The goal of this research project was to develop a new implant annealing process using silane overpressure to maintain crystal integrity. After ion implantation the surface of the SiC wafer is damaged due to high energy of the implant ions. In addition the doping activation is very low. To overcome these problems a new implant annealing process was developed to rectify the surface damage and increase the dopant activation. SiC implant annealing was performed in the silicon carbide (SiC) chemical vapor deposition (CVD) reactor in the Emerging Materials Research Laboratory (EMRL) at Mississippi State University. A process was developed to eliminate surface step bunching, which is evident in argon annealed crystals. The process gas used in the new technique was silane (3 % SiH4 in 97% UHP Ar). The anneal run time was 30 minutes with argon flow rate at 6 slm and silane flow rate at 6 sccm. SiC material (n and p type epitaxial layers) and devices (JBS Diodes and LDMOSFET?s) were annealed using the silane over pressure developed during this research. The process results were characterized using tools such as optical micrograph, capacitance-voltage (C-V), Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). These characterization tools were mainly used to determine the surface roughness of the SiC crystal and the dopant activation after annealing. As compared to an Ar anneal, the SiC material and devices annealed in the silane ambient had a better surface. An empirical process chemistry model was developed to support the experimental results. The model developed showed that the partial pressure of Si is greater than the vapor pressure of SiC in the substrate. Thus it is believed that the partial pressure of Si suppressed any Si out-diffusion from the SiC substrate, thereby maintaining the crystal surface integrity. The model also provided silane flow rates for higher temperature anneals which may be necessary to fully activate other ion species.

INTRODUÇÃO: A qualidade da interface osso-implante pode ser influenciada diretamente por aspectos inerentes ao tratamento da superfície do titânio e determina a forma que as células interagem, aderem e se fixam a ela, podendo potencializar e encurtar o tempo de osseointegração. Este estudo propôs-se a analisar alterações na osseointegração produzidas pela hidrofibilidade das superfícies dos implantes Neoss®. MATERIAIS E MÉTODOS: Foram utilizados 6 cães da raça labrador e instalados 44 implantes Neoss® bilateralmente na mandíbula com defeitos ósseos padronizados na região coronal: 22 implantes apresentavam superfície ProActive (hidrofílica) e outros 22 implantes eram de superfície Bimodal (hidrofóbica). Foram avaliados a resposta biológica nos períodos de uma semana e quatro semanas de osseointegração, utilizando parâmetros histológicos, histomorfométricos, fluorescência e de estabilidade mecânica aferido pelo método de análise de frequência de ressonância (RFA). As superfícies também foram submetidas à análise topográfica por interferometria óptica e quanto a propriedade de hidrofibilidade. RESULTADOS: Nos testes topográficos, a superfície ProActive apresentou valor de Sa de 0,4m contra Sa de 0,8m da superfície Bimodal, sugerindo menor rugosidade da superfície hidrofílica. A umectibillidade da superfície foi maior no grupo ProActive, exibindo valores de ângulos de contato de 27,2° contra 67,2° da superfície Bimodal. Ambas as superfícies apresentaram valores semelhantes nos períodos de uma e quatro semanas no que diz respeito à estabilidade mecânica do implante, aferidos com o RFA e nos parâmetros histomorfométricos em relação deposição óssea ao seu redor CONCLUSÕES: 1) A superfície ProActive apresentou valores menores de rugosidade e aumento da umectibilidade em relação aos implantes com superfície Bimodal. 2) A superfície ProActive utilizada no presente estudo não favoreceu os eventos de osseointegração nas condições períodos de 1 e 4 semanas avaliados. 3) Após 4 semanas de osseointegração, ocorreu aumento da estabilidade dos implantes instalados sem haver diferença entre as superfícies ProActive e Bimodal. 4) A estabilidade dos implantes, avaliados por meio do RFA, aumentou gradativamente durante a osseointegração, sem haver diferença entre as superfícies testadas. / INTRODUCTION: The quality of the bone-implant interface can be directly influenced by factors inherent to titanium surface treatment which determines cells interaction and adherence to shortening the time for osseointegration. This study aimed to assess changes on osseointegration produced by the hidrophibility of Neoss® implants surfaces. MATERIALS AND METHODS: Six labrador dogs were used and 44 Neoss® implants bilaterally installed in the mandible (ProActive with hydrophilic surface) and (Bimodal hydrophobic surface), in standardized bone defects in the coronal region. The biological responses in one and four weeks of osseointegration were evaluated using histological, histomorphometric, fluorescence analysis and mechanical stability measured by Resonance Frequency Analysis (RFA). The surfaces were also subjected to topographic analysis by optical interferometry and hydrophobicity by wettability analysis. RESULTS: The topographic surfaces test showed value of 0.4 micrometers for ProActive implants, against 0.8 micrometers for Bimodal implants, suggesting less hydrophilic surface roughness in the former (p0.05). The wettability values were higher in ProActive surface, with contact angles of 27.2° versus 67.2° of the Bimodal surface (p0.05). Both implant surfaces exhibited similar mechanical stability measured by RFA, as well as the histomorphometric parameters related to bone deposition onto the surfaces. CONCLUSIONS: 1) The ProActive surface showed lower roughness values and increased wettability compared to Bimodal surface. 2) The ProActive surface did not favor osseointegration at 1 and 4 weeks. 3) After 4 weeks of osseointegration the implants increased in stability, with no statistical differences between Bimodal and ProActive surfaces

This project examined the effect of splinting adjacent dental implants of different designs [Sintered porous surface (SPS), Threaded dual acid etched (THR-DAE), Threaded sand-blasted large grit acid etched (THR-SLA)] placed in posterior sites and compared two intraoral radiographic techniques to assess peri-implant crestal bone levels. 799 implants located in 345 patients qualified and were examined retrospectively using an inclusion criteria of a minimum one year in function and having a recent periapical (PA) and vertical bitewing radiograph (vBW). SPS had less bone loss than THR-DAA and THR-SLA. PA views showed approximately 0.10 mm (Range 0.07-0.40 mm) less crestal bone loss than vBW (P<0.01). Splinted implants had more crestal bone loss (0.30 mm; range 0.16-0.38 mm) than non-splinted implants. 49 implants failed with an overall failure rate of 4.9% with a significant difference in the failure rate of SPS and THR-DAA (P<0.0005) and in the time to fail (P<0.0036).

This project examined the effect of splinting adjacent dental implants of different designs [Sintered porous surface (SPS), Threaded dual acid etched (THR-DAE), Threaded sand-blasted large grit acid etched (THR-SLA)] placed in posterior sites and compared two intraoral radiographic techniques to assess peri-implant crestal bone levels. 799 implants located in 345 patients qualified and were examined retrospectively using an inclusion criteria of a minimum one year in function and having a recent periapical (PA) and vertical bitewing radiograph (vBW). SPS had less bone loss than THR-DAA and THR-SLA. PA views showed approximately 0.10 mm (Range 0.07-0.40 mm) less crestal bone loss than vBW (P<0.01). Splinted implants had more crestal bone loss (0.30 mm; range 0.16-0.38 mm) than non-splinted implants. 49 implants failed with an overall failure rate of 4.9% with a significant difference in the failure rate of SPS and THR-DAA (P<0.0005) and in the time to fail (P<0.0036).

Le poignet, complexe articulaire situé entre l'avant-bras et la main, est sujet aux traumatismes. Par exemple, une chute sur le poignet suite à la pratique d'un sport de glisse ou tout simplement dans un accident de la vie quotidienne peut entraîner une lésion du ligament scapho-lunaire. Cette lésion, difficile à diagnostiquer sur une simple radiographie, évolue toujours vers l'arthrose du poignet. Si le diagnostic est fait pendant la phase aigue, proche du traumatisme, la réparation du ligament ou des techniques conservatrices sur parties molles sont possibles. Si la lésion n'est pas détectée à temps, celle-ci engendre une instabilité du carpe évoluant vers l'arthrose.. A ce stade, des techniques plus radicales incluant des arthrodèses partielles ou totales sont bien connues. Cependant, ces techniques de fusion des os engendrent une perte conséquente de mobilité du poignet. L'objectif de la thèse est de définir une méthode de conception et le dimensionnement d'un implant dont le but est de rétablir la cinématique du carpe après une lésion ligamentaire. Ce dispositif devra remplacer la partie dorsale du ligament scapho-lunaire lorsque celui-ci n'est plus réparable et avant apparition de l'arthrose. / ScaphoLunate interosseous ligament (SLIL) lesion can occur when falling on an outstretched, pronated hand and lead to carpal instability. If SLIL tears are detected early, the ligament can be repaired. However, if the ligament is left untreated, SLIL instability can evolve into carpal arthritis called ScaphoLunate Advanced Collapse (SLAC). Well-known SLAC treatments include arthrodeses. These techniques modify the carpal kinematics and involve a range of motion (ROM) loss. Different prostheses are proposed for patients with arthritis. However, these prostheses do not make an acceptable compromise between the ROM allowed and their mechanical strength. This thesis presents an implant to replace the dorsal part of SLIL when the ligament is not repairable and before the apparition of SLAC. The implant must restore normal kinematics and the mechanical behavior of the carpus. Each step of its design is presented. Kinematic constraints of the implant were derived from measured bone displacements. Using a 3D best-fit method, their mean values and uncertainties were determined. The mechanical behavior of the implant was defined by SLIL stiffness and elongation. Strain energy of the native ligament was a characteristic relevant to the implant behavior design. Surgical and anatomical constraints lead to a small amount of space availaible; hence, the design was driven by strain energy distribution. Using an material capability index, the choice of suitable material is discussed. Finally, the implant design and its method are presented, which satisfy all previous constraints. FEA of the most critical case of kinematic constraints was performed to validate the proposed implant design.

INTRODUÇÃO: A qualidade da interface osso-implante pode ser influenciada diretamente por aspectos inerentes ao tratamento da superfície do titânio e determina a forma que as células interagem, aderem e se fixam a ela, podendo potencializar e encurtar o tempo de osseointegração. Este estudo propôs-se a analisar alterações na osseointegração produzidas pela hidrofibilidade das superfícies dos implantes Neoss®. MATERIAIS E MÉTODOS: Foram utilizados 6 cães da raça labrador e instalados 44 implantes Neoss® bilateralmente na mandíbula com defeitos ósseos padronizados na região coronal: 22 implantes apresentavam superfície ProActive (hidrofílica) e outros 22 implantes eram de superfície Bimodal (hidrofóbica). Foram avaliados a resposta biológica nos períodos de uma semana e quatro semanas de osseointegração, utilizando parâmetros histológicos, histomorfométricos, fluorescência e de estabilidade mecânica aferido pelo método de análise de frequência de ressonância (RFA). As superfícies também foram submetidas à análise topográfica por interferometria óptica e quanto a propriedade de hidrofibilidade. RESULTADOS: Nos testes topográficos, a superfície ProActive apresentou valor de Sa de 0,4m contra Sa de 0,8m da superfície Bimodal, sugerindo menor rugosidade da superfície hidrofílica. A umectibillidade da superfície foi maior no grupo ProActive, exibindo valores de ângulos de contato de 27,2° contra 67,2° da superfície Bimodal. Ambas as superfícies apresentaram valores semelhantes nos períodos de uma e quatro semanas no que diz respeito à estabilidade mecânica do implante, aferidos com o RFA e nos parâmetros histomorfométricos em relação deposição óssea ao seu redor CONCLUSÕES: 1) A superfície ProActive apresentou valores menores de rugosidade e aumento da umectibilidade em relação aos implantes com superfície Bimodal. 2) A superfície ProActive utilizada no presente estudo não favoreceu os eventos de osseointegração nas condições períodos de 1 e 4 semanas avaliados. 3) Após 4 semanas de osseointegração, ocorreu aumento da estabilidade dos implantes instalados sem haver diferença entre as superfícies ProActive e Bimodal. 4) A estabilidade dos implantes, avaliados por meio do RFA, aumentou gradativamente durante a osseointegração, sem haver diferença entre as superfícies testadas. / INTRODUCTION: The quality of the bone-implant interface can be directly influenced by factors inherent to titanium surface treatment which determines cells interaction and adherence to shortening the time for osseointegration. This study aimed to assess changes on osseointegration produced by the hidrophibility of Neoss® implants surfaces. MATERIALS AND METHODS: Six labrador dogs were used and 44 Neoss® implants bilaterally installed in the mandible (ProActive with hydrophilic surface) and (Bimodal hydrophobic surface), in standardized bone defects in the coronal region. The biological responses in one and four weeks of osseointegration were evaluated using histological, histomorphometric, fluorescence analysis and mechanical stability measured by Resonance Frequency Analysis (RFA). The surfaces were also subjected to topographic analysis by optical interferometry and hydrophobicity by wettability analysis. RESULTS: The topographic surfaces test showed value of 0.4 micrometers for ProActive implants, against 0.8 micrometers for Bimodal implants, suggesting less hydrophilic surface roughness in the former (p0.05). The wettability values were higher in ProActive surface, with contact angles of 27.2° versus 67.2° of the Bimodal surface (p0.05). Both implant surfaces exhibited similar mechanical stability measured by RFA, as well as the histomorphometric parameters related to bone deposition onto the surfaces. CONCLUSIONS: 1) The ProActive surface showed lower roughness values and increased wettability compared to Bimodal surface. 2) The ProActive surface did not favor osseointegration at 1 and 4 weeks. 3) After 4 weeks of osseointegration the implants increased in stability, with no statistical differences between Bimodal and ProActive surfaces

Abstract Swanson silastic arthroplasty, introduced by Alfred Swanson in the late sixties, has long been the treatment of choice for metacarpophalangeal (MCP) arthroplasty in cases of rheumatoid arthritis. Silastic implant arthroplasty has a significant role in the reconstruction of eroded MCP joints, but the method does not recreate a normal MCP joint. The Sutter implant has been designed to improve the function of the MCP joint, and especially to reduce the extension deficit. There are numerous studies concerning the Swanson implant, but limited number of previous articles on the use of the Sutter implant. The aim of this thesis was to determine the outcome of MCP arthroplasty with the Sutter implant in patients with inflammatory joint disease. This thesis is based on two studies concerning Sutter implant arthroplasty in patients with advanced rheumatoid arthritis. One of these was a prospective study performed at Oulu University Hospital in which patients were randomised into Swanson and Sutter implant groups representing 49 hands and 174 implants, with a mean follow up time of 4.8 years, and the other was a prospective study performed at the Rheumatism Foundation Hospital in Heinola in which Sutter implant arthroplasty was carried out on 117 hands employing 350 implants, with a mean follow-up time of 5.3 years. The main results were that arthroplasty yields similar results with both of these implants with respect to clinical parameters such as range of motion, ulnar deviation, grip strength and pain. Furthermore, the revision rate in our Sutter follow-up study was high, and survival, with revision surgery as the end point, was poor. We created a new radiographic grading system for bone resorption, i.e. osteolysis, in MCP arthroplasty and found this to be more severe after Sutter than Swanson implant arthroplasty, for some unknown reason. Moreover, we found that osteolysis was symptom-free but related to implant fractures. As a conclusion silicone implant arthroplasty should be used only with rheumatoid patients with advanced destruction. High implant fracture rates and high amounts of osteolytic changes in radiographs are not favourable for the use of the Sutter implant. If continuous development of new prostheses achieves implant with as good clinical outcome and reasonable costs as Swanson implant, the use of the silicone implants will be questionable.

Du fait de l'augmentation de la durée de vie de la population et de la fréquence de certains types d'accidents, la problématique de l'évolution des articulations et du vieillissement osseux devient primordiale, ce qui implique de nombreuses opérations chirurgicales nécessitant une pose d'implant. Bien que ces interventions soient réalisées depuis longtemps de façon routinière, il subsiste des risques d'échec chirurgical pouvant avoir des conséquences dramatiques pour le patient. Malgré les évolutions apportées, le taux d'échec implantaire est encore important car les phénomènes mis en jeu restent mal compris du fait de leur complexité et de leur nature multi-échelle. Un des aspects essentiels de la réussite des ces opérations concerne l'ostéointégration de l'implant, c'est-à-dire la capacité de l'os à se régénérer autour de ce corps étranger en l'intégrant durablement. La réussite chirurgicale dépend en premier lieu des caractéristiques physiques de l'interface os-implant transmettant les efforts biomécaniques qui jouent un rôle majeur dans le remodelage osseux. Ces travaux de recherche s'inscrivent dans le cadre du développement d'une approche expérimentale multimodale pour la caractérisation de l'interface os-implant afin d'évaluer l'impact de la reconstruction osseuse sur la réponse mécanique de l'implant. La première partie met en œuvre une approche multiphysique utilisant un modèle animal dédié. Des pastilles en titane sont implantées in vivo sur la partie proximale du tibia du lapin pendant différents temps de cicatrisation. Une technique de nanoindentation permet de mesurer les propriétés mécaniques de l'os néoformé à l'échelle microscopique. La technique de diffusion micro-Brillouin permet de mesurer la vitesse ultrasonore de l'os néoformé à la même échelle. Les résultats obtenus à partir de ces deux techniques permettent de déterminer la différence de densité volumique entre l'os mature et l'os néoformé aux différents temps de cicatrisation considérés. Dans la seconde partie, un dispositif ultrasonore destiné à l'étude de la stabilité d'implants dentaires en titane est présenté. La réponse ultrasonore obtenue en mode échographique est sensible aux propriétés du matériau (os, biomatériau) au contact de l'implant. Premièrement, la réponse ultrasonore d'implants dentaires insérés dans un substitut dentaire bioactif (silicate tricalcique) et sollicités par un protocole de fatigue mécanique in vitro est mesurée. Pour cela, un banc de fatigue mécanique simulant la mastication a été développé. Deuxièmement, ce même dispositif ultrasonore est utilisé pour déterminer in vitro la stabilité primaire d'un implant dentaire placé dans un os bovin. Troisièmement, une étude in vivo utilisant un modèle animal (lapins) a permis de mettre en évidence l'effet du temps de cicatrisation sur la réponse ultrasonore de l'implant. Ce dispositif ultrasonore permet de quantifier la stabilité primaire et secondaire d'un implant dentaire. Les phénomènes de propagation ultrasonore dans l'implant sont modélisés en utilisant des techniques de simulations numériques par éléments finis. Les simulations montrent le potentiel de la technique pour suivre les variations de plusieurs paramètres déterminants pour l'ostéointégration de l'implant dans des conditions contrôlées / Due to the increase of life duration and to the frequency of certain types of accidents, the problematic of the evolution of joints and aging bone has become crucial, leading to an important number of surgical interventions requiring implant placement. Although these interventions are carried out routinely in the clinic, there are still risks of surgical failure, which induce dramatic consequences for the patient. Despite the evolution of the surgical strategies, the implants failure rate remains important because the phenomena involved are not well understood due to their complexity and to their multi-scale nature. One of the main determinants of the success of these surgical interventions lies in the implant osseointegration, that is to say the ability of bone tissue to regenerate around the implant integrating the implant in a sustainable manner. The surgical success depends primarily on the physical characteristics of the bone-implant interface transmitting the biomechanical efforts, which play a major role in bone remodeling. The approach carried out in the present research consist in developing a multimodal experimental approach to characterize the biomechanical properties of the bone-implant interface in order to assess the impact of bone remodeling around the implant on the mechanical response of the implant. In the first part, a multiphysical approach is carried out using a dedicated animal model. Coin-shaped titanium implants are implanted in vivo on the proximal part of the tibia of rabbits during different periods of healing time. A nanoindentation device is used to measure the mechanical properties of the newly formed bone at the microscopic level. A micro-scattering Brillouin device is employed to estimate the ultrasonic velocity of newly formed bone at the same scale. The results obtained with both techniques are used to determine the difference of bone mass density difference between mature bone tissue and newly formed bone tissue for different healing times.In the second part, an ultrasonic device aims at investigating the stability of titanium dental implants. The ultrasonic response is measured in echographic mode and is shown to be sensitive to the properties of the material (bone, biomaterial) in contact with the implant. Firstly, the evolution of the in vitro ultrasonic response of dental implants inserted into a bioactive dental substitute (tricalcium silicate based cement) and loaded using a mechanical protocol stress is assessed. To do so, a mechanical fatigue bench simulating chewing motions was developed. Secondly, the same ultrasonic device is used to determine in vitro the primary stability of an implant placed into bovine bone tissue. Third, an in vivo study using an animal model (rabbit) investigates the effect of healing time on the ultrasonic response of the implant. The ultrasound device is used to quantify the primary and secondary dental implant stability. The phenomena of ultrasonic propagation in the implant are modeled using techniques of numerical simulations by finite elements. The simulations show the potential of the technique to monitor changes in several key parameters for osseointegration of the implant under controlled conditions

No description available.

Ließe sich das Wachstum des Knochengewebes in der Umgebung dentaler Implantate durch Einwirkung externer elektrischer Stimuli beschleunigen, könnte dadurch die Einheilzeit nach der Implantation entscheidend verkürzt und folglich der darauf verankerte Zahnersatz zeiti-ger eingegliedert werden. Ziel dieser experimentellen Studie ist es, den Einfluss elektrischer Stimulation auf humane Knochenzellen zu untersuchen, die zuvor im Bereich der Unterkiefermolaren von Probanden entnommen und auf den zu vergleichenden, klinisch verwendeten Implantatoberflächen Titan, Ticer® und TiWhite® kultiviert worden sind. Dazu wurde in Zusammenarbeit mit der Hochschule Mittweida eine Apparatur konzipiert, mit deren Hilfe die Probekörper unter standardisierten Bedingungen jeweils mit einer Fre-quenz von 3,8 Hz, einer Amplitude von 3 V sowie einem Tastverhältnis von 50 % befeldet wurden. Nach einer Gesamtversuchsdauer von 120 h erfolgte die fluoreszenzoptische Auswertung anhand der Zellzählung sowie der Bestimmung der mit Antikörpern gefärbten Zellkerne und Bone Sialoprotein-Moleküle, wobei letztere besonders in Phasen der Knochenneubildung vermehrt nachweisbar sind und folglich als Marker des Knochenstoffwechsels gelten. Die auf Titan erhobenen Daten können aufgrund der drastisch erhöhten Anzahl von Zellen und der hoch-signifikant gesteigerten Proteinanheftung eine positive Wirkung der Elektro-stimulation nachweisen. Gegenteiliges ist auf der Ticer®-Oberfläche feststellbar; hier sind sowohl die gezählten Zellen als auch die relativen Grauwerte der Zellkern- und Proteinanfärbung bei den befeldeten verglichen mit den unbefeldeten Zellen deutlich erniedrigt. Weniger eindeutig sind die Ergebnisse auf der TiWhite®-Oberfläche. Während in der befel-deten Kultur mehr Zellen gezählt wurden als in der unbefeldeten, differiert der Betrag der Proteinbestimmung zu unterschiedlichen Zeitpunkten und lässt folglich keine präzise Aussage hinsichtlich der durch die Elektrostimulation verursachten Effekte zu.