shielding to the surrounding bone at the implant neck and a more densed distribution at the bottom site compared to the reference implant. From the cell proliferation tests and the immunofluorescence images, 350 and 500 μm pore sized implants demonstrate a better biocompatibility in terms of cell growth, migration and adhesion. Osteogenic genes expression of the 350 μm group is significantly increased alone with the ALP activity test. All these suggest that a pore size of 350 μm provides an optimal provides an optimal potential for improving the mechanical shielding to the surrounding bones and osteoinduction of the implant itself.

Continuous detection and decoding of dexterous finger flexions with implantable myoelectric sensors.

PubMed

Baker, Justin J; Scheme, Erik; Englehart, Kevin; Hutchinson, Douglas T; Greger, Bradley

2010-08-01

A rhesus monkey was trained to perform individuated and combined finger flexions of the thumb, index, and middle finger. Nine implantable myoelectric sensors (IMES) were then surgically implanted into the finger muscles of the monkey's forearm, without any adverse effects over two years postimplantation. Using an inductive link, EMG was wirelessly recorded from the IMES as the monkey performed a finger flexion task. The EMG from the different IMES implants showed very little cross correlation. An offline parallel linear discriminant analysis (LDA) based algorithm was used to decode finger activity based on features extracted from continuously presented frames of recorded EMG. The offline parallel LDA was run on intraday sessions as well as on sessions where the algorithm was trained on one day and tested on following days. The performance of the algorithm was evaluated continuously by comparing classification output by the algorithm to the current state of the finger switches. The algorithm detected and classified seven different finger movements, including individual and combined finger flexions, and a no-movement state (chance performance = 12.5%) . When the algorithm was trained and tested on data collected the same day, the average performance was 43.8+/-3.6% n=10. When the training-testing separation period was five months, the average performance of the algorithm was 46.5+/-3.4% n=8. These results demonstrated that using EMG recorded and wirelessly transmitted by IMES offers a promising approach for providing intuitive, dexterous control of artificial limbs where human patients have sufficient, functional residual muscle following amputation.

An ontology-based annotation of cardiac implantable electronic devices to detect therapy changes in a national registry.

PubMed

Rosier, Arnaud; Mabo, Philippe; Chauvin, Michel; Burgun, Anita

2015-05-01

The patient population benefitting from cardiac implantable electronic devices (CIEDs) is increasing. This study introduces a device annotation method that supports the consistent description of the functional attributes of cardiac devices and evaluates how this method can detect device changes from a CIED registry. We designed the Cardiac Device Ontology, an ontology of CIEDs and device functions. We annotated 146 cardiac devices with this ontology and used it to detect therapy changes with respect to atrioventricular pacing, cardiac resynchronization therapy, and defibrillation capability in a French national registry of patients with implants (STIDEFIX). We then analyzed a set of 6905 device replacements from the STIDEFIX registry. Ontology-based identification of therapy changes (upgraded, downgraded, or similar) was accurate (6905 cases) and performed better than straightforward analysis of the registry codes (F-measure 1.00 versus 0.75 to 0.97). This study demonstrates the feasibility and effectiveness of ontology-based functional annotation of devices in the cardiac domain. Such annotation allowed a better description and in-depth analysis of STIDEFIX. This method was useful for the automatic detection of therapy changes and may be reused for analyzing data from other device registries.

A new system of implant abutment connection: how to improve a two piece implant system sealing.

PubMed

Grecchi, F; DI Girolamo, M; Cura, F; Candotto, V; Carinci, F

2017-01-01

Implant dentistry has become one of the most successful dentistry techniques for replacing missing teeth. The success rate of implant dentistry is above 80%. However, peri-implantitis is a later complication of implant dentistry that if untreated, can lead to implant loss. One of the hypotized causes of peri-implantis is the bacterial leakage at the level of implant-abutment connection. Bacterial leakage is favored to the presence of a micro gap at the implant-abutment interface, allowing microorganisms to penetrate and colonize the inner part of the implant leading to biofilm accumulation and consequently to peri-implantitis development. To identify the capability of the implant to protect the internal space from the external environment, the passage of genetically modified Escherichia coli across implant-abutment interface was evaluated. Implants were immerged in a bacterial culture for twenty-four hours and then bacteria amount was measured inside implant-abutment interface with Real-time PCR. Bacteria were detected inside all studied implants, with a median percentage of 9%. The reported results are better to those of previous studies carried out on different implant systems. Until now, none implant-abutment system has been proven to seal the gap between implant and abutment.

Effect of Fe-ion implantation doping on structural and optical properties of CdS thin films

NASA Astrophysics Data System (ADS)

Chandramohan, S.; Kanjilal, A.; Sarangi, S. N.; Majumder, S.; Sathyamoorthy, R.; Som, T.

2010-06-01

We report on effects of Fe implantation doping-induced changes in structural, optical, morphological, and vibrational properties of cadmium sulfide thin films. Films were implanted with 90 keV Fe+ ions at room temperature for a wide range of fluences from 0.1×1016 to 3.6×1016 ions cm-2 (corresponding to 0.38-12.03 at.% of Fe). Glancing angle X-ray diffraction analysis revealed that the implanted Fe atoms tend to supersaturate by occupying the substitutional cationic sites rather than forming metallic clusters or secondary phase precipitates. In addition, Fe doping does not lead to any structural phase transformation although it induces structural disorder and lattice contraction. Optical absorption studies show a reduction in the optical band gap from 2.39 to 2.17 eV with increasing Fe concentration. This is attributed to disorder-induced band tailing in semiconductors and ion-beam-induced grain growth. The strain associated with a lattice contraction is deduced from micro-Raman scattering measurements and is found that size and shape fluctuations of grains, at higher fluences, give rise to inhomogeneity in strain.

[Role of different scale structures of titanium implant in the biological behaviors of human umbilical vein endothelial cells].

PubMed

Liang, N W; Shi, L; Huang, Y; Deng, X L

2017-02-18

To study the role of different scale structure of Ti implants on the biological behaviors of human umbilical vein endothelial cell (HUVECs) and to reveal the role of material surface topographical features on peri-implant angiogenesis. Titanium (Ti) discs with different surface structures (Ti discs with smooth surface, Ti discs with nano scale structure, Ti discs with micro scale structure and Ti discs with micro/nano scale structure, named as SM-Ti, Nano-Ti, Micro-Ti and Micro/Nano-Ti, respectively) were prepared and their surface topographical features were confirmed via scanning electron microscopy (SEM) observation. HUVECs were cultured on these Ti discs. Biological outcomes of HUVECs on different surfaces were carried out, including cell adhesive capacity, proliferation, vascular endothelial growth factor (VEGF) production and intracellular expression of Ca(2+). The results of SEM images and immunofluorescence double staining of rhodamine-phalloidin and DAPI showed that compared with the SM-Ti and Nano-Ti group, the adhesive capacity and proliferation behavior of HUVECs on the surfaces of Micro-Ti and Micro/Nano-Ti was decreased. The results of culturing HUVECs on different groups of Ti discs after 24 hours showed that the cells number grew from (18±4) to (42±6)/ vision on SM-Ti, (28±6) to (52±10)/vision on Nano-Ti, (20±4) to (21±6)/vision on Micro-Ti and (16±4) to (18±6)/vision on Micro/Nano-Ti. Moreover, compared with the adhesion and proliferation of HUVECs on SM-Ti group and Nano-Ti, the adhesion and proliferation of HUVECs on Micro-Ti group and Micro/Nano-Ti group was significantly reduced (P<0.05).The results of enzyme-linked immunosorbent assay (ELISA) showed that the VEGF productions of SM-Ti, Nano-Ti, Micro-Ti and Micro/Nano-Ti were (690±35) ng/L, (560±20) ng/L, (474±43) ng/L and (517±29) ng/L, respectively. Moreover, compared with the VEGF production of HUVECs on SM-Ti group, the VEGF production of HUVECs on Micro-Ti group and Micro

Compositional and structural analysis of nitrogen incorporated and ion implanted diamond thin films

NASA Astrophysics Data System (ADS)

Garratt, Elias James

Significant progress in area of nano-structured thin film systems has taken place in recent decades. In particular, diamond thin film systems are being widely studied for their wear resistant, optical and electronic properties. Of the various methods researchers use to modify the structure of such films, three techniques in particular are of interest due to their versatility: modification of the growth atmosphere, growth on metalized substrates, providing an interfacial layer, and modification through post-growth ion implantation. The aim of this study is to investigate the effects each has to the structure and composition of elements. Different techniques are applied in each section; nitrogen gas dilution in a microwave plasma CVD system, diamond deposition on a metal interfacial layer and ion implantation in thin nanocrystalline diamond film. The forms of nanocrystalline diamond film resulting from such modifications are investigated using advanced spectroscopic and spectrometric techniques, as well as mechanical testing and surface mapping. The impact of these characterizations will provide valuable perspective to researchers in materials science. Understanding the changes to the structure and properties of this class of thin films, which can be induced through various mechanisms, will allow future researchers to refine these films towards technological applications in areas of hard coatings, electronics and photonics.

Superelastic Orthopedic Implant Coatings

NASA Astrophysics Data System (ADS)

Fournier, Eric; Devaney, Robert; Palmer, Matthew; Kramer, Joshua; El Khaja, Ragheb; Fonte, Matthew

2014-07-01

The demand for hip and knee replacement surgery is substantial and growing. Unfortunately, most joint replacement surgeries will fail within 10-25 years, thereby requiring an arduous, painful, and expensive revision surgery. To address this issue, a novel orthopedic implant coating material ("eXalt") has been developed. eXalt is comprised of super elastic nitinol wire that is knit into a three-dimensional spacer fabric structure. eXalt expands in vivo to conform to the implantation site and is porous to allow for bone ingrowth. The safety and efficacy of eXalt were evaluated through structural analysis, mechanical testing, and a rabbit implantation model. The results demonstrate that eXalt meets or exceeds the performance of current coating technologies with reduced micromotion, improved osseointegration, and stronger implant fixation in vivo.

Persistent photoconductivity in oxygen-ion implanted KNbO3 bulk single crystal

NASA Astrophysics Data System (ADS)

Tsuruoka, R.; Shinkawa, A.; Nishimura, T.; Tanuma, C.; Kuriyama, K.; Kushida, K.

2016-12-01

Persistent Photoconductivity (PPC) in oxygen-ion implanted KNbO3 ([001] oriented bulk single crystals; perovskite structure; ferroelectric with a band gap of 3.16 eV)　is studied in air at room temperature to prevent the degradation of its crystallinity caused by the phase transition. The residual hydrogens in un-implanted samples are estimated to be 5×1014 cm-2 from elastic recoil detection analysis (ERDA). A multiple-energy implantation of oxygen ions into KNbO3 is performed using energies of 200, 400, and 600 keV (each ion fluence:1.0×1014 cm-2). The sheet resistance varies from >108 Ω/□ for an un-implanted sample to 1.9×107 Ω/□ for as-implanted one, suggesting the formation of donors due to hydrogen interstitials and oxygen vacancies introduced by the ion implantation. The PPC is clearly observed with ultraviolet and blue LEDs illumination rather than green, red, and infrared, suggesting the release of electrons from the metastable conductive state below the conduction band relating to the charge states of the oxygen vacancy.

Structural properties of buried conducting layers formed by very low energy ion implantation of gold into polymer

NASA Astrophysics Data System (ADS)

Teixeira, F. S.; Salvadori, M. C.; Cattani, M.; Brown, I. G.

2009-09-01

We have investigated the fundamental structural properties of conducting thin films formed by implanting gold ions into polymethylmethacrylate (PMMA) polymer at 49 eV using a repetitively pulsed cathodic arc plasma gun. Transmission electron microscopy images of these composites show that the implanted ions form gold clusters of diameter ˜2-12 nm distributed throughout a shallow, buried layer of average thickness 7 nm, and small angle x-ray scattering (SAXS) reveals the structural properties of the PMMA-gold buried layer. The SAXS data have been interpreted using a theoretical model that accounts for peculiarities of disordered systems.

Laser beam melting 3D printing of Ti6Al4V based porous structured dental implants: fabrication, biocompatibility analysis and photoelastic study

PubMed Central

Yang, Fei; Chen, Chen; Zhou, QianRong; Gong, YiMing; Li, RuiXue; Li, ChiChi; Klämpfl, Florian; Freund, Sebastian; Wu, XingWen; Sun, Yang; Li, Xiang; Schmidt, Michael; Ma, Duan; Yu, YouCheng

2017-01-01

Fabricating Ti alloy based dental implants with defined porous scaffold structure is a promising strategy for improving the osteoinduction of implants. In this study, we use Laser Beam Melting (LBM) 3D printing technique to fabricate porous Ti6Al4V dental implant prototypes with three controlled pore sizes (200, 350 and 500 μm). The mechanical stress distribution in the surrounding bone tissue is characterized by photoelastography and associated finite element simulation. For in-vitro studies, experiments on implants’ biocompatibility and osteogenic capability are conducted to evaluate the cellular response correlated to the porous structure. As the preliminary results, porous structured implants show a lower stress-shielding to the surrounding bone at the implant neck and a more densed distribution at the bottom site compared to the reference implant. From the cell proliferation tests and the immunofluorescence images, 350 and 500 μm pore sized implants demonstrate a better biocompatibility in terms of cell growth, migration and adhesion. Osteogenic genes expression of the 350 μm group is significantly increased alone with the ALP activity test. All these suggest that a pore size of 350 μm provides an optimal provides an optimal potential for improving the mechanical shielding to the surrounding bones and osteoinduction of the implant itself. PMID:28350007

Time Course of Peri-Implant Bone Regeneration around Loaded and Unloaded Implants in a Rat Model

PubMed Central

Jariwala, Shailly H.; Wee, Hwabok; Roush, Evan P.; Whitcomb, Tiffany L.; Murter, Christopher; Kozlansky, Gery; Lakhtakia, Akhlesh; Kunselman, Allen R.; Donahue, Henry J.; Armstrong, April D.; Lewis, Gregory S.

2018-01-01

The time-course of cancellous bone regeneration surrounding mechanically loaded implants affects implant fixation, and is relevant to determining optimal rehabilitation protocols following orthopaedic surgeries. We investigated the influence of controlled mechanical loading of titanium-coated polyether-ether ketone (PEEK) implants on osseointegration using time-lapsed, non-invasive, in vivo micro-computed tomography (micro-CT) scans. Implants were inserted into proximal tibial metaphyses of both limbs of eight female Sprague-Dawley rats. External cyclic loading (60 μm or 100 μm displacement, 1 Hz, 60 seconds) was applied every other day for 14 days to one implant in each rat, while implants in contralateral limbs served as the unloaded controls. Hind limbs were imaged with high-resolution micro-CT (12.5 μm voxel size) at 2, 5, 9, and 12 days post-surgery. Trabecular changes over time were detected by 3D image registration allowing for measurements of bone-formation rate (BFR) and bone-resorption rate (BRR). At day 9, mean %BV/TV for loaded and unloaded limbs were 35.5 ± 10.0 % and 37.2 ± 10.0 %, respectively, and demonstrated significant increases in bone volume compared to day 2. BRR increased significantly after day 9. No significant differences between bone volumes, BFR, and BRR were detected due to implant loading. Although not reaching significance (p = 0.16), an average 119 % increase in pull-out strength was measured in the loaded implants. PMID:27381807

[Osseontegration of trial implants of carbon fiber reinforced plastics].

PubMed

Schreiner, U; Schwarz, M; Scheller, G; Schroeder-Boersch, H; Jani, L

2000-01-01

To what extent are carbon fibre-reinforced plastics (CFRP) suitable as an osseous integration surface for implants? CFRP test implants having a plexus-structured, rhombus-structured, and plexus-structured, hydroxyapatite surface were implanted in the femura of mini-plgs. Exposure time lasted 12 weeks. The implants were subjected to a macroradiological, a histological-histomorphometrical, and a fluorescence-microscopical evaluation. One half of the uncoated, plexus-structured implants were not osteointegrated, the other half displayed an osteointegration rate of 11.8% in the spongy area and 29.8% in the cortex layer. The HA-coated test implants showed an osteointegration of 29.5% in the spongiosa and 56.8% in the cortex layer. The rhombus-structured test implants had an osteointegration of 29.2% (spongiosa) and 46.2% (cortex layer). Compared to the osteointegration of metallic, especially titanium surfaces the CFRP surfaces tested by us fared worse, especially the uncoated, plexus-structured surfaces. For this reason we view very critically the use of carbon-fibre reinforced plastics together with the surfaces tested by us as osteointegrating surfaces.

Hybrid Titanium/Biodegradable Polymer Implants with an Hierarchical Pore Structure as a Means to Control Selective Cell Movement

PubMed Central

Vrana, Nihal Engin; Dupret, Agnès; Coraux, Christelle; Vautier, Dominique; Debry, Christian; Lavalle, Philippe

2011-01-01

In order to improve implant success rate, it is important to enhance their responsiveness to the prevailing conditions following implantation. Uncontrolled movement of inflammatory cells and fibroblasts is one of these in vivo problems and the porosity properties of the implant have a strong effect on these. Here, we describe a hybrid system composed of a macroporous titanium structure filled with a microporous biodegradable polymer. This polymer matrix has a distinct porosity gradient to accommodate different cell types (fibroblasts and epithelial cells). The main clinical application of this system will be the prevention of restenosis due to excessive fibroblast migration and proliferation in the case of tracheal implants. Methodology/Principal Findings A microbead-based titanium template was filled with a porous Poly (L-lactic acid) (PLLA) body by freeze-extraction method. A distinct porosity difference was obtained between the inner and outer surfaces of the implant as characterized by image analysis and Mercury porosimetry (9.8±2.2 µm vs. 36.7±11.4 µm, p≤0.05). On top, a thin PLLA film was added to optimize the growth of epithelial cells, which was confirmed by using human respiratory epithelial cells. To check the control of fibroblast movement, PKH26 labeled fibroblasts were seeded onto Titanium and Titanium/PLLA implants. The cell movement was quantified by confocal microscopy: in one week cells moved deeper in Ti samples compared to Ti/PLLA. Conclusions In vitro experiments showed that this new implant is effective for guiding different kind of cells it will contact upon implantation. Overall, this system would enable spatial and temporal control over cell migration by a gradient ranging from macroporosity to nanoporosity within a tracheal implant. Moreover, mechanical properties will be dependent mainly on the titanium frame. This will make it possible to create a polymeric environment which is suitable for cells without the need to meet mechanical

Hybrid titanium/biodegradable polymer implants with an hierarchical pore structure as a means to control selective cell movement.

PubMed

Vrana, Nihal Engin; Dupret, Agnès; Coraux, Christelle; Vautier, Dominique; Debry, Christian; Lavalle, Philippe

2011-01-01

In order to improve implant success rate, it is important to enhance their responsiveness to the prevailing conditions following implantation. Uncontrolled movement of inflammatory cells and fibroblasts is one of these in vivo problems and the porosity properties of the implant have a strong effect on these. Here, we describe a hybrid system composed of a macroporous titanium structure filled with a microporous biodegradable polymer. This polymer matrix has a distinct porosity gradient to accommodate different cell types (fibroblasts and epithelial cells). The main clinical application of this system will be the prevention of restenosis due to excessive fibroblast migration and proliferation in the case of tracheal implants. A microbead-based titanium template was filled with a porous Poly (L-lactic acid) (PLLA) body by freeze-extraction method. A distinct porosity difference was obtained between the inner and outer surfaces of the implant as characterized by image analysis and Mercury porosimetry (9.8±2.2 µm vs. 36.7±11.4 µm, p≤0.05). On top, a thin PLLA film was added to optimize the growth of epithelial cells, which was confirmed by using human respiratory epithelial cells. To check the control of fibroblast movement, PKH26 labeled fibroblasts were seeded onto Titanium and Titanium/PLLA implants. The cell movement was quantified by confocal microscopy: in one week cells moved deeper in Ti samples compared to Ti/PLLA. In vitro experiments showed that this new implant is effective for guiding different kind of cells it will contact upon implantation. Overall, this system would enable spatial and temporal control over cell migration by a gradient ranging from macroporosity to nanoporosity within a tracheal implant. Moreover, mechanical properties will be dependent mainly on the titanium frame. This will make it possible to create a polymeric environment which is suitable for cells without the need to meet mechanical requirements with the polymeric structure.

Chemical, corrosion and topographical analysis of stainless steel implants after different implantation periods.

PubMed

Chrzanowski, Wojciech; Armitage, David Andrew; Knowles, Jonathan Campbell; Szade, Jacek; Korlacki, Wojciech; Marciniak, Jan

2008-07-01

The aim of this work is to examine the corrosion properties, chemical composition, and material-implant interaction after different periods of implantation of plates used to correct funnel chest. The implants are made of 316L stainless steel. Examinations are carried out on three implants: new (nonimplanted) and two implanted for 29 and 35 months. The corrosion study reveals that in the potential range that could occur in the physiological condition the new bar has the lowest current density and the highest corrosion potential. This indicates that the new plate has the highest corrosion resistance and the corrosion resistance could be reduced during implantation by the instruments used during the operation. XPS analysis reveals changes in the surface chemistry. The longer the implantation time the more carbon and oxygen are observed and only trace of elements such as Cr, Mo are detected indicating that surface is covered by an organic layer. On some parts of the implants whitish tissue is observed: the thickness of which increased with the time of implantation. This tissue was identified as an organic layer; mainly attached to the surface on the areas close to where the implant was bent to attain anatomical fit and thus where the implant has higher surface roughness. The study indicates that the chest plates are impaired by the implantation procedure and contact with biological environment. The organic layer on the surface shows that the implant did not stay passive but some reactions at the tissue-implant interface occurred. These reactions should be seen as positive, as it indicates that the implants were accepted by the tissues. Nevertheless, if the implants react, they may continue to release chromium, nickel, and other harmful ions long term as indicated by lower corrosion resistance of the implants following implantation.

Optimization of a low noise detection circuit for probing the structure of damage cascades with IBIC

DOE PAGES

Auden, Elizabeth C.; Doyle, Barney L.; Bielejec, Edward; ...

2015-06-18

Optimal detector / pre-amplifier combinations have been identified for the use of light ion IBIC (ion beam induced charge) to probe the physical structure of electrically active defects in damage cascades caused by heavy ion implantation. The ideal detector must have a sufficiently thin dead layer that incident ions will produce the majority of damage cascades in the depletion region of the detector rather than the dead layer. Detector and circuit noise must be low enough to detect the implantation of a single heavy ion as well as the decrease in the light ion IBIC signal caused by Shockley-Read-Hall recombinationmore » when the beam scans regions of the detector damaged by the heavy ion. The IBIC signals from three detectors irradiated with 750 keV He⁺ ions are measured with commercial and bespoke charge sensitive pre-amplifiers to identify the combination with the lowest noise.« less

Cellular Ti-6Al-4V structures with interconnected macro porosity for bone implants fabricated by selective electron beam melting.

PubMed

Heinl, Peter; Müller, Lenka; Körner, Carolin; Singer, Robert F; Müller, Frank A

2008-09-01

Selective electron beam melting (SEBM) was successfully used to fabricate novel cellular Ti-6Al-4V structures for orthopaedic applications. Micro computer tomography (microCT) analysis demonstrated the capability to fabricate three-dimensional structures with an interconnected porosity and pore sizes suitable for tissue ingrowth and vascularization. Mechanical properties, such as compressive strength and elastic modulus, of the tested structures were similar to those of human bone. Thus, stress-shielding effects after implantation might be avoided due to a reduced stiffness mismatch between implant and bone. A chemical surface modification using HCl and NaOH induced apatite formation during in vitro bioactivity tests in simulated body fluid under dynamic conditions. The modified bioactive surface is expected to enhance the fixation of the implant in the surrounding bone as well as to improve its long-term stability.

The Effect of Study Design Biases on the Diagnostic Accuracy of Magnetic Resonance Imaging to Detect Silicone Breast Implant Ruptures: A Meta-Analysis

PubMed Central

Song, Jae W.; Kim, Hyungjin Myra; Bellfi, Lillian T.; Chung, Kevin C.

2010-01-01

Background All silicone breast implant recipients are recommended by the US Food and Drug Administration to undergo serial screening to detect implant rupture with magnetic resonance imaging (MRI). We performed a systematic review of the literature to assess the quality of diagnostic accuracy studies utilizing MRI or ultrasound to detect silicone breast implant rupture and conducted a meta-analysis to examine the effect of study design biases on the estimation of MRI diagnostic accuracy measures. Method Studies investigating the diagnostic accuracy of MRI and ultrasound in evaluating ruptured silicone breast implants were identified using MEDLINE, EMBASE, ISI Web of Science, and Cochrane library databases. Two reviewers independently screened potential studies for inclusion and extracted data. Study design biases were assessed using the QUADAS tool and the STARDS checklist. Meta-analyses estimated the influence of biases on diagnostic odds ratios. Results Among 1175 identified articles, 21 met the inclusion criteria. Most studies using MRI (n= 10 of 16) and ultrasound (n=10 of 13) examined symptomatic subjects. Meta-analyses revealed that MRI studies evaluating symptomatic subjects had 14-fold higher diagnostic accuracy estimates compared to studies using an asymptomatic sample (RDOR 13.8; 95% CI 1.83–104.6) and 2-fold higher diagnostic accuracy estimates compared to studies using a screening sample (RDOR 1.89; 95% CI 0.05–75.7). Conclusion Many of the published studies utilizing MRI or ultrasound to detect silicone breast implant rupture are flawed with methodological biases. These methodological shortcomings may result in overestimated MRI diagnostic accuracy measures and should be interpreted with caution when applying the data to a screening population. PMID:21364405

Ion Implantation Metallurgy: A Study of the Composition, Structure and Corrosion Behavior of Surface Alloys Formed by Ion Implantation.

DTIC Science & Technology

1980-04-01

spots are due to the " phase ). Dark field imaging of the a" phase shows a large density of small precipitates uniformly distributed in the ferrite . In...density of defect structures and small precipitates of Fe 16N2 (a"). Although there exists some evidence of martensitic transformation in aged speci...implantation into 304 stainless steel ha-s been shown to produce a micro- crystalline surface alloy saturated with P. Combined electrochemical and XPS studies

Changes in local surface structure and Sr depletion in Fe-implanted SrTiO3 (001)

NASA Astrophysics Data System (ADS)

Lobacheva, O.; Yiu, Y. M.; Chen, N.; Sham, T. K.; Goncharova, L. V.

2017-01-01

Local surface structure of single crystal strontium titanate SrTiO3 (001) samples implanted with Fe in the range of concentrations between 2 × 1014 to 2 × 1016 Fe/cm2 at 30 keV has been investigated. In order to facilitate Fe substitution (doping), implanted samples were annealed in oxygen at 350 °C. Sr depletion was observed from the near-surface layers impacted by the ion-implantation process, as revealed by Rutherford Backscattering Spectrometry (RBS), X-ray photoelectron spectroscopy (XPS), X-ray Absorption Near Edge Spectroscopy (XANES), and Atomic Force Microscopy (AFM). Hydrocarbon contaminations on the surface may contribute to the mechanisms of Sr depletion, which have important implications for Sr(Ti1-xFex)O3-δ materials in gas sensing applications.

Tuning the surface microstructure of titanate coatings on titanium implants for enhancing bioactivity of implants

PubMed Central

Wang, Hui; Lai, Yue-Kun; Zheng, Ru-Yue; Bian, Ye; Zhang, Ke-Qin; Lin, Chang-Jian

2015-01-01

Biological performance of artificial implant materials is closely related to their surface characteristics, such as microtopography, and composition. Therefore, convenient fabrication of artificial implant materials with a cell-friendly surface structure and suitable composition was of great significance for current tissue engineering. In this work, titanate materials with a nanotubular structure were successfully fabricated through a simple chemical treatment. Immersion test in a simulated body fluid and in vitro cell culture were used to evaluate the biological performance of the treated samples. The results demonstrate that the titanate layer with a nanotubular structure on Ti substrates can promote the apatite-inducing ability remarkably and greatly enhance cellular responses. This highlights the potential of such titanate biomaterials with the special nanoscale structure and effective surface composition for biomedical applications such as bone implants. PMID:26089665

Nanostructured multielement (TiHfZrNbVTa)N coatings before and after implantation of N+ ions (1018 cm-2): Their structure and mechanical properties

NASA Astrophysics Data System (ADS)

Pogrebnjak, A. D.; Bondar, O. V.; Borba, S. O.; Abadias, G.; Konarski, P.; Plotnikov, S. V.; Beresnev, V. M.; Kassenova, L. G.; Drodziel, P.

2016-10-01

Multielement high entropy alloy (HEA) nitride (TiHfZrNbVTa)N coatings were deposited by vacuum arc and their structural and mechanical stability after implantation of high doses of N+ ions, 1018 cm-2, were investigated. The crystal structure and phase composition were characterized by X-ray diffraction (XRD) and Transmission Electron Microscopy, while depth-resolved nanoindentation tests were used to determine the evolution of hardness and elastic modulus along the implantation depth. XRD patterns show that coatings exhibit a main phase with fcc structure, which preferred orientation varies from (1 1 1) to (2 0 0), depending on the deposition conditions. First-principles calculations reveal that the presence of Nb atoms could favor the formation of solid solution with fcc structure in multielement HEA nitride. TEM results showed that amorphous and nanostructured phases were formed in the implanted coating sub-surface layer (∼100 nm depth). Concentration of nitrogen reached 90 at% in the near-surface layer after implantation, and decreased at higher depth. Nanohardness of the as-deposited coatings varied from 27 to 38 GPa depending on the deposition conditions. Ion implantation led to a significant decrease of the nanohardness to 12 GPa in the implanted region, while it reaches 24 GPa at larger depths. However, the H/E ratio is ⩾0.1 in the sub-surface layer due to N+ implantation, which is expected to have beneficial effect on the wear properties.

Prevalence of Dental Implants and Evaluation of Peri-implant Bone Levels in Patients Presenting to a Dental School: A Radiographic Cross-Sectional 2-Year Study.

PubMed

Alkan, Eylem Ayhan; Mau, Lian Ping; Schoolfield, John; Guest, Gary F; Cochran, David L

To evaluate the number of patients with dental implants who present to a dental school clinic for screening and to report the prevalence of peri-implant bone level change detected on digital panoramic radiographs of those subjects. Patient screening files for 9,422 patients over a 2-year period were examined to see how many patients presented with dental implants. Those patients with at least one implant were further evaluated by measuring the bone level on the mesial and distal sides of the implant using the screening radiograph. A total of 187 patients (2%) had at least one implant. In regard to implants, 423 were examined and 146 (33%) had no detectable bone loss defined as bone level below the top of the implant. When thresholds of bone loss were evaluated, 109 implants (25%) had ≥ 2 mm of bone loss on either the mesial or distal sides or both. The median bone loss was 1.74 mm for the 277 implants with detectable bone loss and 2.97 mm for the 109 implants that had ≥ 2 mm bone loss. Interestingly, patients who were ≥ 70 years of age had significantly (P = .03) more bone loss in the mandible compared with the maxilla, while patients who were 60 to 69 years of age had significantly greater loss in the maxilla. These data reveal that for patients presenting to the dental school for a screening over a 2-year period, 1.98% had one or more dental implants. Furthermore, those patients with implants had a minimum amount of bone loss as measured from the top of the implant.

Structural and surface changes in glassy carbon due to strontium implantation and heat treatment

NASA Astrophysics Data System (ADS)

Odutemowo, O. S.; Malherbe, J. B.; Prinsloo, L. C.; Njoroge, E. G.; Erasmus, R.; Wendler, E.; Undisz, A.; Rettenmayr, M.

2018-01-01

There are still questions around the microstructure of glassy carbon (GC), like the observation of the micropores. These were proposed to explain the low density of GC. This paper explains the effect of ion bombardment (200 keV Sr+, 1 × 1016 Sr+/cm2 at RT) on the microstructure of GC. TEM and AFM show that micropores in pristine GC are destroyed leading to densification of GC from 1.42 g/cm3 to 2.03 g/cm3. The amorphisation of glassy carbon was also not complete with graphitic strands embedded within the GC. These were relatively few, as Raman analysis showed that the Sr implantation resulted in a typical amorphous Raman spectrum. Annealing of the sample at 900 °C only resulted in a slight recovery of the GC structure. AFM and SEM analysis showed that the surface of the sample became rougher after Sr implantation. The roughness increased after the sample was annealed at 600 °C due to segregation of Sr towards the surface of the GC. SEM measurements of a sample with both implanted and un-implanted edges after annealing at 900 °C, showed that the high temperature heat treatment did not affect the surface topography of un-irradiated GC.

Peri-Implantitis Associated with Type of Cement: A Retrospective Analysis of Different Types of Cement and Their Clinical Correlation to the Peri-Implant Tissue.

PubMed

Korsch, Michael; Walther, Winfried

2015-10-01

The cementation of fixed implant-supported dental restorations involves the risk of leaving excess cement in the mouth which can promote biofilm formation in the peri-implant sulcus. As a result, an inflammation may develop. The aim of the present study was to investigate the clinical effect of two different luting cements on the peri-implant tissue. Within the scope of a retrospective clinical follow-up study, the prosthetic structures of 22 patients with 45 implants were revised. In all cases, a methacrylate cement (Premier Implant Cement [PIC], Premier® Dental Products Company, Plymouth Meeting, PA, USA) had been used for cementation. In 16 additional patients with 28 implants, the suprastructures were retained with a zinc oxide-eugenol cement (Temp Bond [TB], Kerr Sybron Dental Specialities, Glendora, CA, USA). These patients were evaluated in the course of routine treatment. In both populations, the retention time of the suprastructures was similar (TB 3.77 years, PIC 4.07 years). In the PIC cases, 62% of all implants had excess cement. In the TB cases, excess cement was not detectable on any of the implants. Bleeding on probing was significantly more frequent on implants cemented with PIC (100% with and 94% without excess cement) than on implants cemented with TB (46%). Pocket suppuration was observed on 89% of the PIC-cemented implants with excess cement (PIC without excess cement 24%), whereas implants with TB were not affected by it at all. The peri-implant bone loss was significantly greater in the PIC patients (with excess cement 1.37 mm, without excess cement 0.41 mm) than it was in the TB patients (0.07 mm). The frequency of undetected excess cement depends essentially on the type of cement used. Cements that tend to leave more undetected excess have a higher prevalence for peri-implant inflammation and cause a more severe peri-implant bone loss. © 2014 Wiley Periodicals, Inc.

Molecular Identification of Bacteria from Aseptically Loose Implants

PubMed Central

Kobayashi, Naomi; Procop, Gary W.; Krebs, Viktor; Kobayashi, Hideo

2008-01-01

Polymerase chain reaction (PCR) assays have been used to detect bacteria adherent to failed orthopaedic implants, but some PCR assays have had problems with probable false-positive results. We used a combination of a Staphylococcus species-specific PCR and a universal PCR followed by DNA sequencing to identify bacteria on implants retrieved from 52 patients (92 implants) at revision arthroplasty. We addressed two questions in this study: (1) Is this method able to show the existence of bacterial DNA on presumed aseptic loosed implants?; and (2) What proportion of presumed aseptic or culture-negative implants was positive for bacterial DNA by PCR? Fourteen implants (15%) were believed infected, whereas 74 implants (85%) were believed aseptic. Each implant was sonicated and the resulting solution was submitted for dual real-time PCR assay and culture. All implants believed aseptically loose were culture-negative, but nine of the 74 (12%) had bacterial DNA by PCR; two (2.7%) were PCR-positive and also showed histologic findings suggestive of infection. Uniquely developed PCR and bacterial sequencing assays showed bacterial DNA on 12% of implants removed for presumed aseptic loosening. Additional studies are needed to determine the clinical importance of bacterial DNA detected by PCR but not by conventional culture. Level of Evidence: Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18438724

Breast cancer detection and survival among women with cosmetic breast implants: systematic review and meta-analysis of observational studies.

PubMed

Lavigne, Eric; Holowaty, Eric J; Pan, Sai Yi; Villeneuve, Paul J; Johnson, Kenneth C; Fergusson, Dean A; Morrison, Howard; Brisson, Jacques

2013-04-29

To evaluate whether the stage distribution among women diagnosed as having breast cancer differs between those who have received breast implants for cosmetic purposes and those with no implants and to evaluate whether cosmetic breast augmentation before the detection of breast cancer is a predictor of post-diagnosis survival. Systematic review of observational studies with two meta-analyses. Systematic search of the literature published before September 2012 conducted in Medline, Embase, Global health, CINAHL, IPAB, and PsycINFO. Eligible publications were those that included women diagnosed as having breast cancer and who had had augmentation mammaplasty for cosmetic purposes. The overall odds ratio of the first meta-analysis based on 12 studies was 1.26 (95% confidence interval 0.99 to 1.60; P=0.058; I(2)=35.6%) for a non-localized stage of breast cancer at diagnosis comparing women with implants who had breast cancer and women without implants who had breast cancer. The second meta-analysis, based on five studies, evaluated the relation between cosmetic breast implantation and survival. This meta-analysis showed reduced survival after breast cancer among women who had implants compared with those who did not (overall hazard ratio for breast cancer specific mortality 1.38, 95% confidence interval 1.08 to 1.75). The research published to date suggests that cosmetic breast augmentation adversely affects the survival of women who are subsequently diagnosed as having breast cancer. These findings should be interpreted with caution, as some studies included in the meta-analysis on survival did not adjust for potential confounders. Further investigations are warranted regarding diagnosis and prognosis of breast cancer among women with breast implants.

Structural studies of polytene chromosomes and bone implant coatings: Raman microspectroscopy and atomic force microscopy

NASA Astrophysics Data System (ADS)

de Grauw, Kees

Raman microscopy and atomic force microscopy (AFM) are used for the investigation of the composition and structure of the banding patterns of polytene chromosomes and of hydroxyapatite bone-implant coatings. For Raman microspectroscopy two new measuring methods are introduced: line-scan Raman and Low-wavenumber Raman microspectroscopy. A transparent and easy to use model to predict the depth resolution of a confocal microscope is described. A Chevron-type of filter set was developed for simultaneous measurements of Stokes and anti-Stokes Raman scattering close to the exciting laser frequency. Bands of polytene chromosomes appeared to contain a higher concentration of DNA and proteins compared to interbands. AFM measurements revealed that bands consist of a densely packed chromatin structure and are hardly affected by stretching of the chromosome. Interbands have a more open chromatin structure and are more accessible to solvent molecules. For the study of bone implant coatings Raman micro spectroscopy appeared to provide an easy, non- destructive, way to obtain information about the apatite structure and the degree of crystallinity. It was shown that the degree of crystallinity was constant over coatings produced by plasma spraying while the material density did vary.

Au3+ ion implantation on FTO coated glasses: Effect on structural, electrical, optical and phonon properties

NASA Astrophysics Data System (ADS)

Sahu, Bindu; Dey, Ranajit; Bajpai, P. K.

2017-06-01

Effects of 11.00 MeV Au3+ ions implanted in FTO coated (thickness ≈300 nm) silicate glasses on structural, electrical optical and phonon behavior have been explored. It has been observed that metal clustering near the surface and sub-surface region below glass-FTO interface changes electrical and optical properties significantly. Ion implantation does not affect the crystalline structure of the coated films; however, the unit cell volume decreases with increase in fluence and the tetragonal distortion (c/a ratio) also decreases systematically in the implanted samples. The sheet resistivity of the films increases from 11 × 10-5 ohm-cm (in pristine) to 7.5 × 10-4 ohm-cm for highest ion beam fluence ≈1015 ions/cm2. The optical absorption decreases with increasing fluence whereas, the optical transmittance as well as reflectance increases with increasing fluence. The Raman spectra are observed at ∼530 cm-1 and ∼1103 cm-1 in pristine sample. The broad band at 530 cm-1 shifts towards higher wave number in the irradiated samples. This may be correlated with increased disorder and strain relaxation in the samples as a result of ion beam irradiation.

Characterization of retrieved orthodontic miniscrew implants.

PubMed

Eliades, Theodore; Zinelis, Spiros; Papadopoulos, Moschos A; Eliades, George

2009-01-01

The purposes of this study were to characterize the morphologic, structural, and compositional alterations and to assess any hardness changes in used orthodontic miniscrew implants. Eleven miniscrew implants (Aarhus Anchorage System, Medicon eG, Tuttlingen, Germany) placed in 5 patients were retrieved after successful service of 3.5 to 17.5 months; none showed signs of mobility or failure. These implants, and brand-, type-, and size-matched specimens as controls, were subjected to multi-technique characterization. Optical microscopy indicated loss of gloss with variable discoloration. Scanning electron microscopy and x-ray microanalysis showed morphologic alteration of the miniscrew implant surfaces with integuments formed on the surface. The materials precipitated on the surfaces were sodium, potassium, chlorine, iron, calcium, and phosphorus from the contact of the implant with biologic fluids such as blood and exudates, forming sodium chloride, potassium chloride, and calcium-phosphorus precipitates. The composition of the implant was similar to that of a titanium alloy. X-ray microtomography analysis showed no bulk structure alterations. Vickers microhardness testing showed no increased bulk or surface hardness of the retrieved specimens compared with the controls, excluding the possibility of strain-hardening phenomena as a result of self-tapping and self-drilling placement and related loading conditions. Used titanium-alloy miniscrew implants have morphologic and surface structural alterations including adsorption of an integument that is calcified as a result of contact of the implants with biologic fluids. Randomly organized osseointegration islets on these smooth titanium-alloy miniscrew surfaces might be enhanced by the extended period of retention in alveolar bone in spite of the smooth surface and immediate loading pattern of these implants.

Implant-Abutment Contact Surfaces and Microgap Measurements of Different Implant Connections Under 3-Dimensional X-Ray Microtomography.

PubMed

Scarano, Antonio; Valbonetti, Luca; Degidi, Marco; Pecci, Raffaella; Piattelli, Adriano; de Oliveira, P S; Perrotti, Vittoria

2016-10-01

The presence of a microgap between implant and abutment could produce a bacterial reservoir which could interfere with the long-term health of the periimplant tissues. The aim of this article was to evaluate, by x-ray 3-dimensional microtomography, implant-abutment contact surfaces and microgaps at the implant-abutment interface in different types of implant-abutment connections. A total of 40 implants were used in this in vitro study. Ten implants presented a screw-retained internal hexagon abutment (group I), 10 had a Morse Cone taper internal connection (group II), 10 another type of Morse Cone taper internal connection (group III), and 10 had a screwed trilobed connection (group IV). In both types of Morse Cone internal connections, there was no detectable separation at the implant-abutment in the area of the conical connection, and there was an absolute congruity without any microgaps between abutment and implant. No line was visible separating the implant and the abutment. On the contrary, in the screwed abutment implants, numerous gaps and voids were present. The results of this study support the hypothesis that different types of implant-abutment joints are responsible for the observed differences in bacterial penetration.

Defects in Arsenic Implanted p + -n- and n + -p- Structures Based on MBE Grown CdHgTe Films

NASA Astrophysics Data System (ADS)

Izhnin, I. I.; Fitsych, E. I.; Voitsekhovskii, A. V.; Korotaev, A. G.; Mynbaev, K. D.; Varavin, V. S.; Dvoretsky, S. A.; Mikhailov, N. N.; Yakushev, M. V.; Bonchyk, A. Yu.; Savytskyy, H. V.; Świątek, Z.

2018-02-01

Complex studies of the defect structure of arsenic-implanted (with the energy of 190 keV) Cd x Hg 1-x Te ( x = 0.22) films grown by molecular-beam epitaxy are carried out. The investigations were performed using secondary-ion mass spectroscopy, transmission electron microscopy, optical reflection in the visible region of the spectrum, and electrical measurements. Radiation donor defects were studied in n +- p- and n +- n-structures obtained by implantation and formed on the basis of p-type and n-type materials, respectively, without activation annealing. It is shown that in the layer of the distribution of implanted ions, a layer of large extended defects with low density is formed in the near-surface region followed by a layer of smaller extended defects with larger density. A different character of accumulation of electrically active donor defects in the films with and without a protective graded-gap surface layer has been revealed. It is demonstrated that p +- n- structures are formed on the basis of n-type material upon activation of arsenic in the process of postimplantation thermal annealing with 100% activation of impurity and complete annihilation of radiation donor defects.

Surface smoothing and template partitioning for cranial implant CAD

NASA Astrophysics Data System (ADS)

Min, Kyoung-june; Dean, David

2005-04-01

Employing patient-specific prefabricated implants can be an effective treatment for large cranial defects (i.e., > 25 cm2). We have previously demonstrated the use of Computer Aided Design (CAD) software that starts with the patient"s 3D head CT-scan. A template is accurately matched to the pre-detected skull defect margin. For unilateral cranial defects the template is derived from a left-to-right mirrored skull image. However, two problems arise: (1) slice edge artifacts generated during isosurface polygonalization are inherited by the final implant; and (2) partitioning (i.e., cookie-cutting) the implant surface from the mirrored skull image usually results in curvature discontinuities across the interface between the patient"s defect and the implant. To solve these problems, we introduce a novel space curve-to-surface partitioning algorithm following a ray-casting surface re-sampling and smoothing procedure. Specifically, the ray-cast re-sampling is followed by bilinear interpolation and low-pass filtering. The resulting surface has a highly regular grid-like topological structure of quadrilaterally arranged triangles. Then, we replace the regions to be partitioned with predefined sets of triangular elements thereby cutting the template surface to accurately fit the defect margin at high resolution and without surface curvature discontinuities. Comparisons of the CAD implants for five patients against the manually generated implant that the patient actually received show an average implant-patient gap of 0.45mm for the former and 2.96mm for the latter. Also, average maximum normalized curvature of interfacing surfaces was found to be smoother, 0.043, for the former than the latter, 0.097. This indicates that the CAD implants would provide a significantly better fit.

A Fully-Implantable Cochlear Implant SoC with Piezoelectric Middle-Ear Sensor and Arbitrary Waveform Neural Stimulation.

PubMed

Yip, Marcus; Jin, Rui; Nakajima, Hideko Heidi; Stankovic, Konstantina M; Chandrakasan, Anantha P

2015-01-01

A system-on-chip for an invisible, fully-implantable cochlear implant is presented. Implantable acoustic sensing is achieved by interfacing the SoC to a piezoelectric sensor that detects the sound-induced motion of the middle ear. Measurements from human cadaveric ears demonstrate that the sensor can detect sounds between 40 and 90 dB SPL over the speech bandwidth. A highly-reconfigurable digital sound processor enables system power scalability by reconfiguring the number of channels, and provides programmable features to enable a patient-specific fit. A mixed-signal arbitrary waveform neural stimulator enables energy-optimal stimulation pulses to be delivered to the auditory nerve. The energy-optimal waveform is validated with in-vivo measurements from four human subjects which show a 15% to 35% energy saving over the conventional rectangular waveform. Prototyped in a 0.18 μ m high-voltage CMOS technology, the SoC in 8-channel mode consumes 572 μ W of power including stimulation. The SoC integrates implantable acoustic sensing, sound processing, and neural stimulation on one chip to minimize the implant size, and proof-of-concept is demonstrated with measurements from a human cadaver ear.

Dental Implant Complications.

PubMed

Liaw, Kevin; Delfini, Ronald H; Abrahams, James J

2015-10-01

Dental implants have increased in the last few decades thus increasing the number of complications. Since many of these complications are easily diagnosed on postsurgical images, it is important for radiologists to be familiar with them and to be able to recognize and diagnose them. Radiologists should also have a basic understanding of their treatment. In a pictorial fashion, this article will present the basic complications of dental implants which we have divided into three general categories: biomechanical overload, infection or inflammation, and other causes. Examples of implant fracture, loosening, infection, inflammation from subgingival cement, failure of bone and soft tissue preservation, injury to surround structures, and other complications will be discussed as well as their common imaging appearances and treatment. Lastly, we will review pertinent dental anatomy and important structures that are vital for radiologists to evaluate in postoperative oral cavity imaging. Copyright © 2015 Elsevier Inc. All rights reserved.

XANES study of Fe-implanted strontium titanate

NASA Astrophysics Data System (ADS)

Lobacheva, O.; Goncharova, L. V.; Chavarha, M.; Sham, T. K.

2014-03-01

Properties of strontium titanate SrTiO3 (STO) depend to a great extent on the substitutional dopants and defects of crystal structure. The ion beam implantation method was used for doping STO (001) crystals with Fe at different doses. Implanted samples were then annealed at 350°C in oxygen to induce recrystallization and remove oxygen vacancies produced during ion implantation process. The effect of Fe doping and post-implantation annealing was studied by X-ray Absorption Near Edge Spectroscopy (XANES) method and Superconducting Quantum Interference Device (SQUID). XANES allowed to monitor the change in structure of STO crystals and in the local environment of Fe following the implantation and annealing steps. SQUID measurements revealed correlation between magnetic moment and Fe implantation dose. Ferromagnetic hysteresis was observed on selected Fe-implanted STO at 5 K. The observed magnetic properties can be correlated with the several Fe oxide phases in addition to the presence of O/Ti vacancies.

Applied anatomy of round window and adjacent structures of tympanum related to cochlear implantation.

PubMed

Jain, Shraddha; Gaurkar, Sagar; Deshmukh, Prasad T; Khatri, Mohnish; Kalambe, Sanika; Lakhotia, Pooja; Chandravanshi, Deepshikha; Disawal, Ashish

2018-04-19

Various aspects of the round window anatomy and anatomy of posterior tympanum have relevant implications for designing cochlear implant electrodes and visualizing the round window through facial recess. Preoperative information about possible anatomical variations of the round window and its relationships to the adjacent neurovascular structures can help reduce complications in cochlear implant surgery. The present study was undertaken to assess the common variations in round window anatomy and the relationships to structures of the tympanum that may be relevant for cochlear implant surgery. Thirty-five normal wet human cadaveric temporal bones were studied by dissection for anatomy of round window and its relation to facial nerve, carotid canal, jugular fossa and other structures of posterior tympanum. The dissected bones were photographed by a digital camera of 18 megapixels, which were then imported to a computer to determine various parameters using ScopyDoc 8.0.0.22 version software, after proper calibration and at 1× magnification. When the round window niche is placed posteriorly and inferiorly, the distance between round window and vertical facial nerve decreases, whereas that with horizontal facial nerve increases. In such cases, the distance between oval window and round window also increases. Maximum height of the round window in our study ranged from 0.51-1.27mm (mean of 0.69±0.25mm). Maximum width of round window ranged from 0.51 to 2.04mm (mean of 1.16±0.47mm). Average minimum distance between round window and carotid canal was 3.71±0.88mm (range of 2.79-5.34mm) and that between round window and jugular fossa was 2.47±0.9mm (range of 1.24-4.3mm). The distances from the round window to the oval window and facial nerve are important parameters in identifying a difficult round window niche. Modification of the electrode may be a better option than drilling off the round window margins for insertion of cochlear implant electrodes. Copyright © 2018

Electro-optical detection of THz radiation in Fe implanted LiNbO3

NASA Astrophysics Data System (ADS)

Wang, Yuhua; Ni, Hongwei; Zhan, Weiting; Yuan, Jie; Wang, Ruwu

2013-01-01

In this letter, the authors present first observation of terahertz generation from Fe implantation of LiNbO3 crystal substrate. LiNbO3 single crystal is grown by Czochralski method. Metal nanoparticles synthesized by Fe ion implantation were implanted into LiNbO3 single crystal using metal vapor vacuum arc (MEVVA) ion source. 1 kHz, 35 fs laser pulsed centered at 800 nm were focused onto the samples. Terahertz was generated via optical rectification. The findings suggest that under the investigated implantation parameter, a spectral component in excess of 0.44 THz emission were found from Fe ion implantation of LiNbO3.

Applications of Fault Detection in Vibrating Structures

NASA Technical Reports Server (NTRS)

Eure, Kenneth W.; Hogge, Edward; Quach, Cuong C.; Vazquez, Sixto L.; Russell, Andrew; Hill, Boyd L.

2012-01-01

Structural fault detection and identification remains an area of active research. Solutions to fault detection and identification may be based on subtle changes in the time series history of vibration signals originating from various sensor locations throughout the structure. The purpose of this paper is to document the application of vibration based fault detection methods applied to several structures. Overall, this paper demonstrates the utility of vibration based methods for fault detection in a controlled laboratory setting and limitations of applying the same methods to a similar structure during flight on an experimental subscale aircraft.

Neuropathic pain resulting from implant placement: case report and diagnostic conclusions.

PubMed

Leckel, M; Kress, B; Schmitter, M

2009-07-01

Temporary or persisting dysesthesia of the nervus alveolaris inferior has often been described as a complication of implant surgery of the lower mandible. In most cases, lesion of the nerve results in anaesthesia of the innervated region, a symptom clearly indicative of correct diagnosis. In our case report, however, a minor perforation of the roof of the mandibular canal during implant placement apparently provoked discrete irritation of the nerve, resulting in persistent neuropathic pain without concomitant hypesthesia or dysesthesia. Because the canal could not be detected in conventional dental radiographs, this uncharacteristic situation made correct diagnosis difficult and led to unnecessary surgical procedures including extraction of adjacent teeth. Medical imaging [computed tomography (CT)] finally revealed the close proximity of the apex of the implant and the bony structure of the mandibular canal. The effect on the nervus alveolaris inferior was also demonstrated using an innovative high-resolution dental magnetic-resonance-imaging technique reflecting vascular reactions of the neurovascular bundle after potentially damaging surgical intervention. After removal of the causative implant, the pain gradually faded over a period of a year.

Optimally oriented grooves on dental implants improve bone quality around implants under repetitive mechanical loading.

PubMed

Kuroshima, Shinichiro; Nakano, Takayoshi; Ishimoto, Takuya; Sasaki, Muneteru; Inoue, Maaya; Yasutake, Munenori; Sawase, Takashi

2017-01-15

The aim was to investigate the effect of groove designs on bone quality under controlled-repetitive load conditions for optimizing dental implant design. Anodized Ti-6Al-4V alloy implants with -60° and +60° grooves around the neck were placed in the proximal tibial metaphysis of rabbits. The application of a repetitive mechanical load was initiated via the implants (50N, 3Hz, 1800 cycles, 2days/week) at 12weeks after surgery for 8weeks. Bone quality, defined as osteocyte density and degree of biological apatite (BAp) c-axis/collagen fibers, was then evaluated. Groove designs did not affect bone quality without mechanical loading; however, repetitive mechanical loading significantly increased bone-to-implant contact, bone mass, and bone mineral density (BMD). In +60° grooves, the BAp c-axis/collagen fibers preferentially aligned along the groove direction with mechanical loading. Moreover, osteocyte density was significantly higher both inside and in the adjacent region of the +60° grooves, but not -60° grooves. These results suggest that the +60° grooves successfully transmitted the load to the bone tissues surrounding implants through the grooves. An optimally oriented groove structure on the implant surface was shown to be a promising way for achieving bone tissue with appropriate bone quality. This is the first report to propose the optimal design of grooves on the necks of dental implants for improving bone quality parameters as well as BMD. The findings suggest that not only BMD, but also bone quality, could be a useful clinical parameter in implant dentistry. Although the paradigm of bone quality has shifted from density-based assessments to structural evaluations of bone, clarifying bone quality based on structural bone evaluations remains challenging in implant dentistry. In this study, we firstly demonstrated that the optimal design of dental implant necks improved bone quality defined as osteocytes and the preferential alignment degree of biological

Hearing preservation cochlear implantation in children: The HEARRING Group consensus and practice guide.

PubMed

Rajan, Gunesh; Tavora-Vieira, Dayse; Baumgartner, Wolf-Dieter; Godey, Benoit; Müller, Joachim; O'Driscoll, Martin; Skarzynski, Henryk; Skarzynski, Piotr; Usami, Shin-Ichi; Adunka, Oliver; Agrawal, Sumit; Bruce, Iain; De Bodt, Marc; Caversaccio, Marco; Pilsbury, Harold; Gavilán, Javier; Hagen, Rudolf; Hagr, Abdulrahman; Kameswaran, Mohan; Karltorp, Eva; Kompis, Martin; Kuzovkov, Vlad; Lassaletta, Luis; Yongxin, Li; Lorens, Artur; Manoj, Manikoth; Martin, Jane; Mertens, Griet; Mlynski, Robert; Parnes, Lorne; Pulibalathingal, Sasidharan; Radeloff, Andreas; Raine, Christopher H; Rajeswaran, Ranjith; Schmutzhard, Joachim; Sprinzl, Georg; Staecker, Hinrich; Stephan, Kurt; Sugarova, Serafima; Zernotti, Mario; Zorowka, Patrick; Van de Heyning, Paul

2018-01-01

To provide multidisciplinary cochlear implant teams with a current consensus statement to support hearing preservation cochlear implantation (HPCI) in children, including those children with symptomatic partial deafness (PD) where the intention is to use electric-acoustic stimulation (EAS). The main objectives are to provide guidelines on who is a candidate, how to assess these children and when to implant if Med-El Flex electrode arrays are chosen for implantation. The HEARRING group reviewed the current evidence and practice regarding the management of children to be considered for HPCI surgery emphasizing the assessment needed prior to implantation in order to demonstrate the benefits in these children over time. The consensus statement addresses following three key questions: (1) Should these children be treated? (2) How to identify these children? (3) How to manage these children? The HEARRING group concludes that irrespective of the degree of residual hearing present, the concepts of hearing and structure preservation should be applied in every child undergoing cochlear implantation and that HPCI is a safe and reliable treatment option. Early detection and multidisciplinary assessment are key to the identification of children with symptomatic PD, these children should undergo HPCI as early as possible.

Nano-crystalline diamond-coated titanium dental implants - a histomorphometric study in adult domestic pigs.

PubMed

Metzler, Philipp; von Wilmowsky, Cornelius; Stadlinger, Bernd; Zemann, Wolfgang; Schlegel, Karl Andreas; Rosiwal, Stephan; Rupprecht, Stephan

2013-09-01

Promising biomaterial characteristics of diamond-coatings in biomedicine have been described in the literature. However, there is a lack of knowledge about implant osseointegration of this surface modification compared to the currently used sandblasted acid-etched Ti-Al6-V4 implants. The aim of this study was to investigate the osseointegration of microwave plasma-chemical-vapour deposition (MWP-CVD) diamond-coated Ti-Al6-V4 dental implants after healing periods of 2 and 5 months. Twenty-four MWP-CVD diamond-coated and 24 un-coated dental titanium-alloy implants (Ankylos(®)) were placed in the frontal skull of eight adult domestic pigs. To evaluate the effects of the nano-structured surfaces on bone formation, a histomorphometric analysis was performed after 2 and 5 months of implant healing. Histomorphometry analysed the bone-to-implant contact (BIC). No significant difference in BIC for the diamond-coated implants in comparison to reference implants could be observed for both healing periods. Scanning electron microscopy revealed an adequate interface between the bone and the diamond surface. No delamination or particle-dissociation due to shearing forces could be detected. In this study, diamond-coated dental titanium-alloy implants and sandblasted acid-etched implants showed a comparable degree of osseointegration. Copyright © 2012 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Crowdsourcing seizure detection: algorithm development and validation on human implanted device recordings.

PubMed

Baldassano, Steven N; Brinkmann, Benjamin H; Ung, Hoameng; Blevins, Tyler; Conrad, Erin C; Leyde, Kent; Cook, Mark J; Khambhati, Ankit N; Wagenaar, Joost B; Worrell, Gregory A; Litt, Brian

2017-06-01

There exist significant clinical and basic research needs for accurate, automated seizure detection algorithms. These algorithms have translational potential in responsive neurostimulation devices and in automatic parsing of continuous intracranial electroencephalography data. An important barrier to developing accurate, validated algorithms for seizure detection is limited access to high-quality, expertly annotated seizure data from prolonged recordings. To overcome this, we hosted a kaggle.com competition to crowdsource the development of seizure detection algorithms using intracranial electroencephalography from canines and humans with epilepsy. The top three performing algorithms from the contest were then validated on out-of-sample patient data including standard clinical data and continuous ambulatory human data obtained over several years using the implantable NeuroVista seizure advisory system. Two hundred teams of data scientists from all over the world participated in the kaggle.com competition. The top performing teams submitted highly accurate algorithms with consistent performance in the out-of-sample validation study. The performance of these seizure detection algorithms, achieved using freely available code and data, sets a new reproducible benchmark for personalized seizure detection. We have also shared a 'plug and play' pipeline to allow other researchers to easily use these algorithms on their own datasets. The success of this competition demonstrates how sharing code and high quality data results in the creation of powerful translational tools with significant potential to impact patient care. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Using Aerospace Technology To Design Orthopedic Implants

NASA Technical Reports Server (NTRS)

Saravanos, D. A.; Mraz, P. J.; Davy, D. T.

1996-01-01

Technology originally developed to optimize designs of composite-material aerospace structural components used to develop method for optimizing designs of orthopedic implants. Development effort focused on designing knee implants, long-term goal to develop method for optimizing designs of orthopedic implants in general.

Stress influenced trapping processes in Si based multi-quantum well structures and heavy ions implanted Si

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ciurea, Magdalena Lidia, E-mail: ciurea@infim.ro; Lazanu, Sorina, E-mail: ciurea@infim.ro

2014-10-06

Multi-quantum well structures and Si wafers implanted with heavy iodine and bismuth ions are studied in order to evaluate the influence of stress on the parameters of trapping centers. The experimental method of thermostimullatedcurrents without applied bias is used, and the trapping centers are filled by illumination. By modeling the discharge curves, we found in multilayered structures the parameters of both 'normal' traps and 'stress-induced' ones, the last having a Gaussian-shaped temperature dependence of the cross section. The stress field due to the presence of stopped heavy ions implanted into Si was modeled by a permanent electric field. The increasemore » of the strain from the neighborhood of I ions to the neighborhood of Bi ions produces the broadening of some energy levels and also a temperature dependence of the cross sections for all levels.« less

Stress influenced trapping processes in Si based multi-quantum well structures and heavy ions implanted Si

NASA Astrophysics Data System (ADS)

Ciurea, Magdalena Lidia; Lazanu, Sorina

2014-10-01

Multi-quantum well structures and Si wafers implanted with heavy iodine and bismuth ions are studied in order to evaluate the influence of stress on the parameters of trapping centers. The experimental method of thermostimullatedcurrents without applied bias is used, and the trapping centers are filled by illumination. By modeling the discharge curves, we found in multilayered structures the parameters of both 'normal' traps and 'stress-induced' ones, the last having a Gaussian-shaped temperature dependence of the cross section. The stress field due to the presence of stopped heavy ions implanted into Si was modeled by a permanent electric field. The increase of the strain from the neighborhood of I ions to the neighborhood of Bi ions produces the broadening of some energy levels and also a temperature dependence of the cross sections for all levels.

Percutaneous Implants with Porous Titanium Dermal Barriers: An In Vivo Evaluation of Infection Risk

PubMed Central

Isackson, Dorthyann; McGill, Lawrence D.; Bachus, Kent N.

2010-01-01

Osseointegrated percutaneous implants are a promising prosthetic alternative for a subset of amputees. However, as with all percutaneous implants, they have an increased risk of infection since they breach the skin barrier. Theoretically, host tissues could attach to the metal implant creating a barrier to infection. When compared with smooth surfaces, it is hypothesized that porous surfaces improve the attachment of the host tissues to the implant, and decrease the infection risk. In this study, 4 titanium implants, manufactured with a percutaneous post and a subcutaneous disk, were placed subcutaneously on the dorsum of eight New Zealand White rabbits. Beginning at four weeks post-op, the implants were inoculated weekly with 108 CFU Staphylococcus aureus until signs of clinical infection presented. While we were unable to detect a difference in the incidence of infection of the porous metal implants, smooth surface (no porous coating) percutaneous and subcutaneous components had a 7-fold increased risk of infection compared to the implants with a porous coating on one or both components. The porous coated implants displayed excellent tissue ingrowth into the porous structures; whereas, the smooth implants were surrounded with a thick, organized fibrotic capsule that was separated from the implant surface. This study suggests that porous coated metal percutaneous implants are at a significantly lower risk of infection when compared to smooth metal implants. The smooth surface percutaneous implants were inadequate in allowing a long-term seal to develop with the soft tissue, thus increasing vulnerability to the migration of infecting microorganisms. PMID:21145778

PIP silicone breast implants: rupture rates based on the explantation of 676 implants in a single surgeon series.

PubMed

Quaba, Omar; Quaba, Awf

2013-09-01

To determine the true rupture rates of PIP implants from a large single surgeon cohort and to assess whether rupture rates varied depending on time of implant insertion. In addition, the efficacy of ultra sound scanning (USS) in determining rupture is examined. Predominantly prospectively based analysis of patient records, investigations and surgical findings. 338 patients (676 implants) were included in the study and they all had removal of their implants. The senior author operated on all patients at some stage of their treatment. 160 patients were imaged pre-operatively with USS. Patients had implants inserted between 1999 and 2007 for cosmetic breast augmentation. A total of 144 ruptured implants were removed from 119 patients, giving a rupture rate of 35.2% per patient and 21.3% per implant over a mean implantation period of 7.8 years. A statistical difference (P < 0.001) in rupture rates between implants inserted prior to 2003 and those inserted from 2003 was demonstrated, with higher failure rates in the latter group. There was a significant difference in rupture rates depending on pocket placement of the implants. The sensitivity and specificity of USS at detecting rupture was 90.6% and 98.3% respectively. A proportion of patients (29.4%) demonstrated loco-regional spread of silicone to the axilla on scanning. Our paper has confirmed high rates of PIP implant failure in the largest published series to date. The significant difference in rupture rates between implants inserted prior to 2003 and those after this time supports the view that industrial silicone was used in the devices after 2003. Implants are more likely to rupture if inserted in the sub muscular plane compared to the sub glandular plane. USS is highly effective at detecting rupture in PIP implants and loco-regional spread is high compared to other devices. We believe this paper provides hard data enabling more informed decision making for patients, clinicians and providers in what remains

Method to improve passive fit of frameworks on implant-supported prostheses: An in vitro study.

PubMed

Manzella, Carlo; Bignardi, Cristina; Burello, Valerio; Carossa, Stefano; Schierano, Gianmario

2016-07-01

The passivity of the superstructure to the abutments of implant-supported prostheses is necessary for implant-prosthesis success. Improvements are needed in the methods of verifying passivity. The purpose of this in vitro study was to evaluate an inexpensive, easy to make, and user-friendly device to verify the position of the implant abutment replicas of the definitive cast and to avoid framework misfit before fabrication. Eighty stone devices were constructed on a metal base for the in vitro tests. The horizontal, vertical, and angled positions of the implant replicas were created to simulate misfits. The devices were fitted on the abutment replicas, and their ability to identify misfits was evaluated. A statistical analysis was not indicated, because the probability of fracture of the stone devices was 0 or 1. Two mathematical models were built using computer-aided design software (SolidWorks Premium; Dassault Systèmes SolidWorks Corp), and the finite element method was used (Ansys; ANSYS Inc) to simulate the structural behavior of 2 implant configurations (4 and 6 implants). Horizontal misfits of 150 μm, vertical misfits of 50 μm, and angled misfits of 1 degree were detected during the in vitro tests. Different loads and bone quality in the mathematical models did not change stress in the prosthesis configurations on 4 or 6 implants in a relevant way. The fabricated device was easily able to detect the misfits in accordance with the defined parameters. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Corrosion and fatigue of surgical implants

NASA Technical Reports Server (NTRS)

Lisagor, W. B.

1975-01-01

Implants for the treatment of femoral fractures, mechanisms leading to the failure or degradation of such structures, and current perspectives on surgical implants are discussed. Under the first heading, general usage, materials and procedures, environmental conditions, and laboratory analyses of implants after service are considered. Corrosion, crevice corrosion, stress corrosion cracking, intergranular corrosion, pitting corrosion, fatigue, and corrosion fatigue are the principal degradation mechanisms described. The need for improvement in the reliability of implants is emphasized.

More-reliable SOS ion implantations

NASA Technical Reports Server (NTRS)

Woo, D. S.

1980-01-01

Conducting layer prevents static charges from accumulating during implantation of silicon-on-sapphire MOS structures. Either thick conducting film or thinner film transparent to ions is deposited prior to implantation, and gaps are etched in regions to be doped. Grounding path eliminates charge flow that damages film or cracks sapphire wafer. Prevention of charge buildup by simultaneously exposing structure to opposite charges requires equipment modifications less practical and more expensive than deposition of conducting layer.

3D hybrid electrode structure as implantable interface for a vestibular neural prosthesis in humans.

PubMed

Hoffmann, Klaus-P; Poppendieck, Wigand; Tätzner, Simon; DiGiovanna, Jack; Kos, Maria Izabel; Guinand, Nils; Guyot, Jean-P; Micera, Silvestro

2011-01-01

Implantable interfaces are essential components of vestibular neural prostheses. They interface the biological system with electrical stimulation that is used to restore transfer of vestibular information. Regarding the anatomical situation special 3D structures are required. In this paper, the design and the manufacturing process of a novel 3D hybrid microelectrode structure as interface to the human vestibular system are described. Photolithography techniques, assembling technology and rapid prototyping are used for manufacturing.

An implantable blood pressure and flow transmitter.

NASA Technical Reports Server (NTRS)

Rader, R. D.; Meehan, J. P.; Henriksen, J. K. C.

1973-01-01

A miniature totally implantable FM/FM telemetry system has been developed to simultaneously measure blood pressure and blood flow, thus providing an appreciation of the hemodynamics of the circulation to the entire body or to a particular organ. Developed for work with animal subjects, the telemetry system's transmission time is controlled by an RF signal that permits an operating life of several months. Pressure is detected by a miniature intravascular transducer and flow is detected by an extravascular interferometric ultrasonic technique. Both pressure and flow are calibrated prior to implanting. The pressure calibration can be checked after the implanting by cannulation; flow calibration can be verified only at the end of the experiment by determining the voltage output from the implanted sensing system as a function of several measured flow rates. The utility of this device has been established by its use in investigating canine renal circulation during exercise, emotional encounters, administration of drugs, and application of accelerative forces.

Biomechanical comparison of two different collar structured implants supporting 3-unit fixed partial denture: a 3-D FEM study.

PubMed

Meriç, Gökçe; Erkmen, Erkan; Kurt, Ahmet; Eser, Atilim; Ozden, Ahmet Utku

2012-01-01

The purpose of the study was to compare the effects of two distinct collar geometries of implants on stress distribution in the bone as well as in the fixture-abutment complex, in the framework and in the veneering material of 3-unit fixed partial denture (FPD). The 3-dimensional finite element analysis method was selected to evaluate the stress distribution in the system composed of 3-unit FPD supported by two different dental implant systems with two distinct collar geometries; microthread collar structure (MCS) and non-microthread collar structure (NMCS). In separate load cases, 300 N vertical, 150 N oblique and 60 N horizontal, forces were utilized to simulate the multidirectional chewing forces. Tensile and compressive stress values in the cortical and cancellous bone and von Mises stresses in the fixture-abutment complex, in the framework and veneering material, were simulated as a body and investigated separately. In the cortical bone lower stress values were found in the MCS model, when compared with NMCS. In the cancellous bone, lower stress values were observed in the NMCS model when compared with MCS. In the implant-abutment complex, highest von Mises stress values were noted in the NMCS model; however, in the framework and veneering material, highest stress values were calculated in MCS model. MCS implants when compared with NMCS implants supporting 3-unit FPDs decrease the stress values in the cortical bone and implant-abutment complex. The results of the present study will be evaluated as a base for our ongoing FEA studies focused on stress distribution around the microthread and non-microthread collar geometries with various prosthesis design.

Cone-morse implant connection system significantly reduces bacterial leakage between implant and abutment: an in vitro study.

PubMed

Baj, A; Bolzoni, A; Russillo, A; Lauritano, D; Palmieri, A; Cura, F; Silvestre, F J; Giannì, A B

2017-01-01

Osseointegrated implants are very popular dental treatments today in the world. In osseointegrated implants, the occlusal forces are transmitted from prosthesis through an abutment to a dental implant. The abutment is connected to the implant by mean of a screw. A screw is the most used mean for connecting an implant to an abutment. Frequently the screws break and are lost. There is an alternative to screw retained abutment systems: the cone-morse connection (CMC). The CMC, thanks to the absence of the abutment screw, guarantees no micro-gaps, no micro-movements, and a reduction of bacterial leakage between implant and abutment. As P. gingivalis and T. forsythia penetration might have clinical relevance, it was the purpose of this investigation to evaluate molecular leakage of these two bacteria in a new CMC implants systems (Leone Spa®, Florence, Italy). To identify the capability of the implant to protect the internal space from the external environment, the passage of genetically modified Escherichia coli across implant-abutment interface was evaluated. Four cone-morse Leone implants (Leone® Spa, Florence, Italy) were immerged in a bacterial culture for 24 h and bacteria amount was then measured inside implant-abutment interface with Real-time PCR. Bacteria were detected inside all studied implants, with a median percentage of 3% for P. gingivalis and 4% for T. forsythia. Cone-morse connection implant system has very low bacterial leakage percentage and is similar to one-piece implants.

Release of low molecular weight silicones and platinum from silicone breast implants.

PubMed

Lykissa, E D; Kala, S V; Hurley, J B; Lebovitz, R M

1997-12-01

We have conducted a series of studies addressing the chemical composition of silicone gels from breast implants as well as the diffusion of low molecular weight silicones (LM-silicones) and heavy metals from intact implants into various surrounding media, namely, lipid-rich medium (soy oil), aqueous tissue culture medium (modified Dulbecco's medium, DMEM), or an emulsion consisting of DMEM plus 10% soy oil. LM-silicones in both implants and surrounding media were detected and quantitated using gas chromatography (GC) coupled with atomic emission (GC-AED) as well as mass spectrometric (GC/MS) detectors, which can detect silicones in the nanogram range. Platinum, a catalyst used in the preparation of silicone gels, was detected and quantitated using inductive argon-coupled plasma/mass spectrometry (ICP-MS), which can detect platinum in the parts per trillion range. Our results indicate that GC-detectable low molecular weight silicones contribute approximately 1-2% to the total gel mass and consist predominantly of cyclic and linear poly-(dimethylsiloxanes) ranging from 3 to 20 siloxane [(CH3)2-Si-O] units (molecular weight 200-1500). Platinum can be detected in implant gels at levels of approximately 700 micrograms/kg by ICP-MS. The major component of implant gels appears to be high molecular weight silicone polymers (HM-silicones) too large to be detected by GC. However, these HM-silicones can be converted almost quantitatively (80% by mass) to LM-silicones by heating implant gels at 150-180 degrees C for several hours. We also studied the rates at which LM-silicones and platinum leak through the intact implant outer shell into the surrounding media under a variety of conditions. Leakage of silicones was greatest when the surrounding medium was lipid-rich, and up to 10 mg/day LM-silicones was observed to diffuse into a lipid-rich medium per 250 g of implant at 37 degrees C. This rate of leakage was maintained over a 7-day experimental period. Similarly, platinum was

Hip Implant Modified To Increase Probability Of Retention

NASA Technical Reports Server (NTRS)

Canabal, Francisco, III

1995-01-01

Modification in design of hip implant proposed to increase likelihood of retention of implant in femur after hip-repair surgery. Decreases likelihood of patient distress and expense associated with repetition of surgery after failed implant procedure. Intended to provide more favorable flow of cement used to bind implant in proximal extreme end of femur, reducing structural flaws causing early failure of implant/femur joint.

Effect of implant design and bioactive glass coating on biomechanical properties of fiber-reinforced composite implants.

PubMed

Ballo, Ahmed M; Akca, Eralp; Ozen, Tuncer; Moritz, Niko; Lassila, Lippo; Vallittu, Pekka; Närhi, Timo

2014-08-01

This study aimed to evaluate the influence of implant design and bioactive glass (BAG) coating on the response of bone to fiber-reinforced composite (FRC) implants. Three different FRC implant types were manufactured for the study: non-threaded implants with a BAG coating; threaded implants with a BAG coating; and threaded implants with a grit-blasted surface. Thirty-six implants (six implants for each group per time point) were installed in the tibiae of six pigs. After an implantation period of 4 and 12 wk, the implants were retrieved and prepared for micro-computed tomography (micro-CT), push-out testing, and scanning electron microscopy analysis. Micro-CT demonstrated that the screw-threads and implant structure remained undamaged during the installation. The threaded FRC/BAG implants had the highest bone volume after 12 wk of implantation. The push-out strengths of the threaded FRC/BAG implants after 4 and 12 wk (463°N and 676°N, respectively) were significantly higher than those of the threaded FRC implants (416°N and 549°N, respectively) and the nonthreaded FRC/BAG implants (219°N and 430°N, respectively). Statistically significant correlation was found between bone volume and push-out strength values. This study showed that osseointegrated FRC implants can withstand the static loading up to failure without fracture, and that the addition of BAG significantly improves the push-out strength of FRC implants. © 2014 Eur J Oral Sci.

Fe doped Magnetic Nanodiamonds made by Ion Implantation.

PubMed

Chen, ChienHsu; Cho, I C; Jian, Hui-Shan; Niu, H

2017-02-09

Here we present a simple physical method to prepare magnetic nanodiamonds (NDs) using high dose Fe ion-implantation. The Fe atoms are embedded into NDs through Fe ion-implantation and the crystal structure of NDs are recovered by thermal annealing. The results of TEM and Raman examinations indicated the crystal structure of the Fe implanted NDs is recovered completely. The SQUID-VSM measurement shows the Fe-NDs possess room temperature ferromagnetism. That means the Fe atoms are distributed inside the NDs without affecting NDs crystal structure, so the NDs can preserve the original physical and chemical properties of the NDs. In addition, the ion-implantation-introduced magnetic property might make the NDs to become suitable for variety of medical applications.

Fe doped Magnetic Nanodiamonds made by Ion Implantation

NASA Astrophysics Data System (ADS)

Chen, Chienhsu; Cho, I. C.; Jian, Hui-Shan; Niu, H.

2017-02-01

Here we present a simple physical method to prepare magnetic nanodiamonds (NDs) using high dose Fe ion-implantation. The Fe atoms are embedded into NDs through Fe ion-implantation and the crystal structure of NDs are recovered by thermal annealing. The results of TEM and Raman examinations indicated the crystal structure of the Fe implanted NDs is recovered completely. The SQUID-VSM measurement shows the Fe-NDs possess room temperature ferromagnetism. That means the Fe atoms are distributed inside the NDs without affecting NDs crystal structure, so the NDs can preserve the original physical and chemical properties of the NDs. In addition, the ion-implantation-introduced magnetic property might make the NDs to become suitable for variety of medical applications.

Subcutaneous chronic implantable defibrillation systems in humans.

PubMed

Cappato, Riccardo; Smith, Warren M; Hood, Margaret A; Crozier, Ian G; Jordaens, Luc; Spitzer, Stefan G; Ardashev, Andrey V; Boersma, Lucas; Lupo, Pierpaolo; Grace, Andrew A; Bardy, Gust H

2012-09-01

The recent introduction of subcutaneous implantable cardioverter defibrillator (S-ICD) has raised attention about the potential of this technology for clinical use in daily clinical practice. We review the methods and results of the four studies conducted in humans for approval of this innovative technology for daily practice. Two studies using a temporary S-ICD system (acute human studies) were conducted to search for an appropriate lead configuration and energy requirements. For this purpose, 4 S-ICD configurations were tested in 78 patients at the time of transvenous (TV)-ICD implantation. The optimal configuration was tested in 49 more patients to comparatively assess the subcutaneous defibrillation threshold (S-DFT) versus the standard TV-ICD. Long-term implants were evaluated in 55 patients using an implanted system (chronic human study). The acute humans studies led to an optimal S-ICD configuration comprising a parasternal electrode and left anterolateral thoracic pulse generator. Both configurations successfully terminated 98% of induced ventricular fibrillation (VF), but significantly higher energy levels were required with S-ICD than with TV-ICD systems (36.6 ± 19.8 J vs. 11.1 ± 8.5 J). In the chronic study, all 137 VF episodes induced at time of implant were detected with a 98% conversion rate. Two pocket infections and four lead revisions were required during 10 ± 1 months of follow-up. During this period, survival was 98%, and 12 spontaneous ventricular tachyarrhythmias were detected and treated by the device. These data show that the S-ICD systems here consistently detected and converted VF induced at time of implant as well as sustained ventricular tachyarrhythmias occurring during follow-up (248).

Influence of Yttrium Ion-Implantation on the Growth Kinetics and Micro-Structure of NiO Oxide Film

NASA Astrophysics Data System (ADS)

Jin, Huiming; Adriana, Felix; Majorri, Aroyave

2008-02-01

Isothermal and cyclic oxidation behaviours of pure and yttrium-implanted nickel were studied at 1000°C in air. Scanning electronic microscopy (SEM) and transmission electronic microscopy (TEM) were used to examine the micro-morphology and structure of oxide scales formed on the nickel substrate. It was found that Y-implantation significantly improved the anti-oxidation ability of nickel in both isothermal and cyclic oxidizing experiments. Laser Raman microscopy was also used to study the stress status of oxide scales formed on nickel with and without yttrium. The main reason for the improvement in anti-oxidation of nickel was that Y-implantation greatly reduced the growing speed and grain size of NiO. This fine-grained NiO oxide film might have better high temperature plasticity and could relieve parts of compressive stress by means of creeping, and maintained a ridge character and a relatively low internal stress level. Hence yttrium ion-implantation remarkably enhanced the adhesion of protective NiO oxide scale formed on the nickel substrate.

Cochlear implant in Hong Kong Cantonese.

PubMed

Tang, S O; Luk, W S; Lau, C C; So, K W; Wong, C M; Yiu, M L; Kwok, C L

1990-11-01

Cochlear implant surgery was performed in four Cantonese-speaking postlingually deaf Chinese adults, using the House/3M single channel device. This article outlines the methodology, including preoperative assessment and postoperative rehabilitation; and explains the necessary modifications in speech and audiologic work-up in Cantonese-speaking patients. Salient features of Cantonese phonetics, especially its tonal characteristics, are described. The findings of the study are presented. The results of the cochlear implant would suggest a performance superior to that of the hearing aid. Furthermore, the cochlear implant is able to detect tonal cues. This quality of the cochlear implant may prove to be a valuable asset to a tonal language-speaking cochlear implantee.

A Monte Carlo technique for signal level detection in implanted intracranial pressure monitoring.

PubMed

Avent, R K; Charlton, J D; Nagle, H T; Johnson, R N

1987-01-01

Statistical monitoring techniques like CUSUM, Trigg's tracking signal and EMP filtering have a major advantage over more recent techniques, such as Kalman filtering, because of their inherent simplicity. In many biomedical applications, such as electronic implantable devices, these simpler techniques have greater utility because of the reduced requirements on power, logic complexity and sampling speed. The determination of signal means using some of the earlier techniques are reviewed in this paper, and a new Monte Carlo based method with greater capability to sparsely sample a waveform and obtain an accurate mean value is presented. This technique may find widespread use as a trend detection method when reduced power consumption is a requirement.

Effect of structural transformation of C+-ion implanted PMMA into quasi-continuous carbonaceous layer on its optical and electrical properties

NASA Astrophysics Data System (ADS)

Arif, Shafaq; Rafique, M. Shahid; Saleemi, Farhat; Sagheer, Riffat

2018-02-01

The samples of Polymethylmethacrylate (PMMA) have been implanted with 500 keV C+-ions at different ion fluences ranging from 9.3 × 1013 to 8.4 × 1014 ions/cm2. The structural modifications are examined by Fourier Transform Infrared and Raman spectral studies. For the investigation of optical, electrical and surface morphological properties of implanted samples UV-Visible spectrometer, four probe apparatus and optical microscope have been employed. The FTIR spectra confirmed the cleavage of chemicals bonds as a consequence of polymer chain scission, whereas, Raman studies revealed the transformation of PMMA structure into quasi-continuous amorphous carbon with increasing ion fluences. A continuous reduction has been observed in the optical band gap of PMMA from 3.16 to 1.42 eV. Moreover, the refractive index, extinction coefficient and electrical conductivity of implanted PMMA are found to be an increasing function of the ion fluence. The micrographic images revealed the signatures of ion-induced defects like cracking, dehydrogenation, stress and swelling on the surface of PMMA. These implanted samples have a potential to be used in the field of optical communications and thin plastic flexible electronics.

Current status of grafts and implants in rhinoplasty: Part II. Homologous grafts and allogenic implants.

PubMed

Sajjadian, Ali; Naghshineh, Nima; Rubinstein, Roee

2010-03-01

After reading this article, the participant should be able to: 1. Understand the challenges in restoring volume and structural integrity in rhinoplasty. 2. Identify the appropriate uses of various homologous grafts and allogenic implants in reconstruction, including: (a) freeze-dried acellular allogenic cadaveric dermis grafts, (b) irradiated cartilage grafts, (c) hydroxyapatite mineral matrix, (d) silicone implants, (e) high-density polyethylene implants, (f) polytetrafluoroethylene implants, and (g) injectable filler materials. 3. Identify the advantages and disadvantages of each of these biomaterials. 4. Understand the specific techniques that may aid in the use these grafts or implants. This review specifically addresses the use of homologous grafts and allogenic implants in rhinoplasty. It is important to stress that autologous materials remain the preferred graft material for use in rhinoplasty, owing to their high biocompatibility and low risk of infection and extrusion. However, concerns of donor-site morbidity, graft availability, and graft resorption have motivated the development and use of homologous and allogenic implants.

Suppression of estrus in cats with melatonin implants.

PubMed

Gimenez, F; Stornelli, M C; Tittarelli, C M; Savignone, C A; Dorna, I V; de la Sota, R L; Stornelli, M A

2009-09-01

The objective of this study was to assess the efficacy of a subcutaneous melatonin implant to suppress estrus in queens (felis catus). The hypothesis was that this implant would temporarily and reversibly suppress estrus in queens without producing any clinically detectable side effects. Fourteen adult queens were maintained in cages under artificial illumination (14h light:10h dark) for 45 d and then randomly assigned to one of two treatments. At interestrus, queens received a single subcutaneous melatonin implant (18mg; Melovine [CEVA Sante Animal, Libourne, France]; MEL: n=9), or a single subcutaneous placebo implant without melatonin (0mg; PLA; n=5). At the next estrus, all queens received a second MEL (n=9) or PLA (n=5) implant. Blood samples were taken when queens displayed estrous signs and during interestrus to measure estradiol (E(2)) and progesterone (P(4)), respectively, by radioimmunoassay. There were no significant differences in duration of the interestrus interval in PLA cats, regardless of whether the implants were placed during interestrus or estrus (6.0+/-9.7 d vs. 6.0+/-9.7 d, respectively; least square means [LSM]+/-SEM). However, when MEL implants were placed during interestrus, the duration of interestrus was approximately twice as long as that occurring when MEL implants were placed during estrus (113.3+/-6.1 d vs. 61.1+/-6.8 d, respectively; P<0.01). Serum E(2) and P(4) concentrations were similar in queens with PLA and MEL implants and in queens that received implants in estrus and interestrus. In conclusion, a subcutaneous MEL implant effectively and reversibly suppressed estrus in queens for approximately 2 to 4 mo with no clinically detectable side effects.

Nanoscale electro-structural characterisation of ohmic contacts formed on p-type implanted 4H-SiC

NASA Astrophysics Data System (ADS)

Frazzetto, Alessia; Giannazzo, Filippo; Lo Nigro, Raffaella; di Franco, Salvatore; Bongiorno, Corrado; Saggio, Mario; Zanetti, Edoardo; Raineri, Vito; Roccaforte, Fabrizio

2011-12-01

This work reports a nanoscale electro-structural characterisation of Ti/Al ohmic contacts formed on p-type Al-implanted silicon carbide (4H-SiC). The morphological and the electrical properties of the Al-implanted layer, annealed at 1700°C with or without a protective capping layer, and of the ohmic contacts were studied using atomic force microscopy [AFM], transmission line model measurements and local current measurements performed with conductive AFM. The characteristics of the contacts were significantly affected by the roughness of the underlying SiC. In particular, the surface roughness of the Al-implanted SiC regions annealed at 1700°C could be strongly reduced using a protective carbon capping layer during annealing. This latter resulted in an improved surface morphology and specific contact resistance of the Ti/Al ohmic contacts formed on these regions. The microstructure of the contacts was monitored by X-ray diffraction analysis and a cross-sectional transmission electron microscopy, and correlated with the electrical results.

Detection of deep-level defects and reduced carrier concentration in Mg-ion-implanted GaN before high-temperature annealing

NASA Astrophysics Data System (ADS)

Akazawa, Masamichi; Yokota, Naoshige; Uetake, Kei

2018-02-01

We report experimental results for the detection of deep-level defects in GaN after Mg ion implantation before high-temperature annealing. The n-type GaN samples were grown on GaN free-standing substrates by metalorganic vapor phase epitaxy. Mg ions were implanted at 50 keV with a small dosage of 1.5×1011 cm-2, which did not change the conduction type of the n-GaN. By depositing Al2O3 and a Ni/Au electrode onto the implanted n-GaN, metal-oxide-semiconductor (MOS) diodes were fabricated and tested. The measured capacitance-voltage (C-V) characteristics showed a particular behavior with a plateau region and a region with an anomalously steep slope. Fitting to the experimental C-V curves by simulation showed the existence of deep-level defects and a reduction of the carrier concentration near the GaN surface. By annealing at 800oC, the density of the deep-level defects was reduced and the carrier concentration partially recovered.

Insulation defects in Riata implantable cardioverter-defibrillator leads.

PubMed

Sato, Akinori; Chinushi, Masaomi; Iijima, Kenichi; Izumi, Daisuke; Furushima, Hiroshi

2012-01-01

The structures composing implantable cardioverter-defibrillator (ICD) leads have become more complicated and thinner with technological advances. Silicon insulation defects with and without clinically manifested electrical abnormalities have been reported in Riata leads (St. Jude Medical). The aim of this study was to assess the incidence and clinical implications of insulation defects in Riata leads implanted at our hospital. The subjects included 10 consecutive patients who received 8-French Riata ICD leads with dual-coil conductors (model 1580 or 1581) between 2006 and 2010 at our hospital. Operative records, chest X-rays and interrogation data were reviewed. In all cases, Atlas+ (St. Jude Medical) was used as an ICD generator and the Riata leads were implanted transvenously and fixed to the right ventricular apex. During a mean follow-up period of 52±9 (36-70) months, chest X-rays revealed insulation defects in Riata leads and conductor wires projecting from the bodies of the Riata leads in two of 10 (20%) patients. One of the patients received inappropriate ICD therapies due to T-wave oversensing based on attenuation of R waves and augmentation of T waves 41 months after implantation. In the other patient, an insulation defect without any clinically manifested electrical troubles was detected 50 months after implantation. Riata leads have a high incidence of insulation defects, which may be occasionally accompanied by inappropriate ICD discharges. For patients with Riata leads, careful observation of any changes in the lead-electrical measurements and a routine chest X-ray follow-up are necessary.

Assessing oxygen saturation in retinal vessels in high myopia patients pre- and post-implantable collamer lens implantation surgery.

PubMed

Chen, Pei; Cai, Xiaoxiao; Xu, Lijun; Zhang, Jing; Yang, Ying; Gao, Qianying; Ge, Jian; Yu, Keming; Zhuang, Jing

2017-09-01

To determine whether posterior chamber phakic implantable collamer lens (ICL) surgery in high myopia patients impedes oxygen saturation of retinal vessels. Mean oxygen saturation and diameter in retinal blood vessels were measured before and after ICL implantation surgery to correct high myopia refractive errors (i.e. -6.00 to -20.25 dioptres [D]), using an Oxymap T1 retinal oximeter. In 17 eyes of 17 patients, the Oxymap T1 retinal oximeter detected a small but significant decrease in oxygen saturation of retinal venules, 1-week postoperatively (compared to preoperative measurements). Moreover, at 1 week after ICL implantation, the diameter of patient retinal vessels had consistently contracted, compared to preoperative measurements. By 1 month after ICL surgery, however, both the oxygen saturation and retinal vessel diameter had returned to preoperative levels. Otherwise, no statistically significant difference in oxygen saturation and diameter of retinal arterioles was found when comparing their measurements before and 1 week after implantation. Stable levels of oxygen saturation in retinal vessels, as detected by the Oxymap T1 oximeter, show ICL implantation would not leave lasting impact or adverse effects to retina oxygen saturation in high myopia patients. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Breast fibromatosis associated with breast implants.

PubMed

Seo, Yoon Nae; Park, Young Mi; Yoon, Hye Kyoung; Lee, Sun Joo; Choo, Hye Jung; Ryu, Ji Hwa

2015-09-01

Fibromatosis refers to an extra-abdominal desmoid tumor or aggressive fibromatosis. Breast fibromatosis can develop in association with the capsule around a breast implant, although reports of cases of fibromatosis associated with breast implants are rare. As the demand for breast augmentation has increased, it is important to understand the diseases associated with breast implants. In the present report, we describe a case of breast fibromatosis that developed adjacent to a breast implant and demonstrated a relatively well-defined border even though it invaded the surrounding structures. We also explore the specific imaging features for diagnosing breast fibromatosis in association with implants by reviewing previous literature.

R&D on dental implants breakage

NASA Astrophysics Data System (ADS)

Croitoru, Sorin Mihai; Popovici, Ion Alexandru

2017-09-01

Most used dental implants for human dental prostheses are of two steps type: first step means implantation and, after several months healing and osseointegration, second step is prosthesis fixture. For sure, dental implants and prostheses are meant to last for a lifetime. Still, there are unfortunate cases when dental implants break. This paper studies two steps dental implants breakage and proposes a set of instruments for replacement and restoration of the broken implant. First part of the paper sets the input data of the study: structure of the studied two steps dental implants based on two Romanian patents and values of the loading forces found in practice and specialty papers. In the second part of the paper, using DEFORM 2D™ FEM simulation software, worst case scenarios of loading dental implants are studied in order to determine which zones and components of the dental implant set are affected (broken). Last part of the paper is dedicated to design and presentation of a set for extracting and cutting tools used to restore the broken implant set.

Controlled implant/soft tissue interaction by nanoscale surface modifications of 3D porous titanium implants.

PubMed

Rieger, Elisabeth; Dupret-Bories, Agnès; Salou, Laetitia; Metz-Boutigue, Marie-Helene; Layrolle, Pierre; Debry, Christian; Lavalle, Philippe; Vrana, Nihal Engin

2015-06-07

Porous titanium implants are widely employed in the orthopaedics field to ensure good bone fixation. Recently, the use of porous titanium implants has also been investigated in artificial larynx development in a clinical setting. Such uses necessitate a better understanding of the interaction of soft tissues with porous titanium structures. Moreover, surface treatments of titanium have been generally evaluated in planar structures, while the porous titanium implants have complex 3 dimensional (3D) architectures. In this study, the determining factors for soft tissue integration of 3D porous titanium implants were investigated as a function of surface treatments via quantification of the interaction of serum proteins and cells with single titanium microbeads (300-500 μm in diameter). Samples were either acid etched or nanostructured by anodization. When the samples are used in 3D configuration (porous titanium discs of 2 mm thickness) in vivo (in subcutis of rats for 2 weeks), a better integration was observed for both anodized and acid etched samples compared to the non-treated implants. If the implants were also pre-treated with rat serum before implantation, the integration was further facilitated. In order to understand the underlying reasons for this effect, human fibroblast cell culture tests under several conditions (directly on beads, beads in suspension, beads encapsulated in gelatin hydrogels) were conducted to mimic the different interactions of cells with Ti implants in vivo. Physical characterization showed that surface treatments increased hydrophilicity, protein adsorption and roughness. Surface treatments also resulted in improved adsorption of serum albumin which in turn facilitated the adsorption of other proteins such as apolipoprotein as quantified by protein sequencing. The cellular response to the beads showed considerable difference with respect to the cell culture configuration. When the titanium microbeads were entrapped in cell

Fabricating specialised orthopaedic implants using additive manufacturing

NASA Astrophysics Data System (ADS)

Unwin, Paul

2014-03-01

It has been hypothesised that AM is ideal for patient specific orthopaedic implants such as those used in bone cancer treatment, that can rapidly build structures such as lattices for bone and tissues to in-grow, that would be impossible using current conventional subtractive manufacturing techniques. The aim of this study was to describe the adoption of AM (direct metal laser sintering and electron beam melting) into the design manufacturing and post-manufacturing processes and the early clinical use. Prior to the clinical use of AM implants, extensive metallurgical and mechanical testing of both laser and electron beam fabrications were undertaken. Concurrently, post-manufacturing processes evaluated included hipping, cleaning and coating treatments. The first clinical application of a titanium alloy mega-implant was undertaken in November 2010. A 3D model of the pelvic wing implant was designed from CT scans. Novel key features included extensive lattice structures at the bone interfaces and integral flanges to fix the implant to the bone. The pelvic device was implanted with the aid of navigation and to date the patient remains active. A further 18 patient specific mega-implants have now been implanted. The early use of this advanced manufacturing route for patient specific implants has been very encouraging enabling the engineer to produce more advanced and anatomical conforming implants. However, there are a new set of design, manufacturing and regulatory challenges that require addressing to permit this technique to be used more widely. This technology is changing the design and manufacturing paradigm for the fabrication of specialised orthopaedic implants.

Microdrilled cartilage defects treated with thrombin-solidified chitosan/blood implant regenerate a more hyaline, stable, and structurally integrated osteochondral unit compared to drilled controls.

PubMed

Marchand, Catherine; Chen, Gaoping; Tran-Khanh, Nicolas; Sun, Jun; Chen, Hongmei; Buschmann, Michael D; Hoemann, Caroline D

2012-03-01

This study analyzed the long-term cartilage and subchondral bone repair of microdrilled defects treated with chitosan glycerol-phosphate/blood implant, using thrombin (Factor IIa) to accelerate in situ solidification. We also evaluated the cartilage repair response to six smaller microdrill holes compared with two larger holes. Bilateral knee trochlear cartilage defects were created in n=8 skeletally mature rabbits, drilled with six proximal 0.5 mm and two distal 0.9 mm holes, then covered with in situ-solidified IIa-implants (treated) or with IIa-alone (control). After 6.5 months of repair, cartilage repair tissues were analyzed by histological scoring and histomorphometry for hyaline matrix characteristics and osseous integration. Subchondral repair bone was analyzed by 3D microcomputed tomography and compared to acute defects (n=6) and intact trochlea (n=8). Implant-treated cartilage repair tissues had higher structural integrity through the entire defect (p=0.02), twofold higher percent staining for glycosaminoglycan (p=0.0004), and ~24% more collagen type II staining over the smaller drill holes (p=0.008) compared with controls. Otherwise, hole diameter had no specific effect on cartilage repair. The subchondral bone plate was partially restored in treated and control defects but less dense than intact trochlea, with evidence of incomplete regeneration of the calcified cartilage layer. More residual drill holes (p=0.054) were detected in control versus treated defects, and control defects with more than 40% residual holes presented abnormally thicker trabeculae compared with treated defects. Low osteoclast numbers after 6.5 months repair suggested that bone was no longer remodeling. The subchondral bone plate surrounding the defects exhibited a significant thickening compared with age-matched intact trochlea. These data suggest that debridement and drilling can lead to long-term subchondral bone changes outside the cartilage defect. Compared with drilled

Case studies on local orthodontic traction by minis-implants before implant rehabilitation

PubMed Central

Shen, Pei; Xu, Wei-Feng; Ma, Zhi-Gui; Zhang, Shan-Yong; Zhang, Ying

2015-01-01

Objective: Dentition defect with malocclusion is a common occurrence in the clinical work. To restore proper occlusion, preprosthetic corrections of these malposed teeth are often indispensible. The use of orthodontic mini-implants as temporary anchorage devices provides a plausible treatment for those patients with local problems. The aim of this study was to present two cases using local orthodontic traction in conjunction with mini-implants to provide necessary conditions for implant rehabilitation in three dimensional space. Clinical consideration: Two cases who had dentition defect with malocclusion were included in the present study. As both of them rejected crown reduction or orthodontics treatment, local orthodontic traction by mini-implants was used to restore normal space for implant rehabilitation in three dimensions. Careful mechanics analysis and personalized mechanical device were under consideration. The results showed that the biological responses of the corrected teeth and the surrounding bony structures appeared normal and acceptable. Moreover the patients achieved an ideal local occlusion with a short treatment time. Conclusion: In conclusion local orthodontic traction by mini-implants was a less-invasive and short-term method with favorable effects and less necessary occlusal adjustments. PMID:26221389

Electronic design of a multichannel programmable implant for neuromuscular electrical stimulation.

PubMed

Arabi, K; Sawan, M A

1999-06-01

An advanced stimulator for neuromuscular stimulation of spinal cord injured patients has been developed. The stimulator is externally controlled and powered by a single encoded radio frequency carrier and has four independently controlled bipolar stimulation channels. It offers a wide range of reprogrammability and flexibility, and can be used in many neuromuscular electrical stimulation applications. The implant system is adaptable to patient's needs and to future developments in stimulation algorithms by reprogramming the stimulator. The stimulator is capable of generating a wide range of stimulation waveforms and stimulation patterns and therefore is very suitable for selective nerve stimulation techniques. The reliability of the implant has been increased by using a forward error detection and correction communication protocol and by designing the chip for structural testability based on scan test approach. Implemented testability scheme makes it possible to verify the complete functionality of the implant before and after implantation. The stimulators architecture is designed to be modular and therefore its different blocks can be reused as standard building blocks in the design and implementation of other neuromuscular prostheses. Design for low-power techniques have also been employed to reduce power consumption of the electronic circuitry.

High Structural Stability of Textile Implants Prevents Pore Collapse and Preserves Effective Porosity at Strain

PubMed Central

Klinge, Uwe; Otto, Jens; Mühl, Thomas

2015-01-01

Reinforcement of tissues by use of textiles is encouraged by the reduced rate of recurrent tissue dehiscence but for the price of an inflammatory and fibrotic tissue reaction to the implant. The latter mainly is affected by the size of the pores, whereas only sufficiently large pores are effective in preventing a complete scar entrapment. Comparing two different sling implants (TVT and SIS), which are used for the treatment of urinary incontinence, we can demonstrate that the measurement of the effective porosity reveals considerable differences in the textile construction. Furthermore the changes of porosity after application of a tensile load can indicate a structural instability, favouring pore collapse at stress and questioning the use for purposes that are not “tension-free.” PMID:25973427

Ultrastructural investigation of intact orbital implant surfaces using atomic force microscopy.

PubMed

Choi, Samjin; Lee, Seung Jun; Shin, Jae-Ho; Cheong, Youjin; Lee, Hui-Jae; Paek, Joo Hee; Kim, Jae Sik; Jin, Kyung-Hyun; Park, Hun-Kuk

2011-01-01

This study examined the surface nanostructures of three orbital implants: nonporous poly(methyl methacrylate) (PMMA), porous aluminum oxide and porous polyethylene. The morphological characteristics of the orbital implants surfaces were observed by atomic force microscopy (AFM). The AFM topography, phase shift and deflection images of the intact implant samples were obtained. The surface of the nonporous PMMA implant showed severe scratches and debris. The surface of the aluminum oxide implant showed a porous structure with varying densities and sizes. The PMMA implant showed nodule nanostructures, 215.56 ± 52.34 nm in size, and the aluminum oxide implant showed crystal structures, 730.22 ± 341.02 nm in size. The nonporous PMMA implant showed the lowest roughness compared with other implant biomaterials, followed by the porous aluminum oxide implant. The porous polyethylene implant showed the highest roughness and severe surface irregularities. Overall, the surface roughness of orbital implants might be associated with the rate of complications and cell adhesion. Copyright © 2011 Wiley Periodicals, Inc.

Novel implant for peri-prosthetic proximal tibia fractures.

PubMed

Tran, Ton; Chen, Bernard K; Wu, Xinhua; Pun, Chung Lun

2018-03-01

Repair of peri-prosthetic proximal tibia fractures is very challenging in patients with a total knee replacement or arthroplasty. The tibial component of the knee implant severely restricts the fixation points of the tibial implant to repair peri-prosthetic fractures. A novel implant has been designed with an extended flange over the anterior of tibial condyle to provide additional points of fixation, overcoming limitations of existing generic locking plates used for proximal tibia fractures. Furthermore, the screws fixed through the extended flange provide additional support to prevent the problem of subsidence of tibial component of knee implant. The design methodology involved extraction of bone data from CT scans into a flexible CAD format, implant design and structural evaluation and optimisation using FEM as well as prototype development and manufacture by selective laser melting 3D printing technology with Ti6Al4 V powder. A prototype tibia implant was developed based on a patient-specific bone structure, which was regenerated from the CT images of patient's tibia. The design is described in detail and being applied to fit up to 80% of patients, for both left and right sides based on the average dimensions and shape of the bone structure from a wide range of CT images. A novel tibial implant has been developed to repair peri-prosthetic proximal tibia fractures which overcomes significant constraints from the tibial component of existing knee implant. Copyright © 2018 Elsevier Ltd. All rights reserved.

Fast Track ultrasound protocol to detect acute complications after totally implantable venous access device placement.

PubMed

Wu, Chun-Yu; Lin, Feng-Sheng; Wang, Yi-Chia; Chou, Wei-Han; Lin, Wen-Ying; Sun, Wei-Zen; Lin, Chih-Peng

2015-01-01

The role of ultrasound examination in detection of postprocedure complications from totally implantable venous access devices (TIVAD) placement is still uncertain. In a cohort of 665 cancer outpatients, we assessed a quick ultrasound examination protocol in early detection of mechanical complications of catheterization. Immediately after TIVAD placement, an ultrasound examination and chest radiography were performed to detect hemothorax, pneumothorax, and catheter malposition. The two methods were compared. Of the 668 catheters inserted, 628 were placed into axillary veins and 40 into internal jugular veins. The ultrasound examination took 2.5 ± 1.1 min. No hemothorax was detected, and neither pneumothorax nor catheter malposition was evident among the 40 internal jugular vein cannulations. Ultrasound and chest radiography examinations of the 628 axillary vein cannulations detected five and four instances of pneumothorax, respectively. Ultrasound detected all six catheter malpositions into the internal jugular vein. However, ultrasound failed to detect two out of three malpositions in the contralateral brachiocephalic vein and one kinking inside the superior vena cava. Without revision surgery, the operating time was 34.1 ± 15.6 min. With revision surgery, the operating time was shorter when ultrasound detected catheter malposition than when chest radiography was used (96.8 ± 12.9 vs. 188.8 ± 10.3 min, p < 0.001). Postprocedure ultrasound examination is a quick and sensitive method to detect TIVAD-related pneumothorax. It also precisely detects catheter malposition to internal jugular vein thus reduces time needed for revision surgery while chest radiography remains necessary to confirm catheter final position.

SEM and EDS investigation of a pyrolytic carbon covered C/C composite maxillofacial implant retrieved from the human body after 8 years.

PubMed

Sebők, Béla; Kiss, Gábor; Szabó, Péter J; Rigler, Dániel; Molnár, Milán L; Dobos, Gábor; Réti, Ferenc; Szőcs, Hajnal; Joób, Arpád F; Bogdán, Sándor; Szabó, György

2013-03-01

The long term effect of the human body on a pyrolytic carbon covered C/C composite maxillofacial implant (CarBulat(Tm)) was investigated by comparing the structure, the surface morphology and composition of an implant retrieved after 8 years to a sterilized, but not implanted one. Although the thickness of the carbon fibres constituting the implants did not change during the 8 year period, the surface of the implant retrieved was covered with a thin surface layer not present on the unimplanted implant. The composition of this layer is identical to the composition of the underlying carbon fibres. Calcium can only be detected on the surface as a trace element implying that the new layer is not formed by bone tissue. Residual soft tissue penetrating the bulk material between the carbon fibre bunches was found on the retrieved implant indicating the importance of the surface morphology in tissue growth and adhering to implants.

MR imaging of breast implants.

PubMed

Gorczyca, D P

1994-11-01

MR imaging has proved to be an excellent imaging modality in locating free silicone and evaluating an implant for rupture, with a sensitivity of approximately 94% and specificity of 97%. Silicone has a unique MR resonance frequency and long T1 and T2 relaxation times, which allows several MR sequences to provide excellent diagnostic images. The most commonly used sequences include T2-weighted, STIR, and chemical shift imaging (Figs. 3, 13, and 14). The T2-weighted and STIR sequences are often used in conjunction with chemical water suppression. The most reliable findings on MR images for detection of implant rupture include identification of the collapsed implant shell (linguine sign) and free silicone within the breast parenchyma.

Characterization and evaluation of femtosecond laser-induced sub-micron periodic structures generated on titanium to improve osseointegration of implants

NASA Astrophysics Data System (ADS)

Lee, Bryan E. J.; Exir, Hourieh; Weck, Arnaud; Grandfield, Kathryn

2018-05-01

Reproducible and controllable methods of modifying titanium surfaces for dental and orthopaedic applications are of interest to prevent poor implant outcomes by improving osseointegration. This study made use of a femtosecond laser to generate laser-induced periodic surface structures with periodicities of 300, 620 and 760 nm on titanium substrates. The reproducible rippled patterns showed consistent submicron scale roughness and relatively hydrophobic surfaces as measured by atomic force microscopy and contact angle, respectively. Transmission electron microscopy and Auger electron spectroscopy identified a thicker oxide layer on ablated surfaces compared to controls. In vitro testing was conducted using osteosarcoma Saos-2 cells. Cell metabolism on the laser-ablated surfaces was comparable to controls and alkaline phosphatase activity was notably increased at late time points for the 620 and 760 nm surfaces compared to controls. Cells showed a more elongated shape on laser-ablated surfaces compared to controls and showed perpendicular alignment to the periodic structures. This work has demonstrated the feasibility of generating submicron features on an implant material with the ability to influence cell response and improve implant outcomes.

Application of TXRF for ion implanter dose matching experiments

NASA Astrophysics Data System (ADS)

Frost, M. R.; French, M.; Harris, W.

2004-06-01

Secondary ion mass spectrometry (SIMS) has been utilized for many years to measure the dose of ion implants in silicon for the purpose of verifying the ability of ion implantation equipment to accurately and reproducibly implant the desired species at the target dose. The development of statistically and instrumentally rigorous protocols has lead to high confidence levels, particularly with regard to accuracy and short-term repeatability. For example, high-dose, high-energy B implant dosimetry can be targeted to within ±1%. However, performing dose determination experiments using SIMS does have undesirable aspects, such as being highly labor intensive and sample destructive. Modern total reflection X-ray fluorescence (TXRF) instruments are equipped with capabilities for full 300 mm wafer handling, automated data acquisition software and intense X-ray sources. These attributes enable the technique to overcome the SIMS disadvantages listed above, as well as provide unique strengths that make it potentially highly amenable to implanter dose matching. In this paper, we report on data collected to date that provides confidence that TXRF is an effective and economical method to perform these measurements within certain limitations. We have investigated a number of ion implanted species that are within the "envelope" of TXRF application. This envelope is defined by a few important parameters. Species: For the anode materials used in the more common X-ray sources on the market, each has its own set of elements that can be detected. We have investigated W and Mo X-ray sources, which are the most common in use in commercial instrumentation. Implant energy: In general, if the energy of the implanted species is too high (or more specifically, the distribution of the implanted species is too deep), the amount of dopant not detected by TXRF may be significant, increasing the error of the measurement. Therefore, for each species investigated, the implant energy cannot exceed a

Comparison of morphological changes in efferent lymph nodes after implantation of resorbable and non-resorbable implants in rabbits

PubMed Central

2011-01-01

Background Magnesium alloys as biodegradable implant materials received much interest in recent years. It is known that products of implant degradation can induce several types of immune response. Hence, the aim of this study was to examine the morphological changes of efferent lymph nodes after implantation of different resorbable magnesium alloys (MgCa0.8, LAE442) in comparison to commercially available resorbable (PLA) and non-resorbable (titanium) implant materials as well as control groups without implant material. Methods The different implant materials were inserted intramedullary into the rabbit tibia. After postoperative observation periods of three and six months, popliteal lymph nodes were examined histologically and immunhistologically and compared to lymph nodes of sham operated animals and animals without surgery. Haematoxylin and eosin staining was performed for cell differentiation. Mouse anti-CD79α and rat anti-CD3 monoclonal primary antibodies were used for B- and T-lymphocyte detection, mouse anti-CD68 primary antibodies for macrophage detection. Evaluation of all sections was performed applying a semi quantitative score. Results The histological evaluation demonstrated low and moderate levels of morphological changes for both magnesium alloys (LAE442 and MgCa0.8). Higher than moderate values were reached for titanium in sinus histiocytosis and histiocytic apoptosis (3 months) and for PLA in histiocytic apoptosis (3 and 6 months). The immune response to all investigated implants had a non-specific character and predominantly was a foreign-body reaction. LAE442 provoked the lowest changes which might be due to a lower degradation rate in comparison to MgCa0.8. Therewith it is a promising candidate for implants with low immunogenic potential. Conclusion Both examined magnesium alloys did not cause significantly increased morphological changes in efferent lymph nodes in comparison to the widely used implant materials titanium and PLA. LAE442

Magnetic Resonance Imaging Assessment of Intra-Articular Structures in the Canine Stifle Joint after Implantation of a Titanium Tibial Plateau Levelling Osteotomy Plate.

PubMed

Feichtenschlager, Christian; Gerwing, Martin; Failing, Klaus; Peppler, Christine; Kása, Andreas; Kramer, Martin; von Pückler, Kerstin H

2018-06-02

 To determine the effectiveness of magnetic resonance imaging (MRI) in the evaluation of anatomical stifle structures with respect to implant positioning after tibial plateau levelling osteotomy (TPLO) using a titanium plate.  Selected sagittal and dorsal sequences of pre- and postoperative MRI (1.0 T scanner) of 13 paired ( n  = 26) sound cadaveric stifle joints were evaluated. The effect of susceptibility artifact on adjacent anatomical stifle structures was graded from 0 to 5. The impact of implant positioning regarding assessment score was calculated using Spearman's rank correlation coefficient.  Sagittal turbo spin echo (TSE)-acquired images enabled interpretation of most soft tissue, osseous and cartilage structures without detrimental effect of susceptibility artifact distortions. In T2-weighted TSE images, the cranial cruciate ligament and caudal horn of the medial meniscus could be evaluated, independent of implant position, without any susceptibility artifact in all specimens. T2-weighted fast field echo, water selective, balanced fast field echo and short tau inversion recovery were most markedly affected by susceptibility artifact.  In selected TSE sequences, MRI allows evaluation of critical intra-articular structures after titanium TPLO plate implantation. Further investigations with confirmed stifle pathologies in dogs are required, to evaluate the accuracy of MRI after TPLO in clinical cases in this context. Schattauer GmbH Stuttgart.

The effects of the covalent attachment of 3-(4-hydroxy-3,5-di-tert-butylphenyl) propyl amine to glutaraldehyde pretreated bovine pericardium on structural degeneration, oxidative modification, and calcification of rat subdermal implants.

PubMed

Christian, Abigail J; Alferiev, Ivan S; Connolly, Jeanne M; Ischiropoulos, Harry; Levy, Robert J

2015-07-01

Bioprosthetic heart valves (BHV) fabricated from glutaraldehyde pretreated heterograft materials, porcine aortic valves or bovine pericardium (BP), are widely used in cardiac surgery. BHV progressively fail in clinical use due to structural degeneration. Previously we reported that dityrosine, an oxidized amino acid, was present in failed clinical BP-BHV explants; unimplanted BP had no detectable dityrosine. In the same studies BP were demonstrated in vitro to be susceptible to oxidative damage, that could be mitigated with BP covalently modified with the antioxidant, 3-(4-hydroxy-3,5-di-tert-butylphenyl)propyl amine (DBP). The present studies compared in rat subdermal implants glutaraldehyde pretreated BP to BP modified with either DBP or the chemical reactions used to link DBP. All BP explants regardless of DBP demonstrated reduced hydroxyproline and increased digestibility by collagenase. However, the DBP-BP explants showed significant inhibition of reduced explant shrink temperatures (an index of crosslinking) as compared with control BP. Significant mitigation of calcification was observed in both the BP-DBP and chemically modified explants as compared with BP. Dityrosine was not detectable in the 90 day explants. It is concluded that rat subdermal BP implants undergo both calcific and noncalcific structural degeneration, but without the formation of dityrosine, unlike clinical BP explants. © 2014 Wiley Periodicals, Inc.

[Experimental-morphologic study of bone tissue reaction to carbon-containing material implantation with initiated X-ray contrast property].

PubMed

Grigorian, A S; Nabiev, F Kh; Golovin, R V

2005-01-01

In experimental study on 15 rabbits (chinchilla) influence of titanium plates implanted lapped on adjacent tissues in the region of the lower jaw body (comparison group) and carbon material with added boron in the concentrations of 8 and 15% (the study group) was studied. Results of the experimental-morphological investigation show that carbon-based materials with boron addition (with its content 8 and 15%) did not impede adaptive rebuilding of bone tissues and in particular bone structure regeneration in the process of reactive rebuilding of the "maternal" bone. Moreover, as the result of reactive processes developing in osseous tissues after implantation of the tested materials their successful integration in surrounding tissue structures was detected.

Monopolar Detection Thresholds Predict Spatial Selectivity of Neural Excitation in Cochlear Implants: Implications for Speech Recognition

PubMed Central

2016-01-01

The objectives of the study were to (1) investigate the potential of using monopolar psychophysical detection thresholds for estimating spatial selectivity of neural excitation with cochlear implants and to (2) examine the effect of site removal on speech recognition based on the threshold measure. Detection thresholds were measured in Cochlear Nucleus® device users using monopolar stimulation for pulse trains that were of (a) low rate and long duration, (b) high rate and short duration, and (c) high rate and long duration. Spatial selectivity of neural excitation was estimated by a forward-masking paradigm, where the probe threshold elevation in the presence of a forward masker was measured as a function of masker-probe separation. The strength of the correlation between the monopolar thresholds and the slopes of the masking patterns systematically reduced as neural response of the threshold stimulus involved interpulse interactions (refractoriness and sub-threshold adaptation), and spike-rate adaptation. Detection threshold for the low-rate stimulus most strongly correlated with the spread of forward masking patterns and the correlation reduced for long and high rate pulse trains. The low-rate thresholds were then measured for all electrodes across the array for each subject. Subsequently, speech recognition was tested with experimental maps that deactivated five stimulation sites with the highest thresholds and five randomly chosen ones. Performance with deactivating the high-threshold sites was better than performance with the subjects’ clinical map used every day with all electrodes active, in both quiet and background noise. Performance with random deactivation was on average poorer than that with the clinical map but the difference was not significant. These results suggested that the monopolar low-rate thresholds are related to the spatial neural excitation patterns in cochlear implant users and can be used to select sites for more optimal speech

[On the history of cementless implants in extremity surgery].

PubMed

Dufek, Pavel

2017-05-01

The aim of implantation of cementless hip prostheses is vital ingrowth of bone into the structured metal surface of the implant. Since the 1960s several implants with surfaces made of cobalt-based alloys have been produced for this purpose. In the 1980s a novel hip endoprosthesis with a spongiosa-metal surface was introduced. The three-dimensional ingrowth of bone tissue into the structured surface of the implant could be demonstrated both histologically and using scanning electron microscopy (SEM). These implants made of cobalt-based alloys can also be used in endo-exo prostheses. Titanium implants with a microstructured surface have also been used and very good osseintegration of the surface was also demonstrated by histomorphology. The optimization of the surface and design of the prostheses plays an increasingly more important role in the field of revision endoprostheses.

Structural, optical and magnetic investigation of Gd implanted CeO2 nanocrystals

NASA Astrophysics Data System (ADS)

Kaviyarasu, K.; Murmu, P. P.; Kennedy, J.; Thema, F. T.; Letsholathebe, Douglas; Kotsedi, L.; Maaza, M.

2017-10-01

Gadolinium implanted cerium oxide (Gd-CeO2) nanocomposites is an important candidate which have unique hexagonal structure and high K- dielectric constant. Gd-CeO2 nanoparticles were synthesized using hydrothermal method. X-ray diffraction (XRD) results showed that the peaks are consistent with pure phase cubic structure the XRD pattern also confirmed crystallinity and phase purity of the sample. Nanocrystals sizes were found to be up to 25 nm as revealed by XRD and SEM. It is suggested that Gd gives an affirmative effect on the ion influence behavior of Gd-CeO2. XRD patterns showed formation of new phases and SEM micrographs revealed hexagonal structure. Photoluminescence measurement (PL) reveals the systematic shift of the emission band towards lower wavelength thereby ascertaining the quantum confinement effect (QCE). The PL spectrum has wider broad peak ranging from 390 nm to 770 nm and a sharp one centered on at 451.30 nm which is in tune with Gd ions. In the Raman spectra showed intense band observed between 460 cm-1 and 470 cm-1 which is attributed to oxygen ions into CeO2. Room temperature ferromagnetism was observed in un-doped and Gd implanted and annealed CeO2 nanocrystals. In the recent studies, ceria based materials have been considered as one of the most promising electrolytes for reduced temperature SOFC (solid oxide fuel cell) system due to their high ionic conductivities allowing its use in stainless steel supported fuel cells. CeO2 having an optical bandgap 3.3 eV and n-type carrier density which make it a promising candidate for various technological application such as buffer layer on silicon on insulator devices.

Nanotechnology for dental implants.

PubMed

Tomsia, Antoni P; Lee, Janice S; Wegst, Ulrike G K; Saiz, Eduardo

2013-01-01

With the advent of nanotechnology, an opportunity exists for the engineering of new dental implant materials. Metallic dental implants have been successfully used for decades, but they have shortcomings related to osseointegration and mechanical properties that do not match those of bone. Absent the development of an entirely new class of materials, faster osseointegration of currently available dental implants can be accomplished by various surface modifications. To date, there is no consensus regarding the preferred method(s) of implant surface modification, and further development will be required before the ideal implant surface can be created, let alone become available for clinical use. Current approaches can generally be categorized into three areas: ceramic coatings, surface functionalization, and patterning on the micro- to nanoscale. The distinctions among these are imprecise, as some or all of these approaches can be combined to improve in vivo implant performance. These surface improvements have resulted in durable implants with a high percentage of success and long-term function. Nanotechnology has provided another set of opportunities for the manipulation of implant surfaces in its capacity to mimic the surface topography formed by extracellular matrix components of natural tissue. The possibilities introduced by nanotechnology now permit the tailoring of implant chemistry and structure with an unprecedented degree of control. For the first time, tools are available that can be used to manipulate the physicochemical environment and monitor key cellular events at the molecular level. These new tools and capabilities will result in faster bone formation, reduced healing time, and rapid recovery to function.

Surface and mechanical analysis of explanted Poly Implant Prosthèse silicone breast implants.

PubMed

Yildirimer, L; Seifalian, A M; Butler, P E

2013-05-01

The recent events surrounding Poly Implant Prosthèse (PIP) breast implants have renewed the debate about the safety profile of silicone implants. The intentional use of industrial-grade instead of certified medical-grade silicone is thought to be responsible for reportedly higher frequencies of implant rupture in vivo. The differences in mechanical and viscoelastic properties between PIP and medical-grade silicone implant shells were investigated. Surface characterization of shells and gels was carried out to determine structural changes occurring after implantation. Breast implants were obtained from women at the Royal Free Hospital (London, UK). PIP implants were compared with medical-grade control silicone implants. Tensile strength, tear resistance and elongation at break were assessed using a tensile tester. Surfaces were analysed using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Spearman correlation analyses and Kruskal-Wallis one-way statistical tests were performed for mechanical data. There were 18 PIP and four medical-grade silicone implants. PIP silicone shells had significantly weaker mechanical strength than control shells (P < 0·009). There were negative correlations between mechanical properties of PIP shells and implantation times, indicative of deterioration of PIP shells over time in vivo (r(s) = -0·75, P = 0·009 for tensile strength; r(s) = -0·76, P = 0·001 for maximal strain). Comparison of ATR-FTIR spectra of PIP and control silicones demonstrated changes in material characteristics during the period of implantation suggestive of time-dependent bond breakage and degradation of the material. This study demonstrated an increased weakness of PIP shells with time and therefore supports the argument for prophylactic removal of PIP breast implants. © 2013 British Journal of Surgery Society Ltd. Published by John Wiley & Sons Ltd.

Definitive diagnosis of breast implant rupture using magnetic resonance imaging.

PubMed

Ahn, C Y; Shaw, W W; Narayanan, K; Gorczyca, D P; Sinha, S; Debruhl, N D; Bassett, L W

1993-09-01

Breast implant rupture is an important complication of augmented and reconstructed breasts. Although several techniques such as mammography, xeromammography, ultrasound, thermography, and computed tomographic (CT) scanning have been proven to be useful to detect implant rupture, they have several disadvantages and lack specificity. In the current study, we have established magnetic resonance imaging (MRI) as a definitive, reliable, and reproducible technique to diagnose both intracapsular and extracapsular ruptures. The study was conducted in 100 symptomatic patients. Our imaging parameters were able to identify ruptures in implants with silicone shells. All the ruptures showed the presence of wavy lines, free-floating silicone shell within the gel ("free-floating loose-thread sign" or "linguine sign"). We had a 3.75 percent incidence of false-positive and false-negative results. The sensitivity for detection of silicone implant rupture was 76 percent, with a specificity of 97 percent. In addition, we also were able to identify the artifacts that may interfere with the definitive diagnosis of implant rupture.

Implanted Silicon Resistor Layers for Efficient Terahertz Absorption

NASA Technical Reports Server (NTRS)

Chervenak, J. A.; Abrahams, J.; Allen, C. A.; Benford, D. J.; Henry, R.; Stevenson, T.; Wollack, E.; Moseley, S. H.

2005-01-01

Broadband absorption structures are an essential component of large format bolometer arrays for imaging GHz and THz radiation. We have measured electrical and optical properties of implanted silicon resistor layers designed to be suitable for these absorbers. Implanted resistors offer a low-film-stress, buried absorber that is robust to longterm aging, temperature, and subsequent metals processing. Such an absorber layer is readily integrated with superconducting integrated circuits and standard micromachining as demonstrated by the SCUBA II array built by ROE/NIST (1). We present a complete characterization of these layers, demonstrating frequency regimes in which different recipes will be suitable for absorbers. Single layer thin film coatings have been demonstrated as effective absorbers at certain wavelengths including semimetal (2,3), thin metal (4), and patterned metal films (5,6). Astronomical instrument examples include the SHARC II instrument is imaging the submillimeter band using passivated Bi semimetal films and the HAWC instrument for SOFIA, which employs ultrathin metal films to span 1-3 THz. Patterned metal films on spiderweb bolometers have also been proposed for broadband detection. In each case, the absorber structure matches the impedance of free space for optimal absorption in the detector configuration (typically 157 Ohms per square for high absorption with a single or 377 Ohms per square in a resonant cavity or quarter wave backshort). Resonant structures with -20% bandwidth coupled to bolometers are also under development; stacks of such structures may take advantage of instruments imaging over a wide band. Each technique may enable effective absorbers in imagers. However, thin films tend to age, degrade or change during further processing, can be difficult to reproduce, and often exhibit an intrinsic granularity that creates complicated frequency dependence at THz frequencies. Thick metal films are more robust but the requirement for

Personalized hip implants manufacturing and testing

NASA Astrophysics Data System (ADS)

Croitoru, A. Sorin Mihai; Pacioga, B. Adrian; Comsa, C. Stanca

2017-09-01

Two models of Ti6Al4V personalized femoral stems for hip replacement have been designed and laser sintered with different sizes of fenestrated architecture that mimics the natural structure of bone, ensuring postoperative bone ingrowth and increasing the elasticity of the entire structure. They were tested statically and dynamically versus a commercial femoral stem. Mechanical tests were performed in order to determine the fatigue limit using the Locati method. The tests were conducted in a thermostatic bath (37°±1°) with the implants immersed in distilled water salted solution 0.91%. For probe embedment poly-methyl methacrylate (PMMA) was used. The characteristic curves of the two personalized fenestrated implants reveal an elastic behaviour by their nonlinear appearance. After dynamic tests an inverse relationship between displacements obtained in the static tests and the fatigue limit was observed. Large fenestrations conferred the desired elasticity to the implant, but contributed to a life service reduction. The fatigue limit for both implants was much above the minimum value specified by ISO 7602: 2010, so both models can be safely used in the medical practice, leading to increased life service of implants.

Multi-Dimensional Damage Detection for Surfaces and Structures

NASA Technical Reports Server (NTRS)

Williams, Martha; Lewis, Mark; Roberson, Luke; Medelius, Pedro; Gibson, Tracy; Parks, Steen; Snyder, Sarah

2013-01-01

Current designs for inflatable or semi-rigidized structures for habitats and space applications use a multiple-layer construction, alternating thin layers with thicker, stronger layers, which produces a layered composite structure that is much better at resisting damage. Even though such composite structures or layered systems are robust, they can still be susceptible to penetration damage. The ability to detect damage to surfaces of inflatable or semi-rigid habitat structures is of great interest to NASA. Damage caused by impacts of foreign objects such as micrometeorites can rupture the shell of these structures, causing loss of critical hardware and/or the life of the crew. While not all impacts will have a catastrophic result, it will be very important to identify and locate areas of the exterior shell that have been damaged by impacts so that repairs (or other provisions) can be made to reduce the probability of shell wall rupture. This disclosure describes a system that will provide real-time data regarding the health of the inflatable shell or rigidized structures, and information related to the location and depth of impact damage. The innovation described here is a method of determining the size, location, and direction of damage in a multilayered structure. In the multi-dimensional damage detection system, layers of two-dimensional thin film detection layers are used to form a layered composite, with non-detection layers separating the detection layers. The non-detection layers may be either thicker or thinner than the detection layers. The thin-film damage detection layers are thin films of materials with a conductive grid or striped pattern. The conductive pattern may be applied by several methods, including printing, plating, sputtering, photolithography, and etching, and can include as many detection layers that are necessary for the structure construction or to afford the detection detail level required. The damage is detected using a detector or

Application of Ti6Al7Nb Alloy for the Manufacture of Biomechanical Functional Structures (BFS) for Custom-Made Bone Implants.

PubMed

Szymczyk, Patrycja; Ziółkowski, Grzegorz; Junka, Adam; Chlebus, Edward

2018-06-08

Unlike conventional manufacturing techniques, additive manufacturing (AM) can form objects of complex shape and geometry in an almost unrestricted manner. AM’s advantages include higher control of local process parameters and a possibility to use two or more various materials during manufacture. In this work, we applied one of AM technologies, selective laser melting, using Ti6Al7Nb alloy to produce biomedical functional structures (BFS) in the form of bone implants. Five types of BFS structures (A1, A2, A3, B, C) were manufactured for the research. The aim of this study was to investigate such technological aspects as architecture, manufacturing methods, process parameters, surface modification, and to compare them with such functional properties such as accuracy, mechanical, and biological in manufactured implants. Initial in vitro studies were performed using osteoblast cell line hFOB 1.19 (ATCC CRL-11372) (American Type Culture Collection). The results of the presented study confirm high applicative potential of AM to produce bone implants of high accuracy and geometric complexity, displaying desired mechanical properties. The experimental tests, as well as geometrical accuracy analysis, showed that the square shaped (A3) BFS structures were characterized by the lowest deviation range and smallestanisotropy of mechanical properties. Moreover, cell culture experiments performed in this study proved that the designed and obtained implant’s internal porosity (A3) enhances the growth of bone cells (osteoblasts) and can obtain predesigned biomechanical characteristics comparable to those of the bone tissue.

Evaluation of an education and follow-up programme for implantable cardioverter defibrillator-implanted patients.

PubMed

Cinar, Fatma I; Tosun, Nuran; Kose, Sedat

2013-09-01

To determine the experiences, problems and the need for care and education of implantable cardioverter defibrillator-implanted patients and to assess the effects of an education and nurse follow-up programme on their quality of life, anxiety, depression and knowledge level. Although implantable cardioverter defibrillator has become a well-established therapy for people experiencing potentially lethal dysrhythmias, implantable cardioverter defibrillator patients may have physical and psychosocial problems due to the implantation. Applying a planning education and follow-up programme to implantable cardioverter defibrillator-implanted patients may prevent the need for more intensive treatment during the postimplantation period. A mixed methods design that used both qualitative and quantitative data collections and analysis was used for this study. The study was performed in the cardiology department in Turkey between 2009-2010. The data were collected using the 'Semi-Structured Interview Form', 'Form for Assessment of Patients' Knowledge Level about implantable cardioverter defibrillator', 'Spielberger's State-Trait Anxiety Inventory', 'Beck Depression Inventory II' and 'The Short-Form 36 Health Survey'. All forms were completed at the beginning of the study and at six months. The study included 27 patients in the experimental group and 27 patients in the control group. The results showed that the patients were living with various physical and psychosocial problems and insufficient knowledge regarding the implantable cardioverter defibrillator. Education and follow-up programme increased knowledge levels, decreased anxiety and depression scores and improved several subscales of quality of life in the experimental group patients. It was recommended that education and follow-up programme be used for patients scheduled to undergo implantable cardioverter defibrillator implantation, starting before implantation and continuing thereafter, to help patients adapt to a life

Evaluating cochlear implant trauma to the scala vestibuli.

PubMed

Adunka, O; Kiefer, J; Unkelbach, M H; Radeloff, A; Gstoettner, W

2005-04-01

Placement of cochlear implant electrodes into the scala vestibuli may be intentional, e.g. in case of blocked scala tympani or unintentional as a result of trauma to the basilar membrane or erroneous location of the cochieostomy. The aim of this study was to evaluate the morphological consequences and cochlear trauma after implantation of different cochlear implant electrode arrays in the scala vestibuli. Human temporal bone study with histological and radiological evaluation. Twelve human cadaver temporal bones were implanted with different cochlear implant electrodes. Implanted bones were processed using a special method to section undecalcified bone. Cochlear trauma and intracochlear positions. All implanted electrodes were implanted into the scala vestibuli using a special approach that allows direct scala vestibuli insertions. Fractures of the osseous spiral lamina were evaluated in some bones in the basal cochlear regions. In most electrodes, delicate structures of the organ of Corti were left intact, however, Reissner's membrane was destroyed in all specimens and the electrode lay upon the tectorial membrane. In some bones the organ of Corti was destroyed. Scala vestibuli insertions did not cause severe trauma to osseous or neural structures, thus preserving the basis for electrostimulation of the cochlea. However, destruction of Reissner's membrane and impact on the Organ of Corti can be assumed to destroy residual hearing.

A Retrospective Analysis of Dental Implants Replacing Failed Implants in Grafted Maxillary Sinus: A Case Series.

PubMed

Manor, Yifat; Chaushu, Gavriel; Lorean, Adi; Mijiritzky, Eithan

2015-01-01

To evaluate the survival rate of dental implants replacing failed implants in grafted maxillary sinuses using the lateral approach vs nongrafted posterior maxillae. A retrospective analysis was conducted to study the survival of secondary dental implants inserted in the posterior maxilla in previously failed implant sites between the years 2000 and 2010. The study group consisted of patients who had also undergone maxillary sinus augmentation, and the control group consisted of patients in whom implants in the posterior maxilla had failed. Clinical and demographic data were analyzed using a structured form. Seventy-five patients with a total of 75 replaced implants were included in the study. The study group comprised 40 patients and the control group, 35 patients. None of the replaced implants in the study group failed, resulting in an overall survival of 100%; three replaced implants in the control group failed (92% survival). The main reason for the primary implant removal was lack of osseointegration (35 [87.5%] of 40 study group implants and 23 [65.7%] of 35 control group implants [P = .027]). The difference between the groups with regard to the timing of primary implant failure was statistically significant. The study group had more early failures of the primary implant than did the control group (77% vs 62%; P = .038). Dental implants replaced in the posterior maxilla had a high survival rate. A higher rate of survival was found in augmented maxillary sinus sites. Within the limits of the present study, it can be concluded that previous implant failures in the grafted maxillary sinus should not discourage practitioners from a second attempt.

The effects of the covalent attachment of 3-(4-hydroxy-3,5-di-tert-butylphenyl)propyl amine to glutaraldehyde pre-treated bovine pericardium on structural degeneration, oxidative modification and calcification of rat subdermal implants

PubMed Central

Christian, Abigail J.; Alferiev, Ivan S.; Connolly, Jeanne M.; Ischiropoulos, Harry; Levy, Robert J.

2014-01-01

Bioprosthetic heart valves (BHV) fabricated from glutaraldehyde pretreated heterograft materials, porcine aortic valves or bovine pericardium (BP), are widely used in cardiac surgery. BHV progressively fail in clinical use due to structural degeneration. Previously we reported that dityrosine, an oxidized amino acid, was present in failed clinical BP-BHV explants; unimplanted BP had no detectable dityrosine. In the same studies BP were demonstrated in vitro to be susceptible to oxidative damage, that could be mitigated with BP covalently modified with the antioxidant, 3-(4-hydroxy-3,5-di-tert-butylphenyl)propyl amine (DBP). The present studies compared in rat subdermal implants glutaraldehyde pretreated BP to BP modified with either DBP or the chemical reactions used to link DBP. All BP explants regardless of DBP demonstrated reduced hydroxyproline and increased digestibility by collagenase. However, the DBP-BP explants showed significant inhibition of reduced explant shrink temperatures (an index of crosslinking) compared to control BP. Significant mitigation of calcification was observed in both the BP-DBP and chemically modified explants compared to BP. Dityrosine was not detectable in the 90 day explants. It is concluded that rat subdermal BP implants undergo both calcific and non-calcific structural degeneration, but without the formation of dityrosine, unlike clinical BP explants. PMID:25546235

Are marginal bone levels and implant stability/mobility affected by single-stage platform switched dental implants? A comparative clinical study.

PubMed

Dursun, Erhan; Tulunoglu, Ibrahim; Canpınar, Pınar; Uysal, Serdar; Akalın, Ferda Alev; Tözüm, Tolga F

2012-10-01

The aim of this study was to evaluate short-term bone level and stability/mobility measurement alterations at platform switched (PS) and standard platform (SP) implants placed in mandibular premolar/molar regions using a single-stage protocol. Sixteen PS and 16 SP implants restorated with fixed prosthesis were included. Standard implant dimensions were used for both implant systems. After 3 months of osseointegration, implants were connected to abutments and final restorations were performed. Marginal bone loss was measured by standardized periapical radiographs. Implant stability/mobility was determined by resonance frequency analysis (RFA) and mobility measuring (MM) device values. Peri-implant parameters were evaluated with clinical periodontal indices and all parameters were assessed at baseline, 1, 3, and 6 months after the surgery. After 6 months, all implants showed uneventful healing. Radiographic evaluation showed a mean bone loss of 0.72 mm for PS and 0.56 mm for SP implants, and there were no significant differences between implant types. At 6 months, mean implant stability quotient (ISQ) values were 73.38 and 77 for PS and SP implants, respectively. Mean MM values were -4.75 for PS and -6.38 for SP implants. Mean MM values were lower for SP implants compared to PS implants at all time points. No significant differences were detected between implant types according to clinical peri-implant parameters. The micro-gap at crestal level which immediately exposed to the oral cavity in non-submerged two part implants seems to have adverse influence on the marginal bone level. © 2011 John Wiley & Sons A/S.

Formation of silicon nanocrystals in sapphire by ion implantation and the origin of visible photoluminescence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yerci, S.; Serincan, U.; Dogan, I.

2006-10-01

Silicon nanocrystals, average sizes ranging between 3 and 7 nm, were formed in sapphire matrix by ion implantation and subsequent annealing. Evolution of the nanocrystals was detected by Raman spectroscopy and x-ray diffraction (XRD). Raman spectra display that clusters in the matrix start to form nanocrystalline structures at annealing temperatures as low as 800 deg. C in samples with high dose Si implantation. The onset temperature of crystallization increases with decreasing dose. Raman spectroscopy and XRD reveal gradual transformation of Si clusters into crystalline form. Visible photoluminescence band appears following implantation and its intensity increases with subsequent annealing process. Whilemore » the center of the peak does not shift, the intensity of the peak decreases with increasing dose. The origin of the observed photoluminescence is discussed in terms of radiation induced defects in the sapphire matrix.« less

Electrical conduction in 100 keV Kr+ ion implanted poly (ethylene terephthalate)

NASA Astrophysics Data System (ADS)

Goyal, P. K.; Kumar, V.; Gupta, Renu; Mahendia, S.; Anita, Kumar, S.

2012-06-01

Polyethylene terephthalate (PET) samples have been implanted to 100 keV Kr+ ions at the fluences 1×1015-- 1×1016 cm-2. From I-V characteristics, the conduction mechanism was found to be shifted from ohmic to space charge limited conduction (SCLC) after implantation. The surface conductivity of these implanted samples was found to increase with increasing implantation dose. The structural alterations in the Raman spectra of implanted PET samples indicate that such an increase in the conductivity may be attributed to the formation of conjugated double bonded carbonaceous structure in the implanted layer of PET.

Effects of Nano-Hydroxyapatite/Polyetheretherketone-Coated, Sandblasted, Large-Grit, and Acid-Etched Implants on Inflammatory Cytokines and Osseointegration in a Peri-Implantitis Model in Beagle Dogs.

PubMed

Yang, Hua-Wei; Tang, Xiao-Shan; Tian, Zhuo-Wei; Wang, Yang; Yang, Wen-Yi; Hu, Jing-Zhou

2017-09-25

BACKGROUND This study explored the effects of nano-hydroxyapatite/polyetheretherketone (n-HA/PEEK)- coated sandblasted, large-grit, and acid-etched (SLA) implants on inflammatory cytokines and osseointegration in peri-implantitis model beagle dogs. MATERIAL AND METHODS Peri-implantitis models were established. Eight beagle dogs were randomly and evenly assigned into SLA tied, SLA + n-HA/PEEK tied, SLA untied, or SLA + n-HA/PEEK untied groups. A special periodontal probe was used to detect the plaque index (PLI), probing depth (PD), and modified Sulcus Bleeding Index (mSBI). Gingival crevicular fluid was collected and an ELISA kit was utilized to detect IL-1, IL-6, and IL-17 levels. The colony-forming units were counted and the maximum shear strength of implants was tested using the axial pullout test. HE staining was used to detect the inflammation of peri-implant bone tissues. Osseointegration was observed through toluidine blue staining. Bone-to-implant contact (BIC) was obtained through histological observation and the mineral apposition rate (MAR) was calculated after immune fluorescent double staining. RESULTS The SLA tied group demonstrated higher levels of PLI, PD, mSBI, IL-1, IL-6, and IL-17 and a higher degree of inflammation than the SLA + n-HA/PEEK tied group. The tied groups also displayed similar results over the untied groups at the same time point. The maximum shear strength, BIC, and MAR in the SLA tied group were significantly lower than in the SLA + n-HA/PEEK tied group. CONCLUSIONS Our findings demonstrate that SLA + n-HA/PEEK implants can promote osseointegration and relieve the inflammation response of peri-implantitis in beagle dogs.

Optical and Structural Properties of Ion-implanted InGaZnO Thin Films Studied with Spectroscopic Ellipsometry and Transmission Electron Microscopy

NASA Astrophysics Data System (ADS)

Park, Jun Woo; Jeong, Pil Seong; Choi, Suk-Ho; Lee, Hosun; Kong, Bo Hyun; Koun Cho, Hyung

2009-11-01

Amorphous InGaZnO (IGZO) thin films were grown using RF sputtering deposition at room temperature and their corresponding dielectric functions were measured. In order to reduce defects and increase carrier concentrations, we examined the effect of forming gas annealing and ion implantation. The band gap energy increased with increasing forming gas annealing temperature. We implanted the IGZO thin films with F- ions in order to decrease oxygen vacancies. For comparison, we also implanted InO- ions. Transmission electron microscopy showed that the amorphous phase undergoes transformation to a nanocrystalline phase due to annealing. We also observed InGaZnO4 nanocrystals having an In-(Ga/Zn) superlattice structure. As the annealing temperature increased, the optical gap energy increased due to crystallization. After annealing, we observed an oxygen-vacancy-related 1.9 eV peak for both unimplanted and InO-implanted samples. However, F- ion implantation substantially reduced the amplitude of the 1.9 eV peak, which disappeared completely at a F fluence of 5×1015 cm-2. We observed other defect-related peaks at 3.6 and 4.2 eV after annealing, which also disappeared after F implantation.

Detecting Structural Failures Via Acoustic Impulse Responses

NASA Technical Reports Server (NTRS)

Bayard, David S.; Joshi, Sanjay S.

1995-01-01

Advanced method of acoustic pulse reflectivity testing developed for use in determining sizes and locations of failures within structures. Used to detect breaks in electrical transmission lines, detect faults in optical fibers, and determine mechanical properties of materials. In method, structure vibrationally excited with acoustic pulse (a "ping") at one location and acoustic response measured at same or different location. Measured acoustic response digitized, then processed by finite-impulse-response (FIR) filtering algorithm unique to method and based on acoustic-wave-propagation and -reflection properties of structure. Offers several advantages: does not require training, does not require prior knowledge of mathematical model of acoustic response of structure, enables detection and localization of multiple failures, and yields data on extent of damage at each location.

Distribution of peri-implant stresses with a countertorque device.

PubMed

Sendyk, Claudio Luiz; Lopez, Thais Torralbo; de Araujo, Cleudmar Amaral; Sendyk, Wilson Roberto; Goncalvez, Valdir Ferreira

2013-01-01

To verify the effectiveness of a countertorque device in dental implants in redistributing stress to the bone-implant interface during tightening of the abutment screw. Two prismatic photoelastic samples containing implants were made, one with a 3.75-mm-diameter implant and the other with a 5.0-mm-diameter implant (both implants had an external-hexagon interface) and the respective abutments were attached (CeraOne). The samples were placed in a support and submitted to torques of 10, 20, 32, and 45 Ncm with an electronic torque meter. The torque application was repeated 10 times on each sample (n = 10) with and without a countertorque device. Photoelastic patterns were detected; thus, a photographic register of each test was selected. The fringe patterns were analyzed at discrete points near the implants' external arch. In both implants analyzed, a stress gradient reduction was observed through the implant with the countertorque device. The countertorque device used in this study proved to be effective in reducing the stresses generated in the peri-implant bone tissue during torque application.

Tardive Dyskinesia, Oral Parafunction, and Implant-Supported Rehabilitation.

PubMed

Lumetti, S; Ghiacci, G; Macaluso, G M; Amore, M; Galli, C; Calciolari, E; Manfredi, E

2016-01-01

Oral movement disorders may lead to prosthesis and implant failure due to excessive loading. We report on an edentulous patient suffering from drug-induced tardive dyskinesia (TD) and oral parafunction (OP) rehabilitated with implant-supported screw-retained prostheses. The frequency and intensity of the movements were high, and no pharmacological intervention was possible. Moreover, the patient refused night-time splint therapy. A series of implant and prosthetic failures were experienced. Implant failures were all in the maxilla and stopped when a rigid titanium structure was placed to connect implants. Ad hoc designed studies are desirable to elucidate the mutual influence between oral movement disorders and implant-supported rehabilitation.

Tardive Dyskinesia, Oral Parafunction, and Implant-Supported Rehabilitation

PubMed Central

Amore, M.

2016-01-01

Oral movement disorders may lead to prosthesis and implant failure due to excessive loading. We report on an edentulous patient suffering from drug-induced tardive dyskinesia (TD) and oral parafunction (OP) rehabilitated with implant-supported screw-retained prostheses. The frequency and intensity of the movements were high, and no pharmacological intervention was possible. Moreover, the patient refused night-time splint therapy. A series of implant and prosthetic failures were experienced. Implant failures were all in the maxilla and stopped when a rigid titanium structure was placed to connect implants. Ad hoc designed studies are desirable to elucidate the mutual influence between oral movement disorders and implant-supported rehabilitation. PMID:28050290

Implanted near-infrared spectroscopy for cardiac monitoring

NASA Astrophysics Data System (ADS)

Bhunia, Sourav K.; Cinbis, Can

2011-02-01

Implanted Cardioverter Defibrillator (ICD) provides one of the most effective therapies for the prevention of sudden cardiac death, but also delivers some high voltage shocks inappropriately, causing morbidity and mortality. Implanted near-infrared spectroscopy (NIRS) may augment ICD arrhythmia detection by monitoring skeletal muscle perfusion. A two-wavelength, single-distance, continuous-wave implanted NIRS has been evaluated in-vivo. A weighted difference of the changes in attenuation at two wavelengths, across the isobestic point of the hemoglobin spectra, was taken to be the microvascular oxygenation trend indicator (O2 Index). Although the exact weight depends on the local vascular distribution and their oxygen levels, the hypothesis that a constant weight may be adequate for hemodynamic trending during short arrhythmic episodes, was tested. The sensor was implanted subcutaneously both on fresh tissue and inside scar tissue that formed around a pre-existing implant, in 3 animals each. Attenuations were recorded at 660 and 890 nm during normal sinus rhythm (NSR) and induced ventricular fibrillation (VF). The slope of the O2 Index over 10 seconds was computed for 7 NSR and 8 VF episodes in fresh and 13 NSR and 15 VF episodes in scar tissue pockets. The mean O2 Index slope was significantly different (p<0.0001) between NSR and VF rhythms for both the fresh and scar tissue pockets. Therefore implanted NIRS may be useful for preventing inappropriate detection of VF during electromagnetic interference, double counting of ECG T-wave as an R-wave, ICD lead failure, electrocardiographic aberrancy etc.

High Mobility SiGe/Si Transistor Structures on Sapphire Substrates Using Ion Implantation

NASA Technical Reports Server (NTRS)

Alterovitz, S. A.; Mueller, C. H.; Croke, E. T.

2003-01-01

High mobility n-type SiGe/Si transistor structures have been fabricated on sapphire substrates by ion implanting phosphorus ions into strained 100 Angstrom thick silicon channels for the first time. The strained Si channels were sandwiched between Si(sub 0.7)Ge(sub 0.3) layers, which, in turn, were deposited on Si(sub 0.7)Ge(sub 0.3) virtual substrates and graded SiGe buffer layers. After the molecular beam epitaxy (MBE) film growth process was completed, ion thick silicon channels implantation and post-annealing were used to introduce donors. The phosphorous ions were preferentially located in the Si channel at a peak concentration of approximately 1x10(exp 18)/cu cm. Room temperature electron mobilities exceeding 750 sq cm/V-sec at carrier densities of 1x10(exp 12)/sq cm were measured. Electron concentration appears to be the key factor that determines mobility, with the highest mobility observed for electron densities in the 1 - 2x10(exp 12)/sq cm range.

Leveraging disjoint communities for detecting overlapping community structure

NASA Astrophysics Data System (ADS)

Chakraborty, Tanmoy

2015-05-01

Network communities represent mesoscopic structure for understanding the organization of real-world networks, where nodes often belong to multiple communities and form overlapping community structure in the network. Due to non-triviality in finding the exact boundary of such overlapping communities, this problem has become challenging, and therefore huge effort has been devoted to detect overlapping communities from the network. In this paper, we present PVOC (Permanence based Vertex-replication algorithm for Overlapping Community detection), a two-stage framework to detect overlapping community structure. We build on a novel observation that non-overlapping community structure detected by a standard disjoint community detection algorithm from a network has high resemblance with its actual overlapping community structure, except the overlapping part. Based on this observation, we posit that there is perhaps no need of building yet another overlapping community finding algorithm; but one can efficiently manipulate the output of any existing disjoint community finding algorithm to obtain the required overlapping structure. We propose a new post-processing technique that by combining with any existing disjoint community detection algorithm, can suitably process each vertex using a new vertex-based metric, called permanence, and thereby finds out overlapping candidates with their community memberships. Experimental results on both synthetic and large real-world networks show that PVOC significantly outperforms six state-of-the-art overlapping community detection algorithms in terms of high similarity of the output with the ground-truth structure. Thus our framework not only finds meaningful overlapping communities from the network, but also allows us to put an end to the constant effort of building yet another overlapping community detection algorithm.

Trophinin expression in the mouse uterus coincides with implantation and is hormonally regulated but not induced by implanting blastocysts.

PubMed

Suzuki, N; Nadano, D; Paria, B C; Kupriyanov, S; Sugihara, K; Fukuda, M N

2000-11-01

Trophinin mediates apical cell adhesion between two human cell lines, trophoblastic teratocarcinoma and endometrial adenocarcinoma. In humans, trophinin is specifically expressed in cells involved in implantation and early placentation. The present study was undertaken to establish trophinin expression by the mouse uterus. In the pregnant mouse uterus, trophinin transcripts are expressed during the time which coincides with the timing of blastocyst implantation. Trophinin is also expressed in the nonpregnant mouse uterus at estrus stage. Uteri from ovariectomized mice did not express trophinin, whereas strong expression was induced by estrogen but not by progesterone. Trophinin transcripts and protein were found in the pseudopregnant mouse uterus. No differences were detected in trophinin expression by the uteri in the pregnant, pseudopregnant, and pseudopregnant received blastocysts. In delayed implantation model, trophinin proteins were found in both luminal and glandular epithelium, whereas dormant blastocysts were negative for trophinin. Upon activation with estrogen, however, no significant changes were detected either in the blastocyst or in the uterus. These results indicate that ovarian hormones regulate trophinin expression by the mouse uterus, and that an implanting blastocyst has no effect on trophinin expression in the surrounding endometrial luminal epithelial cells.

Falling Leaves Inspired ZnO Nanorods-Nanoslices Hierarchical Structure for Implant Surface Modification with Two Stage Releasing Features.

PubMed

Liao, Hang; Miao, Xinxin; Ye, Jing; Wu, Tianlong; Deng, Zhongbo; Li, Chen; Jia, Jingyu; Cheng, Xigao; Wang, Xiaolei

2017-04-19

Inspired from falling leaves, ZnO nanorods-nanoslices hierarchical structure (NHS) was constructed to modify the surfaces of two widely used implant materials: titanium (Ti) and tantalum (Ta), respectively. By which means, two-stage release of antibacterial active substances were realized to address the clinical importance of long-term broad-spectrum antibacterial activity. At early stages (within 48 h), the NHS exhibited a rapid releasing to kill the bacteria around the implant immediately. At a second stage (over 2 weeks), the NHS exhibited a slow releasing to realize long-term inhibition. The excellent antibacterial activity of ZnO NHS was confirmed once again by animal test in vivo. According to the subsequent experiments, the ZnO NHS coating exhibited the great advantage of high efficiency, low toxicity, and long-term durability, which could be a feasible manner to prevent the abuse of antibiotics on implant-related surgery.

Salivary bacterial leakage into implant-abutment connections: preliminary results of an in vitro study.

PubMed

Mencio, F; Papi, P; Di Carlo, S; Pompa, G

2016-06-01

The occurrence of bacterial leakage in the internal surface of implants, through implant-abutment interface (IAI), is one of the parameters for analyzing the fabrication quality of the connections. The aim of this in vitro study is to evaluate two different types of implant-abutment connections: the screwed connection (Group 1) and the cemented connection (Group 2), analyzing the permeability of the IAI to bacterial colonization, using human saliva as culture medium. A total of twelve implants were tested, six in each experimental group. Five healthy patients were enrolled in this study. Two milliliters of non-stimulated saliva were collected from each subject and mixed in a test tube. After 14 days of incubation of the bacteria sample in the implant fixtures, a PCR-Real Time analysis was performed. Fisher's exact test was used to compare the proportions of implant-abutment assembled structures detected with bacterial leakage. Differences in the bacterial counts of the two groups were compared using the Mann-Whitney U test. A p value < 0.05 was considered significant. The results showed a decreased stability with the screwed implant-abutment connections compared to the cemented implant-abutment connections. A mean total bacterial count of 1.2E+07 (± 0.25E+07) for Group 1 and of 7.2E+04 (± 14.4E+04) for Group 2 was found, with a high level of significance, p = .0001. Within the limitations of this study it can be concluded that bacterial species from human saliva may penetrate along the implant-abutment interface in both connections, however the cemented connection implants showed the lowest amount of bacterial colonization.

Assessing the role of spectral and intensity cues in spectral ripple detection and discrimination in cochlear-implant users.

PubMed

Anderson, Elizabeth S; Oxenham, Andrew J; Nelson, Peggy B; Nelson, David A

2012-12-01

Measures of spectral ripple resolution have become widely used psychophysical tools for assessing spectral resolution in cochlear-implant (CI) listeners. The objective of this study was to compare spectral ripple discrimination and detection in the same group of CI listeners. Ripple detection thresholds were measured over a range of ripple frequencies and were compared to spectral ripple discrimination thresholds previously obtained from the same CI listeners. The data showed that performance on the two measures was correlated, but that individual subjects' thresholds (at a constant spectral modulation depth) for the two tasks were not equivalent. In addition, spectral ripple detection was often found to be possible at higher rates than expected based on the available spectral cues, making it likely that temporal-envelope cues played a role at higher ripple rates. Finally, spectral ripple detection thresholds were compared to previously obtained speech-perception measures. Results confirmed earlier reports of a robust relationship between detection of widely spaced ripples and measures of speech recognition. In contrast, intensity difference limens for broadband noise did not correlate with spectral ripple detection measures, suggesting a dissociation between the ability to detect small changes in intensity across frequency and across time.

Assessing the role of spectral and intensity cues in spectral ripple detection and discrimination in cochlear-implant users

PubMed Central

Anderson, Elizabeth S.; Oxenham, Andrew J.; Nelson, Peggy B.; Nelson, David A.

2012-01-01

Measures of spectral ripple resolution have become widely used psychophysical tools for assessing spectral resolution in cochlear-implant (CI) listeners. The objective of this study was to compare spectral ripple discrimination and detection in the same group of CI listeners. Ripple detection thresholds were measured over a range of ripple frequencies and were compared to spectral ripple discrimination thresholds previously obtained from the same CI listeners. The data showed that performance on the two measures was correlated, but that individual subjects’ thresholds (at a constant spectral modulation depth) for the two tasks were not equivalent. In addition, spectral ripple detection was often found to be possible at higher rates than expected based on the available spectral cues, making it likely that temporal-envelope cues played a role at higher ripple rates. Finally, spectral ripple detection thresholds were compared to previously obtained speech-perception measures. Results confirmed earlier reports of a robust relationship between detection of widely spaced ripples and measures of speech recognition. In contrast, intensity difference limens for broadband noise did not correlate with spectral ripple detection measures, suggesting a dissociation between the ability to detect small changes in intensity across frequency and across time. PMID:23231122

In situ plasma fabrication of ceramic-like structure on polymeric implant with enhanced surface hardness, cytocompatibility and antibacterial capability.

PubMed

Liu, Jun; Zhang, Wei; Shi, Haigang; Yang, Kun; Wang, Gexia; Wang, Pingli; Ji, Junhui; Chu, Paul K

2016-05-01

Polymeric materials are commonly found in orthopedic implants due to their unique mechanical properties and biocompatibility but the poor surface hardness and bacterial infection hamper many biomedical applications. In this study, a ceramic-like surface structure doped with silver is produced by successive plasma implantation of silicon (Si) and silver (Ag) into the polyamine 66 (PA66) substrate. Not only the surface hardness and elastic modulus are greatly enhanced due to the partial surface carbonization and the ceramic-like structure produced by the reaction between energetic Si and the carbon chain of PA66, but also the antibacterial activity is improved because of the combined effects rendered by Ag and SiC structure. Furthermore, the modified materials which exhibit good cytocompatibility upregulate bone-related genes and proteins expressions of the contacted bone mesenchymal stem cells (BMSCs). For the first time, it explores out that BMSCs osteogenesis on the antibacterial ceramic-like structure is mediated via the iNOS and nNOS signal pathways. The results reveal that in situ plasma fabrication of an antibacterial ceramic-like structure can endow PA66 with excellent surface hardness, cytocompatibility, as well as antibacterial capability. © 2016 Wiley Periodicals, Inc.

Medical Textiles as Vascular Implants and Their Success to Mimic Natural Arteries

PubMed Central

Singh, Charanpreet; Wong, Cynthia S.; Wang, Xungai

2015-01-01

Vascular implants belong to a specialised class of medical textiles. The basic purpose of a vascular implant (graft and stent) is to act as an artificial conduit or substitute for a diseased artery. However, the long-term healing function depends on its ability to mimic the mechanical and biological behaviour of the artery. This requires a thorough understanding of the structure and function of an artery, which can then be translated into a synthetic structure based on the capabilities of the manufacturing method utilised. Common textile manufacturing techniques, such as weaving, knitting, braiding, and electrospinning, are frequently used to design vascular implants for research and commercial purposes for the past decades. However, the ability to match attributes of a vascular substitute to those of a native artery still remains a challenge. The synthetic implants have been found to cause disturbance in biological, biomechanical, and hemodynamic parameters at the implant site, which has been widely attributed to their structural design. In this work, we reviewed the design aspect of textile vascular implants and compared them to the structure of a natural artery as a basis for assessing the level of success as an implant. The outcome of this work is expected to encourage future design strategies for developing improved long lasting vascular implants. PMID:26133386

Structures and optical properties of \\text{H}_{2}^{+} -implanted GaN epi-layers

NASA Astrophysics Data System (ADS)

Li, B. S.; Wang, Z. G.

2015-06-01

The implantation damage build-up and optical properties of GaN epitaxial films under \\text{H}2+ ion implantation have been investigated by a combination of Rutherford backscattering in channeling geometry, Raman spectroscopy, UV-visible spectroscopy and transmission electron microscopy. GaN epitaxial films were implanted with 134 keV \\text{H}2+ ions to doses ranging from 3.75   ×   1016 to 1.75   ×   1017 \\text{H}2+  cm-2 at room temperature or the same dose of 1.5   ×   1017 \\text{H}2+  cm-2 at room temperature, 573 and 723 K. The dependence of lattice disorder induced by \\text{H}2+ -implantation on the ion dose can be divided into a three-step damage process. A strong influence of the H concentration on the defect accumulation is discussed. The decrease in relative Ga disorder induced by \\text{H}2+ -implantation is linear with increasing implantation temperature. The absorption coefficient of GaN epitaxial films increases with increasing ion dose, leading to the decrease in Raman scattering spectra of Ga-N vibration. With increasing implantation doses up to 5   ×   1016 \\text{H}2+  cm-2, nanoscale hydrogen bubbles are observed in the H deposition peak region. Interstitial-type dislocation loops are observed in the damaged layer located near the damage peak region, and the geometry of the dislocation loops produced by H implantation is analyzed. The surface layer is almost free of lattice disorder induced by \\text{H}2+ -implantation.

Structural modifications of silicon-implanted GaAs induced by the athermal annealing technique

NASA Astrophysics Data System (ADS)

Qadri, S. B.; Yousuf, M.; Kendziora, C. A.; Nachumi, B.; Fischer, R.; Grun, J.; Rao, M. V.; Tucker, J.; Siddiqui, S.; Ridgway, M. C.

2004-12-01

We have used high-resolution X-ray diffraction and Raman spectroscopy to investigate structural modifications inside and outside the focal region of Si-implanted GaAs samples that have been irradiated at high power by a focused short-pulse laser. Si atoms implanted into the GaAs matrix generate exciton-induced local lattice expansion, resulting in a satellite on the lower-angle side of the Bragg peak. After the laser pulse irradiation, surface features inside and outside the focal spot suggest the presence of Bernard convection cells, indicating that a rapid melting and re-crystallization has taken place. Moreover, the laser irradiation induces a compressive strain inside the focal spot, since the satellite appears on the higher-angle side of the Bragg peak. The stress maximizes at the center of the focal spot and extends far outside the irradiated area (approximately 2.5-mm away from the bull’s eye), suggesting the propagation of a laser-induced mechanical wave. The maximum compressive stress inside the focal spot corresponds to 2.7 GPa. Raman spectra inside the focal spot resemble that of pristine GaAs, indicating that rapid melting has introduced significant heterogeneity, with zones of high and low Si concentration. X-ray measurements indicate that areas inside the focal spot and annealed areas outside of the focal spot contain overtones of a minor tetragonal distortion of the lattice, consistent with the observed relaxation of Raman selection rules when compared with the parent zinc-blende structure.

Determination of metallic traces in kidneys, livers, lungs and spleens of rats with metallic implants after a long implantation time.

PubMed

Rubio, Juan Carlos; Garcia-Alonso, Maria Cristina; Alonso, Concepcion; Alobera, Miguel Angel; Clemente, Celia; Munuera, Luis; Escudero, Maria Lorenza

2008-01-01

Metallic transfer from implants does not stop at surrounding tissues, and metallic elements may be transferred by proteins to become lodged in organs far from the implant. This work presents an in vivo study of metallic implant corrosion to measure metallic element accumulation in organs located far from the implant, such as kidneys, livers, lungs and spleens. The studied metallic implant materials were CoCr alloy, Ti, and the experimental alloy MA956 coated with alpha-alumina. The implants were inserted in the hind legs of Wistar rats. Analysis for Co, Cr, Ti and Al metallic traces was performed after a long exposure time of 12 months by Inductively Coupled Plasma (ICP) with Mass Spectrometry (MS). According to the results, the highest Cr and Ti concentrations were detected in spleens. Co is mainly found in kidneys, since this element is eliminated via urine. Cr and Ti traces increased significantly in rat organs after the long implantation time. The organs of rats implanted with the alpha-alumina coated experimental MA956 did not present any variation in Al content after 12 months, which means there was no degradation of the alumina layer surface.

Effects of thermal annealing on the structural and optical properties of carbon-implanted SiO2.

PubMed

Poudel, P R; Paramo, J A; Poudel, P P; Diercks, D R; Strzhemechny, Y M; Rout, B; McDaniel, F D

2012-03-01

Amorphous carbon (a-C) nanoclusters were synthesized by the implantation of carbon ions (C-) into thermally grown silicon dioxide film (-500 nm thick) on a Si (100) wafer and processed by high temperature thermal annealing. The carbon ions were implanted with an energy of 70 keV at a fluence of 5 x 10(17) atoms/cm2. The implanted samples were annealed at 1100 degrees C for different time periods in a gas mixture of 96% Ar+4% H2. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and High Resolution Transmission Electron Microscopy (HRTEM) were used to study the structural properties of both the as-implanted and annealed samples. HRTEM reveals the formation of nanostructures in the annealed samples. The Raman spectroscopy also confirms the formation of carbon nano-clusters in the samples annealed for 10 min, 30 min, 60 min and 90 min. No Raman features originating from the carbon-clusters are observed for the sample annealed further to 120 min, indicating a complete loss of implanted carbon from the SiO2 layer. The loss of the implanted carbon in the 120 min annealed sample from the SiO2 layer was also observed in the XPS depth profile measurements. Room temperature photoluminescence (PL) spectroscopy revealed visible emissions from the samples pointing to carbon ion induced defects as the origin of a broad 2.0-2.4 eV band, and the intrinsic defects in SiO2 as the possible origin of the -2.9 eV bands. In low temperature photoluminescence spectra, two sharp and intense photoluminescence lines at -3.31 eV and -3.34 eV appear for the samples annealed for 90 min and 120 min, whereas no such bands are observed in the samples annealed for 10 min, 30 min, and 60 min. The Si nano-clusters forming at the Si-SiO2 interface could be the origin of these intense peaks.

Detection of Structural Abnormalities Using Neural Nets

NASA Technical Reports Server (NTRS)

Zak, M.; Maccalla, A.; Daggumati, V.; Gulati, S.; Toomarian, N.

1996-01-01

This paper describes a feed-forward neural net approach for detection of abnormal system behavior based upon sensor data analyses. A new dynamical invariant representing structural parameters of the system is introduced in such a way that any structural abnormalities in the system behavior are detected from the corresponding changes to the invariant.

The potential of isotopically enriched magnesium to study bone implant degradation in vivo.

PubMed

Draxler, Johannes; Martinelli, Elisabeth; Weinberg, Annelie M; Zitek, Andreas; Irrgeher, Johanna; Meischel, Martin; Stanzl-Tschegg, Stefanie E; Mingler, Bernhard; Prohaska, Thomas

2017-03-15

This pilot study highlights the substantial potential of using isotopically enriched (non-radioactive) metals to study the fate of biodegradable metal implants. It was possible to show that magnesium (Mg) release can be observed by combining isotopic mass spectrometry and isotopic pattern deconvolution for data reduction, even at low amounts of Mg released a from slowly degrading 26 Mg enriched (>99%) Mg metal. Following implantation into rats, structural in vivo changes were monitored by μCT. Results showed that the applied Mg had an average degradation rate of 16±5μmyear -1 , which corresponds with the degradation rate of pure Mg. Bone and tissue extraction was performed 4, 24, and 52weeks after implantation. Bone cross sections were analyzed by laser ablation inductively coupled plasma mass spectrometry (ICP-MS) to determine the lateral 26 Mg distribution. The 26 Mg/ 24 Mg ratios in digested tissue and excretion samples were analyzed by multi collector ICP-MS. Isotope pattern deconvolution in combination with ICP-MS enabled detection of Mg pin material in amounts as low as 200ppm in bone tissues and 20ppm in tissues up to two fold increased Mg levels with a contribution of pin-derived Mg of up to 75% (4weeks) and 30% (24weeks) were found adjacent to the implant. After complete degradation, no visual bone disturbance or residual pin-Mg could be detected in cortical bone. In organs, increased Δ 26 Mg/ 24 Mg values up to 16‰ were determined compared to control samples. Increased Δ 26 Mg/ 24 Mg values were detected in serum samples at a constant total Mg level. In contrast to urine, feces did not show a shift in the 26 Mg/ 24 Mg ratios. This investigation showed that the organism is capable of handling excess Mg well and that bones fully recover after degradation. Magnesium alloys as bone implants have faced increasing attention over the past years. In vivo degradation and metabolism studies of these implant materials have shown the promising application in

Influence of Palatal Coverage and Implant Distribution on Implant Strain in Maxillary Implant Overdentures.

PubMed

Takahashi, Toshihito; Gonda, Tomoya; Mizuno, Yoko; Fujinami, Yozo; Maeda, Yoshinobu

2016-01-01

Maxillary implant overdentures are often used in clinical practice. However, there is no agreement or established guidelines regarding prosthetic design or optimal implant placement configuration. The purpose of this study was to examine the influence of palatal coverage and implant number and distribution in relation to impact strain under maxillary implant overdentures. A maxillary edentulous model with implants and experimental overdentures with and without palatal coverage was fabricated. Four strain gauges were attached to each implant, and they were positioned in the anterior, premolar, and molar areas. A vertical occlusal load of 98 N was applied through a mandibular complete denture, and the implant strains were compared using one-way analysis of variance (P = .05). The palatolabial strain was much higher on anterior implants than on other implants in both denture types. Although there was no significant difference between the strain under dentures with and without palatal coverage, palateless dentures tended to result in higher implant strain than dentures with palatal coverage. Dentures supported by only two implants registered higher strain than those supported by four or six implants. Implants under palateless dentures registered higher strain than those under dentures with palatal coverage. Anterior implants exhibited higher palatolabial strain than other implants regardless of palatal coverage and implant configuration; it is therefore recommended that maxillary implant overdentures should be supported by six implants with support extending to the distal end of the arch.

A novel bioerodible deep scleral lamellar cyclosporine implant for uveitis.

PubMed

Gilger, Brian C; Salmon, Jacklyn H; Wilkie, David A; Cruysberg, Lars P J; Kim, Jonghyeon; Hayat, Matt; Kim, Hyuncheol; Kim, Stephanie; Yuan, Peng; Lee, Susan S; Harrington, Susan M; Murray, Patrick R; Edelhauser, Henry F; Csaky, Karl G; Robinson, Michael R

2006-06-01

To determine the feasibility, safety, and effectiveness of an episcleral or deep scleral lamellar sustained release cyclosporine (CsA) device in a naturally occurring animal model of uveitis. A two-compartment perfusion chamber was used to assess in vitro human and equine scleral permeability of fluorescein, dexamethasone-fluorescein, or CsA. A biodegradable, matrix-reservoir CsA implant was designed, and release rates of CsA were determined in vitro. Tissue CsA levels were measured in eyes with the implant. Horses with equine recurrent uveitis (ERU) received episcleral or deep scleral lamellar CsA implants and were monitored for up to 3 years. Dexamethasone-fluorescein and CsA penetrated the in vitro equine sclera poorly; however, low but detectable levels of CsA were detected intraocularly in vivo. The implant placed episclerally failed to control inflammatory episodes in ERU. CsA implants placed in the deep sclera adjacent to the suprachoroidal space resulted in high levels of CsA in most ocular tissues. In clinical equine patients with ERU, frequency of uveitic flare-ups was significantly decreased after implantation of a deep scleral lamellar CsA implant. Diffusion of CsA across the sclera from the episcleral space was not a feasible method of drug delivery to the equine eye. However, placing a deep scleral lamellar CsA implant adjacent to the suprachoroidal space was effective in achieving therapeutic ocular drug concentrations and controlling uveitis in horses with ERU.

Trans-Oval-Window Implants, A New Approach for Drug Delivery to the Inner Ear: Extended Dexamethasone Release From Silicone-based Implants.

PubMed

Sircoglou, Julie; Gehrke, Maria; Tardivel, Meryem; Siepmann, Florence; Siepmann, Juergen; Vincent, Christophe

2015-09-01

The purpose of this study was to develop a new strategy to deliver drugs to the inner ear from dexamethasone (DXM)-loaded silicone implants and to evaluate the distribution of the drug in the cochlea with confocal microscopy. Systemic drug administration for the treatment of inner ear disorders is tricky because of the blood-cochlear barrier, a difficult anatomical access, the small size of the cochlea, and can cause significant adverse effects. An effective way to overcome these obstacles is to administer drugs locally. In vitro, the drug release from DXM-loaded silicone-based thin films and tiny implants into artificial perilymph was thoroughly analyzed by high-performance liquid chromatography. In vivo, a silicone implant loaded with 10% DXM and 5% polyethylene glycol 400 was implanted next to the stapes's footplate of gerbils. Delivery of DXM into the inner ear was proved by confocal microscopy imaging of the whole cochlea and the organ of Corti. The study showed a continuous and prolonged release during 90 days in vitro. This was confirmed by confocal microscopy that allowed detection of DXM by fluorescence labeling in the cell body of the hair cells for at least 30 days. Interestingly, fluorescence was already observed after 20 minutes of implantation, reached a climax at day 7, and could still be detected 30 days after implantation. Thus, we developed a new device for local corticosteroids delivery into the oval window with an extended drug release of DXM to the inner ear.

Role of clinician's experience and implant design on implant stability. An ex vivo study in artificial soft bones.

PubMed

Romanos, Georgios E; Basha-Hijazi, Abdulaziz; Gupta, Bhumija; Ren, Yan-Fang; Malmstrom, Hans

2014-04-01

Clinical experience in implant placement is important in order to prevent implant failures. However, the implant design affects the primary implant stability (PS) especially in poor quality bones. Therefore, the aim of this study was to compare the effect of clinician surgical experience on PS, when placing different type of implant designs. A total of 180 implants (90 parallel walled-P and 90 tapered-T) were placed in freshly slaughtered cow ribs. Bone quality was evaluated by two examiners during surgery and considered as 'type IV' bone. Implants (ø 5 mm, length: 15 mm, Osseotite, BIOMET 3i, Palm Beach Gardens, FL, USA) were placed by three different clinicians (master/I, good/II, non-experienced/III, under direct supervision of a manufacturer representative; 30 implants/group). An independent observer assessed the accuracy of placement by resonance frequency analysis (RFA) with implant stability quotient (ISQ) values. Two-way analysis of variance (ANOVA) and Tukey's post hoc test were used to detect the surgical experience of the clinicians and their interaction and effects of implant design on the PS. All implants were mechanically stable. The mean ISQ values were: 49.57(± 18.49) for the P-implants and 67.07(± 8.79) for the T-implants. The two-way ANOVA showed significant effects of implant design (p < .0001), clinician (p < .0001), and their interaction (p < .0001). The Tukey's multiple comparison test showed significant differences in RFA for the clinician group I/II (p = .015) and highly significant (p < .0001) between I/III and II/III. The P-implants presented (for I, II, and III) mean ISQ values 31.25/49.18/68.17 and the T-implants showed higher ISQ values, 70.15/62.08/68.98, respectively. Clinicians I and II did not show extreme differences for T-implants (p = .016). In contrast, clinician III achieved high ISQ values using P- and T-implants following the exact surgical protocol based on the manufacturer guidelines. T-implants

Intracapsular implant rupture: MR findings of incomplete shell collapse.

PubMed

Soo, M S; Kornguth, P J; Walsh, R; Elenberger, C; Georgiade, G S; DeLong, D; Spritzer, C E

1997-01-01

The objective of this study was to determine the frequency and significance of the MR findings of incomplete shell collapse for detecting implant rupture in a series of surgically removed breast prostheses. MR images of 86 breast implants in 44 patients were studied retrospectively and correlated with surgical findings at explantation. MR findings included (a) complete shell collapse (linguine sign), 21 implants; (b) incomplete shell collapse (subcapsular line sign, teardrop sign, and keyhole sign), 33 implants; (c) radial folds, 31 implants; and (d) normal, 1 implant. The subcapsular line sign was seen in 26 implants, the teardrop sign was seen in 27 implants, and the keyhole sign was seen in 23 implants. At surgery, 48 implants were found to be ruptured and 38 were intact. The MR findings of ruptured implants showed signs of incomplete collapse in 52% (n = 25), linguine sign in 44% (n = 21), and radial folds in 4% (n = 2). The linguine sign perfectly predicted implant rupture, but sensitivity was low. Findings of incomplete shell collapse improved sensitivity and negative predictive values, and the subcapsular line sign produced a significant incremental increase in predictive ability. MRI signs of incomplete shell collapse were more common than the linguine sign in ruptured implants and are significant contributors to the high sensitivity and negative predictive values of MRI for evaluating implant integrity.

Acidification of uterine epithelium during embryo implantation in mice†

PubMed Central

Xiao, Shuo; Li, Rong; El Zowalaty, Ahmed E.; Diao, Honglu; Zhao, Fei; Choi, Yongwon; Ye, Xiaoqin

2017-01-01

Abstract Uterine luminal epithelium (LE) is essential for establishing uterine receptivity. Previous microarray analysis revealed upregulation of Atp6v0d2 in gestation day 4.5 (D4.5) LE in mice. Realtime PCR showed upregulation of uterine Atp6v0d2 starting right before embryo attachment ∼D4.0. In situ hybridization demonstrated specific uterine localization of Atp6v0d2 in LE upon embryo implantation. Atp6v0d2 encodes one subunit for vacuolar-type H+-ATPase (V-ATPase), which regulates acidity of intracellular organelles and extracellular environment. LysoSensor Green DND-189 detected acidic signals in LE and glandular epithelium upon embryo implantation, correlating with Atp6v0d2 upregulation in early pregnant uterus. Atp6v0d2−/− females had significantly reduced implantation rate and marginally reduced delivery rate from first mating only, but comparable number of implantation sites and litter size compared to control and comparable fertility to control from subsequent matings, suggesting a nonessential role of Atp6v0d2 subunit in embryo implantation. Successful implantation in both control and Atp6v0d2−/− females was associated with uterine epithelial acidification. No significant compensatory upregulation of Atp6v0d1 mRNA was detected in D4.5 Atp6v0d2−/− uteri. To determine the role of V-ATPase instead of a single subunit in embryo implantation, a specific V-ATPase inhibitor bafilomycin A1 (2.5 μg/kg) was injected via uterine fat pad on D3 18:00 h. This treatment resulted in reduced uterine epithelial acidification, delayed implantation, and reduced number of implantation sites. It also suppressed oil-induced artificial decidualization. These data demonstrate uterine epithelial acidification as a novel phenomenon during embryo implantation and V-ATPase is involved in uterine epithelial acidification and uterine preparation for embryo implantation. PMID:28395338

Biomaterial-host interactions: consequences, determined by implant retrieval analysis.

PubMed

Kaplan, S S

1994-01-01

Prosthetic biomaterials have had a profound impact on reconstructive surgery but complete biocompatability remains illusive. This review considers the retrieval analysis of four common prosthetic structures: the hip, the knee, heart valves, and blood vessels. We show that despite a fine record of early success, deterioration due to mechanical failure or deleterious host responses to the implant may compromise long term function. The eventual retrieval and detailed analysis of implanted structures provides an invaluable opportunity to determine the characteristics of implant success or failure and to provoke the development of still better materials.

Overdentures on implants placed in bone augmented with fresh frozen bone.

PubMed

Rigo, L; Viscioni, A; Franco, M; Lucchese, A; Zollino, I; Brunelli, G; Carinci, F

2011-01-01

In the last decade several studies have been performed to evaluate the clinical outcome of one or two stage loaded implants supporting overdentures. Since fresh frozen bone (FFB) has an ever-increasing number of clinical applications and few reports are available on implants inserted into FFB, we performed a retrospective study on fixtures inserted in FFB and bearing overdentures. In the period between December 2003 and December 2006, 17 patients (14 females and 3 males with a median age of about 56 years) were grafted and 60 implants inserted thereafter. A total of 17 overdentures were delivered: 8 in the mandible and 9 in the maxilla. Multiple implant systems were used: 22 Double etched, 7 SLA, 9 Anodic oxidized, and 22 CaPo4 ceramic-blasted. Implant diameter ranged from 3.25 to 4.3 mm and length from 11.5 to 16.0 mm. Implants were inserted to replace 23 incisors, 9 cuspids, 20 premolars and 8 molars. No implants were lost (i.e., survival rate=100%) and no differences were detected among the studied variables. Kaplan Meier algorithm and Cox regression did not reveal any statistical differences among the studied variables also as regards the success rate. Implants inserted FFB and bearing overdentures have a high survival rate and success rates, which are comparable to those of implants inserted in non-grafted bone. FFB bone is a reliable material for alveolar ridge augmentation. No difference was detected among removable prostheses supported by two or more implants.

Design of a Biorthogonal Wavelet Transform Based R-Peak Detection and Data Compression Scheme for Implantable Cardiac Pacemaker Systems.

PubMed

Kumar, Ashish; Kumar, Manjeet; Komaragiri, Rama

2018-04-19

Bradycardia can be modulated using the cardiac pacemaker, an implantable medical device which sets and balances the patient's cardiac health. The device has been widely used to detect and monitor the patient's heart rate. The data collected hence has the highest authenticity assurance and is convenient for further electric stimulation. In the pacemaker, ECG detector is one of the most important element. The device is available in its new digital form, which is more efficient and accurate in performance with the added advantage of economical power consumption platform. In this work, a joint algorithm based on biorthogonal wavelet transform and run-length encoding (RLE) is proposed for QRS complex detection of the ECG signal and compressing the detected ECG data. Biorthogonal wavelet transform of the input ECG signal is first calculated using a modified demand based filter bank architecture which consists of a series combination of three lowpass filters with a highpass filter. Lowpass and highpass filters are realized using a linear phase structure which reduces the hardware cost of the proposed design approximately by 50%. Then, the location of the R-peak is found by comparing the denoised ECG signal with the threshold value. The proposed R-peak detector achieves the highest sensitivity and positive predictivity of 99.75 and 99.98 respectively with the MIT-BIH arrhythmia database. Also, the proposed R-peak detector achieves a comparatively low data error rate (DER) of 0.002. The use of RLE for the compression of detected ECG data achieves a higher compression ratio (CR) of 17.1. To justify the effectiveness of the proposed algorithm, the results have been compared with the existing methods, like Huffman coding/simple predictor, Huffman coding/adaptive, and slope predictor/fixed length packaging.

Preventing Bacterial Infections using Metal Oxides Nanocoatings on Bone Implant

NASA Astrophysics Data System (ADS)

Duceac, L. D.; Straticiuc, S.; Hanganu, E.; Stafie, L.; Calin, G.; Gavrilescu, S. L.

2017-06-01

Nowadays bone implant removal is caused by infection that occurs around it possibly acquired after surgery or during hospitalization. The purpose of this study was to reveal some metal oxides applied as coatings on bone implant thus limiting the usual antibiotics-resistant bacteria colonization. Therefore ZnO, TiO2 and CuO were synthesized and structurally and morphologically analized in order to use them as an alternative antimicrobial agents deposited on bone implant. XRD, SEM, and FTIR characterization techniques were used to identify structure and texture of these nanoscaled metal oxides. These metal oxides nanocoatings on implant surface play a big role in preventing bacterial infection and reducing surgical complications.

Systemic levels of metallic ions released from orthodontic mini-implants.

PubMed

de Morais, Liliane Siqueira; Serra, Glaucio Guimarães; Albuquerque Palermo, Elisabete Fernandes; Andrade, Leonardo Rodrigues; Müller, Carlos Alberto; Meyers, Marc André; Elias, Carlos Nelson

2009-04-01

Orthodontic mini-implants are a potential source of metallic ions to the human body because of the corrosion of titanium (Ti) alloy in body fluids. The purpose of this study was to gauge the concentration of Ti, aluminum (Al), and vanadium (V), as a function of time, in the kidneys, livers, and lungs of rabbits that had Ti-6Al-4V alloy orthodontic mini-implants placed in their tibia. Twenty-three New Zealand rabbits were randomly divided into 4 groups: control, 1 week, 4 weeks, and 12 weeks. Four orthodontic mini-implants were placed in the left proximal tibia of 18 rabbits. Five control rabbits had no orthodontic mini-implants. After 1, 4, and 12 weeks, the rabbits were killed, and the selected tissues were extracted and prepared for analysis by graphite furnace atomic absorption spectrophotometry. Low amounts of Ti, Al, and V were detectable in the 1-week, 4-weeks, and 12-weeks groups, confirming that release of these metals from the mini-implants occurs, with diffusion and accumulation in remote organs. Despite the tendency of ion release when using the Ti alloy as orthodontic mini-implants, the amounts of metals detected were significantly below the average intake of these elements through food and drink and did not reach toxic concentrations.

Study on the neotype zirconia's implant coated nanometer hydroxyapatite ceramics

NASA Astrophysics Data System (ADS)

Zhu, J. W.; Yang, D. W.

2007-07-01

In recent years, biologic ceramics is a popular material of implants and bioactive surface modification of dental implant became a research emphasis, which aims to improve bioactivity of implants materials and acquire firmer implants-bone interface. The zirconia ceramic has excellent mechanical properties and nanometer HA ceramics is a bioceramic well known for its bioactivity, therefore, nanometer HA ceramics coating on zirconia, allows combining the excellent mechanical properties of zirconia substrates with its bioactivity. This paper shows a new method for implant shape design and bioactive modification of dental implants surface. Zirconia's implant substrate was prepared by sintered method, central and lateral tunnels were drilled in the zirconia hollow porous cylindrical implants by laser processing. The HA powders and needle-like HA crystals were made by a wet precipitation and calcining method. Its surface was coated with nanometer HA ceramics which was used brush HA slurry and vacuum sintering. Mechanical testing results revealed that the attachment strength of nanometer HA ceramics coated zirconia samples is high. SEM and interface observation after inserted experiment indicated that calcium and phosphor content increased and symmetrically around coated implant-bone tissue interface. A significantly higher affinity index was demonstrated in vivo by histomorphometric evaluation in coated versus uncoated implants. SEM analysis demonstrated better bone adhesion to the material in coated implant at any situation. In addition, the hollow porous cylindrical implant coated with nanometer HA ceramics increase the interaction of bone and implant, the new bone induced into the surface of hollow porous cylindrical implant and through the most tunnels filled into central hole. The branch-like structure makes the implant and bone a body, which increased the contact area and decreased elastic ratio. Therefore, the macroscopical and microcosmic nested structure of

Nondestructive Structural Damage Detection in Flexible Space Structures Using Vibration Characterization

NASA Technical Reports Server (NTRS)

Ricles, James M.

1991-01-01

Spacecraft are susceptible to structural damage over their operating life from impact, environmental loads, and fatigue. Structural damage that is not detected and not corrected may potentially cause more damage and eventually catastrophic structural failure. NASA's current fleet of reusable spacecraft, namely the Space Shuttle, has been flown on several missions. In addition, configurations of future NASA space structures, e.g. Space Station Freedom, are larger and more complex than current structures, making them more susceptible to damage as well as being more difficult to inspect. Consequently, a reliable structural damage detection capability is essential to maintain the flight safety of these structures. Visual inspections alone can not locate impending material failure (fatigue cracks, yielding); it can only observe post-failure situations. An alternative approach is to develop an inspection and monitoring system based on vibration characterization that assesses the integrity of structural and mechanical components. A methodology for detecting structural damage is presented. This methodology is based on utilizing modal test data in conjunction with a correlated analytical model of the structure to: (1) identify the structural dynamic characteristics (resonant frequencies and mode shapes) from measurements of ambient motions and/or force excitation; (2) calculate modal residual force vectors to identify the location of structural damage; and (3) conduct a weighted sensitivity analysis in order to assess the extent of mass and stiffness variations, where structural damage is characterized by stiffness reductions. The approach is unique from other existing approaches in that varying system mass and stiffness, mass center locations, the perturbation of both the natural frequencies and mode shapes, and statistical confidence factors for structural parameters and experimental instrumentation are all accounted for directly.

Silicone gel breast implants: science and testing.

PubMed

Kinney, Brian M; Jeffers, Lynn L C; Ratliff, Gregory E; Carlisle, Dan A

2014-07-01

Since the first generation of breast implants, major design innovations, including consistency of the gel, palpability and thickness of the shell, and barrier materials in the shell, have been introduced. Surgeons have not had metrics to assess and compare available implants. Research at independent laboratories included 4 tests: gel elasticity (the gel's ability to retain its shape), gel compression fracture (the resistance to permanent gel deformation), gel-shell peel (the integration of the gel with shell as a cohesive unit), and morphological analysis. Sientra's round High-Strength Cohesive (HSC) experienced the least gel elasticity (5.805 mm), whereas Allergan's round implants experienced the most (7.465 mm). Among shaped implants, Allergan 410 experienced the least gel elasticity (3.242 mm), whereas the Sientra HSC+ implant experienced the most (4.270 mm). Sientra's round (36.32 lbf) and shaped (44.16 lbf) implants demonstrated the highest resistance to gel fracture, with Allergan's implants demonstrating the least among round (23.06 lbf) implants and Mentor Contour Profile Gel (CPG) among shaped (30.45 lbf) implants. For the gel-shell peel test, Sientra's implant required over 26% greater force than Allergan's implant and over 35% greater force than Mentor's implant. Sientra's shaped implants required more than double the peel force than Allergan 410 (119% greater) and Mentor CPG (130% greater). Morphological results showed Sientra's implants preserved structural integrity (-1.10% change). The initial findings show that these implant characteristics are individual factors to be considered separately and are not necessarily correlative. Further study of implants using these and other testing techniques will help clinicians choose between implants.

Development and testing of an algorithm to detect implantable cardioverter-defibrillator lead failure.

PubMed

Gunderson, Bruce D; Gillberg, Jeffrey M; Wood, Mark A; Vijayaraman, Pugazhendhi; Shepard, Richard K; Ellenbogen, Kenneth A

2006-02-01

Implantable cardioverter-defibrillator (ICD) lead failures often present as inappropriate shock therapy. An algorithm that can reliably discriminate between ventricular tachyarrhythmias and noise due to lead failure may prevent patient discomfort and anxiety and avoid device-induced proarrhythmia by preventing inappropriate ICD shocks. The goal of this analysis was to test an ICD tachycardia detection algorithm that differentiates noise due to lead failure from ventricular tachyarrhythmias. We tested an algorithm that uses a measure of the ventricular intracardiac electrogram baseline to discriminate the sinus rhythm isoelectric line from the right ventricular coil-can (i.e., far-field) electrogram during oversensing of noise caused by a lead failure. The baseline measure was defined as the product of the sum (mV) and standard deviation (mV) of the voltage samples for a 188-ms window centered on each sensed electrogram. If the minimum baseline measure of the last 12 beats was <0.35 mV-mV, then the detected rhythm was considered noise due to a lead failure. The first ICD-detected episode of lead failure and inappropriate detection from 24 ICD patients with a pace/sense lead failure and all ventricular arrhythmias from 56 ICD patients without a lead failure were selected. The stored data were analyzed to determine the sensitivity and specificity of the algorithm to detect lead failures. The minimum baseline measure for the 24 lead failure episodes (0.28 +/- 0.34 mV-mV) was smaller than the 135 ventricular tachycardia (40.8 +/- 43.0 mV-mV, P <.0001) and 55 ventricular fibrillation episodes (19.1 +/- 22.8 mV-mV, P <.05). A minimum baseline <0.35 mV-mV threshold had a sensitivity of 83% (20/24) with a 100% (190/190) specificity. A baseline measure of the far-field electrogram had a high sensitivity and specificity to detect lead failure noise compared with ventricular tachycardia or fibrillation.

Ion-implanted epitaxially grown ZnSe

NASA Technical Reports Server (NTRS)

Chernow, F.

1975-01-01

The use of ZnSe to obtain efficient, short wavelength injection luminescence was investigated. It was proposed that shorter wavelength emission and higher efficiency be achieved by employing a p-i-n diode structure rather than the normal p-n diode structure. The intervening i layer minimizes concentration quenching effects and the donor-acceptor pair states leading to long wavelength emission. The surface p layer was formed by ion implantation; implantation of the i layer rather than the n substrate permits higher, uncompensated p-type doping. An ion implanted p-n junction in ZnSe is efficiency-limited by high electron injection terminating in nonradiative recombination at the front surface, and by low hole injection resulting from the inability to obtain high conductivity p-type surface layers. While the injection ratio in p-n junctions was determined by the radio of majority carrier concentrations, the injection ratio in p-i-n structures was determined by the mobility ratios and/or space charge neutrality requirements in the i layer.

Structural Damage Detection Using Virtual Passive Controllers

NASA Technical Reports Server (NTRS)

Lew, Jiann-Shiun; Juang, Jer-Nan

2001-01-01

This paper presents novel approaches for structural damage detection which uses the virtual passive controllers attached to structures, where passive controllers are energy dissipative devices and thus guarantee the closed-loop stability. The use of the identified parameters of various closed-loop systems can solve the problem that reliable identified parameters, such as natural frequencies of the open-loop system may not provide enough information for damage detection. Only a small number of sensors are required for the proposed approaches. The identified natural frequencies, which are generally much less sensitive to noise and more reliable than the identified natural frequencies, are used for damage detection. Two damage detection techniques are presented. One technique is based on the structures with direct output feedback controllers while the other technique uses the second-order dynamic feedback controllers. A least-squares technique, which is based on the sensitivity of natural frequencies to damage variables, is used for accurately identifying the damage variables.

The bacterial sealing capacity of morse taper implant-abutment systems in vitro.

PubMed

Ranieri, Rogerio; Ferreira, Andreia; Souza, Emmanuel; Arcoverde, Joao; Dametto, Fabio; Gade-Neto, Cicero; Seabra, Flavio; Sarmento, Carlos

2015-05-01

The use of Morse taper systems in dental implantology has been associated widely with a more precise adaptation between implants and their respective abutments. This may lead to an increase in the stability of the implant system and may also prevent microbial invasion through the implant-abutment interface. The aim of this study was to investigate in vitro the ability of four commercially available Morse taper system units to impede bacterial penetration through their implant-abutment interfaces. Abutments were screwed onto the implants, and the units were subsequently immersed in Streptococcus sanguinis bacterial broth (1 × 10(8) colony forming units/mL) for 48 hours. The units were examined by scanning electron microscopy (SEM) under three conditions: 1) with the implant-abutment components assembled as units to investigate for both the existence of microgaps and the presence of bacteria; 2) with the implants and abutments separated for examination of internal surfaces; and 3) with the implant-abutment components again assembled as units to measure any microgaps detected. The mean size of the microgaps in each unit was determined by measuring, under SEM, their width in four equidistant points. Microgaps were detected in all units with no significant differences in dimension (Kruskal-Wallis test, P >0.05). Within all units, the presence of bacteria was also observed. The seals provided by the interfaces of the commercially available Morse taper implant-abutment units tested were not sufficiently small to shield the implant from bacterial penetration.

PIP breast implants: rupture rate and correlation with breast cancer.

PubMed

Moschetta, M; Telegrafo, M; Cornacchia, I; Vincenti, L; Ranieri, V; Cirili, A; Rella, L; Stabile Ianora, A A; Angelelli, G

2014-01-01

To evaluate the incidence of Poly Implant Prosthése (PIP) rupture as assessed by magnetic resonance imaging (MRI), the prevalence of the detected signs and the potential correlation with breast carcinoma. 67 patients with silicone breast implants and clinical indications for breast MRI were evaluated for a total of 125 implants: 40 (32%) PIP in 21 patients and 85 non-PIP in 46 patients (68%), the latest considered as control group. A 1.5-T MR imaging device was used in order to assess implant integrity with dedicated sequences and in 6 cases a dynamic study was performed for characterizing breast lesions. Two radiologists with more than 5 years' experience in the field of MRI evaluated in consensus all MR images searching for the presence of clear signs of intra or extra-capsular implant rupture. 20/40 (50%) PIP implants presented signs of intra-capsular rupture: linguine sign in 20 cases (100%), tear-drop sign in 6 (30%). In 12/20 cases (60%), MRI signs of extra-capsular rupture were detected. In the control group, an intra-capsular rupture was diagnosed in 12/85 cases (14%) associated with extra-capsular one in 5/12 cases (42%). Among the six cases with suspected breast lesions, in 2/21 patients with PIP implants (10%) a breast carcinoma was diagnosed (mucinous carcinoma, n=1; invasive ductal carcinoma, n=1). In 4/46 patients (9%) with non-PIP implants, an invasive ductal carcinoma was diagnosed. The rupture rate of PIP breast implants is significantly higher than non-PIP (50% vs 14%). MRI represents the most accurate imaging tool for evaluating breast prostheses and the linguine sign is the most common MRI sign to be searched. The incidence of breast carcinoma does not significantly differ between the PIP and non-PIP implants and a direct correlation with breast cancer can not been demonstrated.

Integration of an Axcelis Optima HD Single Wafer High Current Implanter for p- and n-S/D Implants in an Existing Batch Implanter Production Line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmeide, Matthias; Kontratenko, Serguei; Krimbacher, Bernhard

2008-11-03

This paper is focused on the integration and qualification of an Axcelis Optima HD single wafer high current spot beam implanter in an existing 200 mm production line with different types of Axcelis batch implanters for high current applications. Both the design of the beamline and the beam shape are comparable between single wafer and batch high current spot beam implanters. In contrast to the single wafer high current ribbon beam implanter, energy contamination is not a concern for the considered spot beam tool because the drift mode can be used down to energies in the 2 keV region. Themore » most important difference between single wafer and batch high current implanters is the significantly higher dose rate and, therefore, the higher damage rate for the single wafer tool due to the different scanning architecture. The results of the integration of high dose implantations, mainly for p- and n-S/D formation, for DRAM 110 nm without pre-amorphization implantation (PAI), CMOS Logic from around 250 nm down to 90 nm without and with PAI, are presented and discussed. Dopant concentration profile analysis using SIMS was performed for different technologies and implantation conditions. The impurity activation was measured using sheet resistance and in some cases spreading resistance technique was applied. The amorphous layer thickness was measured using TEM. Finally, device data are presented in combination with dose, energy and beam current variations. The results have shown that the integration of implantation processes into crystalline structure without PAI is more complex and time consuming than implantations into amorphous layer where the damage difference due to the different dose rates is negligible.« less

Capacitive Feedthroughs for Medical Implants

PubMed Central

Grob, Sven; Tass, Peter A.; Hauptmann, Christian

2016-01-01

Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging. PMID:27660602

Capacitive Feedthroughs for Medical Implants.

PubMed

Grob, Sven; Tass, Peter A; Hauptmann, Christian

2016-01-01

Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging.

Structural impact detection with vibro-haptic interfaces

NASA Astrophysics Data System (ADS)

Jung, Hwee-Kwon; Park, Gyuhae; Todd, Michael D.

2016-07-01

This paper presents a new sensing paradigm for structural impact detection using vibro-haptic interfaces. The goal of this study is to allow humans to ‘feel’ structural responses (impact, shape changes, and damage) and eventually determine health conditions of a structure. The target applications for this study are aerospace structures, in particular, airplane wings. Both hardware and software components are developed to realize the vibro-haptic-based impact detection system. First, L-shape piezoelectric sensor arrays are deployed to measure the acoustic emission data generated by impacts on a wing. Unique haptic signals are then generated by processing the measured acoustic emission data. These haptic signals are wirelessly transmitted to human arms, and with vibro-haptic interface, human pilots could identify impact location, intensity and possibility of subsequent damage initiation. With the haptic interface, the experimental results demonstrate that human could correctly identify such events, while reducing false indications on structural conditions by capitalizing on human’s classification capability. Several important aspects of this study, including development of haptic interfaces, design of optimal human training strategies, and extension of the haptic capability into structural impact detection are summarized in this paper.

[Impact of anchorage implant design factors on its primary stability].

PubMed

Zhang, J N; Lu, H P; Zhong, C

2017-08-09

During the past decade, the anchorage implants have been widely used in the orthodontic treatment. Many scholars have studied the influence of different factors on anchorage implant's primary stability, including anchorage implant's material properties, structural design, surgical procedure, bone condition, loading force's magnitude and direction. This article is to review the influence of anchorage implant's shape, dimension, neck design and thread design on its primary stability.

Troublesome Crystal Structures: Prevention, Detection, and Resolution

PubMed Central

Harlow, Richard L.

1996-01-01

A large number of incorrect crystal structures is being published today. These structures are proving to be a particular problem to those of us who are interested in comparing structural moieties found in the databases in order to develop structure-property relationships. Problems can reside in the input data, e.g., wrong unit cell or low quality intensity data, or in the structural model, e.g., wrong space group or atom types. Many of the common mistakes are, however, relatively easy to detect and thus should be preventable; at the very least, suspicious structures can be flagged, if not by the authors then by the referees and, ultimately, the crystallographic databases. This article describes some of the more common mistakes and their effects on the resulting structures, lists a series of tests that can be used to detect incorrect structures, and makes a strong plea for the publication of higher quality structures. PMID:27805169

Influence of 400 keV carbon ion implantation on structural, optical and electrical properties of PMMA

NASA Astrophysics Data System (ADS)

Arif, Shafaq; Rafique, M. Shahid; Saleemi, Farhat; Sagheer, Riffat; Naab, Fabian; Toader, Ovidiu; Mahmood, Arshad; Rashid, Rashad; Mahmood, Mazhar

2015-09-01

Ion implantation is a useful technique to modify surface properties of polymers without altering their bulk properties. The objective of this work is to explore the 400 keV C+ ion implantation effects on PMMA at different fluences ranging from 5 × 1013 to 5 × 1015 ions/cm2. The surface topographical examination of irradiated samples has been performed using Atomic Force Microscope (AFM). The structural and chemical modifications in implanted PMMA are examined by Raman and Fourier Infrared Spectroscopy (FTIR) respectively. The effects of carbon ion implantation on optical properties of PMMA are investigated by UV-Visible spectroscopy. The modifications in electrical conductivity have been measured using a four point probe technique. AFM images reveal a decrease in surface roughness of PMMA with an increase in ion fluence from 5 × 1014 to 5 × 1015 ions/cm2. The existence of amorphization and sp2-carbon clusterization has been confirmed by Raman and FTIR spectroscopic analysis. The UV-Visible data shows a prominent red shift in absorption edge as a function of ion fluence. This shift displays a continuous reduction in optical band gap (from 3.13 to 0.66 eV) due to formation of carbon clusters. Moreover, size of carbon clusters and photoconductivity are found to increase with increasing ion fluence. The ion-induced carbonaceous clusters are believed to be responsible for an increase in electrical conductivity of PMMA from (2.14 ± 0.06) × 10-10 (Ω-cm)-1 (pristine) to (0.32 ± 0.01) × 10-5 (Ω-cm)-1 (irradiated sample).

Chemical characterization of 4140 steel implanted by nitrogen ions

NASA Astrophysics Data System (ADS)

Niño, E. D. V.; Pinto, J. L.; Dugar-Zhabon, V.; Henao, J. A.

2012-06-01

AISI SAE 4140 steel samples of different surface roughness which are implanted with 20 keV and 30 keV nitrogen ions at a dose of 1017 ions/cm2 are studied. The crystal phases of nitrogen compositions of the implanted samples, obtained with help of an x-ray diffraction method, are confronted with the data reported by the International Centre for Diffraction Data (ICDD) PDF-2. The implantation treatment is realized in high-voltage pulsed discharges at low pressures. The crystal structure of the implanted solid surfaces is analyzed by the x-ray diffraction technique which permits to identify the possible newly formed compounds and to identify any change in the surface structure of the treated samples. A decrease in the intensity of the plane (110), a reduction of the cell unity in values of 2-theta and a diminishing of the crystallite dimensions in comparison with non-implanted samples are observed.

Clinical Management of Implant Prostheses in Patients with Bruxism

PubMed Central

Komiyama, Osamu; Lobbezoo, Frank; De Laat, Antoon; Iida, Takashi; Kitagawa, Tsuyoshi; Murakami, Hiroshi; Kato, Takao; Kawara, Misao

2012-01-01

There is general agreement that excessive stress to the bone-implant interface may result in implant overload and failure. Early failure of the implant due to excessive loading occurs shortly after uncovering the implant. Excess load on a final restoration after successful implant integration can result in physical failure of the implant structure. Many clinicians believe that overload of dental implants is a risk factor for vertical peri-implant bone loss and/or may be detrimental for the suprastructure in implant prostheses. It has been documented that occlusal parafunction, such as, bruxism (tooth grinding and clenching) affects the outcome of implant prostheses, but there is no evidence for a causal relation between the failures and overload of dental implants. In spite of this lack of evidence, often metal restorations are preferred instead of porcelain for patients in whom bruxism is presumed on the basis of tooth wear. The purpose of this paper is to discuss the importance of the occlusal scheme used in implant restorations for implant longevity and to suggest a clinical approach and occlusal materials for implant prostheses in order to prevent complications related to bruxism. PMID:22701484

Peri-implantitis.

PubMed

Schwarz, Frank; Derks, Jan; Monje, Alberto; Wang, Hom-Lay

2018-06-01

This narrative review provides an evidence-based overview on peri-implantitis for the 2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions. A literature review was conducted addressing the following topics: 1) definition of peri-implantitis; 2) conversion from peri-implant mucositis to peri-implantitis, 3) onset and pattern of disease progression, 4) characteristics of peri-implantitis, 5) risk factors/indicators for peri-implantitis, and 6) progressive crestal bone loss in the absence of soft tissue inflammation. 1)Peri-implantitis is a pathological condition occurring in tissues around dental implants, characterized by inflammation in the peri-implant connective tissue and progressive loss of supporting bone. 2)The histopathologic and clinical conditions leading to the conversion from peri-implant mucositis to peri-implantitis are not completely understood. 3)The onset of peri-implantitis may occur early during follow-up and the disease progresses in a non-linear and accelerating pattern. 4a)Peri-implantitis sites exhibit clinical signs of inflammation and increased probing depths compared to baseline measurements. 4b)At the histologic level, compared to periodontitis sites, peri-implantitis sites often have larger inflammatory lesions. 4c)Surgical entry at peri-implantitis sites often reveals a circumferential pattern of bone loss. 5a)There is strong evidence that there is an increased risk of developing peri-implantitis in patients who have a history of chronic periodontitis, poor plaque control skills, and no regular maintenance care after implant therapy. Data identifying "smoking" and "diabetes" as potential risk factors/indicators for peri-implantitis are inconclusive. 5b)There is some limited evidence linking peri-implantitis to other factors such as: post-restorative presence of submucosal cement, lack of peri-implant keratinized mucosa and positioning of implants that make it difficult to perform oral hygiene

Metal elements in tissue with dental peri-implantitis: a pilot study.

PubMed

Fretwurst, Tobias; Buzanich, Guenter; Nahles, Susanne; Woelber, Johan Peter; Riesemeier, Heinrich; Nelson, Katja

2016-09-01

Dental peri-implantitis is characterized by a multifactorial etiology. The role of metal elements as an etiological factor for peri-implantitis is still unclear. The aim of this study was to investigate the incidence of metal elements in bone and mucosal tissues around dental Grade 4 CP titanium implants with signs of peri-implantitis in human patients. In this prospective pilot study, all patients were enrolled consecutively in two study centers. Bone and soft tissue samples of patients with peri-implantitis with indication for explantation were analyzed for the incidence of different elements (Ca, P, Ti, Fe) by means of synchrotron radiation X-ray fluorescence spectroscopy (SRXRF) and polarized light microscopy (PLM). The existence of macrophages and lymphocytes in the histologic specimens was analyzed. Biopsies of 12 patients (seven bone samples, five mucosal samples) were included and analyzed. In nine of the 12 samples (75%), the SRXRF examination revealed the existence of titanium (Ti) and an associated occurrence with Iron (Fe). Metal particles were detected in peri-implant soft tissue using PLM. In samples with increased titanium concentration, lymphocytes were detected, whereas M1 macrophages were predominantly seen in samples with metal particles. Titanium and Iron elements were found in soft and hard tissue biopsies retrieved from peri-implantitis sites. Further histologic and immunohistochemical studies need to clarify which specific immune reaction metal elements/particles induce in dental peri-implant tissue. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Reflectivity modification of polymethylmethacrylate by silicon ion implantation

NASA Astrophysics Data System (ADS)

Hadjichristov, Georgi B.; Ivanov, Victor; Faulques, Eric

2008-05-01

The effect of silicon ion implantation on the optical reflection of bulk polymethylmethacrylate (PMMA) was examined in the visible and near UV. A low-energy (30 and 50 keV) Si + beam at fluences in the range from 10 13 to 10 17 cm -2 was used for ion implantation of PMMA. The results show that a significant enhancement of the reflectivity from Si +-implanted PMMA occurs at appropriate implantation energy and fluence. The structural modifications of PMMA by the silicon ion implantation were characterized by means of photoluminescence and Raman spectroscopy. Formation of hydrogenated amorphous carbon (HAC) layer beneath the surface of the samples was established and the corresponding HAC domain size was estimated.

Comprehensive evaluation of a child with an auditory brainstem implant.

PubMed

Eisenberg, Laurie S; Johnson, Karen C; Martinez, Amy S; DesJardin, Jean L; Stika, Carren J; Dzubak, Danielle; Mahalak, Mandy Lutz; Rector, Emily P

2008-02-01

We had an opportunity to evaluate an American child whose family traveled to Italy to receive an auditory brainstem implant (ABI). The goal of this evaluation was to obtain insight into possible benefits derived from the ABI and to begin developing assessment protocols for pediatric clinical trials. Case study. Tertiary referral center. Pediatric ABI Patient 1 was born with auditory nerve agenesis. Auditory brainstem implant surgery was performed in December, 2005, in Verona, Italy. The child was assessed at the House Ear Institute, Los Angeles, in July 2006 at the age of 3 years 11 months. Follow-up assessment has continued at the HEAR Center in Birmingham, Alabama. Auditory brainstem implant. Performance was assessed for the domains of audition, speech and language, intelligence and behavior, quality of life, and parental factors. Patient 1 demonstrated detection of sound, speech pattern perception with visual cues, and inconsistent auditory-only vowel discrimination. Language age with signs was approximately 2 years, and vocalizations were increasing. Of normal intelligence, he exhibited attention deficits with difficulty completing structured tasks. Twelve months later, this child was able to identify speech patterns consistently; closed-set word identification was emerging. These results were within the range of performance for a small sample of similarly aged pediatric cochlear implant users. Pediatric ABI assessment with a group of well-selected children is needed to examine risk versus benefit in this population and to analyze whether open-set speech recognition is achievable.

Mechanical stresses and amorphization of ion-implanted diamond

NASA Astrophysics Data System (ADS)

Khmelnitsky, R. A.; Dravin, V. A.; Tal, A. A.; Latushko, M. I.; Khomich, A. A.; Khomich, A. V.; Trushin, A. S.; Alekseev, A. A.; Terentiev, S. A.

2013-06-01

Scanning white light interferometry and Raman spectroscopy were used to investigate the mechanical stresses and structural changes in ion-implanted natural diamonds with different impurity content. The uniform distribution of radiation defects in implanted area was obtained by the regime of multiple-energy implantation of keV He+ ions. A modification of Bosia's et al. (Nucl. Instrum. Meth. B 268 (2010) 2991) method for determining the internal stresses and the density variation in an ion-implanted diamond layer was proposed that suggests measuring, in addition to the surface swelling of a diamond plate, the radius of curvature of the plate. It is shown that, under multiple-energy implantation of He+, mechanical stresses in the implanted layer may be as high as 12 GPa. It is shown that radiation damage reaches saturation for the implantation fluence characteristic of amorphization of diamond but is appreciably lower than the graphitization threshold.

Structural valve deterioration in a starr-edwards mitral caged-disk valve prosthesis.

PubMed

Aoyagi, Shigeaki; Tayama, Kei-Ichiro; Okazaki, Teiji; Shintani, Yusuke; Kono, Michitaka; Wada, Kumiko; Kosuga, Ken-Ichi; Mori, Ryusuke; Tanaka, Hiroyuki

2013-01-01

The durability of the Starr-Edwards (SE) mitral caged-disk valve, model 6520, is not clearly known, and structural valve deterioration in the SE disk valve is very rare. Replacement of the SE mitral disk valve was performed in 7 patients 23-40 years after implantation. Macroscopic examination of the removed disk valves showed no structural abnormalities in 3 patients, in whom the disk valves were removed at <26 years after implantation. Localized disk wear was found at the sites where the disk abutted the struts of the cage, in disk valves excised >36 years after implantation in 4 patients. Disk fracture, a longitudinal split in the disk along its circumference at the site of incorporation of the titanium ring, was detected in the valves removed 36 and 40 years after implantation, respectively, and many cracks were also observed on the outflow aspect of the disk removed 40 years after implantation. Disk fracture and localized disk wear were found in the SE mitral disk valves implanted >36 years previously. The present results suggest that SE mitral caged-disk valves implanted >20 years previously should be carefully followed up, and that those implanted >30 years previously should be electively replaced with modern prosthetic valves

Teicoplanin-loaded borate bioactive glass implants for treating chronic bone infection in a rabbit tibia osteomyelitis model.

PubMed

Zhang, Xin; Jia, Weitao; Gu, Yifei; Xiao, Wei; Liu, Xin; Wang, Deping; Zhang, Changqing; Huang, Wenhai; Rahaman, Mohamed N; Day, Delbert E; Zhou, Nai

2010-08-01

The treatment of chronic osteomyelitis (bone infection) remains a clinical challenge. In this work, pellets composed of a chitosan-bonded mixture of borate bioactive glass particles (<50microm) and teicoplanin powder (antibiotic), were evaluated in vitro and in vivo for treating chronic osteomyelitis induced by methicillin-resistant Staphylococcus aureus (MRSA) in a rabbit model. When immersed in phosphate-buffered saline, the pellets showed sustained release of teicoplanin over 20-30 days, while the bioactive glass converted to hydroxyapatite (HA) within 7 days, eventually forming a porous HA structure. Implantation of the teicoplanin-loaded pellets in a rabbit tibia osteomyelitis model resulted in the detection of teicoplanin in the blood for about 9 days. The implants converted to a bone-like HA graft, and supported the ingrowth of new bone into the tibia defects within 12 weeks of implantation. Microbiological, histological and scanning electron microscopy techniques showed that the implants provided a cure for the bone infection. The results indicate that the teicoplanin-loaded borate bioactive glass implant, combining sustained drug release with the ability to support new bone ingrowth, could provide a method for treating chronic osteomyelitis. Copyright 2010 Elsevier Ltd. All rights reserved.

Genotoxicity of corrosion eluates obtained from endosseous implants.

PubMed

Ribeiro, Daniel Araki; Matsumoto, Mariza Akemi; Padovan, Luís Eduardo Marques; Marques, Mariângela Esther Alencar; Salvadori, Daisy Maria Fávero

2007-03-01

Commercially pure titanium alloys are currently used as metallic biomaterials in implantology. Corrosion phenomena appear to play a decisive role in metallic implant long-term behavior. Thus, the goal of this study was to examine the genotoxic potential of corrosion eluates obtained from dental implants using Chinese ovary hamster cells in vitro by the single-cell gel (comet) assay. This technique detects deoxyribonucleic acid strand breaks in individual cells in alkaline conditions. The materials tested included 3 dental implants commercially available. Each of the tested materials was corroded in a solution consisting of equal amounts of acetic acid and sodium chloride (0.1 M) for 1, 3, 7, 14, and 21 days. The Chinese ovary hamster cultures were then exposed to all corrosion eluates obtained from endosseous dental implants for 30 minutes at 37 degrees C. None of the eluates was found to exhibit genotoxicity, regardless of the type of dental implant used. The results suggest that all dental implants tested in this study did not induce deoxyribonucleic acid breakage as depicted by the single-cell gel (comet) assay.

Superior Rhythm Discrimination With the SmartShock Technology Algorithm　- Results of the Implantable Defibrillator With Enhanced Features and Settings for Reduction of Inaccurate Detection (DEFENSE) Trial.

PubMed

Oginosawa, Yasushi; Kohno, Ritsuko; Honda, Toshihiro; Kikuchi, Kan; Nozoe, Masatsugu; Uchida, Takayuki; Minamiguchi, Hitoshi; Sonoda, Koichiro; Ogawa, Masahiro; Ideguchi, Takeshi; Kizaki, Yoshihisa; Nakamura, Toshihiro; Oba, Kageyuki; Higa, Satoshi; Yoshida, Keiki; Tsunoda, Soichi; Fujino, Yoshihisa; Abe, Haruhiko

2017-08-25

Shocks delivered by implanted anti-tachyarrhythmia devices, even when appropriate, lower the quality of life and survival. The new SmartShock Technology ® (SST) discrimination algorithm was developed to prevent the delivery of inappropriate shock. This prospective, multicenter, observational study compared the rate of inaccurate detection of ventricular tachyarrhythmia using the SST vs. a conventional discrimination algorithm.Methods and Results:Recipients of implantable cardioverter defibrillators (ICD) or cardiac resynchronization therapy defibrillators (CRT-D) equipped with the SST algorithm were enrolled and followed up every 6 months. The tachycardia detection rate was set at ≥150 beats/min with the SST algorithm. The primary endpoint was the time to first inaccurate detection of ventricular tachycardia (VT) with conventional vs. the SST discrimination algorithm, up to 2 years of follow-up. Between March 2012 and September 2013, 185 patients (mean age, 64.0±14.9 years; men, 74%; secondary prevention indication, 49.5%) were enrolled at 14 Japanese medical centers. Inaccurate detection was observed in 32 patients (17.6%) with the conventional, vs. in 19 patients (10.4%) with the SST algorithm. SST significantly lowered the rate of inaccurate detection by dual chamber devices (HR, 0.50; 95% CI: 0.263-0.950; P=0.034). Compared with previous algorithms, the SST discrimination algorithm significantly lowered the rate of inaccurate detection of VT in recipients of dual-chamber ICD or CRT-D.

Effects of Hearing Preservation on Psychophysical Responses to Cochlear Implant Stimulation

PubMed Central

Kang, Stephen Y.; Colesa, Deborah J.; Swiderski, Donald L.; Su, Gina L.; Raphael, Yehoash

2009-01-01

Previous studies have shown that residual acoustic hearing supplements cochlear implant function to improve speech recognition in noise as well as perception of music. The current study had two primary objectives. First, we sought to determine how cochlear implantation and electrical stimulation over a time period of 14 to 21 months influence cochlear structures such as hair cells and spiral ganglion neurons. Second, we sought to investigate whether the structures that provide acoustic hearing also affect the perception of electrical stimulation. We compared psychophysical responses to cochlear implant stimulation in two groups of adult guinea pigs. Group I (11 animals) received a cochlear implant in a previously untreated ear, while group II (ten animals) received a cochlear implant in an ear that had been previously infused with neomycin to destroy hearing. Psychophysical thresholds were measured in response to pulse-train and sinusoidal stimuli. Histological analysis of all group I animals and a subset of group II animals was performed. Nine of the 11 group I animals showed survival of the organ of Corti and spiral ganglion neurons adjacent to the electrode array. All group I animals showed survival of these elements in regions apical to the electrode array. Group II animals that were examined histologically showed complete loss of the organ of Corti in regions adjacent and apical to the electrode array and severe spiral ganglion neuron loss, consistent with previous reports for neomycin-treated ears. Behaviorally, group II animals had significantly lower thresholds than group I animals in response to 100 Hz sinusoidal stimuli. However, group I animals had significantly lower thresholds than group II animals in response to pulse-train stimuli (0.02 ms/phase; 156 to 5,000 pps). Additionally, the two groups showed distinct threshold versus pulse rate functions. We hypothesize that the differences in detection thresholds between groups are caused by the

Implanting inequality: empirical evidence of social and ethical risks of implantable radio-frequency identification (RFID) devices.

PubMed

Monahan, Torin; Fisher, Jill A

2010-10-01

The aim of this study was to assess empirically the social and ethical risks associated with implantable radio-frequency identification (RFID) devices. Qualitative research included observational studies in twenty-three U.S. hospitals that have implemented new patient identification systems and eighty semi-structured interviews about the social and ethical implications of new patient identification systems, including RFID implants. The study identified three primary social and ethical risks associated with RFID implants: (i) unfair prioritization of patients based on their participation in the system, (ii) diminished trust of patients by care providers, and (iii) endangerment of patients who misunderstand the capabilities of the systems. RFID implants may aggravate inequalities in access to care without any clear health benefits. This research underscores the importance of critically evaluating new healthcare technologies from the perspective of both normative ethics and empirical ethics.

Titanium hydride and hydrogen concentration in acid-etched commercially pure titanium and titanium alloy implants: a comparative analysis of five implant systems.

PubMed

Szmukler-Moncler, S; Bischof, M; Nedir, R; Ermrich, M

2010-09-01

Acid etching is a popular method to texture the surface of dental implants. During etching, the titanium oxide protective layer is dissolved and small native hydrogen ions diffuse into the unprotected implant surface. They enrich the implant surface with hydrogen and precipitate into titanium hydride (TiH). The aim of this study was to measure the concentration of TiH at the implant surface and the total concentration of Hydrogen at five commercially available implant systems, made of either commercially pure (cp) titanium or titanium alloy. X-Ray diffraction (XRD) was conducted on each implant system to determine the compounds present at the implant surface. Following a TiH(2)/Ti calibration curve, the concentration of TiH was determined. Concentration of hydrogen in the implants was measured by the inert gas fusion thermal conductivity/infrared detection method. XRD data showed that TiH was present on all cp titanium implants but not on the alloyed implants. TiH concentration varied between 5% and 37%. Hydrogen concentration varied between 43 and 108 ppm, no difference in uptake was found between the cp titanium and alloyed implants. Low solubility of hydrogen in alpha-titanium is responsible for precipitation into TiH. Stronger etching conditions led to higher concentration of TiH2-x. High solubility of hydrogen in the beta-phase of the alloy is preventing hydrogen from precipitating into TiH. All implants, even those lacking TiH at the surface, were enriched with hydrogen. In all implants, hydrogen concentration was within the normative limit of 130 ppm.

The Failure Envelope Concept Applied To The Bone-Dental Implant System.

PubMed

Korabi, R; Shemtov-Yona, K; Dorogoy, A; Rittel, D

2017-05-17

Dental implants interact with the jawbone through their common interface. While the implant is an inert structure, the jawbone is a living one that reacts to mechanical stimuli. Setting aside mechanical failure considerations of the implant, the bone is the main component to be addressed. With most failure criteria being expressed in terms of stress or strain values, their fulfillment can mean structural flow or fracture. However, in addition to those effects, the bony structure is likely to react biologically to the applied loads by dissolution or remodeling, so that additional (strain-based) criteria must be taken into account. While the literature abounds in studies of particular loading configurations, e.g. angle and value of the applied load to the implant, a general study of the admissible implant loads is still missing. This paper introduces the concept of failure envelopes for the dental implant-jawbone system, thereby defining admissible combinations of vertical and lateral loads for various failure criteria of the jawbone. Those envelopes are compared in terms of conservatism, thereby providing a systematic comparison of the various failure criteria and their determination of the admissible loads.

Corrosion processes of physical vapor deposition-coated metallic implants.

PubMed

Antunes, Renato Altobelli; de Oliveira, Mara Cristina Lopes

2009-01-01

Protecting metallic implants from the harsh environment of physiological fluids is essential to guaranteeing successful long-term use in a patient's body. Chemical degradation may lead to the failure of an implant device in two different ways. First, metal ions may cause inflammatory reactions in the tissues surrounding the implant and, in extreme cases, these reactions may inflict acute pain on the patient and lead to loosening of the device. Therefore, increasing wear strength is beneficial to the performance of the metallic implant. Second, localized corrosion processes contribute to the nucleation of fatigue cracks, and corrosion fatigue is the main reason for the mechanical failure of metallic implants. Common biomedical alloys such as stainless steel, cobalt-chrome alloys, and titanium alloys are prone to at least one of these problems. Vapor-deposited hard coatings act directly to improve corrosion, wear, and fatigue resistances of metallic materials. The effectiveness of the corrosion protection is strongly related to the structure of the physical vapor deposition layer. The aim of this paper is to present a comprehensive review of the correlation between the structure of physical vapor deposition layers and the corrosion properties of metallic implants.

Evaluation of stress patterns produced by implant-retained overdentures and implant-retained fixed partial denture.

PubMed

Mazaro, José Vitor Quinelli; Filho, Humberto Gennari; Vedovatto, Eduardo; Pellizzer, Eduardo Piza; Rezende, Maria Cristina Rosifini Alves; Zavanelli, Adriana Cristina

2011-11-01

The purposes of this study were to photoelastically measure the biomechanical behavior of 4 implants retaining different cantilevered bar mandibular overdenture designs and to compare a fixed partial denture (FPD). A photoelastic model of a human edentulous mandible was fabricated, which contained 4 screw-type implants (3.75 × 10 mm) embedded in the parasymphyseal area. An FPD and 3 overdenture designs with the following attachments were evaluated: 3 plastic Hader clips, 1 Hader clip with 2 posterior resilient cap attachments, and 3 ball/O-ring attachments. Vertical occlusal forces of 100 N were applied between the central incisor and unilaterally to the right and left second premolars and second molars. Stresses that developed in the supporting structure were monitored photoelastically and recorded photographically. The results showed that the anterior loading, the overdenture with 3 plastic Hader clips, displayed the largest stress concentration at the medium implant. With premolar loading, the FPD and overdenture with 3 plastic Hader clips displayed the highest stresses to the ipsilateral terminal implant. With molar loading, the overdenture with 3 ball/O-ring attachments displayed the most uniform stress distribution in the posterior edentulous ridge, with less overloading in the terminal implant. It was concluded that vertical forces applied to the bar-clip overdenture and FPD created immediate stress patterns of greater magnitude and concentration on the ipsilateral implants, whereas the ball/O-ring attachments transferred minimal stress to the implants. The increased cantilever in the FPD caused the highest stresses to the terminal implant.

Correlation of Fractal Dimension Values with Implant Insertion Torque and Resonance Frequency Values at Implant Recipient Sites.

PubMed

Suer, Berkay Tolga; Yaman, Zekai; Buyuksarac, Bora

2016-01-01

Fractal analysis is a mathematical method used to describe the internal architecture of complex structures such as trabecular bone. Fractal analysis of panoramic radiographs of implant recipient sites could help to predict the quality of the bone prior to implant placement. This study investigated the correlations between the fractal dimension values obtained from panoramic radiographs and the insertion torque and resonance frequency values of mandibular implants. Thirty patients who received a total of 55 implants of the same brand, diameter, and length in the mandibular premolar and molar regions were included in the study. The same surgical procedures were applied to each patient, and the insertion torque and resonance frequency values were recorded for each implant at the time of placement. The radiographic fractal dimensions of the alveolar bone in the implant recipient area were calculated from preoperative panoramic radiographs using a box-counting algorithm. The insertion torque and resonance frequency values were compared with the fractal dimension values using the Spearman test. All implants were successful, and none were lost during the follow-up period. Linear correlations were observed between the fractal dimension and resonance frequency, between the fractal dimension and insertion torque, and between resonance frequency and insertion torque. These results suggest that the noninvasive measurement of the fractal dimension from panoramic radiographs might help to predict the bone quality, and thus the primary stability of dental implants, before implant surgery.

Determining the Young's modulus of a cellular titanium implant by FEM simulation

NASA Astrophysics Data System (ADS)

Loginov, Yu. N.; Golodnov, A. I.; Stepanov, S. I.; Kovalev, E. Yu.

2017-12-01

The role of additive manufacturing is noted for the construction of titanium medical implants. The purpose of the study is to determine the Young's modulus of cellular titanium implants, which is based on calculations performed by finite element analysis. A honeycomb structure from intersecting cylinder surfaces is offered for the implant made of the Ti-6Al-4V alloy. Boundary conditions are stated for the loading of the implant structure. It is demonstrated that the Young's modulus can be reduced more than three times comparing to a solid titanium alloy. Zones of strain and stress localization located near the abutment of the cylindrical surfaces. Recommendations for the further improvement of the implant architecture are generated.

Improved osseointegration with as-built electron beam melted textured implants and improved peri‑implant bone volume with whole body vibration.

PubMed

Ruppert, David S; Harrysson, Ola L A; Marcellin-Little, Denis J; Dahners, Laurence E; Weinhold, Paul S

2018-06-11

Transcutaneous osseointegrated prostheses provide stable connections to the skeleton while eliminating skin lesions experienced with socket prosthetics. Additive manufacturing can create custom textured implants capable of interfacing with amputees' residual bones. Our objective was to compare osseointegration of textured surface implants made by electron beam melting (EBM), an additive manufacturing process, to machine threaded implants. Whole body vibration was investigated to accelerate osseointegration. Two cohorts of Sprague-Dawley rats received bilateral, titanium implants (EBM vs. threaded) in their tibiae. One cohort comprising five groups vibrated at 45 Hz: 0.0 (control), 0.15, 0.3, 0.6 or 1.2 g was followed for six weeks. Osseointegration was evaluated through torsional testing and bone volume fraction (BV/TV). A second cohort, divided into two groups (control and 0.6 g), was followed for 24 days and evaluated for resonant frequency, bone-implant contact (BIC) and fluorochrome labeling. The EBM textured implants exhibited significantly improved mechanical stability independent of vibration, highlighting the benefits of using EBM to produce custom textured surfaces. Bone formation on and around the EBM textured implants increased compared to machined implants, as seen by BIC and fluorescence. No difference in torque, BIC or fluorescence among vibration levels was detected. BV/TV significantly increased at 0.6 g compared to control for both implant types. Copyright © 2018 IPEM. Published by Elsevier Ltd. All rights reserved.

Optimal design of composite hip implants using NASA technology

NASA Technical Reports Server (NTRS)

Blake, T. A.; Saravanos, D. A.; Davy, D. T.; Waters, S. A.; Hopkins, D. A.

1993-01-01

Using an adaptation of NASA software, we have investigated the use of numerical optimization techniques for the shape and material optimization of fiber composite hip implants. The original NASA inhouse codes, were originally developed for the optimization of aerospace structures. The adapted code, which was called OPORIM, couples numerical optimization algorithms with finite element analysis and composite laminate theory to perform design optimization using both shape and material design variables. The external and internal geometry of the implant and the surrounding bone is described with quintic spline curves. This geometric representation is then used to create an equivalent 2-D finite element model of the structure. Using laminate theory and the 3-D geometric information, equivalent stiffnesses are generated for each element of the 2-D finite element model, so that the 3-D stiffness of the structure can be approximated. The geometric information to construct the model of the femur was obtained from a CT scan. A variety of test cases were examined, incorporating several implant constructions and design variable sets. Typically the code was able to produce optimized shape and/or material parameters which substantially reduced stress concentrations in the bone adjacent of the implant. The results indicate that this technology can provide meaningful insight into the design of fiber composite hip implants.

Capacitance-based damage detection sensing for aerospace structural composites

NASA Astrophysics Data System (ADS)

Bahrami, P.; Yamamoto, N.; Chen, Y.; Manohara, H.

2014-04-01

Damage detection technology needs improvement for aerospace engineering application because detection within complex composite structures is difficult yet critical to avoid catastrophic failure. Damage detection is challenging in aerospace structures because not all the damage detection technology can cover the various defect types (delamination, fiber fracture, matrix crack etc.), or conditions (visibility, crack length size, etc.). These defect states are expected to become even more complex with future introduction of novel composites including nano-/microparticle reinforcement. Currently, non-destructive evaluation (NDE) methods with X-ray, ultrasound, or eddy current have good resolutions (< 0.1 mm), but their detection capabilities is limited by defect locations and orientations and require massive inspection devices. System health monitoring (SHM) methods are often paired with NDE technologies to signal out sensed damage, but their data collection and analysis currently requires excessive wiring and complex signal analysis. Here, we present a capacitance sensor-based, structural defect detection technology with improved sensing capability. Thin dielectric polymer layer is integrated as part of the structure; the defect in the structure directly alters the sensing layer's capacitance, allowing full-coverage sensing capability independent of defect size, orientation or location. In this work, capacitance-based sensing capability was experimentally demonstrated with a 2D sensing layer consisting of a dielectric layer sandwiched by electrodes. These sensing layers were applied on substrate surfaces. Surface indentation damage (~1mm diameter) and its location were detected through measured capacitance changes: 1 to 250 % depending on the substrates. The damage detection sensors are light weight, and they can be conformably coated and can be part of the composite structure. Therefore it is suitable for aerospace structures such as cryogenic tanks and rocket

Research on dental implant and its industrialization stage

NASA Astrophysics Data System (ADS)

Dongjoon, Yang; Sukyoung, Kim

2017-02-01

Bone cell attachment to Ti implant surfaces is the most concerned issue in the clinical implant dentistry. Many attempts to achieve the fast and strong integration between bone and implant have been tried in many ways, such as selection of materials (for example, Ti, ZrO2), shape design of implant (for example, soft tissue level, bone level, taped or conical, etc), and surface modification of implants (for example, roughed. coated, hybrid), etc. Among them, a major consideration is the surface design of dental implants. The surface with proper structural characteristics promotes or induces the desirable responses of cells and tissues. To obtain such surface which has desirable cell and tissue response, a variety of surface modification techniques has been developed and employed for many years. In this review, the method and trend of surface modification will be introduced and explained in terms of the surface topography and chemistry of dental implants.

Biomechanical behavior of 2-implant-and single-implant-retained mandibular overdentures with conventional or mini implants.

PubMed

Pisani, Marina Xavier; Presotto, Anna Gabriella Camacho; Mesquita, Marcelo Ferraz; Barão, Valentim Adelino Ricardo; Kemmoku, Daniel Takanori; Del Bel Cury, Altair Antoninha

2018-04-24

The use of single or mini dental implants to retain mandibular overdentures is still questionable. The purpose of this finite element analysis (FEA) study was to investigate the biomechanical behavior of 2- and single-implant-retained mandibular overdentures with conventional or mini implants. Four 3-dimensional (3D) finite element models were constructed with the following designs of mandibular overdentures: 2 (group 2-C) and single (group 1-C) conventional external hexagon implants with ball or O-ring attachment and 2 (group 2-M) and single (group 1-M) 1-piece mini implants. A 150-N axial load was applied bilaterally and simultaneously on the first molar. Overdenture displacement, von Mises equivalent stress (implants and/or prosthetic components), and maximum principal stresses (peri-implant bone) were recorded numerically and then color-coded and compared among the groups. The overdenture displacement (in mm) was higher for the 1-M (0.16) and 2-M (0.17) groups when compared with 1-C (0.09) and 2-C (0.08). Irrespective of the type of implant, the single-implant groups presented higher values of stress (in MPa) on the implants than did the 2-implant groups (1-C=52.53; 1-M=2.95; 2-C=34.66; 2-M=2.37), ball attachment (1-C=201.33; 2-C=159.06), housing or O-ring (1-C=125.01; 1-M=1.96; 2-C=88.84; 2-M=1.27), and peri-implant cortical bone (1-C=19.37; 1-M=1.47; 2-C=15.70; 2-M=1.06). The mini implant overdentures presented lower stress values on the implants, housing or O-ring, and peri-implant bone than did the conventional implant overdentures, regardless of the number of implants. The 2-implant-retained overdentures exhibited lower stresses than the single- implant-retained overdentures, irrespective of the type of implant. The mini implants demonstrated higher overdenture displacement and lower stresses than did conventional implant overdentures for single- and 2-implant-retained overdentures. Copyright © 2018 Editorial Council for the Journal of Prosthetic

Telemedicine and cardiac implants: what is the benefit?

PubMed Central

Varma, Niraj; Ricci, Renato Pietro

2013-01-01

Cardiac implantable electronic devices are increasing in prevalence. The post-implant follow-up is important for monitoring both device function and patient condition. However, practice is inconsistent. For example, ICD follow-up schedules vary from 3 monthly to yearly according to facility and physician preference and availability of resources. Recommended follow-up schedules impose significant burden. Importantly, no surveillance occurs between follow-up visits. In contrast, implantable devices with automatic remote monitoring capability provide a means for performing constant surveillance, with the ability to identify salient problems rapidly. Remote home monitoring reduces the volume of device clinic visits and provides early detection of patient and/or system problems. PMID:23211231

Polymorphisms of Il-10 (-1082) and RANKL (-438) Genes and the Failure of Dental Implants

PubMed Central

Ribeiro, Rodrigo; Melo, Rayanne; Tortamano Neto, Pedro; Vajgel, André

2017-01-01

Background. Genetic polymorphisms in certain cytokines and chemokines have been investigated to understand why some individuals display implant flaws despite having few risk factors at the time of implant. Purpose. To investigate the association of genetic polymorphisms in interleukin- (IL-) 10 [-1082 region (A/G)] and RANKL [-438 region (A/G)] with the failure of dental implants. Materials and Methods. This study included 90 partially edentulous male and female patients who were rehabilitated with a total of 245 Straumann dental implants. An implant was considered a failure if any of the following occurred: mobility, persistent subjective complaint, recurrent peri-implant infection with suppuration, continuous radiolucency around the implant, probing depth ≥ 5 mm, and bleeding on probing. Buccal mucosal cells were collected for analysis of RANKL438 and IL-10. Results. The implant success rate in this population was 34.4%. The mutant allele (G) in RANKL had an incidence of 52.3% and mutant allele (A) in IL-10 was observed in 37.8%. No statistically significant difference was detected between the failure of the implant and the genotypes and allelic frequencies. Conclusion. No association was detected between the genetic polymorphisms of RANKL (-438) and IL-10 (-1082) and the failure of dental implants in the population studied. PMID:28348592

Polymorphisms of Il-10 (-1082) and RANKL (-438) Genes and the Failure of Dental Implants.

PubMed

Ribeiro, Rodrigo; Melo, Rayanne; Tortamano Neto, Pedro; Vajgel, André; Souza, Paulo Roberto Eleutério; Cimões, Renata

2017-01-01

Background . Genetic polymorphisms in certain cytokines and chemokines have been investigated to understand why some individuals display implant flaws despite having few risk factors at the time of implant. Purpose . To investigate the association of genetic polymorphisms in interleukin- (IL-) 10 [-1082 region (A/G)] and RANKL [-438 region (A/G)] with the failure of dental implants. Materials and Methods . This study included 90 partially edentulous male and female patients who were rehabilitated with a total of 245 Straumann dental implants. An implant was considered a failure if any of the following occurred: mobility, persistent subjective complaint, recurrent peri-implant infection with suppuration, continuous radiolucency around the implant, probing depth ≥ 5 mm, and bleeding on probing. Buccal mucosal cells were collected for analysis of RANKL438 and IL-10 . Results . The implant success rate in this population was 34.4%. The mutant allele (G) in RANKL had an incidence of 52.3% and mutant allele (A) in IL-10 was observed in 37.8%. No statistically significant difference was detected between the failure of the implant and the genotypes and allelic frequencies. Conclusion . No association was detected between the genetic polymorphisms of RANKL (-438) and IL-10 (-1082) and the failure of dental implants in the population studied.

Revival of pure titanium for dynamically loaded porous implants using additive manufacturing.

PubMed

Wauthle, Ruben; Ahmadi, Seyed Mohammad; Amin Yavari, Saber; Mulier, Michiel; Zadpoor, Amir Abbas; Weinans, Harrie; Van Humbeeck, Jan; Kruth, Jean-Pierre; Schrooten, Jan

2015-09-01

Additive manufacturing techniques are getting more and more established as reliable methods for producing porous metal implants thanks to the almost full geometrical and mechanical control of the designed porous biomaterial. Today, Ti6Al4V ELI is still the most widely used material for porous implants, and none or little interest goes to pure titanium for use in orthopedic or load-bearing implants. Given the special mechanical behavior of cellular structures and the material properties inherent to the additive manufacturing of metals, the aim of this study is to investigate the properties of selective laser melted pure unalloyed titanium porous structures. Therefore, the static and dynamic compressive properties of pure titanium structures are determined and compared to previously reported results for identical structures made from Ti6Al4V ELI and tantalum. The results show that porous Ti6Al4V ELI still remains the strongest material for statically loaded applications, whereas pure titanium has a mechanical behavior similar to tantalum and is the material of choice for cyclically loaded porous implants. These findings are considered to be important for future implant developments since it announces a potential revival of the use of pure titanium for additively manufactured porous implants. Copyright © 2015 Elsevier B.V. All rights reserved.

[Photoelastic stress analysis of human femurs before and after implantation of different models of femur neck prostheses].

PubMed

Wieners, G; Pech, M; Streitparth, F; Jansson, V; Plitz, W

2007-01-01

The aim of this study was the detection of areas at risk at the proximal femur after implantation of different femur neck prostheses using the photoelastic stress analysis. Twelve pairs of human femurs were used as examination material. The analysis of the stress pattern was done with a stepwise increasing load up to the quadruple of body weight before and after implantation of three models of femur neck prostheses which were implanted cementless. The "CUT" and "Cigar" models are coated with a tripod structure. The "Cigar" model has a lateral thrust plate. The lateral end of the "CUT" model is curved and this end is attached to the lateral corticalis. The third model, the "rip prosthesis" has two layers for rotational stability. Subsequently, the micromotions of the implanted prosthesis in the femural neck were examined with alternating weight loads (1000 +/- 700 N). The Cigar prosthesis showed the most changes of stress distribution because of the lateral thrust plate with concentration of isochromatic lines to the lateral boring. In the region of the oseotomy an increase of strain up 1440 microm/m could be detected for the Cigar and up to 1000 microm/m for the rib prosthesis. The stress pattern after implantation of the CUT prosthesis remained very similar apart from a slight increase of stress values (720 microm/m). Only for the Cigar prostheses were the measured micromotions below the critical value for a possible osteointegration with a mean value of 134 microm/m. The stress pattern after implantation of the CUT prosthesis remained most similar to the preinterventional stress distribution. Because of this, it is to be expected that the osseous modification would stay at a low level. The question of osteointegration can only be answered in long-term in-vivo studies.

A novel hydroxyapatite film coated with ionic silver via inositol hexaphosphate chelation prevents implant-associated infection

NASA Astrophysics Data System (ADS)

Funao, Haruki; Nagai, Shigenori; Sasaki, Aya; Hoshikawa, Tomoyuki; Tsuji, Takashi; Okada, Yasunori; Koyasu, Shigeo; Toyama, Yoshiaki; Nakamura, Masaya; Aizawa, Mamoru; Matsumoto, Morio; Ishii, Ken

2016-03-01

Various silver-coated implants have been developed to prevent implant-associated infections, and have shown dramatic effects in vitro. However, the in vivo results have been inconsistent. Recent in vitro studies showed that silver exerts antibacterial activity by mediating the generation of reactive oxygen species in the presence of oxygen. To maintain its antibacterial activity in vivo, the silver should remain in an ionic state and be stably bound to the implant surface. Here, we developed a novel bacteria-resistant hydroxyapatite film in which ionic silver is immobilized via inositol hexaphosphate chelation using a low-heat immersion process. This bacteria-resistant coating demonstrated significant antibacterial activity both in vitro and in vivo. In a murine bioluminescent osteomyelitis model, no bacteria were detectable 21 days after inoculation with S. aureus and placement of this implant. Serum interleukin-6 was elevated in the acute phase in this model, but it was significantly lower in the ionic-silver group than the control group on day 2. Serum C-reactive protein remained significantly higher in the control group than the ionic-silver group on day 14. Because this coating is produced by a low-heat immersion process, it can be applied to complex structures of various materials, to provide significant protection against implant-associated infections.

Laser-based structural sensing and surface damage detection

NASA Astrophysics Data System (ADS)

Guldur, Burcu

Damage due to age or accumulated damage from hazards on existing structures poses a worldwide problem. In order to evaluate the current status of aging, deteriorating and damaged structures, it is vital to accurately assess the present conditions. It is possible to capture the in situ condition of structures by using laser scanners that create dense three-dimensional point clouds. This research investigates the use of high resolution three-dimensional terrestrial laser scanners with image capturing abilities as tools to capture geometric range data of complex scenes for structural engineering applications. Laser scanning technology is continuously improving, with commonly available scanners now capturing over 1,000,000 texture-mapped points per second with an accuracy of ~2 mm. However, automatically extracting meaningful information from point clouds remains a challenge, and the current state-of-the-art requires significant user interaction. The first objective of this research is to use widely accepted point cloud processing steps such as registration, feature extraction, segmentation, surface fitting and object detection to divide laser scanner data into meaningful object clusters and then apply several damage detection methods to these clusters. This required establishing a process for extracting important information from raw laser-scanned data sets such as the location, orientation and size of objects in a scanned region, and location of damaged regions on a structure. For this purpose, first a methodology for processing range data to identify objects in a scene is presented and then, once the objects from model library are correctly detected and fitted into the captured point cloud, these fitted objects are compared with the as-is point cloud of the investigated object to locate defects on the structure. The algorithms are demonstrated on synthetic scenes and validated on range data collected from test specimens and test-bed bridges. The second objective of

Evaluation of nano-technology-modified zirconia oral implants: a study in rabbits.

PubMed

Lee, Jaebum; Sieweke, Janet H; Rodriguez, Nancy A; Schüpbach, Peter; Lindström, Håkan; Susin, Cristiano; Wikesjö, Ulf M E

2009-07-01

The objective of this study was to screen candidate nano-technology-modified, micro-structured zirconia implant surfaces relative to local bone formation and osseointegration. Proprietary nano-technology surface-modified (calcium phosphate: CaP) micro-structured zirconia implants (A and C), control micro-structured zirconia implants (ZiUnite), and titanium porous oxide implants (TiUnite) were implanted into the femoral condyle in 40 adult male New Zealand White rabbits. Each animal received one implant in each hind leg; thus, 20 animals received A and C implants and 20 animals received ZiUnite and TiUnite implants in contralateral hind legs. Ten animals/group were euthanized at weeks 3 and 6 when biopsies of the implant sites were processed for histometric analysis using digital photomicrographs produced using backscatter scanning electron microscopy. The TiUnite surface demonstrated significantly greater bone-implant contact (BIC) (77.6+/-2.6%) compared with the A (64.6+/-3.6%) and C (62.2+/-3.1%) surfaces at 3 weeks (p<0.05). Numerical differences between ZiUnite (70.5+/-3.1%) and A and C surfaces did not reach statistical significance (p>0.05). Similarly, there were non-significant differences between the TiUnite and the ZiUnite surfaces (p>0.05). At 6 weeks, there were no significant differences in BIC between the TiUnite (67.1+/-4.2%), ZiUnite (69.7+/-5.7%), A (68.6+/-1.9%), and C (64.5+/-4.1%) surfaces (p>0.05). TiUnite and ZiUnite implant surfaces exhibit high levels of osseointegration that, in this model, confirm their advanced osteoconductive properties. Addition of CaP nano-technology to the ZiUnite surface does not enhance the already advanced osteoconductivity displayed by the TiUnite and ZiUnite implant surfaces.

Spectrophotometric and visual evaluation of peri-implant soft tissue color.

PubMed

Benic, Goran I; Scherrer, Daniela; Sancho-Puchades, Manuel; Thoma, Daniel S; Hämmerle, Christoph H F

2017-02-01

To spectrophotometrically and visually test whether the peri-implant mucosal color differs from the color of the natural gingiva. Forty single implants in the incisor and premolar region of 40 patients were assessed 3-7 years after implant placement. The differences of the color components lightness, chroma along red-green axis, chroma along yellow-blue axis, and the total color difference ΔE between peri-implant mucosa and natural gingiva were measured with a spectrophotometer. The color difference between peri-implant mucosa and natural gingiva was visually evaluated by clinicians and rated as "clinically visible" or "clinically invisible" from speaking distance. The dimensions of peri-implant mucosa and gingiva at the mid-buccal aspect were evaluated by using cone-beam CT. Spearman analysis was performed to detect correlations between different variables. Two-sided t-test, ANOVA, Mann-Whitney, and Kruskal-Wallis tests were applied to detect differences between the groups. The spectrophotometrically assessed color difference ΔE between peri-implant mucosa and natural gingiva amounted to 7.0 ± 3.9. The peri-implant mucosa presented a significant dark, greenish and bluish discoloration in comparison with gingiva at control teeth. Clinical investigation revealed that in 60% of sites the color difference between peri-implant mucosa and natural gingiva was clinically visible from speaking distance. The threshold value ΔE for the extraoral clinical distinction of mucosal color differences measured 7.5. When comparing the groups with visible and invisible color differences with respect to the three color components, a significant difference was found only for chroma along yellow-blue axis. In the group with visible color difference, mucosa presented a bluish discoloration. Correlation analysis indicated that with an increase in mucosal thickness, a trend for smaller ΔE was found. The spectrophotometrically assessed color of the peri-implant mucosa revealed more

PIP breast implants: rupture rate and correlation with breast cancer

PubMed Central

MOSCHETTA, M.; TELEGRAFO, M.; CORNACCHIA, I.; VINCENTI, L.; RANIERI, V.; CIRILLI, A.; RELLA, L.; IANORA, A.A. STABILE; ANGELELLI, G.

2014-01-01

Aim To evaluate the incidence of Poly Implant Prosthése (PIP) rupture as assessed by magnetic resonance imaging (MRI), the prevalence of the detected signs and the potential correlation with breast carcinoma. Patients and methods 67 patients with silicone breast implants and clinical indications for breast MRI were evaluated for a total of 125 implants: 40 (32%) PIP in 21 patients and 85 non-PIP in 46 patients (68%), the latest considered as control group. A 1.5-T MR imaging device was used in order to assess implant integrity with dedicated sequences and in 6 cases a dynamic study was performed for characterizing breast lesions. Two radiologists with more than 5 years’ experience in the field of MRI evaluated in consensus all MR images searching for the presence of clear signs of intra or extra-capsular implant rupture. Results 20/40 (50%) PIP implants presented signs of intra-capsular rupture: linguine sign in 20 cases (100%), tear-drop sign in 6 (30%). In 12/20 cases (60%), MRI signs of extra-capsular rupture were detected. In the control group, an intra-capsular rupture was diagnosed in 12/85 cases (14%) associated with extra-capsular one in 5/12 cases (42%). Among the six cases with suspected breast lesions, in 2/21 patients with PIP implants (10%) a breast carcinoma was diagnosed (mucinous carcinoma, n=1; invasive ductal carcinoma, n=1). In 4/46 patients (9%) with non-PIP implants, an invasive ductal carcinoma was diagnosed. Conclusion The rupture rate of PIP breast implants is significantly higher than non-PIP (50% vs 14%). MRI represents the most accurate imaging tool for evaluating breast prostheses and the linguine sign is the most common MRI sign to be searched. The incidence of breast carcinoma does not significantly differ between the PIP and non-PIP implants and a direct correlation with breast cancer can not been demonstrated. PMID:25644728

Structural and surface property characterization of titanium dioxide nanotubes for orthopedic implants

NASA Astrophysics Data System (ADS)

Shokuhfar, Tolou

This research focused on the to modification of the surface structure of titanium implants with nanostructured morphology of TiO2 nanotubes and studied the interaction of nanotubes with osteoblast cells to understand the parameters that affect the cell growth. The electrical, mechanical, and structural properties of TiO2 nanotubes were characterized to establish a better understanding on the properties of such nanoscale morphological structures. To achieve the objectives of this research work I transformed the titanium and its alloys, either in bulk sheet form, bulk machined form, or thin film deposited on another substrate into a surface of titania nanotubes using a low cost and environmentally friendly process. The process requires only a simple electrolyte, low cost electrode, and a DC power supply. With this simple approach of scalable nanofabrication, a typical result is nanotubes that are each approximately 100nm in diameter and have a wall thickness of about 20nm. By changing the fabrication parameters, independent nanotubes can be fabricated with open volume between them. Titanium in this form is termed onedimensional since electron transport is narrowly confined along the length of the nanotube. My Ph.D. accomplishments have successfully shown that osteoblast cells, the cells that are the precursors to bone, have a strong tendency to attach to the inside and outside of the titanium nanotubes onto which they are grown using their filopodia -- cell's foot used for locomotion -- anchored to titanium nanotubes. In fact it was shown that the cell prefers to find many anchoring sites. These sites are critical for cell locomotion during the first several weeks of maturity and upon calcification as a strongly anchored bone cell. In addition I have shown that such a surface has a greater cell density than a smooth titanium surface. My work also developed a process that uses a focused and controllably rastered ion beam as a nano-scalpel to cut away sections of the

Physicochemical and microscopic characterization of implant-abutment joints.

PubMed

Lopes, Patricia A; Carreiro, Adriana F P; Nascimento, Rubens M; Vahey, Brendan R; Henriques, Bruno; Souza, Júlio C M

2018-01-01

The purpose of this study was to investigate Morse taper implant-abutment joints by chemical, mechanical, and microscopic analysis. Surfaces of 10 Morse taper implants and the correlated abutments were inspected by field emission gun-scanning electron microscopy (FEG-SEM) before connection. The implant-abutment connections were tightened at 32 Ncm. For microgap evaluation by FEG-SEM, the systems were embedded in epoxy resin and cross-sectioned at a perpendicular plane of the implant-abutment joint. Furthermore, nanoindentation tests and chemical analysis were performed at the implant-abutment joints. Results were statistically analyzed via one-way analysis of variance, with a significance level of P < 0.05. Defects were noticed on different areas of the abutment surfaces. The minimum and maximum size of microgaps ranged from 0.5 μm up to 5.6 μm. Furthermore, defects were detected throughout the implant-abutment joint that can, ultimately, affect the microgap size after connection. Nanoindentation tests revealed a higher hardness (4.2 ± 0.4 GPa) for abutment composed of Ti6Al4V alloy when compared to implant composed of commercially pure Grade 4 titanium (3.2 ± 0.4 GPa). Surface defects produced during the machining of both implants and abutments can increase the size of microgaps and promote a misfit of implant-abutment joints. In addition, the mismatch in mechanical properties between abutment and implant can promote the wear of surfaces, affecting the size of microgaps and consequently the performance of the joints during mastication.

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

Properties of arsenic-implanted Hg1-xCdxTe MBE films

NASA Astrophysics Data System (ADS)

Izhnin, Igor I.; Voitsekhovskii, Alexandr V.; Korotaev, Alexandr G.; Fitsych, Olena I.; Bonchyk, Oleksandr Yu.; Savytskyy, Hrygory V.; Mynbaev, Karim D.; Varavin, Vasilii S.; Dvoretsky, Sergey A.; Yakushev, Maxim V.; Jakiela, Rafal; Trzyna, Malgorzata

2017-01-01

Defect structure of arsenic-implanted Hg1-xCdxTe films (x=0.23-0.30) grown with molecular-beam epitaxy on Si substrates was investigated with the use of optical methods and by studying the electrical properties of the films. The structural perfection of the films remained higher after implantation with more energetic arsenic ions (350 keV vs 190 keV). 100%-activation of implanted ions as a result of post-implantation annealing was achieved, as well as the effective removal of radiation-induced donor defects. In some samples, however, activation of acceptor-like defects not related to mercury vacancies as a result of annealing was observed, possibly related to the effect of the substrate.

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

A Suggested Model for Building Robust Biomedical Implants Registries.

PubMed

Aloufi, Bader; Alshagathrah, Fahad; Househ, Mowafa

2017-01-01

Registries are an essential source of information for clinical and non-clinical decision-makers; because they provide evidence for post-market clinical follow-up and early detection of safety signals for biomedical implants. Yet, many of todays biomedical implants registries are facing a variety of challenges relating to a poorly designed dataset, the reliability of inputted data and low clinician and patient participation. The purpose of this paper is to present a best practice model for the implementation and use of biomedical implants registries to monitor the safety and effectiveness of implantable medical devices. Based on a literature review and an analysis of multiple national relevant registries, we identified six factors that address contemporary challenges and are believed to be the keys for building a successful biomedical implants registry, which include: sustainable development, international comparability, data reliability, purposeful design, ease of patient participation, and collaborative development at the national level.

Treatment of subgingival implant surfaces with Teflon-coated sonic and ultrasonic scaler tips and various implant curettes. An in vitro study.

PubMed

Rühling, A; Kocher, T; Kreusch, J; Plagmann, H C

1994-03-01

Removal of plaque and calculus by means of sonic and ultrasonic scalers causes considerable damage to implants. With a view to avoiding the aggressive effects of these instruments, an experimental study was carried out for which conventional sonic and ultrasonic scalers were coated with Teflon. The effects of these instruments on implant surfaces was then compared with that of plastic and metal implant curettes. Stereo-microscopy, scanning electron microscopy and surface profilometry were used to detect and record damage to implant surfaces and changes in surface roughness. Generation and propagation of heat in subgingival simulation of use of sonic and ultrasonic scalers were also recorded by means of temperature measurements at the implant surface. The results revealed that no discernible damage was caused by Teflon-coated sonic and ultrasonic scalers or implant curettes made of plastic on smooth titanium surfaces. Instrument material residues were found on rough implant surfaces. It was not the intention of this study to provide an analysis of the prerequisites for the cleaning of rough implant surfaces, but rather to determine what type of damage is to be expected when contact is made with smooth and rough surfaces unintentionally. Temperature measurements during the subgingival use of sonic and ultrasonic scalers indicated satisfactory functioning of the cooling system. Coating of sonic and ultrasonic scaler tips with Teflon thus facilitates the use of high-frequency instruments to achieve professional cleaning of implants.

Topographic measurements of eyelids and orbit in enucleated eyes with hydroxyapatite integrated implant versus PMMA implant.

PubMed

Gradinaru, S; Totir, M; Iancu, R; Leasu, C; Pricopie, S; Yasin, S; Ciuluvica, R; Ungureanu, E

2014-01-01

This study reports our results relating to palpebral eyelid fissure and orbital measurements following evisceration with orbital implantation of hydroxyapatite integrated implant and PMMA implant. This study is a prospective study of 43 patients that underwent evisceration for different ocular affections at University Emergency Hospital Bucharest, Ophthalmology department between January 2009 and September 2010 (Group A comprising of twenty patients had the coralline hydroxyapatite implant -Integrated Ocular Implants, USA and Group B comprising of twenty-three received non-integrated PMMA ocular implants) .The outcomes measured were the degree of exo /enophthalmos, horizontal eyelid fissure and palpebral fissure height at 4 years after surgical intervention related to measurement to the contralateral eye. Horizontal eyelid fissure (HEF) was suffering a shortening of 7.4% in the group B versus the contralateral eye, and only 1.9% in the group A related to the contralateral eye. Eyelid fissure height was greater in the group B with 5.2% regarding the contralateral eye, and 1.2% in group A. The degree of enophthalmia was higher in the group B of 4 mm versus the contralateral eye and lower in group A 1.5 mm regarding the contralateral eye. . Although a hydroxyapatite implant may be not as economic as a PMMA implant, a patient must be warned about the effect on its ocular structures in time and that cosmetic appearance over years will change more dramatically than in the fellow normal eye. Therefore preoperative counseling of the patient is crucial in long term patient satisfaction.

Structural modifications and corrosion behavior of martensitic stainless steel nitrided by plasma immersion ion implantation

NASA Astrophysics Data System (ADS)

Figueroa, C. A.; Alvarez, F.; Zhang, Z.; Collins, G. A.; Short, K. T.

2005-07-01

In this work we report a study of the structural modifications and corrosion behavior of martensitic stainless steels (MSS) nitrided by plasma immersion ion implantation (PI3). The samples were characterized by x-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, photoemission electron spectroscopy, and potentiodynamic electrochemical measurements. Depending on the PI3 treatment temperature, three different material property trends are observed. At lower implantation temperatures (e.g., 360 °C), the material corrosion resistance is improved and a compact phase of ɛ-(Fe,Cr)3N, without changes in the crystal morphology, is obtained. At intermediate temperatures (e.g., 430 °C), CrN precipitates form principally at grain boundaries, leading to a degradation in the corrosion resistance compared to the original MSS material. At higher temperatures (e.g., 500 °C), the relatively great mobility of the nitrogen and chromium in the matrix induced random precipitates of CrN, transforming the original martensitic phase into α-Fe (ferrite), and causing a further degradation in the corrosion resistance.

Amplitude modulation detection with concurrent frequency modulation.

PubMed

Nagaraj, Naveen K

2016-09-01

Human speech consists of concomitant temporal modulations in amplitude and frequency that are crucial for speech perception. In this study, amplitude modulation (AM) detection thresholds were measured for 550 and 5000 Hz carriers with and without concurrent frequency modulation (FM), at AM rates crucial for speech perception. Results indicate that adding 40 Hz FM interferes with AM detection, more so for 5000 Hz carrier and for frequency deviations exceeding the critical bandwidth of the carrier frequency. These findings suggest that future cochlear implant processors, encoding speech fine-structures may consider limiting the FM to narrow bandwidth and to low frequencies.

Biomechanical evaluation of implant-supported prosthesis with various tilting implant angles and bone types in atrophic maxilla: A finite element study.

PubMed

Gümrükçü, Zeynep; Korkmaz, Yavuz Tolga; Korkmaz, Fatih Mehmet

2017-07-01

The purpose of this study is to evaluate and compare bone stress that occurs as a result of using vertical implants with simultaneous sinus augmentation with bone stress generated from oblique implants without sinus augmentation in atrophic maxilla. Six, three-dimensional (3D) finite element (FE) models of atrophic maxilla were generated with SolidWorks software. The maxilla models were varied for two different bone types. Models 2a, 2b and 2c represent maxilla models with D2 bone type. Models 3a, 3b and 3c represent maxilla models with D3 bone type. Five implants were embedded in each model with different configurations for vertical implant insertion with sinus augmentation: Model 2a/Model 3a, 30° tilted insertion; Model 2b/Model 3b and 45° tilted insertion; Model 2c/Model 3c. A 150 N load was applied obliquely on the hybrid prosthesis. The maximum von Mises stress values were comparatively evaluated using color scales. The von Mises stress values predicted by the FE models were higher for all D3 bone models in both cortical and cancellous bone. For the vertical implant models, lower stress values were found in cortical bone. Tilting of the distal implants by 30° increased the stress in the cortical layer compared to vertical implant models. Tilting of the distal implant by 45° decreased the stress in the cortical bone compared to the 30° models, but higher stress values were detected in the 45° models compared to the vertical implant models. Augmentation should be the first treatment option in atrophic maxilla in terms of biomechanics. Tilted posterior implants can create higher stress values than vertical posterior implants. During tilting implant planning, the use of a 45° tilted implant results in better biomechanical performance in peri-implant bone than 30° tilted implant due to the decrease in cantilever length. Copyright © 2017 Elsevier Ltd. All rights reserved.

Short dental implants: an emerging concept in implant treatment.

PubMed

Al-Hashedi, Ashwaq Ali; Taiyeb Ali, Tara Bai; Yunus, Norsiah

2014-06-01

Short implants have been advocated as a treatment option in many clinical situations where the use of conventional implants is limited. This review outlines the effectiveness and clinical outcomes of using short implants as a valid treatment option in the rehabilitation of edentulous atrophic alveolar ridges. Initially, an electronic search was performed on the following databases: Medline, PubMed, Embase, Cochrane Database of Systematic Reviews, and DARE using key words from January 1990 until May 2012. An additional hand search was included for the relevant articles in the following journals: International Journal of Oral and Maxillofacial Implants, Clinical Oral Implants Research, Journal of Clinical Periodontology, International Journal of Periodontics, Journal of Periodontology, and Clinical Implant Dentistry and Related Research. Any relevant papers from the journals' references were hand searched. Articles were included if they provided detailed data on implant length, reported survival rates, mentioned measures for implant failure, were in the English language, involved human subjects, and researched implants inserted in healed atrophic ridges with a follow-up period of at least 1 year after implant-prosthesis loading. Short implants demonstrated a high rate of success in the replacement of missing teeth in especially atrophic alveolar ridges. The advanced technology and improvement of the implant surfaces have encouraged the success of short implants to a comparable level to that of standard implants. However, further randomized controlled clinical trials and prospective studies with longer follow-up periods are needed.

FRF-based structural damage detection of controlled buildings with podium structures: Experimental investigation

NASA Astrophysics Data System (ADS)

Xu, Y. L.; Huang, Q.; Zhan, S.; Su, Z. Q.; Liu, H. J.

2014-06-01

How to use control devices to enhance system identification and damage detection in relation to a structure that requires both vibration control and structural health monitoring is an interesting yet practical topic. In this study, the possibility of using the added stiffness provided by control devices and frequency response functions (FRFs) to detect damage in a building complex was explored experimentally. Scale models of a 12-storey main building and a 3-storey podium structure were built to represent a building complex. Given that the connection between the main building and the podium structure is most susceptible to damage, damage to the building complex was experimentally simulated by changing the connection stiffness. To simulate the added stiffness provided by a semi-active friction damper, a steel circular ring was designed and used to add the related stiffness to the building complex. By varying the connection stiffness using an eccentric wheel excitation system and by adding or not adding the circular ring, eight cases were investigated and eight sets of FRFs were measured. The experimental results were used to detect damage (changes in connection stiffness) using a recently proposed FRF-based damage detection method. The experimental results showed that the FRF-based damage detection method could satisfactorily locate and quantify damage.

Qualitative and quantitative observations of bone tissue reactions to anodised implants.

PubMed

Sul, Young-Taeg; Johansson, Carina B; Röser, Kerstin; Albrektsson, Tomas

2002-04-01

Research projects focusing on biomaterials related factors; the bulk implant material, the macro-design of the implant and the microsurface roughness are routinely being conducted at our laboratories. In this study, we have investigated the bone tissue reactions to turned commercially pure (c.p.) titanium implants with various thicknesses of the oxide films after 6 weeks of insertion in rabbit bone. The control c.p. titanium implants had an oxide thickness of 17-200 nm while the test implants revealed an oxide thickness between 600 and 1000 nm. Routine histological investigations of the tissue reactions around the implants and enzyme histochemical detections of alkaline and acid phosphatase activities demonstrated similar findings around both the control and test implants. In general, the histomorphometrical parameters (bone to implant contact and newly formed bone) revealed significant quantitative differences between the control and test implants. The test implants demonstrated a greater bone response histomorphometrically than control implants and the osteoconductivity was more pronounced around the test implant surfaces. The parameters that differed between the implant surfaces, i.e. the oxide thickness, the pore size distribution, the porosity and the crystallinity of the surface oxides may represent factors that have an influence on the histomorphometrical results indicated by a stronger bone tissue response to the test implant surfaces, with an oxide thickness of more than 600 nm.

Susceptibility of metallic magnesium implants to bacterial biofilm infections.

PubMed

Rahim, Muhammad Imran; Rohde, Manfred; Rais, Bushra; Seitz, Jan-Marten; Mueller, Peter P

2016-06-01

Magnesium alloys have promising mechanical and biological properties as biodegradable medical implant materials for temporary applications during bone healing or as vascular stents. Whereas conventional implants are prone to colonization by treatment resistant microbial biofilms in which bacteria are embedded in a protective matrix, magnesium alloys have been reported to act antibacterial in vitro. To permit a basic assessment of antibacterial properties of implant materials in vivo an economic but robust animal model was established. Subcutaneous magnesium implants were inoculated with bacteria in a mouse model. Contrary to the expectations, bacterial activity was enhanced and prolonged in the presence of magnesium implants. Systemic antibiotic treatments were remarkably ineffective, which is a typical property of bacterial biofilms. Biofilm formation was further supported by electron microscopic analyses that revealed highly dense bacterial populations and evidence for the presence of extracellular matrix material. Bacterial agglomerates could be detected not only on the implant surface but also at a limited distance in the peri-implant tissue. Therefore, precautions may be necessary to minimize risks of metallic magnesium-containing implants in prospective clinical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1489-1499, 2016. © 2016 Wiley Periodicals, Inc.

Use of prefabricated titanium abutments and customized anatomic lithium disilicate structures for cement-retained implant restorations in the esthetic zone.

PubMed

Lin, Wei-Shao; Harris, Bryan T; Zandinejad, Amirali; Martin, William C; Morton, Dean

2014-03-01

This report describes the fabrication of customized abutments consisting of prefabricated 2-piece titanium abutments and customized anatomic lithium disilicate structures for cement-retained implant restorations in the esthetic zone. The heat-pressed lithium disilicate provides esthetic customized anatomic structures and crowns independently of the computer-aided design and computer-aided manufacturing process. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

A macro- and nanostructure evaluation of a novel dental implant.

PubMed

Tetè, Stefano; Mastrangelo, Filiberto; Traini, Tonino; Vinci, Raffaele; Sammartino, Gilberto; Marenzi, Gaetano; Gherlone, Enrico

2008-09-01

Success in implant dentistry also comes from the implant macrodesign and nanostructure of its surface. Titanium implant surface treatments have been shown to enhance osseointegration, maximize bone healing, and bone-to-implant contact for predictable clinical results. The aim of the study, was to evaluate the geometric macrodesign and the surface nanostructure of a novel dental implant full contact covering (FCC) obtained by electrochemical procedures. FCC implants were analyzed by scanning electronic microscope, profilometer, and x-ray photoelectron spectroscopy and compared with commercial sandblasted and sandblasted, large-grit acid-etched dental implants. Sample analysis allowed to distinguish the different implant macrodesigns, the step and the profile of the coils that cover the fixture, and the surface characteristics. FCC implant showed novel macro-characteristic of crestal module, coils, and apical zone compared with sandblasted and sandblasted and acid-etched dental implants. Moreover, the FCC nanostructure surface showed roughness values statistically higher than the 2 other surfaces, with a more homogeneity in a peaks and valleys arrangement. Finally, the x-ray photoelectron spectroscopy analysis detected differences between the examined surfaces, with the presence of several contaminants according to the different treatment procedures. Research on new macrostructures and nano morphology should result in a better qualitative and quantitative osseointegration response, with a predictability of the clinical results and long-term success of the implants.

Perception of Binaural Cues Develops in Children Who Are Deaf through Bilateral Cochlear Implantation

PubMed Central

Gordon, Karen A.; Deighton, Michael R.; Abbasalipour, Parvaneh; Papsin, Blake C.

2014-01-01

There are significant challenges to restoring binaural hearing to children who have been deaf from an early age. The uncoordinated and poor temporal information available from cochlear implants distorts perception of interaural timing differences normally important for sound localization and listening in noise. Moreover, binaural development can be compromised by bilateral and unilateral auditory deprivation. Here, we studied perception of both interaural level and timing differences in 79 children/adolescents using bilateral cochlear implants and 16 peers with normal hearing. They were asked on which side of their head they heard unilaterally or bilaterally presented click- or electrical pulse- trains. Interaural level cues were identified by most participants including adolescents with long periods of unilateral cochlear implant use and little bilateral implant experience. Interaural timing cues were not detected by new bilateral adolescent users, consistent with previous evidence. Evidence of binaural timing detection was, for the first time, found in children who had much longer implant experience but it was marked by poorer than normal sensitivity and abnormally strong dependence on current level differences between implants. In addition, children with prior unilateral implant use showed a higher proportion of responses to their first implanted sides than children implanted simultaneously. These data indicate that there are functional repercussions of developing binaural hearing through bilateral cochlear implants, particularly when provided sequentially; nonetheless, children have an opportunity to use these devices to hear better in noise and gain spatial hearing. PMID:25531107

Quality standards for bone conduction implants.

PubMed

Gavilan, Javier; Adunka, Oliver; Agrawal, Sumit; Atlas, Marcus; Baumgartner, Wolf-Dieter; Brill, Stefan; Bruce, Iain; Buchman, Craig; Caversaccio, Marco; De Bodt, Marc T; Dillon, Meg; Godey, Benoit; Green, Kevin; Gstoettner, Wolfgang; Hagen, Rudolf; Hagr, Abdulrahman; Han, Demin; Kameswaran, Mohan; Karltorp, Eva; Kompis, Martin; Kuzovkov, Vlad; Lassaletta, Luis; Li, Yongxin; Lorens, Artur; Martin, Jane; Manoj, Manikoth; Mertens, Griet; Mlynski, Robert; Mueller, Joachim; O'Driscoll, Martin; Parnes, Lorne; Pulibalathingal, Sasidharan; Radeloff, Andreas; Raine, Christopher H; Rajan, Gunesh; Rajeswaran, Ranjith; Schmutzhard, Joachim; Skarzynski, Henryk; Skarzynski, Piotr; Sprinzl, Georg; Staecker, Hinrich; Stephan, Kurt; Sugarova, Serafima; Tavora, Dayse; Usami, Shin-Ichi; Yanov, Yuri; Zernotti, Mario; Zorowka, Patrick; de Heyning, Paul Van

2015-01-01

Bone conduction implants are useful in patients with conductive and mixed hearing loss for whom conventional surgery or hearing aids are no longer an option. They may also be used in patients affected by single-sided deafness. To establish a consensus on the quality standards required for centers willing to create a bone conduction implant program. To ensure a consistently high level of service and to provide patients with the best possible solution the members of the HEARRING network have established a set of quality standards for bone conduction implants. These standards constitute a realistic minimum attainable by all implant clinics and should be employed alongside current best practice guidelines. Fifteen items are thoroughly analyzed. They include team structure, accommodation and clinical facilities, selection criteria, evaluation process, complete preoperative and surgical information, postoperative fitting and assessment, follow-up, device failure, clinical management, transfer of care and patient complaints.

Number of implants for mandibular implant overdentures: a systematic review

PubMed Central

Lee, Jeong-Yol; Kim, Ha-Young; Bryant, S. Ross

2012-01-01

PURPOSE The aim of this systematic review is to address treatment outcomes of Mandibular implant overdentures relative to implant survival rate, maintenance and complications, and patient satisfaction. MATERIALS AND METHODS A systematic literature search was conducted by a PubMed search strategy and hand-searching of relevant journals from included studies. Randomized Clinical Trials (RCT) and comparative clinical trial studies on mandibular implant overdentures until August, 2010 were selected. Eleven studies from 1098 studies were finally selected and data were analyzed relative to number of implants. RESULTS Six studies presented the data of the implant survival rate which ranged from 95% to 100% for 2 and 4 implant group and from 81.8% to 96.1% for 1 and 2 implant group. One study, which statistically compared implant survival rate showed no significant differences relative to the number of implants. The most common type of prosthetic maintenance and complications were replacement or reattaching of loose clips for 2 and 4 implant group, and denture repair due to the fracture around an implant for 1 and 2 implant groups. Most studies showed no significant differences in the rate of prosthetic maintenance and complication, and patient satisfaction regardless the number of implants. CONCLUSION The implant survival rate of mandibular overdentures is high regardless of the number of implants. Denture maintenance is likely not inflenced substantially by the number of implants and patient satisfaction is typically high again regardless os the number of implants. PMID:23236572

A Novel Percutaneous Electrode Implant for Improving Robustness in Advanced Myoelectric Control

PubMed Central

Hahne, Janne M.; Farina, Dario; Jiang, Ning; Liebetanz, David

2016-01-01

Despite several decades of research, electrically powered hand and arm prostheses are still controlled with very simple algorithms that process the surface electromyogram (EMG) of remnant muscles to achieve control of one prosthetic function at a time. More advanced machine learning methods have shown promising results under laboratory conditions. However, limited robustness has largely prevented the transfer of these laboratory advances to clinical applications. In this paper, we introduce a novel percutaneous EMG electrode to be implanted chronically with the aim of improving the reliability of EMG detection in myoelectric control. The proposed electrode requires a minimally invasive procedure for its implantation, similar to a cosmetic micro-dermal implant. Moreover, being percutaneous, it does not require power and data telemetry modules. Four of these electrodes were chronically implanted in the forearm of an able-bodied human volunteer for testing their characteristics. The implants showed significantly lower impedance and greater robustness against mechanical interference than traditional surface EMG electrodes used for myoelectric control. Moreover, the EMG signals detected by the proposed systems allowed more stable control performance across sessions in different days than that achieved with classic EMG electrodes. In conclusion, the proposed implants may be a promising interface for clinically available prostheses. PMID:27065783

Cochlear Implants.

ERIC Educational Resources Information Center

Clark, Catherine; Scott, Larry

This brochure explains what a cochlear implant is, lists the types of individuals with deafness who may be helped by a cochlear implant, describes the process of evaluating people for cochlear implants, discusses the surgical process for implanting the aid, traces the path of sound through the cochlear implant to the brain, notes the costs of…

Intrinsic point-defect balance in self-ion-implanted ZnO.

PubMed

Neuvonen, Pekka T; Vines, Lasse; Svensson, Bengt G; Kuznetsov, Andrej Yu

2013-01-04

The role of excess intrinsic atoms for residual point defect balance has been discriminated by implanting Zn or O ions into Li-containing ZnO and monitoring Li redistribution and electrical resistivity after postimplant anneals. Strongly Li-depleted regions were detected in the Zn-implanted samples at depths beyond the projected range (R(p)) upon annealing ≥ 600 °C, correlating with a resistivity decrease. In contrast, similar anneals of the O-implanted samples resulted in Li accumulation at R(p) and an increased resistivity. Control samples implanted with Ar or Ne ions, yielding similar defect production as for the Zn or O implants but with no surplus of intrinsic atoms, revealed no Li depletion. Thus, the depletion of Li shows evidence of excess Zn interstitials (Zn(I)) being released during annealing of the Zn-implanted samples. These Zn(I)'s convert substitutional Li atoms (Li(Zn)) into highly mobile interstitial ones leading to the strongly Li-depleted regions. In the O-implanted samples, the high resistivity provides evidence of stable O(I)-related acceptors.

Rupture of poly implant prothèse silicone breast implants: an implant retrieval study.

PubMed

Swarts, Eric; Kop, Alan M; Nilasaroya, Anastasia; Keogh, Catherine V; Cooper, Timothy

2013-04-01

Poly Implant Prothèse implants were recalled in Australia in April of 2010 following concerns of higher than expected rupture rates and the use of unauthorized industrial grade silicone as a filler material. Although subsequent investigations found that the gel filler material does not pose a threat to human health, the important question of what caused a relatively modern breast implant to have such a poor outcome compared with contemporary silicone breast implants is yet to be addressed. From a cohort of 27 patients, 19 ruptured Poly Implant Prothèse breast implants were subjected to a range of mechanical tests and microscopic/macroscopic investigations to evaluate possible changes in properties as a result of implantation. New Poly Implant Prothèse implants were used as controls. All samples, explanted and controls, complied with the requirements for shell integrity as specified in the International Organization for Standardization 14607. Compression testing revealed rupture rates similar to those reported in the literature. Shell thickness was highly variable, with most shells having regions below the minimum thickness of 0.57 mm that was specified by the manufacturer. Potential regions of stress concentration were observed on the smooth inner surfaces and outer textured surfaces. The high incidence of Poly Implant Prothèse shell rupture is most likely a result of inadequate quality control, with contributory factors being shell thickness variation and manufacturing defects on both inner and outer surfaces of the shell. No evidence of shell degradation with implantation time was determined.

Ultracompact Implantable Design With Integrated Wireless Power Transfer and RF Transmission Capabilities.

PubMed

Sun, Guilin; Muneer, Badar; Li, Ying; Zhu, Qi

2018-04-01

This paper presents an ultracompact design of biomedical implantable devices with integrated wireless power transfer (WPT) and RF transmission capabilities for implantable medical applications. By reusing the spiral coil in an implantable device, both RF transmission and WPT are realized without the performance degradation of both functions in ultracompact size. The complete theory of WPT based on magnetic resonant coupling is discussed and the design methodology of an integrated structure is presented in detail, which can guide the design effectively. A system with an external power transmitter and implantable structure is fabricated to validate the proposed approach. The experimental results show that the implantable structure can receive power wirelessly at 39.86 MHz with power transfer efficiency of 47.2% and can also simultaneously radiate at 2.45 GHz with an impedance bandwidth of 10.8% and a gain of -15.71 dBi in the desired direction. Furthermore, sensitivity analyses are carried out with the help of experiment and simulation. The results reveal that the system has strong tolerance to the nonideal conditions. Additionally, the specific absorption rate distribution is evaluated in the light of strict IEEE standards. The results reveal that the implantable structure can receive up to 115 mW power from an external transmitter and radiate 6.4 dB·m of power safely.

Detection of lobular structures in normal breast tissue.

PubMed

Apou, Grégory; Schaadt, Nadine S; Naegel, Benoît; Forestier, Germain; Schönmeyer, Ralf; Feuerhake, Friedrich; Wemmert, Cédric; Grote, Anne

2016-07-01

Ongoing research into inflammatory conditions raises an increasing need to evaluate immune cells in histological sections in biologically relevant regions of interest (ROIs). Herein, we compare different approaches to automatically detect lobular structures in human normal breast tissue in digitized whole slide images (WSIs). This automation is required to perform objective and consistent quantitative studies on large data sets. In normal breast tissue from nine healthy patients immunohistochemically stained for different markers, we evaluated and compared three different image analysis methods to automatically detect lobular structures in WSIs: (1) a bottom-up approach using the cell-based data for subsequent tissue level classification, (2) a top-down method starting with texture classification at tissue level analysis of cell densities in specific ROIs, and (3) a direct texture classification using deep learning technology. All three methods result in comparable overall quality allowing automated detection of lobular structures with minor advantage in sensitivity (approach 3), specificity (approach 2), or processing time (approach 1). Combining the outputs of the approaches further improved the precision. Different approaches of automated ROI detection are feasible and should be selected according to the individual needs of biomarker research. Additionally, detected ROIs could be used as a basis for quantification of immune infiltration in lobular structures. Copyright © 2016 Elsevier Ltd. All rights reserved.

Detection of entrapped moisture in honeycomb sandwich structures

NASA Technical Reports Server (NTRS)

Hallmark, W. B.

1967-01-01

Thermal neutron moisture detection system detects entrapped moisture in intercellular areas of bonded honeycomb sandwich structures. A radium/beryllium fast neutron source bombards a specimen. The emitted thermal neutrons from the target nucleus are detected and counted by a boron trifluoride thermal neutron detector.

Modelling and structural analysis of skull/cranial implant: beyond mid-line deformities.

PubMed

Bogu, V Phanindra; Kumar, Y Ravi; Kumar Khanara, Asit

2017-01-01

This computational study explores modelling and finite element study of the implant under Intracranial pressure (ICP) conditions with normal ICP range (7 mm Hg to 15 mm Hg) or increased ICP (>I5 mm Hg). The implant fixation points allow implant behaviour with respect to intracranial pressure conditions. However, increased fixation points lead to variation in deformation and equivalent stress. Finite element analysis is providing a valuable insight to know the deformation and equivalent stress. The patient CT data (Computed Tomography) is processed in Mimics software to get the mesh model. The implant is modelled by using modified reverse engineering technique with the help of Rhinoceros software. This modelling method is applicable for all types of defects including those beyond the middle line and multiple ones. It is designed with eight fixation points and ten fixation points to fix an implant. Consequently, the mechanical deformation and equivalent stress (von Mises) are calculated in ANSYS 15 software with distinctive material properties such as Titanium alloy (Ti6Al4V), Polymethyl methacrylate (PMMA) and polyether-ether-ketone (PEEK). The deformation and equivalent stress results are obtained through ANSYS 15 software. It is observed that Ti6Al4V material shows low deformation and PEEK material shows less equivalent stress. Among all materials PEEK shows noticeably good result. Hence, a concept was established and more clinically relevant results can be expected with implementation of realistic 3D printed model in the future. This will allow physicians to gain knowledge and decrease surgery time with proper planning.

Primary prevention of peri-implantitis: managing peri-implant mucositis.

PubMed

Jepsen, Søren; Berglundh, Tord; Genco, Robert; Aass, Anne Merete; Demirel, Korkud; Derks, Jan; Figuero, Elena; Giovannoli, Jean Louis; Goldstein, Moshe; Lambert, France; Ortiz-Vigon, Alberto; Polyzois, Ioannis; Salvi, Giovanni E; Schwarz, Frank; Serino, Giovanni; Tomasi, Cristiano; Zitzmann, Nicola U

2015-04-01

Over the past decades, the placement of dental implants has become a routine procedure in the oral rehabilitation of fully and partially edentulous patients. However, the number of patients/implants affected by peri-implant diseases is increasing. As there are--in contrast to periodontitis--at present no established and predictable concepts for the treatment of peri-implantitis, primary prevention is of key importance. The management of peri-implant mucositis is considered as a preventive measure for the onset of peri-implantitis. Therefore, the remit of this working group was to assess the prevalence of peri-implant diseases, as well as risks for peri-implant mucositis and to evaluate measures for the management of peri-implant mucositis. Discussions were informed by four systematic reviews on the current epidemiology of peri-implant diseases, on potential risks contributing to the development of peri-implant mucositis, and on the effect of patient and of professionally administered measures to manage peri-implant mucositis. This consensus report is based on the outcomes of these systematic reviews and on the expert opinion of the participants. Key findings included: (i) meta-analysis estimated a weighted mean prevalence for peri-implant mucositis of 43% (CI: 32-54%) and for peri-implantitis of 22% (CI: 14-30%); (ii) bleeding on probing is considered as key clinical measure to distinguish between peri-implant health and disease; (iii) lack of regular supportive therapy in patients with peri-implant mucositis was associated with increased risk for onset of peri-implantitis; (iv) whereas plaque accumulation has been established as aetiological factor, smoking was identified as modifiable patient-related and excess cement as local risk indicator for the development of peri-implant mucositis; (v) patient-administered mechanical plaque control (with manual or powered toothbrushes) has been shown to be an effective preventive measure; (vi) professional intervention

Development of ion implanted gallium arsenide transistors

NASA Technical Reports Server (NTRS)

Hunsperger, R.; Baron, R.

1972-01-01

Techniques were developed for creating bipolar microwave transistors in GaAs by ion implantation doping. The electrical properties of doped layers produced by the implantation of the light ions Be, Mg, and S were studied. Be, Mg, and S are suitable for forming the relatively deep base-collector junction at low ion energies. The electrical characteristics of ion-implanted diodes of both the mesa and planar types were determined. Some n-p-n planar transistor structures were fabricated by implantation of Mg to form the base regions and Si to form the emitters. These devices were found to have reasonably good base-collector and emitter-base junctions, but the current gain beta was small. The low was attributable to radiative recombination in the base region, which was extremely wide.

Materials and technologies for soft implantable neuroprostheses

NASA Astrophysics Data System (ADS)

Lacour, Stéphanie P.; Courtine, Grégoire; Guck, Jochen

2016-10-01

Implantable neuroprostheses are engineered systems designed to restore or substitute function for individuals with neurological deficits or disabilities. These systems involve at least one uni- or bidirectional interface between a living neural tissue and a synthetic structure, through which information in the form of electrons, ions or photons flows. Despite a few notable exceptions, the clinical dissemination of implantable neuroprostheses remains limited, because many implants display inconsistent long-term stability and performance, and are ultimately rejected by the body. Intensive research is currently being conducted to untangle the complex interplay of failure mechanisms. In this Review, we emphasize the importance of minimizing the physical and mechanical mismatch between neural tissues and implantable interfaces. We explore possible materials solutions to design and manufacture neurointegrated prostheses, and outline their immense therapeutic potential.

Zirconia Dental Implants: Investigation of Clinical Parameters, Patient Satisfaction, and Microbial Contamination.

PubMed

Holländer, Jens; Lorenz, Jonas; Stübinger, Stefan; Hölscher, Werner; Heidemann, Detlef; Ghanaati, Shahram; Sader, Robert

2016-01-01

In recent years, dental implants made from zirconia have been further developed and are considered a reliable treatment method for replacing missing teeth. The aim of this study was to analyze dental implants made from zirconia regarding their clinical performance compared with natural teeth (control). One hundred six zirconia implants in 38 adults were analyzed in a clinical study after 1 year of loading. The plaque index (PI), bleeding on probing (BOP), probing pocket depth (PPD), probing attachment level (PAL), and creeping or recession (CR/REC) of the gingiva were detected and compared with natural control teeth (CT). Furthermore, the papilla index (PAP), Periotest values (PTV), microbial colonization of the implant/dental sulcus fluid, and patient satisfaction were assessed. The survival rate was 100%. No statistical significance was observed between implants and teeth regarding BOP, PPD, and PAL. A statistical significance was detected regarding PI and CR/REC with significantly less plaque accumulation and recession in the study group. Mean PAP was 1.76 ± 0.55, whereas the mean PTV was -1.31 ± 2.24 (range from -5 to +6). A non-statistically significant higher colonization of periodontitis/peri-implantitis bacteria was observed in the implant group. The questionnaire showed that the majority of the patients were satisfied with the overall treatment. One-piece zirconia dental implants exhibited similar clinical results (BOP, PPD, and PAL) compared with natural teeth in regard to adhesion of plaque (PI) and creeping attachment (CR/REC); zirconia implants performed even better. The favorable results for PAL and CR/REC reflect the comparable low affinity of zirconia for plaque adhesion. Patient satisfaction indicated a high level of acceptance for zirconia implants. However, a long-term follow-up is needed to support these findings.

Increased crown-to-implant ratio may not be a risk factor for dental implant failure under appropriate plaque control.

PubMed

Okada, Shinsuke; Koretake, Katsunori; Miyamoto, Yasunari; Oue, Hiroshi; Akagawa, Yasumasa

2013-01-01

The aim of this study was to evaluate whether increased crown-to-implant (C/I) ratio influences implant stability or not under proper healthy control of peri-implant mucosa. The hypothesis of this study is that implant stability can be maintained despite High C/I, under appropriate plaque control. Five male Beagle-Labrador hybrid dogs (2 years old) were used. Their bilateral mandibular premolar extraction was performed. After allowing 12 weeks for bone healing, 3 types of vertical marginal bone loss were simultaneously prepared randomly. Then, 30 titanium implants were placed in the edentulous areas and defined as High C/I, Mid C/I and Low C/I groups. This time point was designated as the baseline (0 Week). Twelve weeks after implant placement, metal superstructures were cemented to the implants and an occlusal plate was set at the opposite side. At the same time, Calcein green was injected for remodeling evaluation. Implants were loaded by feeding the dogs a hard pellet diet. Tooth brushing was performed 5 days per week during the study to maintain healthy peri-implant mucosa. Twenty-four weeks following implant placement, the interface structure was evaluated clinically, radiologically, and histologically. Implant stability quotient (ISQ) increased with time in all 3 groups, without any significant correlation with the C/I value (p >0.05). Moreover, mean marginal bone loss adjacent around implants in all 3 groups ranged between 0.11 and 0.19 mm, with no significant difference (p >0.05). Many fluorescence-labeled bones are shown in the High C/I group. It is considered that high remodeling activity prevent marginal bone loss in the High C/I group and this may provide favorable implant stability under proper plaque control. These findings suggest that increased C/I may not be a risk factor for implant failure if the peri-implant mucosa is kept healthy, as was the case in this animal model.

Community structure detection based on the neighbor node degree information

NASA Astrophysics Data System (ADS)

Tang, Li-Ying; Li, Sheng-Nan; Lin, Jian-Hong; Guo, Qiang; Liu, Jian-Guo

2016-11-01

Community structure detection is of great significance for better understanding the network topology property. By taking into account the neighbor degree information of the topological network as the link weight, we present an improved Nonnegative Matrix Factorization (NMF) method for detecting community structure. The results for empirical networks show that the largest improved ratio of the Normalized Mutual Information value could reach 63.21%. Meanwhile, for synthetic networks, the highest Normalized Mutual Information value could closely reach 1, which suggests that the improved method with the optimal λ can detect the community structure more accurately. This work is helpful for understanding the interplay between the link weight and the community structure detection.

Solute diffusion through fibrotic tissue formed around protective cage system for implantable devices.

PubMed

Prihandana, Gunawan Setia; Ito, Hikaru; Tanimura, Kohei; Yagi, Hiroshi; Hori, Yuki; Soykan, Orhan; Sudo, Ryo; Miki, Norihisa

2015-08-01

This article presents the concept of an implantable cage system that can house and protect implanted biomedical sensing and therapeutic devices in the body. Cylinder-shaped cages made of porous polyvinyl alcohol (PVA) sheets with an 80-µm pore size and/or stainless steel meshes with 0.54-mm openings were implanted subcutaneously in the dorsal region of rats for 5 weeks. Analysis of the explanted cages showed the formation of fibrosis tissue around the cages. PVA cages had fibrotic tissue growing mostly along the outer surface of cages, while stainless steel cages had fibrotic tissue growing into the inside surface of the cage structure, due to the larger porosity of the stainless steel meshes. As the detection of target molecules with short time lags for biosensors and mass transport with low diffusion resistance into and out of certain therapeutic devices are critical for the success of such devices, we examined whether the fibrous tissue formed around the cages were permeable to molecules of our interest. For that purpose, bath diffusion and microfluidic chamber diffusion experiments using solutions containing the target molecules were performed. Diffusion of sodium, potassium and urea through the fibrosis tissue was confirmed, thus suggesting the potential of these cylindrical cages surrounded by fibrosis tissue to successfully encase implantable sensors and therapeutic apparatus. © 2014 Wiley Periodicals, Inc.

Diode Laser and Periodontal Regeneration-Assisted Management of Implant Complications in Anterior Maxilla.

PubMed

Salaria, Sanjeev Kumar; Sharma, Isha; Brar, Navjot Kaur; Kaur, Satwant

2018-01-01

Dental implant is being considered successful if the patient is pleased with both of its functional and esthetic outcome. As implant complications (such as peri-implantitis, inappropriate implant position, wrong angulation, and implant location too close to anatomical structures) have been frequently encountered in dental practice, therefore, thorough knowledge to manage such complications is the key prerequisite to prevent the failure of implant. The present case report discussed the etiology, diagnosis of early peri-implantitis, and periodontal abscess with their successful management through periodontal regeneration and diode laser-assisted therapy.

Relationship Between Peripheral and Psychophysical Measures of Amplitude Modulation Detection in Cochlear Implant Users.

PubMed

Tejani, Viral D; Abbas, Paul J; Brown, Carolyn J

This study investigates the relationship between electrophysiological and psychophysical measures of amplitude modulation (AM) detection. Prior studies have reported both measures of AM detection recorded separately from cochlear implant (CI) users and acutely deafened animals, but no study has made both measures in the same CI users. Animal studies suggest a progressive loss of high-frequency encoding as one ascends the auditory pathway from the auditory nerve to the cortex. Because the CI speech processor uses the envelope of an ongoing acoustic signal to modulate pulse trains that are subsequently delivered to the intracochlear electrodes, it is of interest to explore auditory nerve responses to modulated stimuli. In addition, psychophysical AM detection abilities have been correlated with speech perception outcomes. Thus, the goal was to explore how the auditory nerve responds to AM stimuli and to relate those physiologic measures to perception. Eight patients using Cochlear Ltd. Implants participated in this study. Electrically evoked compound action potentials (ECAPs) were recorded using a 4000 pps pulse train that was sinusoidally amplitude modulated at 125, 250, 500, and 1000 Hz rates. Responses were measured for each pulse over at least one modulation cycle for an apical, medial, and basal electrode. Psychophysical modulation detection thresholds (MDTs) were also measured via a three-alternative forced choice, two-down, one-up adaptive procedure using the same modulation frequencies and electrodes. ECAPs were recorded from individual pulses in the AM pulse train. ECAP amplitudes varied sinusoidally, reflecting the sinusoidal variation in the stimulus. A modulated response amplitude (MRA) metric was calculated as the difference in the maximal and minimum ECAP amplitudes over the modulation cycles. MRA increased as modulation frequency increased, with no apparent cutoff (up to 1000 Hz). In contrast, MDTs increased as the modulation frequency increased. This

Patients' perceptions of implant placement surgery, the post-surgical healing and the transitional implant prostheses: a qualitative study.

PubMed

Kashbour, Wafa A; Rousseau, Nikki; Thomason, J Mark; Ellis, Janice S

2017-07-01

This study aimed to explore patients' thoughts, feelings about, and experiences of, implant placement surgery (IPS), the post-surgical healing stage and the immediate post-surgical transitional implant prosthesis (TIP) (fixed and removable). A qualitative study design was chosen and 38 semi-structured telephone and face-to-face interviews were conducted with 34 patients at different stages of implant treatment. The interviews were transcribed verbatim; the data collection and coding process followed the principles of thematic analysis, which was facilitated through the use of NVivo10. Patients anticipated that surgery would be painful and unpleasant but were prepared to accept this temporary discomfort for the expected benefits of implant treatment. However, a key finding was that patients felt they had overestimated the trauma of surgery but underestimated the discomfort and difficulties of the healing phase. A number of difficulties were also identified with the TIP phase following implant surgery. Existing research has tended to focus on the longer term benefits of dental implant treatment. This qualitative study has investigated in-depth patients' perceptions of dental implant surgery, including their experiences related to sedation, and of transitional implant restoration. While patients felt their concerns were overestimated in relation to the implant surgery, they experienced greater morbidity than they expected in the healing phase. Recommendations are made for relatively small changes in care provision which might improve the overall patient experience. Partial dentate patients treated with a fixed transitional prosthesis experienced advantages more quickly than patients with an overdenture. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Method of fabricating optical waveguides by ion implantation doping

DOEpatents

Appleton, Bill R.; Ashley, Paul R.; Buchal, Christopher J.

1989-01-01

A method for fabricating high-quality optical waveguides in optical quality oxide crystals by ion implantation doping and controlled epitaxial recrystallization is provided. Masked LiNbO.sub.3 crystals are implanted with high concentrations of Ti dopant at ion energies of about 350 keV while maintaining the crystal near liquid nitrogen temperature. Ion implantation doping produces an amorphous, Ti-rich nonequilibrium phase in the implanted region. Subsequent thermal annealing in a water-saturated oxygen atmosphere at up to 1000.degree. C. produces solid-phase epitaxial regrowth onto the crystalline substrate. A high-quality single crystalline layer results which incorporates the Ti into the crystal structure at much higher concentrations than is possible by standard diffusion techniques, and this implanted region has excellent optical waveguides properties.

Method of fabricating optical waveguides by ion implantation doping

DOEpatents

Appleton, B.R.; Ashley, P.R.; Buchal, C.J.

1987-03-24

A method for fabricating high-quality optical waveguides in optical quality oxide crystals by ion implantation doping and controlled epitaxial recrystallization is provided. Masked LiNbO/sub 3/ crystals are implanted with high concentrations of Ti dopant at ion energies of about 360 keV while maintaining the crystal near liquid nitrogen temperature. Ion implantation doping produces an amorphous, Ti-rich nonequilibrium phase in the implanted region. Subsequent thermal annealing in a water-saturated oxygen atmosphere at up to 1000/degree/C produces solid-phase epitaxial regrowth onto the crystalline substrate. A high-quality crystalline layer results which incorporates the Ti into the crystal structure at much higher concentrations than is possible by standard diffusion techniques, and this implanted region has excellent optical waveguiding properties.

Updates on ultrasound research in implant dentistry: a systematic review of potential clinical indications.

PubMed

Bhaskar, Vaishnavi; Chan, Hsun-Liang; MacEachern, Mark; Kripfgans, Oliver D

2018-05-23

Ultrasonography has shown promising diagnostic value in dental implant imaging research; however, exactly how ultrasound was used and at what stage of implant therapy it can be applied has not been systematically evaluated. Therefore, the aim of this review is to investigate potential indications of ultrasound use in the three implant treatment phases, namely planning, intraoperative and postoperative phase. Eligible manuscripts were searched in major databases with a combination of key words related to the use of ultrasound imaging in implant therapy. An initial search yielded 414 articles, after further review, 28 articles were finally included for this systematic review. Ultrasound was found valuable, though at various development stages, for evaluating (1) soft tissues, (2) hard tissues (3) vital structures and (4) implant stability. B-mode, the main function to image anatomical structures of interest, has been evaluated in pre-clinical and clinical studies. Quantitative ultrasound parameters, e.g. sound speed and amplitude, are being developed to evaluate implant-bone stability, mainly in simulation and pre-clinical studies. Ultrasound could be potentially useful in all 3 treatment phases. In the planning phase, ultrasound could evaluate vital structures, tissue biotype, ridge width/density, and cortical bone thickness. During surgery, it can provide feedback by identifying vital structures and bone boundary. At follow-up visits, it could evaluate marginal bone level and implant stability. Understanding the current status of ultrasound imaging research for implant therapy would be extremely beneficial for accelerating translational research and its use in dental clinics.

Improvement of wireless power transmission efficiency of implantable subcutaneous devices by closed magnetic circuit mechanism.

PubMed

Jo, Sung-Eun; Joung, Sanghoon; Suh, Jun-Kyo Francis; Kim, Yong-Jun

2012-09-01

Induction coils were fabricated based on flexible printed circuit board for inductive transcutaneous power transmission. The coil had closed magnetic circuit (CMC) structure consisting of inner and outer magnetic core. The power transmission efficiency of the fabricated device was measured in the air and in vivo condition. It was confirmed that the CMC coil had higher transmission efficiency than typical air-core coil. The power transmission efficiency during a misalignment between primary coil and implanted secondary coil was also evaluated. The decrease of mutual inductance between the two coils caused by the misalignment led to a low efficiency of the inductive link. Therefore, it is important to properly align the primary coil and implanted secondary coil for effective power transmission. To align the coils, a feedback coil was proposed. This was integrated on the backside of the primary coil and enabled the detection of a misalignment of the primary and secondary coils. As a result of using the feedback coil, the primary and secondary coils could be aligned without knowledge of the position of the implanted secondary coil.

Short Implants Versus Standard Implants: Midterm Outcomes of a Clinical Study.

PubMed

Benlidayi, M Emre; Ucar, Yurdanur; Tatli, Ufuk; Ekren, Orhun; Evlice, Burcu; Kisa, Halil Ibrahim; Baksi, Uygar

2018-02-01

The aim of this study was to evaluate the midterm survival rate, marginal bone resorption (MBR), and stability of short implants and to compare the results with standard length implants. A total of 38 patients were included. In total, 147 implants (Nucleoss Implants, Izmir, Turkey) were placed (86 short implants and 61 standard implants). Cement-retained metal-ceramic prostheses were fabricated. MBR was evaluated on periapical radiographs taken at implant placement, at the time of crown insertion and annually thereafter. The stability of the implants was evaluated by resonance frequency analysis. The 3- and 5-year cumulative survival rates for standard implants was 98.4% and for short implants was 96.5% (P = 0.644). The MBR of the short implants was significantly lower than that of the standard implants after 1, 2, and 3 years of loading (P < 0.05). No significant differences were found between 2 groups after 6 and 12 months of loading in terms of implant stability (implant stability quotient values) (P > 0.05). Within the limits of this study, it is concluded that short implants achieved similar results as standard implants after 3 to 5 years of loading.

3D analysis of bone formation around titanium implants using micro-computed tomography (μCT)

NASA Astrophysics Data System (ADS)

Bernhardt, Ricardo; Scharnweber, Dieter; Müller, Bert; Beckmann, Felix; Goebbels, Jürgen; Jansen, John; Schliephake, Henning; Worch, Hartmut

2006-08-01

The quantitative analysis of bone formation around biofunctionalised metallic implants is an important tool for the further development of implants with higher success rates. This is, nowadays, especially important in cases of additional diseases like diabetes or osteoporosis. Micro computed tomography (μCT), as non-destructive technique, offers the possibility for quantitative three-dimensional recording of bone close to the implant's surface with micrometer resolution, which is the range of the relevant bony structures. Within different animal models using cylindrical and screw-shaped Ti6Al4V implants we have compared visualization and quantitative analysis of newly formed bone by the use of synchrotron-radiation-based CT-systems in comparison with histological findings. The SRμCT experiments were performed at the beamline BW 5 (HASYLAB at DESY, Hamburg, Germany; at the BAMline (BESSY, Berlin, Germany). For the experiments, PMMA-embedded samples were prepared with diameters of about 8 mm, which contain in the center the implant surrounded by the bony tissue. To (locally) quantify the bone formation, models were developed and optimized. The comparison of the results obtained by SRμCT and histology demonstrates the advantages and disadvantages of both approaches, although the bone formation values for the different biofunctionalized implants are identical within the error bars. SRμCT allows the clear identification of fully mineralized bone around the different titanium implants. As hundreds of virtual slices were easily generated for the individual samples, the quantification and interactive bone detection led to conclusions of high precision and statistical relevance. In this way, SRμCT in combination with interactive data analysis is proven to be more significant with respect to classical histology.

Salient Object Detection via Structured Matrix Decomposition.

PubMed

Peng, Houwen; Li, Bing; Ling, Haibin; Hu, Weiming; Xiong, Weihua; Maybank, Stephen J

2016-05-04

Low-rank recovery models have shown potential for salient object detection, where a matrix is decomposed into a low-rank matrix representing image background and a sparse matrix identifying salient objects. Two deficiencies, however, still exist. First, previous work typically assumes the elements in the sparse matrix are mutually independent, ignoring the spatial and pattern relations of image regions. Second, when the low-rank and sparse matrices are relatively coherent, e.g., when there are similarities between the salient objects and background or when the background is complicated, it is difficult for previous models to disentangle them. To address these problems, we propose a novel structured matrix decomposition model with two structural regularizations: (1) a tree-structured sparsity-inducing regularization that captures the image structure and enforces patches from the same object to have similar saliency values, and (2) a Laplacian regularization that enlarges the gaps between salient objects and the background in feature space. Furthermore, high-level priors are integrated to guide the matrix decomposition and boost the detection. We evaluate our model for salient object detection on five challenging datasets including single object, multiple objects and complex scene images, and show competitive results as compared with 24 state-of-the-art methods in terms of seven performance metrics.

Regulation and Biological Significance of Formation of Osteoclasts and Foreign Body Giant Cells in an Extraskeletal Implantation Model

PubMed Central

Ahmed, Gazi Jased; Tatsukawa, Eri; Morishita, Kota; Shibata, Yasuaki; Suehiro, Fumio; Kamitakahara, Masanobu; Yokoi, Taishi; Koji, Takehiko; Umeda, Masahiro; Nishimura, Masahiro; Ikeda, Tohru

2016-01-01

The implantation of biomaterials induces a granulomatous reaction accompanied by foreign body giant cells (FBGCs). The characterization of multinucleated giant cells (MNGCs) around bone substitutes implanted in bone defects is more complicated because of healing with bone admixed with residual bone substitutes and their hybrid, and the appearance of two kinds of MNGCs, osteoclasts and FBGCs. Furthermore, the clinical significance of osteoclasts and FBGCs in the healing of implanted regions remains unclear. The aim of the present study was to characterize MNGCs around bone substitutes using an extraskeletal implantation model and evaluate the clinical significance of osteoclasts and FBGCs. Beta-tricalcium phosphate (β-TCP) granules were implanted into rat subcutaneous tissue with or without bone marrow mesenchymal cells (BMMCs), which include osteogenic progenitor cells. We also compared the biological significance of plasma and purified fibrin, which were used as binders for implants. Twelve weeks after implantation, osteogenesis was only detected in specimens implanted with BMMCs. The expression of two typical osteoclast markers, tartrate-resistant acid phosphatase (TRAP) and cathepsin-K (CTSK), was analyzed, and TRAP-positive and CTSK-positive osteoclasts were only detected beside bone. In contrast, most of the MNGCs in specimens without the implantation of BMMCs were FBGCs that were negative for TRAP, whereas the degradation of β-TCP was detected. In the region implanted with β-TCP granules with plasma, FBGCs tested positive for CTSK, and when β-TCP granules were implanted with purified fibrin, FBGCs tested negative for CTSK. These results showed that osteogenesis was essential to osteoclastogenesis, two kinds of FBGCs, CTSK-positive and CTSK-negative, were induced, and the expression of CTSK was plasma-dependent. In addition, the implantation of BMMCs was suggested to contribute to osteogenesis and the replacement of implanted β-TCP granules to bone. PMID

A Hydrogel-Endothelial Cell implant Mimics Infantile Hemangioma: Modulation by Survivin and the Hippo pathway*

PubMed Central

Tsuneki, Masayuki; Hardee, Steven; Michaud, Michael; Morotti, Raffaella; Lavik, Erin; Madri, Joseph A.

2015-01-01

Microvascular endothelial cells cultured in three-dimensional hydrogel scaffolds form a network of microvessel structures when implanted subcutaneously in mice, inosculate with host vessels and over time remodel into large ectatic vascular structures resembling hemangiomas. When compared to infantile hemaniomas similarities were noted including a temporal progression from a morphological appearance of a proliferative phase to the appearance of an involuted phase mimicking the proliferative and involutional phases of infantile hemangioma. Consistent with the progression of a proliferative phase to an involuted phase, both the murine implants and human biopsy tissue exhibit reduced expression of Ajuba, YAP and Survivin labeling as they progressed over time. Significant numbers of CD45+, CD11b+, Mac3+ mononuclear cells were found at the 2 week time point in our implant model which correlated with the presence of CD45+, CD68+ mononuclear cells observed in biopsies of human proliferative phase hemangiomas. At the 4 week time point in our implant model only small numbers of CD45+ cells were detected, which again correlated with our findings of significantly diminished CD45+, CD68+ mononuclear cells in human involutional phase hemangiomas. The demonstration of mononuclear cell infiltration transiently in the proliferative phase of these lesions suggests that the vascular proliferation and/or regression may be driven in part by an immune response. Gross and microscopic morphological appearances of human proliferative and involutional hemangiomas and our implant model correlate well with each other as do the expression levels of Hippo pathway components (Ajuba and YAP) and Survivin and correlate with proliferation in these entities. Inhibitors of Survivin and Ajuba (which we have demonstrated to inhibit proliferation and increase apoptosis in murine hemangioma cell tissue culture) may have potential as other beneficial treatments for proliferating infantile hemangiomas

Effects of non-equilibrium plasma in the treatment of ligature-induced peri-implantitis.

PubMed

Shi, Qi; Song, Ke; Zhou, Xincai; Xiong, Zilan; Du, Tianfeng; Lu, Xinpei; Cao, Yingguang

2015-05-01

To evaluate the effects of non-equilibrium plasma in the treatment of ligature-induced peri-implantitis in beagle dogs. Six beagles received 12 implants installed in the position of the fourth mandibular premolars. Ligature-induced peri-implantitis was initiated at 3 months post-implantation. When approximately 40% of the supporting bone was lost, the ligatures were removed. The implants were subjected to the muco-periosteal scaling and chlorhexidine irrigation with or without plasma irrigation. Three months later, clinical, radiographic and microbiological analyses were performed. Block biopsies were prepared for micro-CT and histomorphometric analysis. The primary outcome was the difference in bone healing of peri-implant sites, and the secondary outcomes included changes in clinical parameters (SBI, PD) and bacterial detection. At baseline, no significant differences were observed between the two groups. At 3 months post-treatment, the plasma group showed a significantly higher bone level than the control group (p < 0.05), a significantly decreased detection of bacteria (Porphyromonas gingivalis and Tannerella forsythia) (p < 0.05), and a significant improvement in clinical examination (p < 0.05). Within the limits of this study, non-equilibrium plasma treatment as an adjunct to the conventional therapy is a feasible approach for the treatment of peri-implantitis. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Hollow fiber: a biophotonic implant for live cells

NASA Astrophysics Data System (ADS)

Silvestre, Oscar F.; Holton, Mark D.; Summers, Huw D.; Smith, Paul J.; Errington, Rachel J.

2009-02-01

The technical objective of this study has been to design, build and validate biocompatible hollow fiber implants based on fluorescence with integrated biophotonics components to enable in fiber kinetic cell based assays. A human osteosarcoma in vitro cell model fiber system has been established with validation studies to determine in fiber cell growth, cell cycle analysis and organization in normal and drug treated conditions. The rationale for implant development have focused on developing benchmark concepts in standard monolayer tissue culture followed by the development of in vitro hollow fiber designs; encompassing imaging with and without integrated biophotonics. Furthermore the effect of introducing targetable biosensors into the encapsulated tumor implant such as quantum dots for informing new detection readouts and possible implant designs have been evaluated. A preliminary micro/macro imaging approach has been undertaken, that could provide a mean to track distinct morphological changes in cells growing in a 3D matrix within the fiber which affect the light scattering properties of the implant. Parallel engineering studies have showed the influence of the optical properties of the fiber polymer wall in all imaging modes. Taken all together, we show the basic foundation and the opportunities for multi-modal imaging within an in vitro implant format.

Metallic artifact in MRI after removal of orthopedic implants.

PubMed

Bagheri, Mohammad Hadi; Hosseini, Mehrdad Mohammad; Emami, Mohammad Jafar; Foroughi, Amin Aiboulhassani

2012-03-01

The aim of the present study was to evaluate the metallic artifacts in MRI of the orthopedic patients after removal of metallic implants. From March to August 2009, 40 orthopedic patients operated for removal of orthopedic metallic implants were studied by post-operative MRI from the site of removal of implants. A grading scale of 0-3 was assigned for artifact in MR images whereby 0 was considered no artifact; and I-III were considered mild, moderate, and severe metallic artifacts, respectively. These grading records were correlated with other variables including the type, size, number, and composition of metallic devices; and the site and duration of orthopedic devices stay in the body. Metallic susceptibly artifacts were detected in MRI of 18 of 40 cases (45%). Screws and pins in removed hardware were the most important factors for causing artifacts in MRI. The artifacts were found more frequently in the patients who had more screws and pins in the removed implants. Gender, age, site of implantation of the device, length of the hardware, composition of the metallic implants (stainless steel versus titanium), and duration of implantation of the hardware exerted no effect in producing metallic artifacts after removal of implants. Short TE sequences of MRI (such as T1 weighted) showed fewer artifacts. Susceptibility of metallic artifacts is a frequent phenomenon in MRI of patients upon removal of metallic orthopedic implants. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Effect of nitrogen ion implantation on the structural and optical properties of indium oxide thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sethi, Riti; Aziz, Anver; Siddiqui, Azher M., E-mail: amsiddiqui@jmi.ac.in

2016-06-10

: We report here synthesis and subsequent nitrogen ion implantation of indium oxide (In{sub 2}O{sub 3}) thin films. The films were implanted with 25 keV N{sup +} beam for different ion doses between 3E15 to 1E16 ions/cm{sup 2}. The resulting changes in structural and optical properties were investigated using XRD, SEM-EDAX and UV-Vis Spectrometry. XRD studies reveal decrease in crystallite size from 20.06 to 12.42 nm with increase in ion dose. SEM micrographs show an increase in the grain size from 0.8 to 1.35 µm with increase in ion dose because of the agglomeration of the grains. Also, from EDAXmore » data on pristine and N-implanted thin films the presence of indium and oxygen without any traces of impurity elements could be seen. However, at lower ion doses such as 3E15 and 5E15 ions/cm{sup 2}, no evidence of the presence of nitrogen ion was seen. However, for the ion dose of 1E16 ions/cm{sup 2}, evidence of presence of nitrogen can be seen in the EDAX data. Band gap calculations reveal a decrease in band gap from 3.54 to 3.38 eV with increasing ion dose. However, the band gap was found to again show an increase to 3.58 eV at the highest ion dose owing to quantum confinement effect.« less

Elucidation of Iron Gettering Mechanisms in Boron-Implanted Silicon Solar Cells

DOE PAGES

Laine, Hannu S.; Vahanissi, Ville; Liu, Zhengjun; ...

2017-12-15

To facilitate cost-effective manufacturing of boron-implanted silicon solar cells as an alternative to BBr 3 diffusion, we performed a quantitative test of the gettering induced by solar-typical boron-implants with the potential for low saturation current density emitters (< 50 fA/cm 2). We show that depending on the contamination level and the gettering anneal chosen, such boron-implanted emitters can induce more than a 99.9% reduction in bulk iron point defect concentration. The iron point defect results as well as synchrotron-based Nano-X-ray-fluorescence investigations of iron precipitates formed in the implanted layer imply that, with the chosen experimental parameters, iron precipitation is themore » dominant gettering mechanism, with segregation-based gettering playing a smaller role. We reproduce the measured iron point defect and precipitate distributions via kinetics modeling. First, we simulate the structural defect distribution created by the implantation process, and then we model these structural defects as heterogeneous precipitation sites for iron. Unlike previous theoretical work on gettering via boron- or phosphorus-implantation, our model is free of adjustable simulation parameters. The close agreement between the model and experimental results indicates that the model successfully captures the necessary physics to describe the iron gettering mechanisms operating in boron-implanted silicon. Furthermore, this modeling capability allows high-performance, cost-effective implanted silicon solar cells to be designed.« less

Elucidation of Iron Gettering Mechanisms in Boron-Implanted Silicon Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laine, Hannu S.; Vahanissi, Ville; Liu, Zhengjun

To facilitate cost-effective manufacturing of boron-implanted silicon solar cells as an alternative to BBr 3 diffusion, we performed a quantitative test of the gettering induced by solar-typical boron-implants with the potential for low saturation current density emitters (< 50 fA/cm 2). We show that depending on the contamination level and the gettering anneal chosen, such boron-implanted emitters can induce more than a 99.9% reduction in bulk iron point defect concentration. The iron point defect results as well as synchrotron-based Nano-X-ray-fluorescence investigations of iron precipitates formed in the implanted layer imply that, with the chosen experimental parameters, iron precipitation is themore » dominant gettering mechanism, with segregation-based gettering playing a smaller role. We reproduce the measured iron point defect and precipitate distributions via kinetics modeling. First, we simulate the structural defect distribution created by the implantation process, and then we model these structural defects as heterogeneous precipitation sites for iron. Unlike previous theoretical work on gettering via boron- or phosphorus-implantation, our model is free of adjustable simulation parameters. The close agreement between the model and experimental results indicates that the model successfully captures the necessary physics to describe the iron gettering mechanisms operating in boron-implanted silicon. Furthermore, this modeling capability allows high-performance, cost-effective implanted silicon solar cells to be designed.« less

Surgical evaluation of candidates for cochlear implants

NASA Technical Reports Server (NTRS)

Black, F. O.; Lilly, D. J.; Fowler, L. P.; Stypulkowski, P. H.

1987-01-01

The customary presentation of surgical procedures to patients in the United States consists of discussions on alternative treatment methods, risks of the procedure(s) under consideration, and potential benefits for the patient. Because the contents of the normal speech signal have not been defined in a way that permits a surgeon systematically to provide alternative auditory signals to a deaf patient, the burden is placed on the surgeon to make an arbitrary selection of candidates and available devices for cochlear prosthetic implantation. In an attempt to obtain some information regarding the ability of a deaf patient to use electrical signals to detect and understand speech, the Good Samaritan Hospital and Neurological Sciences Institute cochlear implant team has routinely performed tympanotomies using local anesthesia and has positioned temporary electrodes onto the round windows of implant candidates. The purpose of this paper is to review our experience with this procedure and to provide some observations that may be useful in a comprehensive preoperative evaluation for totally deaf patients who are being considered for cochlear implantation.

Predictors of Arrhythmic Events Detected by Implantable Loop Recorders in Renal Transplant Candidates

PubMed Central

Silva, Rodrigo Tavares; Martinelli Filho, Martino; Peixoto, Giselle de Lima; de Lima, José Jayme Galvão; de Siqueira, Sérgio Freitas; Costa, Roberto; Gowdak, Luís Henrique Wolff; de Paula, Flávio Jota; Kalil Filho, Roberto; Ramires, José Antônio Franchini

2015-01-01

Background The recording of arrhythmic events (AE) in renal transplant candidates (RTCs) undergoing dialysis is limited by conventional electrocardiography. However, continuous cardiac rhythm monitoring seems to be more appropriate due to automatic detection of arrhythmia, but this method has not been used. Objective We aimed to investigate the incidence and predictors of AE in RTCs using an implantable loop recorder (ILR). Methods A prospective observational study conducted from June 2009 to January 2011 included 100 consecutive ambulatory RTCs who underwent ILR and were followed-up for at least 1 year. Multivariate logistic regression was applied to define predictors of AE. Results During a mean follow-up of 424 ± 127 days, AE could be detected in 98% of patients, and 92% had more than one type of arrhythmia, with most considered potentially not serious. Sustained atrial tachycardia and atrial fibrillation occurred in 7% and 13% of patients, respectively, and bradyarrhythmia and non-sustained or sustained ventricular tachycardia (VT) occurred in 25% and 57%, respectively. There were 18 deaths, of which 7 were sudden cardiac events: 3 bradyarrhythmias, 1 ventricular fibrillation, 1 myocardial infarction, and 2 undetermined. The presence of a long QTc (odds ratio [OR] = 7.28; 95% confidence interval [CI], 2.01–26.35; p = 0.002), and the duration of the PR interval (OR = 1.05; 95% CI, 1.02–1.08; p < 0.001) were independently associated with bradyarrhythmias. Left ventricular dilatation (LVD) was independently associated with non-sustained VT (OR = 2.83; 95% CI, 1.01–7.96; p = 0.041). Conclusions In medium-term follow-up of RTCs, ILR helped detect a high incidence of AE, most of which did not have clinical relevance. The PR interval and presence of long QTc were predictive of bradyarrhythmias, whereas LVD was predictive of non-sustained VT. PMID:26351983

Characterization of porous glass fiber-reinforced composite (FRC) implant structures: porosity and mechanical properties.

PubMed

Ylä-Soininmäki, Anne; Moritz, Niko; Lassila, Lippo V J; Peltola, Matti; Aro, Hannu T; Vallittu, Pekka K

2013-12-01

The aim of this study was to characterize the microstructure and mechanical properties of porous fiber-reinforced composites (FRC). Implants made of the FRC structures are intended for cranial applications. The FRC specimens were prepared by impregnating E-glass fiber sheet with non-resorbable bifunctional bis-phenyl glycidyl dimethacrylate and triethylene glycol dimethacrylate resin matrix. Four groups of porous FRC specimens were prepared with a different amount of resin matrix. Control group contained specimens of fibers, which were bound together with sizing only. Microstructure of the specimens was analyzed using a micro computed tomography (micro-CT) based method. Mechanical properties of the specimens were measured with a tensile test. The amount of resin matrix in the specimens had an effect on the microstructure. Total porosity was 59.5 % (median) in the group with the lowest resin content and 11.2 % (median) in the group with the highest resin content. In control group, total porosity was 94.2 % (median). Correlations with resin content were obtained for all micro-CT based parameters except TbPf. The tensile strength of the composites was 21.3 MPa (median) in the group with the highest resin content and 43.4 MPa (median) in the group with the highest resin content. The tensile strength in control group was 18.9 MPa (median). There were strong correlations between the tensile strength of the specimens and most of the micro-CT based parameters. This experiment suggests that porous FRC structures may have the potential for use in implants for cranial bone reconstructions, provided further relevant in vitro and in vivo tests are performed.

Bioactive macroporous titanium implants highly interconnected.

PubMed

Caparrós, Cristina; Ortiz-Hernandez, Mónica; Molmeneu, Meritxell; Punset, Miguel; Calero, José Antonio; Aparicio, Conrado; Fernández-Fairén, Mariano; Perez, Román; Gil, Francisco Javier

2016-10-01

Intervertebral implants should be designed with low load requirements, high friction coefficient and low elastic modulus in order to avoid the stress shielding effect on bone. Furthermore, the presence of a highly interconnected porous structure allows stimulating bone in-growth and enhancing implant-bone fixation. The aim of this study was to obtain bioactive porous titanium implants with highly interconnected pores with a total porosity of approximately 57 %. Porous Titanium implants were produced by powder sintering route using the space holder technique with a binder phase and were then evaluated in an in vivo study. The size of the interconnection diameter between the macropores was about 210 μm in order to guarantee bone in-growth through osteblastic cell penetration. Surface roughness and mechanical properties were analyzed. Stiffness was reduced as a result of the powder sintering technique which allowed the formation of a porous network. Compression and fatigue tests exhibited suitable properties in order to guarantee a proper compromise between mechanical properties and pore interconnectivity. Bioactivity treatment effect in novel sintered porous titanium materials was studied by thermo-chemical treatments and were compared with the same material that had undergone different bioactive treatments. Bioactive thermo-chemical treatment was confirmed by the presence of sodium titanates on the surface of the implants as well as inside the porous network. Raman spectroscopy results suggested that the identified titanate structures would enhance in vivo apatite formation by promoting ion exchange for the apatite formation process. In vivo results demonstrated that the bioactive titanium achieved over 75 % tissue colonization compared to the 40 % value for the untreated titanium.

Peri-implant bone length changes and survival rates of implants penetrating the sinus membrane at the posterior maxilla in patients with limited vertical bone height.

PubMed

Kim, Hae-Young; Yang, Jin-Yong; Chung, Bo-Yoon; Kim, Jeong Chan; Yeo, In-Sung

2013-04-01

The aim of this study was to measure the peri-implant bone length surrounding implants that penetrate the sinus membrane at the posterior maxilla and to evaluate the survival rate of these implants. Treatment records and orthopantomographs of 39 patients were reviewed and analyzed. The patients had partial edentulism at the posterior maxilla and limited vertical bone height below the maxillary sinus. Implants were inserted into the posterior maxilla, penetrating the sinus membrane. Four months after implant insertion, provisional resin restorations were temporarily cemented to the abutments and used for one month. Then, a final impression was taken at the abutment level, and final cement-retained restorations were delivered with mutually protected occlusion. The complications from the implant surgery were examined, the number of failed implants was counted, and the survival rate was calculated. The peri-implant bone lengths were measured using radiographs. The changes in initial and final peri-implant bone lengths were statistically analyzed. Nasal bleeding occurred after implant surgery in three patients. No other complications were found. There were no failures of the investigated implants, resulting in a survival rate of 100%. Significantly more bone gain around the implants (estimated difference=-0.6 mm, P=0.025) occurred when the initial residual bone height was less than 5 mm compared to the >5 mm groups. No significant change in peri-implant bone length was detected when the initial residual bone height was 5 mm or larger. This study suggests that implants penetrating the sinus membrane at the posterior maxilla in patients with limited vertical bone height may be safe and functional.

Dual-modal photoacoustic and ultrasound imaging of dental implants

NASA Astrophysics Data System (ADS)

Lee, Donghyun; Park, Sungjo; Kim, Chulhong

2018-02-01

Dental implants are common method to replace decayed or broken tooth. As the implant treatment procedures varies according to the patients' jawbone, bone ridge, and sinus structure, appropriate examinations are necessary for successful treatment. Currently, radiographic examinations including periapical radiology, panoramic X-ray, and computed tomography are commonly used for diagnosing and monitoring. However, these radiographic examinations have limitations in that patients and operators are exposed to radioactivity and multiple examinations are performed during the treatment. In this study, we demonstrated photoacoustic (PA) and ultrasound (US) combined imaging of dental implant that can lower the total amount of absorbed radiation dose in dental implant treatment. An acoustic resolution PA macroscopy and a clinical PA/US system was used for dental implant imaging. The acquired dual modal PA/US imaging results support that the proposed photoacoustic imaging strategy can reduce the radiation dose rate during dental implant treatment.

Electrical and structural properties of In-implanted Si 1–xGe x alloys

DOE PAGES

Feng, Ruixing; Kremer, F.; Sprouster, D. J.; ...

2016-01-14

Here, we report on the effects of dopant concentration and substrate stoichiometry on the electrical and structural properties of In-implanted Si 1–xGe x alloys. Correlating the fraction of electrically active In atoms from Hall Effect measurements with the In atomic environment determined by X-ray absorption spectroscopy, we observed the transition from electrically active, substitutional In at low In concentration to electrically inactive metallic In at high In concentration. The In solid-solubility limit has been quantified and was dependent on the Si 1–xGe x alloy stoichiometry; the solid-solubility limit increased as the Ge fraction increased. This result was consistent with densitymore » functional theory calculations of two In atoms in a Si 1–xGe x supercell that demonstrated that In–In pairing was energetically favorable for x ≲ 0.7 and energetically unfavorable for x ≳ 0.7. Transmission electron microscopy imaging further complemented the results described earlier with the In concentration and Si 1–xGe x alloy stoichiometry dependencies readily visible. We have demonstrated that low resistivity values can be achieved with In implantation in Si 1–xGe x alloys, and this combination of dopant and substrate represents an effective doping protocol.« less

Why are mini-implants lost: the value of the implantation technique!

PubMed

Romano, Fabio Lourenço; Consolaro, Alberto

2015-01-01

The use of mini-implants have made a major contribution to orthodontic treatment. Demand has aroused scientific curiosity about implant placement procedures and techniques. However, the reasons for instability have not yet been made totally clear. The aim of this article is to establish a relationship between implant placement technique and mini-implant success rates by means of examining the following hypotheses: 1) Sites of poor alveolar bone and little space between roots lead to inadequate implant placement; 2) Different sites require mini-implants of different sizes! Implant size should respect alveolar bone diameter; 3) Properly determining mini-implant placement site provides ease for implant placement and contributes to stability; 4) The more precise the lancing procedures, the better the implant placement technique; 5) Self-drilling does not mean higher pressures; 6) Knowing where implant placement should end decreases the risk of complications and mini-implant loss.

Digital photoelastic analysis applied to implant dentistry

NASA Astrophysics Data System (ADS)

Ramesh, K.; Hariprasad, M. P.; Bhuvanewari, S.

2016-12-01

Development of improved designs of implant systems in dentistry have necessitated the study of stress fields in the implant regions of the mandible/maxilla for better understanding of the biomechanics involved. Photoelasticity has been used for various studies related to dental implants in view of whole field visualization of maximum shear stress in the form of isochromatic contours. The potential of digital photoelasticity has not been fully exploited in the field of implant dentistry. In this paper, the fringe field in the vicinity of the connected implants (All-On-Four® concept) is analyzed using recent advances in digital photoelasticity. Initially, a novel 3-D photoelastic model making procedure, to closely mimic all the anatomical features of the human mandible is proposed. By choosing appropriate orientation of the model with respect to the light path, the essential region of interest were sought to be analysed while keeping the model under live loading conditions. Need for a sophisticated software module to carefully identify the model domain has been brought out. For data extraction, five-step method is used and isochromatics are evaluated by twelve fringe photoelasticity. In addition to the isochromatic fringe field, whole field isoclinic data is also obtained for the first time in implant dentistry, which could throw important information in improving the structural stability of the implant systems. Analysis is carried out for the implant in the molar as well as the incisor region. In addition, the interaction effects of loaded molar implant on the incisor area are also studied.

Fiber-optic bending sensor for cochlear implantation

NASA Astrophysics Data System (ADS)

Li, Enbang; Yao, Jianquan

2006-09-01

Cochlear implantation has been proved as a great success in treating profound sensorineural deafness in both children and adults. Cochlear electrode array implantation is a complex and delicate surgical process. Surgically induced damage to the inner wall of the scala tympani could happen if the insertion angle of the electrode is incorrect and an excessive insertion force is applied to the electrode. This damage could lead to severe degeneration of the remaining neural elements. It is therefore of vital importance to monitor the shape and position of the electrode during the implantation surgery. In this paper, we report a fiber-optic bending sensor which can be integrated with the electrode and used to guide the implantation process. The sensor consists of a piece of optical fiber. The end of the fiber is coated with aluminum layer to form a mirror. Bending the fiber with the electrode introduces loss to the light transmitting in the fiber. By detecting the power of the reflected light, we can detennine the bending happened to the fiber, and consequently measure the curved shape of the electrode. Experimental results show that the proposed fiber sensor is a promising technique to make in-situ monitoring of the shape and position of the electrode during the implantation process.

Nitrogen implantation with a scanning electron microscope.

PubMed

Becker, S; Raatz, N; Jankuhn, St; John, R; Meijer, J

2018-01-08

Established techniques for ion implantation rely on technically advanced and costly machines like particle accelerators that only few research groups possess. We report here about a new and surprisingly simple ion implantation method that is based upon a widespread laboratory instrument: The scanning electron microscope. We show that it can be utilized to ionize atoms and molecules from the restgas by collisions with electrons of the beam and subsequently accelerate and implant them into an insulating sample by the effect of a potential building up at the sample surface. Our method is demonstrated by the implantation of nitrogen ions into diamond and their subsequent conversion to nitrogen vacancy centres which can be easily measured by fluorescence confocal microscopy. To provide evidence that the observed centres are truly generated in the way we describe, we supplied a 98% isotopically enriched 15 N gas to the chamber, whose natural abundance is very low. By employing the method of optically detected magnetic resonance, we were thus able to verify that the investigated centres are actually created from the 15 N isotopes. We also show that this method is compatible with lithography techniques using e-beam resist, as demonstrated by the implantation of lines using PMMA.

Home monitoring after ambulatory implanted primary cardiac implantable electronic devices: The home ambulance pilot study.

PubMed

Parahuleva, Mariana S; Soydan, Nedim; Divchev, Dimitar; Lüsebrink, Ulrich; Schieffer, Bernhard; Erdogan, Ali

2017-11-01

The Home Monitoring (HM) system of cardiac implantable electronic devices (CIEDs) permits early detection of arrhythmias or device system failures. The aim of this pilot study was to examine how the safety and efficacy of the HM system in patients after ambulatory implanted primary CIEDs compare to patients with a standard procedure and hospitalization. We hypothesized that HM and their modifications would be a useful extension of the present concepts for ambulatory implanted CIEDs. This retrospective analysis evaluates telemetric data obtained from 364 patients in an ambulatory single center over 6 years. Patients were assigned to an active group (n = 217), consisting of those who were discharged early on the day of implantation of the primary CIED, or to a control group (n = 147), consisting of those discharged and followed up with the HM system according to usual medical practices. The mean duration of hospitalization was 73.2% shorter in the active group than in the control group, corresponding to 20.5 ± 13 fewer hours (95% confidence interval [CI]: 6.3-29.5; P < 0.01) spent in the hospital (7.5 ± 1.5 vs 28 ± 4.5 h). This shorter mean hospital stay was attributable to a 78.8% shorter postoperative period in the active group. The proportion of patients with treatment-related adverse events was 11% (n = 23) in the active group and 17% (n = 25) in the control group (95% CI: 5.5-8.3; P = 0.061). This 6% absolute risk reduction (95% CI: 3.3-9.1; P = 0.789) confirmed the noninferiority of the ambulatory implanted CIED when compared with standard management of these patients. Early discharge with the HM system after ambulatory CIED implantation was safe and not inferior to the classic medical procedure. Thus, together with lower costs, HM and its modifications would be a useful extension of the present concepts for ambulatory implanted CIEDs. © 2017 Wiley Periodicals, Inc.

Structural and Functional Evaluations for the Early Detection of Glaucoma.

PubMed

Lucy, Katie A; Wollstein, Gadi

2016-01-01

The early detection of glaucoma is imperative in order to preserve functional vision. Structural and functional methods are utilized to detect and monitor glaucomatous damage and the vision loss it causes. The relationship between these detection measures is complex and differs between individuals, especially in early glaucoma. Using both measures together is advised in order to ensure the highest probability of glaucoma detection, and new testing methods are continuously developed with the goals of earlier disease detection and improvement of disease monitoring. The purpose of this review is to explore the relationship between structural and functional glaucoma detection and discuss important technological advances for early glaucoma detection.

Structural and Functional Evaluations for the Early Detection of Glaucoma

PubMed Central

Lucy, Katie A.; Wollstein, Gadi

2016-01-01

The early detection of glaucoma is imperative in order to preserve functional vision. Structural and functional methods are utilized to detect and monitor glaucomatous damage and the vision loss it causes. The relationship between these detection measures is complex and differs between individuals, especially in early glaucoma. Using both measures together is advised in order to ensure the highest probability of glaucoma detection, and new testing methods are continuously developed with the goals of earlier disease detection and improvement of disease monitoring. The purpose of this review is to explore the relationship between structural and functional glaucoma detection and discuss important technological advances for early glaucoma detection. PMID:28603546

[Design on tester of pull-out force for orthodontic micro implant].

PubMed

Su, He; Wu, Pei; Wang, Huiyuan; Chen, Yan; Bao, Xuemei

2013-09-01

A special device for measuring the pull-out force of orthodontic micro implant was designed, which has the characteristics of simple construction and easy operation, and can be used to detect the pull-out-force of orthodontic micro implant. The tested data was stored and analyzed by a computer, and as the results, the pull-out-force curve, maximum pull-out force as well as average pull-out force were outputted, which was applied in analyzing or investigating the initial stability and immediate loading property of orthodontic micro implant.

Unsupervised Structure Detection in Biomedical Data.

PubMed

Vogt, Julia E

2015-01-01

A major challenge in computational biology is to find simple representations of high-dimensional data that best reveal the underlying structure. In this work, we present an intuitive and easy-to-implement method based on ranked neighborhood comparisons that detects structure in unsupervised data. The method is based on ordering objects in terms of similarity and on the mutual overlap of nearest neighbors. This basic framework was originally introduced in the field of social network analysis to detect actor communities. We demonstrate that the same ideas can successfully be applied to biomedical data sets in order to reveal complex underlying structure. The algorithm is very efficient and works on distance data directly without requiring a vectorial embedding of data. Comprehensive experiments demonstrate the validity of this approach. Comparisons with state-of-the-art clustering methods show that the presented method outperforms hierarchical methods as well as density based clustering methods and model-based clustering. A further advantage of the method is that it simultaneously provides a visualization of the data. Especially in biomedical applications, the visualization of data can be used as a first pre-processing step when analyzing real world data sets to get an intuition of the underlying data structure. We apply this model to synthetic data as well as to various biomedical data sets which demonstrate the high quality and usefulness of the inferred structure.

Additively manufactured porous tantalum implants.

PubMed

Wauthle, Ruben; van der Stok, Johan; Amin Yavari, Saber; Van Humbeeck, Jan; Kruth, Jean-Pierre; Zadpoor, Amir Abbas; Weinans, Harrie; Mulier, Michiel; Schrooten, Jan

2015-03-01

The medical device industry's interest in open porous, metallic biomaterials has increased in response to additive manufacturing techniques enabling the production of complex shapes that cannot be produced with conventional techniques. Tantalum is an important metal for medical devices because of its good biocompatibility. In this study selective laser melting technology was used for the first time to manufacture highly porous pure tantalum implants with fully interconnected open pores. The architecture of the porous structure in combination with the material properties of tantalum result in mechanical properties close to those of human bone and allow for bone ingrowth. The bone regeneration performance of the porous tantalum was evaluated in vivo using an orthotopic load-bearing bone defect model in the rat femur. After 12 weeks, substantial bone ingrowth, good quality of the regenerated bone and a strong, functional implant-bone interface connection were observed. Compared to identical porous Ti-6Al-4V structures, laser-melted tantalum shows excellent osteoconductive properties, has a higher normalized fatigue strength and allows for more plastic deformation due to its high ductility. It is therefore concluded that this is a first step towards a new generation of open porous tantalum implants manufactured using selective laser melting. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

3D printed Ti6Al4V implant surface promotes bone maturation and retains a higher density of less aged osteocytes at the bone-implant interface.

PubMed

Shah, Furqan A; Snis, Anders; Matic, Aleksandar; Thomsen, Peter; Palmquist, Anders

2016-01-01

For load-bearing orthopaedic applications, metal implants having an interconnected pore structure exhibit the potential to facilitate bone ingrowth and the possibility for reducing the stiffness mismatch between the implant and bone, thus eliminating stress-shielding effects. 3D printed solid and macro-porous Ti6Al4V implants were evaluated after six-months healing in adult sheep femora. The ultrastructural composition of the bone-implant interface was investigated using Raman spectroscopy and electron microscopy, in a correlative manner. The mineral crystallinity and the mineral-to-matrix ratios of the interfacial tissue and the native bone were found to be similar. However, lower Ca/P ratios, lower carbonate content, but higher proline, phenylalanine and tyrosine levels indicated that the interfacial tissue remained less mature. Bone healing was more advanced at the porous implant surface (vs. the solid implant surface) based on the interfacial tissue ν1 CO3(2-)/ν2 PO4(3-) ratio, phenylalanine and tyrosine levels approaching those of the native bone. The mechanosensing infrastructure in bone, the osteocyte lacuno-canalicular network, retained ∼40% more canaliculi per osteocyte lacuna, i.e., a 'less aged' morphology at the interface. The osteocyte density per mineralised surface area was ∼36-71% higher at the interface after extended healing periods. In osseointegration research, the success of an implant surface or design is commonly determined by quantifying the amount of new bone, rather than its maturation, composition and structure. This work describes a novel correlative methodology to investigate the ultrastructure and composition of bone formed around and within 3D printed Ti6Al4V implants having an interconnected open-pore structure. Raman spectroscopy demonstrates that the molecular composition of the interfacial tissue at different implant surfaces may vary, suggesting differences in the extent to which bone maturation occurs even after long

Hydroxyapatite ocular implant and non-integrated implants in eviscerated patients

PubMed Central

Gradinaru, S; Popescu, V; Leasu, C; Pricopie, S; Yasin, S; Ciuluvica, R; Ungureanu, E

2015-01-01

Introduction: This study compares the outcomes and complications of hydroxyapatite ocular implant and non-integrated ocular implants following evisceration. Materials and Methods: This is a retrospective study of 90 patients who underwent evisceration for different ocular affections, in the Ophthalmology Department of the University Emergency Hospital Bucharest, between January 2009 and December 2013. The outcomes measured were conjunctival dehiscence, socket infection, implant exposure and extrusion rate. Results: Forty-three patients had the hydroxyapatite implant (coralline–Integrated Ocular Implants, USA or synthetic–FCI, France) and forty-seven received non-integrated ocular implants (24 acrylic and 23 silicone). Five cases of socket infection, thirteen cases of extrusion and two cases of conjunctival dehiscence were encountered. Conclusions: There was a higher rate of conjunctival dehiscence with hydroxyapatite ocular implant, but implant extrusion and socket infection were found in non-integrated ocular implants. PMID:25914747

Biocompatibility of Advanced Manufactured Titanium Implants-A Review.

PubMed

Sidambe, Alfred T

2014-12-19

Titanium (Ti) and its alloys may be processed via advanced powder manufacturing routes such as additive layer manufacturing (or 3D printing) or metal injection moulding. This field is receiving increased attention from various manufacturing sectors including the medical devices sector. It is possible that advanced manufacturing techniques could replace the machining or casting of metal alloys in the manufacture of devices because of associated advantages that include design flexibility, reduced processing costs, reduced waste, and the opportunity to more easily manufacture complex or custom-shaped implants. The emerging advanced manufacturing approaches of metal injection moulding and additive layer manufacturing are receiving particular attention from the implant fabrication industry because they could overcome some of the difficulties associated with traditional implant fabrication techniques such as titanium casting. Using advanced manufacturing, it is also possible to produce more complex porous structures with improved mechanical performance, potentially matching the modulus of elasticity of local bone. While the economic and engineering potential of advanced manufacturing for the manufacture of musculo-skeletal implants is therefore clear, the impact on the biocompatibility of the materials has been less investigated. In this review, the capabilities of advanced powder manufacturing routes in producing components that are suitable for biomedical implant applications are assessed with emphasis placed on surface finishes and porous structures. Given that biocompatibility and host bone response are critical determinants of clinical performance, published studies of in vitro and in vivo research have been considered carefully. The review concludes with a future outlook on advanced Ti production for biomedical implants using powder metallurgy.

Immediate direct-to-implant breast reconstruction using anatomical implants.

PubMed

Kim, Sung-Eun; Jung, Dong-Woo; Chung, Kyu-Jin; Lee, Jun Ho; Kim, Tae Gon; Kim, Yong-Ha; Lee, Soo Jung; Kang, Su Hwan; Choi, Jung Eun

2014-09-01

In 2012, a new anatomic breast implant of form-stable silicone gel was introduced onto the Korean market. The intended use of this implant is in the area of aesthetic breast surgery, and many reports are promising. Thus far, however, there have been no reports on the use of this implant for breast reconstruction in Korea. We used this breast implant in breast reconstruction surgery and report our early experience. From November 2012 to April 2013, the Natrelle Style 410 form-stable anatomically shaped cohesive silicone gel-filled breast implant was used in 31 breasts of 30 patients for implant breast reconstruction with an acellular dermal matrix. Patients were treated with skin-sparing mastectomies followed by immediate breast reconstruction. The mean breast resection volume was 240 mL (range, 83-540 mL). The mean size of the breast implants was 217 mL (range, 125-395 mL). Breast shape outcomes were considered acceptable. Infection and skin thinning occurred in one patient each, and hematoma and seroma did not occur. Three cases of wound dehiscence occurred, one requiring surgical intervention, while the others healed with conservative treatment in one month. Rippling did not occur. So far, complications such as capsular contracture and malrotation of breast implant have not yet arisen. By using anatomic breast implants in breast reconstruction, we achieved satisfactory results with aesthetics better than those obtained with round breast implants. Therefore, we concluded that the anatomical implant is suitable for breast reconstruction.

Outcomes of Late Implantation in Usher Syndrome Patients.

PubMed

Hoshino, Ana Cristina H; Echegoyen, Agustina; Goffi-Gomez, Maria Valéria Schmidt; Tsuji, Robinson Koji; Bento, Ricardo Ferreira

2017-04-01

Introduction  Usher syndrome (US) is an autosomal recessive disorder characterized by hearing loss and progressive visual impairment. Some deaf Usher syndrome patients learn to communicate using sign language. During adolescence, as they start losing vision, they are usually referred to cochlear implantation as a salvage for their new condition. Is a late implantation beneficial to these children? Objective  The objective of this study is to describe the outcomes of US patients who received cochlear implants at a later age. Methods  This is a retrospective study of ten patients diagnosed with US1. We collected pure-tone thresholds and speech perception tests from pre and one-year post implant. Results  Average age at implantation was 18.9 years (5-49). Aided average thresholds were 103 dB HL and 35 dB HL pre and one-year post implant, respectively. Speech perception was only possible to be measured in four patients preoperatively, who scored 13.3; 26.67; 46% vowels and 56% 4-choice. All patients except one had some kind of communication. Two were bilingual. After one year of using the device, seven patients were able to perform the speech tests (from four-choice to close set sentences) and three patients abandoned the use of the implant. Conclusion  We observed that detection of sounds can be achieved with late implantation, but speech recognition is only possible in patients with previous hearing stimulation, since it depends on the development of hearing skills and the maturation of the auditory pathways.

Cardiac or Other Implantable Electronic Devices and Sleep-disordered Breathing - Implications for Diagnosis and Therapy.

PubMed

Fox, Henrik; Bitter, Thomas; Gutleben, Klaus-Jürgen; Horstkotte, Dieter; Oldenburg, Olaf

2014-08-01

Sleep-disordered breathing (SDB) is of growing interest in cardiology because SDB is a highly prevalent comorbidity in patients with a variety of cardiovascular diseases. The prevalence of SDB is particularly high in patients with cardiac dysrhythmias and/or heart failure. In this setting, many patients now have implantable cardiac devices, such as pacemakers, implantable cardioverter-defibrillators or implanted cardiac resynchronisation therapy devices (CRT). Treatment of SDB using implantable cardiac devices has been studied previously, with atrial pacing and CRT being shown not to bring about satisfactory results in SDB care. The latest generations of these devices have the capacity to determine transthoracic impedance, to detect and quantify breathing efforts and to identify SDB. The capability of implantable cardiac devices to detect SDB is of potential importance for patients with cardiovascular disease, allowing screening for SDB, monitoring of the course of SDB in relation to cardiac status, and documenting of the effects of treatment.

3D silicon shapes through bulk nano structuration by focused ion beam implantation and wet etching

NASA Astrophysics Data System (ADS)

Salhi, Billel; Troadec, David; Boukherroub, Rabah

2017-05-01

The work presented in this paper concerns the synthesis of silicon (Si) 2D and 3D nanostructures using the delayed effect, caused by implanted Ga ions, on the dissolution of Si in aqueous solutions of tetramethylammonium hydroxide (TMAH). The crystalline silicon substrates (100) are first cleaned and then hydrogenated by immersion in an aqueous solution of hydrofluoric acid. The ion implantation is then carried out by a focused ion beam by varying the dose and the exposure time. Chemical etching in aqueous solutions of TMAH at 80 °C leads to the selective dissolution of the Si planes not exposed to the ions. The preliminary results obtained in the laboratory made it possible to optimize the experimental conditions for the synthesis of 2D and 3D nanoobjects of controlled shape and size. Analysis by transmission electron microscopy and energy dispersive x-ray showed the amorphous nature of the nanostructures obtained and the presence of 5%-20% Ga in these nanoobjects. The first experiments of recrystallization by rapid thermal annealing allowed to reconstitute the crystal structure of these nanoobjects.

3D silicon shapes through bulk nano structuration by focused ion beam implantation and wet etching.

PubMed

Salhi, Billel; Troadec, David; Boukherroub, Rabah

2017-05-19

The work presented in this paper concerns the synthesis of silicon (Si) 2D and 3D nanostructures using the delayed effect, caused by implanted Ga ions, on the dissolution of Si in aqueous solutions of tetramethylammonium hydroxide (TMAH). The crystalline silicon substrates (100) are first cleaned and then hydrogenated by immersion in an aqueous solution of hydrofluoric acid. The ion implantation is then carried out by a focused ion beam by varying the dose and the exposure time. Chemical etching in aqueous solutions of TMAH at 80 °C leads to the selective dissolution of the Si planes not exposed to the ions. The preliminary results obtained in the laboratory made it possible to optimize the experimental conditions for the synthesis of 2D and 3D nanoobjects of controlled shape and size. Analysis by transmission electron microscopy and energy dispersive x-ray showed the amorphous nature of the nanostructures obtained and the presence of 5%-20% Ga in these nanoobjects. The first experiments of recrystallization by rapid thermal annealing allowed to reconstitute the crystal structure of these nanoobjects.

Survival of dental implants placed in sites of previously failed implants.

PubMed

Chrcanovic, Bruno R; Kisch, Jenö; Albrektsson, Tomas; Wennerberg, Ann

2017-11-01

To assess the survival of dental implants placed in sites of previously failed implants and to explore the possible factors that might affect the outcome of this reimplantation procedure. Patients that had failed dental implants, which were replaced with the same implant type at the same site, were included. Descriptive statistics were used to describe the patients and implants; survival analysis was also performed. The effect of systemic, environmental, and local factors on the survival of the reoperated implants was evaluated. 175 of 10,096 implants in 98 patients were replaced by another implant at the same location (159, 14, and 2 implants at second, third, and fourth surgeries, respectively). Newly replaced implants were generally of similar diameter but of shorter length compared to the previously placed fixtures. A statistically significant greater percentage of lost implants were placed in sites with low bone quantity. There was a statistically significant difference (P = 0.032) in the survival rates between implants that were inserted for the first time (94%) and implants that replaced the ones lost (73%). There was a statistically higher failure rate of the reoperated implants for patients taking antidepressants and antithrombotic agents. Dental implants replacing failed implants had lower survival rates than the rates reported for the previous attempts of implant placement. It is suggested that a site-specific negative effect may possibly be associated with this phenomenon, as well as the intake of antidepressants and antithrombotic agents. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Neural progenitor cell implants modulate vascular endothelial growth factor and brain-derived neurotrophic factor expression in rat axotomized neurons.

PubMed

Talaverón, Rocío; Matarredona, Esperanza R; de la Cruz, Rosa R; Pastor, Angel M

2013-01-01

Axotomy of central neurons leads to functional and structural alterations which largely revert when neural progenitor cells (NPCs) are implanted in the lesion site. The new microenvironment created by NPCs in the host tissue might modulate in the damaged neurons the expression of a high variety of molecules with relevant roles in the repair mechanisms, including neurotrophic factors. In the present work, we aimed to analyze changes in neurotrophic factor expression in axotomized neurons induced by NPC implants. For this purpose, we performed immunofluorescence followed by confocal microscopy analysis for the detection of vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and nerve growth factor (NGF) on brainstem sections from rats with axotomy of abducens internuclear neurons that received NPC implants (implanted group) or vehicle injections (axotomized group) in the lesion site. Control abducens internuclear neurons were strongly immunoreactive to VEGF and BDNF but showed a weak staining for NT-3 and NGF. Comparisons between groups revealed that lesioned neurons from animals that received NPC implants showed a significant increase in VEGF content with respect to animals receiving vehicle injections. However, the immunoreactivity for BDNF, which was increased in the axotomized group as compared to control, was not modified in the implanted group. The modifications induced by NPC implants on VEGF and BDNF content were specific for the population of axotomized abducens internuclear neurons since the neighboring abducens motoneurons were not affected. Similar levels of NT-3 and NGF immunolabeling were obtained in injured neurons from axotomized and implanted animals. Among all the analyzed neurotrophic factors, only VEGF was expressed by the implanted cells in the lesion site. Our results point to a role of NPC implants in the modulation of neurotrophic factor expression by lesioned central neurons, which might

Influence of implant diameter in the displacement of dental implants in trabecular bovine bone under a static lateral load: experimental results and computational modeling.

PubMed

Engelke, Wilfried; Decco, Oscar A; Cura, Andrea C; Maldonado, Isai; Crippa, Federico G

2014-12-01

Primary stability and micromovement of dental implants depend on structural properties of the surrounding bone and on implant dimension and design. The purpose of this study was to provide objective data for the influence of implant diameter on the displacement of titanium screw implants. Ninety Semados implants (length 15 mm, diameter 3.25, 3.75, and 4.5 mm; Bego, Bremen, Germany) were inserted in trabecular bone specimens. All implants were inserted with a torque up to 30 N·cm and loaded horizontally with 10, 20, and 30 N for 2 seconds. All implants showed primary stability. With increasing force, a gradual increase of micromovement was observed (Kruskal-Wallis test, P = 0.000). No significant differences were found (Kruskal-Wallis test, P = 0.148) comparing different diameters for every force. Variation of the diameter of standard implants between 3.25 and 4.5 mm does not seem to influence the primary stability in trabecular bone specimen. Differences between experimental and computational results may be due to the simplification used when modeling.