Papers by Keyword: Implant

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Authors: Zi Yuan Zhu, Fu Qiang Zhang, You Tao Xie, Yi Kai Chen, Xue Bin Zheng
Abstract: Failure of dental implant is often caused by specific pathogenic bacteria. In this paper, antibacterial HA coating was prepared by vacuum plasma spraying with silver loaded zirconium phosphate containing HA as feedstock. The antibacterial activity against Aa,Fn and Pg was evaluated using a film covering method. MTT colorimetric assay was used to measure cytotoxic effect of the antibacterial HA coatings. Results show that the HA coatings displayed significant antibacterial activity against Aa,Fn, Pg and no cytotoxicity to L929 murine cell lines when the content of silver-loaded zirconium phosphate antimicrobial is between 5wt% to 10wt%. The sensitivity of the bacteria to the antibacterial HA coating is in sequence of Pg >Fn >Aa.
Authors: Ana Cristina P. Machado, Marize Varella de Oliveira, Robson Pacheco Pereira, Yasmin R. Carvalho, Carlos Alberto Alves Cairo
Abstract: The osseointegration of porous titanium implants was evaluated in the present work. Implants were fabricated from ASTM grade 2 titanium by a powder metallurgy method. Part of these implants were submitted to chemical and thermal treatment in order to deposit a biomimetic coating, aiming to evaluate its influence on the osseointegration of the implants. The implants were characterized by Scanning Electron Microscopy (SEM), Electron Dispersive X-Ray Spectroscopy (EDS) and Raman Spectroscopy. Three coated and three control (uncoated) implants were surgically inserted into thirty albino rabbits’ left and right tibiae, respectively. Tibiae samples were submitted to histological and histomorphometric analyses, utilizing SEM, optical microscopy and mechanical tests. EDS results indicated calcium (Ca) and phosphorous (P) at the surface and Raman spectra exhibited an intense peak, characteristic of hydroxyapatite (HA). Bone neoformation was detected at the bone-implant interface and inside the pores, including the central ones. The mean bone neoformation percentage in the coated implants was statistically higher at 15 days, compared to 30 and 45 days. The mechanical tests showed that coated implants presented higher resistance to displacement, especially after 30 and 45 days.
Authors: Jian Ping Wang, He Jia Liu, Shao Kai Sun, Shi He Jian
Abstract: To provide the doctors a basis for treating sacral fractures and offer optimal surgical program, three-dimensional (3D) finite element method was used to simulate normal pelvis and the unstable pelvis sufferedIsection, IIsection and III section sacral fracture respectively.The unstable pelvises were respectively fixed with five different internal fixation implants types, which are respectively rectangular plate with cannulated screw, rectangular plate with solid screw, expansile bolt, convex plate with cannulated screw, convex plate with solid screw. The stress distribution and the X, Y, Z direction displacement of the sacrum were calculated for each sacral fracture treatment of five internal fixation implants after giving 500N axial load on lumbar vertebra and were compared with the normal pelvis, then the optimal surgery program were determined. After the analysis, by comparing the five combinations for each sacral fracture treatment of five internal fixation implants, the preferred combinations for the reset treatment of theIsection sacral fractures were rectangular plate with cannulated screw and convex plate with cannulated screw; The preferred combination for the reset treatment of the II section sacral fractures was expansile bolt; The preferred combination for the reset treatment of the III section sacral fractures was convex plate with cannulated screw.
Authors: Gang Chen, Xiao Feng Song, Song Bai, Li Li, Yun Li, Zheng Chen, Wen Wang
Abstract: A silicon carbide (SiC) vertical channel junction field effect transistor (VJFET) was fabricated based on in-house SiC epitaxial wafer with lift-off trenched and implanted method. Its blocking voltage exceeds 1300V at gate bias VG = -6V and forward drain current is in excess of 5A at gate bias VG = 3V and drain bias VD = 3V. The SiC VJFET device’s current density is 240A/cm2 at VG= 3V and VD = 3V, with related specific on-resistance 8.9mΩ•cm2. Further analysis reveals that the on-resistance depends greatly on ohmic contact resistance and the bonding spun gold. The specific on-resistance can be further reduced by improving the doping concentration of SiC channel epilayer and the device’s ohmic contact.
Authors: Arne Biesiekierski, James Wang, Cui'e Wen
Abstract: In the realm of bioimplantation, titanium-based Shape Memory Alloys (SMAs) exhibit phenomenal versatility, with successful application in diverse fields. One area of particular interest is that of orthopaedics, where the unique properties of SMAs offer a range of benefits. That said, existing alloys still have unresolved issues concerning biocompatibility and osseointegration. Primary concerns include carcinogenicity, allergenicity and a significant mismatch between the Young’s moduli of bone and osteoimplants; issues that could be addressed via a novel porous titanium alloy. With that in mind, this paper seeks to provide a review identifying promising candidates for new, perfectly biocompatible alloys for production via powder metallurgy. Furthermore, an attempt will also be made to summarise existing research into appropriate methods for the production of a porous Ti-based SMA implant.
Authors: Frank Lüthen, Claudia Bergemann, Ulrike Bulnheim, Cornelia Prinz, Hans Georg Neumann, Andreas Podbielski, Rainer Bader, Joachim Rychly
Abstract: To stimulate bone regeneration, the design of bioactive implants is a great challenge in current orthopedic research. We reasoned that implants should be suitable both to stimulate osteogenic differentiation of mesenchymal stem cells and prevent infections at the site of implantation. Therefore, we focus on copper ions, which are known to exert antimicrobial effects. On the other hand, copper is essential for the cell physiology, including the formation of the extracellular matrix. We studied the influence of copper ions on mesenchymal stem cells at various concentrations and identified the limits of copper concentrations for cell survival. Below the critical concentration for cell survival we analysed proliferation and osteogenic differentiation of the cells in the presence of copper ions. We found that copper stimulated the proliferation of the mesemchymal stem cells at 0.1 mM. Osteogenic differentiation decreased after 14 days at a concentration of 0.05 - 0.1 mM copper ions in osteogenic medium measured by the expression of osteogenic proteins, like alkaline phosphatase (ALP), bone sialoprotein (BSP) and collagen I (COL). We argue that at the implant surface a higher concentration of copper could prevent biofilm formation of bacteria and physiological concentrations in the vicinity of the implant would stimulate stem cell expansion. Together, copper is an interesting agent to control both bacteria and stem cells in the field of implant technology.
Authors: Sang Bae Lee, Kyeong Jun Park, Doug Youn Lee, Jeong Jong Park, Jae Sun Hwang, Yong Keun Lee, Kyoung Nam Kim, Kwang Mahn Kim
Abstract: In this study, the osteoconductive properties of novel cyanoacrylate-based filling materials for bone defect were evaluated. A new filling material was prepared by mixing Histoacryl® and acid-treated  -tricalcium phosphate ( -TCP). Mixing weight ratio of acid-treated  -TCP to Histoacryl® was 5:1. 12 male Spraque-Dawley rats were used in this study. The animals were divided into 4 groups. Critical-sized calvarial defects (8 mm) were created in 9 animals, and then the defects were treated with dense pellet specimen, porous cement-like specimen, and untreated defect for surgical control group. Augmentation treatments were carried out in 3 animals. Histological analysis revealed excellent ostgeoconductive properties of new filling materials. But, some of  -TCP particle in the cement-like group were encapsulated by fibrous connective tissue. For the dense pellet group and augmentation treatment group, shape and stability were better maintained during the implantation time than cement like group. These results indicate that our novel  -TCP/Histoacryl® composite have the potential to serve as filling materials for bone defects in the dental and plastic surgery.
Authors: Faik N. Oktar, S. Ozsoy, Lutfiye Sevgi Özyeğin
Authors: W. Xu, F. Shao, D. Ewins
Abstract: The osseointegration trans-femoral implant is a new orthopedic anchoring method to attach prosthetic limb. The success of this technique depends on how healthy the osseointegration between implant and bone can be achieved and how the post-surgical rehabilitation is progressed. The current clinical practice is based on patient fitness feeling. To achieve a high success rate of osseointegration and an optimal rehabilitation process, a quantitative measurement of the degree of osseointegration is required. In this paper, the authors present a non-invasive method to determine the stability of an osseointegration trans-femoral implant system. It uses resonant frequency of implant system to observe the integration between the implant and bone. The vibration signals of a trans-femoral implant system were collected using an accelerometer attached to the implant abutment and analyzed using Fast Fourier Transform (FFT). The results of in vitro tests are presented to demonstrate that the developed instrument system can be used in future in vivo clinical research.
Authors: Iuliana Babiuc, Mihaela Pauna
Abstract: Purpose: To establish the incidence of chipping of zirconia-based restorations, either implant or tooth supported in a retrospective study. Material and methods: Sixty patients received 222 cemented units of zirconia-based restorations. One hundred thirteen units were cemented on teeth, 97 on implants and 12 units were pontics. After the delivery of the restorations, during the recalls, the patients were examined in regard to the presence of chipping of the veneering ceramic. Location of the restoration, the type of support and the design of the restoration were assessed as possible factors influencing chipping rate. Results: During an observation period of up to 5,5 years, 27 (12,16%) zirconia-based units showed chipping of the veneering ceramic. A total of 14 units had to be remade, resulting in a survival rate of 93,69% of the zirconia-based restorations. The chipping rate seemed to be higher in restorations on implants than those supported by teeth. In the molar region chipping occured twice as often as in the premolar and front regions (15,83% vs 7,84%). An increased chipping rate was observed in multi-unit restorations (13,95%) as compared to single-unit restorations (9,67%). Conclusion: Chipping of the porcelain veneering is the most frequent complication of zirconia-based restorations. They should be recommended with care in the molar region, especially as multi-unit restorations.
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