Desenvolvimento da peri-implantite induzida por ligadura em diferentes superfícies de implantes osseointegrados. Análise clínica e radiográfica em cães

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Modificação de superfície empregando-se laser e recobrimento de implantes dentários de titânio com apatitas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento de uma nova liga quaternária Ti25Ta25Nb3Sn para aplicações odontológicas

Pós-graduação em Engenharia Mecânica - FEG

Titanium-35niobium alloy as a potential material for biomedical implants: in vitro study

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Design of cell adhesive and angiogenic titanium surfaces for cellular stimulation

Die Förderung der Zelladhäsion durch sogenannte biomimetische Oberflächen wird in der Medizin als vielversprechender Ansatz gesehen, um Komplikationen wie z. B. Fremdkörperreaktionen nach der Implantation entgegenzuwirken. Neben der Immobilisierung einzelner Biomoleküle wie z. B. dem RGD-Peptid, Proteinen und Wachstumsfaktoren auf verschiedenen Materialien, konzentriert man sich derzeit in der Forschung auf die Co-Immobilisierung zweier Moleküle gleichzeitig. Hierbei werden die funktionellen Gruppen z. B. von Kollagen unter Verwendung von nur einer Kopplungschemie verwendet, wodurch die Kopplungseffizienz der einzelnen Komponenten nur begrenzt kontrollierbar ist. Das Ziel der vorliegenden Arbeit war die Entwicklung eines Immobilisierungsverfahrens, welches die unabhängige Kopplung zweier Faktoren kontrolliert ermöglicht. Dabei sollten exemplarisch das adhäsionsfördernde RGD-Peptid (Arginin-Glycin-Asparaginsäure) zusammen mit dem Wachstumsfaktor VEGF (Vascular Endothelial Growth Factor) auf Titan gebunden werden. In weiteren Experimenten sollten dann die pro-adhäsiven Faktoren Fibronektin, Kollagen, Laminin und Osteopontin immobilisiert und untersucht werden. rnDie Aminofunktionalisierung von Titan durch plasma polymerisierte Allylaminschichten wurde als Grundlage für die Entwicklung des nasschemischen Co-immobilisierungsverfahren verwendet. Für eine unabhängige und getrennte Anbindung der verschiedenen Biomoleküle stand in diesem Zusammenhang die Entwicklung eines geeigneten Crosslinker Systems im Vordergrund. Die Oberflächencharakterisierung der entwickelten Oberflächen erfolgte mittels Infrarot Spektroskopie, Surface Plasmon Resonance Spektroskopie (SPR), Kontaktwinkelmessungen, Step Profiling und X-Ray Photoelectron Spektroskopie (XPS). Zur Analyse der Anbindungsprozesse in Echtzeit wurden SPR-Kinetik Messungen durchgeführt. Die biologische Funktionalität der modifizierten Oberflächen wurde in vitro an Endothelzellen (HUVECs) und Osteoblasten (HOBs) und in vivo in einem Tiermodell-System an der Tibia von Kaninchen untersucht.rnDie Ergebnisse zeigen, dass alle genannten Biomoleküle sowohl einzeln auf Titan kovalent gekoppelt als auch am Bespiel von RGD und VEGF in einem getrennten Zwei-Schritt-Verfahren co-immobilisiert werden können. Des Weiteren wurde die biologische Funktionalität der gebundenen Faktoren nachgewiesen. Im Falle der RGD modifizierten Oberflächen wurde nach 7 Tagen eine geförderte Zelladhäsion von HUVECs mit einer signifikant erhöhten Zellbesiedlungsdichte von 28,5 % (p<0,05) gezeigt, wohingegen auf reinem Titan Werte von nur 13 % beobachtet wurden. Sowohl VEGF als auch RGD/VEGF modifizierte Proben wiesen im Vergleich zu Titan schon nach 24 Stunden eine geförderte Zelladhäsion und eine signifikant erhöhte Zellbesiedlungsdichte auf. Bei einer Besiedlung von 7,4 % auf Titan, zeigten VEGF modifizierte Proben mit 32,3 % (p<0,001) eine deutlichere Wirkung auf HUVECs als RGD/VEGF modifizierte Proben mit 13,2 % (p<0,01). Die pro-adhäsiven Faktoren zeigten eine deutliche Stimulation der Zelladhäsion von HUVECs und HOBs im Vergleich zu reinem Titan. Die deutlich höchsten Besiedlungsdichten von HUVECs konnten auf Fibronektin mit 44,6 % (p<0,001) und Kollagen mit 39,9 % (p<0,001) nach 24 Stunden beobachtet werden. Laminin zeigte keine und Osteopontin nur eine sehr geringe Wirkung auf HUVECs. Bei Osteoblasten konnten signifikant erhöhte Besiedlungsdichten im Falle aller pro-adhäsiven Faktoren beobachtet werden, jedoch wurden die höchsten Werte nach 7 Tagen auf Kollagen mit 90,6 % (p<0,001) und Laminin mit 86,5 % (p<0,001) im Vergleich zu Titan mit 32,3 % beobachtet. Die Auswertung der Tierexperimente ergab, dass die VEGF modifizierten Osteosyntheseplatten, im Vergleich zu den reinen Titankontrollen, eine gesteigerte Knochenneubildung auslösten. Eine solche Wirkung konnte für RGD/VEGF modifizierte Implantate nicht beobachtet werden. rnInsgesamt konnte gezeigt werden, dass mittels plasmapolymerisierten Allylamin Schichten die genannten Biomoleküle sowohl einzeln gebunden als auch getrennt und kontrolliert co-immobilisiert werden können. Des Weiteren konnte eine biologische Funktionalität für alle Faktoren nach erfolgter Kopplung in vitro gezeigt werden. Wider Erwarten konnte jedoch kein zusätzlicher biologischer Effekt durch die Co-immobilisierung von RGD und VEGF im Vergleich zu den einzeln immobilisierten Faktoren gezeigt werden. Um zu einer klinischen Anwendung zu gelangen, ist es nun notwendig, das entwickelte Verfahren in Bezug auf die immobilisierten Mengen der verschiedenen Faktoren hin zu optimieren. rn

In vitro precision of fit of computer-aided designed and computer-aided manufactured titanium screw-retained fixed dental prostheses before and after ceramic veneering

OBJECTIVE To compare the precision of fit of full-arch implant-supported screw-retained computer-aided designed and computer-aided manufactured (CAD/CAM) titanium-fixed dental prostheses (FDP) before and after veneering. The null-hypothesis was that there is no difference in vertical microgap values between pure titanium frameworks and FDPs after porcelain firing. MATERIALS AND METHODS Five CAD/CAM titanium grade IV frameworks for a screw-retained 10-unit implant-supported reconstruction on six implants (FDI tooth positions 15, 13, 11, 21, 23, 25) were fabricated after digitizing the implant platforms and the cuspid-supporting framework resin pattern with a laser scanner (CARES(®) Scan CS2; Institut Straumann AG, Basel, Switzerland). A bonder, an opaquer, three layers of porcelain, and one layer of glaze were applied (Vita Titankeramik) and fired according to the manufacturer's preheating and fire cycle instructions at 400-800°C. The one-screw test (implant 25 screw-retained) was applied before and after veneering of the FDPs to assess the vertical microgap between implant and framework platform with a scanning electron microscope. The mean microgap was calculated from interproximal and buccal values. Statistical comparison was performed with non-parametric tests. RESULTS All vertical microgaps were clinically acceptable with values <90 μm. No statistically significant pairwise difference (P = 0.98) was observed between the relative effects of vertical microgap of unveneered (median 19 μm; 95% CI 13-35 μm) and veneered FDPs (20 μm; 13-31 μm), providing support for the null-hypothesis. Analysis within the groups showed significantly different values between the five implants of the FDPs before (P = 0.044) and after veneering (P = 0.020), while a monotonous trend of increasing values from implant 23 (closest position to screw-retained implant 25) to 15 (most distant implant) could not be observed (P = 0.169, P = 0.270). CONCLUSIONS Full-arch CAD/CAM titanium screw-retained frameworks have a high accuracy. Porcelain firing procedure had no impact on the precision of fit of the final FDPs. All implant microgap measurements of each FDP showed clinically acceptable vertical misfit values before and after veneering. Thus, the results do not only show accurate performance of the milling and firing but show also a reproducible scanning and designing process.

Role of Platinum Deposited on TiO2 in Photocatalytic Methanol Oxidation and Dehydrogenation Reactions

Titania modified nanoparticles have been prepared by the photodeposition method employing platinum particles on the commercially available titanium dioxide (Hombikat UV 100). The properties of the prepared photocatalysts were investigated by means of the Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), atomic force microscopy (AFM), and UV-visible diffuse spectrophotometry (UV-Vis). XRD was employed to determine the crystallographic phase and particle size of both bare and platinised titanium dioxide. The results indicated that the particle size was decreased with the increasing of platinum loading. AFM analysis showed that one particle consists of about 9 to 11 crystals. UV-vis absorbance analysis showed that the absorption edge shifted to longer wavelength for 0.5% Pt loading compared with bare titanium dioxide. The photocatalytic activity of pure and Pt-loaded TiO2 was investigated employing the photocatalytic oxidation and dehydrogenation of methanol. The results of the photocatalytic activity indicate that the platinized titanium dioxide samples are always more active than the corresponding bare TiO2 for both methanol oxidation and dehydrogenation processes. The loading with various platinum amounts resulted in a significant improvement of the photocatalytic activity of TiO2. This beneficial effect was attributed to an increased separation of the photogenerated electron-hole charge carriers.

Surface characterization of Ti-7.5Mo alloy modified by biomimetic method

Titanium and its alloys have been used in dentistry due to their excellent corrosion resistance and biocompatibility. It was shown that even a pure titanium metal and its alloys spontaneously form a bone-like apatite layer on their surfaces within a living body. The purpose of this work was to evaluate the growth of calcium phosphates at the surface of the experimental alloy Ti-7.5Mo. We produced ingots from pure titanium and molybdenum using an arc-melting furnace We then submitted these Ingots to heat treatment at 1100 degrees C for one hour, cooled the samples in water, and cold-worked the cooled material by swaging and machining. We measured the media roughness (Ra) with a roughness meter (1.3 and 2.6 mu m) and cut discs (13 mm in diameter and 4 mm in thickness) from each sample group. The samples were treated by biomimetic methods for 7 or 14 days to form an apatite coating on the surface. We then characterized the surfaces with an optical profilometer, a scanning electron microscope and contact angle measurements. The results of this study indicate that apatite can form on the surface of a Ti-7.5Mo alloy, and that a more complete apatite layer formed on the Ra = 2 6 mu m material. This Increased apatite formation resulted in a lower contact angle (C) 2010 Elsevier B.V. All rights reserved

Finite Element Modeling for Development and Optimization of a Bone Plate for Mandibular Fracture in Dogs

This study aimed to develop a plate to treat fractures of the mandibular body in dogs and to validate the project using finite elements and biomechanical essays. Mandible prototypes were produced with 10 oblique ventrorostral fractures (favorable) and 10 oblique ventrocaudal fractures (unfavorable). Three groups were established for each fracture type. Osteosynthesis with a pure titanium plate of double-arch geometry and blocked monocortical screws offree angulanon were used. The mechanical resistance of the prototype with unfavorable fracture was lower than that of the fcworable fracture. In both fractures, the deflection increased and the relative stiffness decreased proportionally to the diminishing screw number The finite element analysis validated this plate study, since the maximum tension concentration observed on the plate was lower than the resistance limit tension admitted by the titanium. In conclusion, the double-arch geometry plate fixed with blocked monocortical screws has sufficient resistance to stabilize oblique,fractures, without compromising mandibular dental or neurovascular structures. J Vet Dent 24 (7); 212 - 221, 2010

Degradação fotocatalítica de petróleo e seus derivados através da utilização de nanopartículas de dióxido de titânio puro e misturado com óxido de grafeno reduzido

Dissertação de mestrado integrado em Engenharia de Materiais

Development of multifunctional coatings deposited on polymers based sensors for biomedical applications

Tese de Doutoramento (Programa Doutoral em Engenharia de Materiais)

Keraamisten teräpalojen käyttö niukkaseosteisten terästen lastuamiseen normaaleissa toimitustiloissa

Tämän tutkimuksen tavoitteena oli tutkia keraamisten kääntöterien soveltuvuus niukkaseosteräksille ja M-käsittelyn vaikutus teränkestoaikoihin. Lisäksi tavoitteena oli tutkia keraamiseosten erityisominaisuudet ja muodostaa käsitys keraamisilla kääntöterillä sorvaamisen erityisvaatimuksista. Kirjallisuusosassa selvitettiin tutkimushetkellä saatavissa olleet keraamiset teräaineseokset ja niiden ominaisuudet sekä selvitettiin keraamisten kääntöterien viimeaikaiset kehitystrendit. Lastuamistutkimus toteutettiin standardin ISO 3685:1993 mukaisesti, minkä lisäksi mitattiin lastuamisvoimat ja tehtiin kokeessa käytetyille terille lastunmurtokoe. Koemateriaalit olivat Imatra Steelin GreenCut, Hydax 25, M-käsittelemätön 42CrMo4 ja M-käsitelty MoC410M. Kokeissa käytetyt kääntöterät olivat eri valmistajien alumiinioksiditeriä, titaanikarbidiseostettuja alumiinioksiditeriä, kuituvahvisteisia ja yksi puhdas titaanikarbidiseosteinen terä. Koetulosten perusteella hyvän teränkestoajan saavuttamiseksi on tärkeää valita oikea keraamiseos ja sille soveltuvat parametrit. Oikein valituilla parametreilla M-terästä sorvattaessa tulokset ylittävät kovametalleilla saavutettavissa olevat arvot. Tulosten perusteella niukkaseostettujen terästen sorvaus onnistuu hyvin keraamisilla kääntöterillä, mutta kovametallisorvaukseen verrattuna syöttöä on laskettava ja lastuamisnopeutta lisättävä. Tämän työn tuloksia voidaan soveltaa sopivissa olosuhteissa toteutettavassa kappaletavaratuotannossa. Sovelluksen onnistuminen vaatii tukevat työstöolosuhteet ja riittävien lastuamisnopeuksien saavuttamisen.

Estudo das características físico-químicas e biológicas pela adesão de osteoblastos em superfícies de titânio modificadas pela nitretação em plasma

SILVA, J. S. P. Estudo das características físico-químicas e biológicas pela adesão de osteoblastos em superfícies de titânio modificadas pela nitretação em plasma. 2008. 119 f. Tese (Doutorado) - Faculdade de Medicina, Universidade de São Paulo. São Paulo, 2008.

Efeito do tratamento térmico do titânio sobre a proliferação de células pré-osteoblásticas

Titanium is a biomaterial widely employed in biomedical applications (implants, prostheses, valves, stents). Several heat treatments are usually used in order to obtain physical properties required to different applications. This work studied the influence of the heat treatment on microstructure of commercial pure titanium, and their consequences in growth and proliferation of MC3T3-E1 cells. Discs of titanium were treated in different temperatures, and characterized by optical microscopy, image analysis, wettabillity, roughness, hardness and X-ray diffraction. After the heat treatment, significant modifications in these properties were observed. Pattern images of titanium, before and after the cell culture, were compared by overlapping to analyze the influence of microstructure in microstructure and preferences guidance cells. However, in general, titanium discs that showed a higher residual strength also presented an increase of cells numbers on surface

Desenvolvimento e caracterização de dispositivos para reposição de filmes finos por descarga em cátodo oco

In the present work we use a plasma jet system with a hollow cathode to deposit thin TiO2 films on silicon substrates as alternative at sol-gel, PECVD, dip-coating e magnetron sputtering techniques. The cylindrical cathode, made from pure titanium, can be negatively polarized between 0 e 1200 V and supports an electrical current of up to 1 A. An Ar/O2 mixture, with a total flux of 20 sccm and an O2 percentage ranging between 0 and 30%, is passed through a cylindrical hole machined in the cathode. The plasma parameters and your influence on the properties of deposited TiO2 films and their deposition rate was studied. When discharge occurs, titanium atoms are sputtered/evaporated. They are transported by the jet and deposited on the Si substrates located on the substrate holder facing the plasma jet system at a distance ranging between10 and 50 mm from the cathode. The working pressure was 10-3 mbar and the deposition time was 10 -60 min. Deposited films were characterized by scanning electron microscopy and atomic force microscopy to check the film uniformity and morphology and by X-ray diffraction to analyze qualitatively the phases present. Also it is presented the new dispositive denominate ionizing cage, derived from the active screen plasma nitriding (ASPN), but based in hollow cathode effect, recently developed. In this process, the sample was involved in a cage, in which the cathodic potential was applied. The samples were placed on an insulator substrate holder, remaining in a floating potential, and then it was treated in reactive plasma in hollow cathode regime. Moreover, the edge effect was completely eliminated, since the plasma was formed on the cage and not directly onto the samples and uniformity layer was getting in all sampl