Papers by Keyword: Implant

Abstract: Dental Implant is a sophisticated dental surgery. Dentists must suffer fine oral surgery training so that the development of a professional dentist is quite time-consuming. We combine the medical image processing reconstruction and optical tracking techniques to provide a realistic teaching environment. The system can help dentists learning all steps during the surgery. We hope this system can increase the success ratio of surgery and lower the surgery risks. Our medical image reconstruction is reached by the toolkits named VTK. The stereo vision algorithm is introduced into this study to construct the optical tracking system. This system will provide a good study experience for dentists and to assist them during the implant surgery. After several dental medical materials show, most responses are positive. Most dentists are very interested in our system and recognize our system can greatly shorten the dental training time. During the surgery, the difficulty will also be drop down with the assistance of our system.

Abstract: The development of cobalt alloys for the development of HIP implants has been evolving overtime. Accordingly, in this work an overview of the main microstructural factors that impact the mechanical properties, as well as the effect of interstitials such as carbon and nitrogen. In addition the role alloy pre-straining and heat treating on the amount of ε-martensite and on the exhibited mechanical properties is described. In general, it is shown that as the amount of ε-martensite exceeds 60 vol. percent, the alloy ductility is drastically reduced as the HCP phase becomes dominant in the matrix.

Abstract: Many techniques are used to assess biomaterials implants, always intending to measure osseointegration success and tissue response facing the implanted material. Calcium phosphates are widely used as biomaterial and a major component of bone. Many processing methods have been used to achieve porous materials to allow bone ingrowth with an osteoconductive scaffold for bone. To obtain the macroporous BCP implant it was processed by direct consolidation using the protein-action technique, a globular protein based consolidation with ovalbumin. The samples were sintered at 1250°C for 30 minutes, after sintering samples were cut in 4mm diameter cylinders, with 73% volume of porosity and mean pore size ranging about 100 µm. In the present work the macroporous BCP of HAp:β-TCP is assessed after bone implantation in rabbits tibia by lectinhistochemistry (LHC) technique. Lectins are proteins from non-imune origin which binds with strong specificity carbohydrates, LHC is a technique which mark histologically carbohydrates present in glycoproteins of cells. The macroporous BCP cylindrical samples were implanted in male rabbits tibia to the evaluation of biocompatibility and osseointegration in a period of 2 weeks to 4 weeks. After euthanasia of rabbits, tibia samples from the surgery site were taken and fixed with formalin, decalcified, dehydrated and embedded with paraffin to perform histological slides for both morphological and molecular evaluation. The morphological evaluation were performed on histological slides stained with Haematoxilin and Eosin (HE), while for molecular evaluation LHC was performed on histological slides using the lectins PNA, UEA-1, WGA, sWGA and RCA-1 (Vector Labs). All samples osseointegrated well with the bone and the neoformed bone surrounding the implant took the shape of its surface. The implants also allowed bone ingrowth inside the pores towards the center of implant, characterized by islets of round bone present in the HE stained slides.

Abstract: mplant fixation is correlated with direct bone apposition on the implant surface. In a former study it was reported that a new coating material enhances the bone-to-implant-contact in comparison to machined and rough surfaces. This study is aimed at clarifying the effect of an enhanced bone-to-implant-contact that is induced by a new coating material. The coating is produced by spin and spray coating and consists of a silica matrix, in which nanocrystalline hydroxyapatite is embedded. The coating material exhibits a high porosity in the micrometer and nanometer scale. Coated implants were inserted subcutaneously in Wistar Rats. The specimens were excised after 6 and 12 days. EDX and SEM analysis showed a reduction of the silica amount within 6 days. In accordance to former results of a bone grafting material with the same structure, this matrix change is responsible for an initial bone formation at early stages.

Abstract: Calcium phosphate/ titanium oxide/ titanium/ plastic composite implants with 1.6-mm diameter and 7-mm length were successfully formed using a DC/ RF magnetron sputtering machine. The sample had no cracks and the surface of the sample was uniformly smooth. The chemical composition of the >10-nm-thick calcium phosphate layer was Ca: P: O=1.0: 0.79: 2.8. The sample was implanted into the tibia of an male 8-week-old SD rat for 28 days. When 0.70-μm sections of the tibia were prepared, the titanium layer with titanium oxide layer of the implant was not broken and the surfaces of the layer of the implant had not decomposed. The interaction between living bone and the implant could be clearly observed by light microscope and TEM.

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.

Abstract: Titanium and its alloys are widely used as biomaterials and interact well with bone tissue. In order, to evaluate more than just morphological osseointegration by histological slides the work aimed to approach a molecular evaluation of bone-implant using lectinhistochemistry (LHC), which binds with high specificity carbohydrates (sugar residues) presents in membrane glycoproteins with the use of lectins. The implanted samples were obtained by powder metallurgy, Ti-13Nb-13Zr alloy with and without gelatin. Pores were achieved by adding gellatin 5 wt% to the hydrogenated metallic powder, after near net shape processing, the samples were thermal treated in vacuum (300 °C/90min) and sintered in high-vacuum (1150 °C/14h). The samples were characterized for porosity (~30%), and subsequently were implanted in rat’s femur bone. After 4 weeks of healing process, bone with implant were sampled to perform LHC in paraffin embedded tissue in histological slides using the lectins PNA, UEA-1, WGA, sWGA and RCA-1. All samples osseointegrated well with the bone, no fibrous capsule was present in the bone which was in contact with the implant. With the molecular approach of osseointegration, adjustments in the processing and structure of macroporous titanium based implants can be performed to achieve friendly structure.

Abstract: The Calcium Phosphate Cement (CFC) has been used as filling material for bone defects because of osteoconductivity properties, bioactivity and biocompatibility. Recent studies, mostly in animals, indicate its use as an adjunct to treatment with osseointegrated implants. Thus this work aims reporting the event in which post-extraction socket was filled with CFC-based α-tricalcium phosphate and calcium sulfate and after four months, the implant was installed through the cement which was not reabsorbed with good primary stability. Upon reopening of the implants after six months, the clinical appearance of peri-implant region was considered normal. Radiographically, there wasnt radiopaque appearance of CFCs in the alveolar region of the test anymore. Histologically, remaining CFC in direct contact with bone without intervening fibrous connective tissue was noticed. Its concluded that the CFC showed osteoconductive behavior. The material tested seems to be an acceptable option for filling the post-extraction socket with the purpose of maintaining bone volume, however, more research is needed to generalize the indication.

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.

Abstract: The magnesium alloys has been intensively studied for their suitable mechanical properties, excellent biocompatibility and their ability to biodegrade in biological environments. Although magnesium biodegradable implants possess many desirable properties, it is important that the alloy is able to be tolerated by the body- the constitutional elements of magnesium-based alloys should be toxic free. In this study two binary magnesium alloys Mg-Ca0,8 and Mg-Ca1,8 were experimentally obtained by casting and was characterized in order to investigate the microstructure, mechanical properties and how alloying elements influenced the characteristics of this new alloys potentially used for orthopedic implants.