Osseointegration is defined as the direct physical and practical relation between the living tissue and implant surface. Although, success rate of dental implants is high, implant failure occurs. Overloading implants from occlusal forces are known as one of the main reasons. In order to have successful implant, a dynamic balance must be provided between mechanical and biological elements (Isidor, Flemming 1996). Şimşek et al. reported bone quality, oral sanitation, host medical condition and biomechanical parameters as the main reasons for implants failure. Also, implant fixture micromotion and inappropriate stress in the bone implant interface is known as the potential reasons for early bone loss and implant failure (Şimşek, Barış 2006). Even so, implant position in jawbone, bone density; biomaterial properties of implant surface, treatment technique, loading history and patient clinical status are the influential factors in implant success (Brunski, J.B. 1999). Although there are many studies on stress distribution of implants in bone-implant interface, majority are limited to current implants in the market. However, current designs have been developed by marketing purposes rather than scientific considerations. Therefore, there is need to introduce and analyse new designs in order to optimize implant structure. Recent investigations have shown reliability of FEA method in simulating human jawbone situation. This research aims to develop a new dental implant with better life expectancies and introduce an optimized implant based on FEA stress analyses and experimental tests. Therefore, based on literature recommendations a series of new design factors are defined and analysed. In this study, a primary design is created in AutoCAD and yields to 3 different implants developed in SolidWorks. Branemark MK IV was selected as the bench model to play role of control group. Then, CT-scan images of human jawbone are imported to MIMICS to create a host bone model. Implant and jawbone models are assembled in 3-Matic and exported to Abaqus for final analyses. A series of loadings are defined to examine implant performance in different conditions. Branemark and C-3 implants are manufactured from Titanium for experimental analyses. Mechanical tests on sawbone foam blocks and cadavers are targeted to portray realistic performance. This research demonstrates C-3 model as the optimized dental implant, which presents a new design profile and better performance in low bone densities. The FEA and experimental results validate the benefit of the new design compare to the conventional ones. Furthermore, results can provide a basis for future designers to develop further optimizations.

No description available.

O desenho do implante é um fator de grande relevância na distribuição das tensões geradas nos tecidos perimplantares. A proposição deste estudo foi avaliar a distribuição das tensões de cinco diferentes desenhos de implantes, quando submetidos a carregamentos axiais uniformemente distribuídos. Foram confeccionadas cinco mandíbulas fotoelásticas, nas quais estavam inseridas os implantes utilizados nesta pesquisa Tappered Effect (TE 4.1X12mm- Straumann Dental Implant System), Bone Level (BL 4.1X12mm- Straumann Dental Implant System), Regular Neck Standard Plus (RNSP 4.1X12mm- Straumann Dental Implant System), Ankylos (AK 4.5X11mm- Dentsply Ind e Com Ltda) , Branemark MKIII (MKIII 3.75mmX11.5mm- Nobel Biocare AB). Estas mandíbulas foram posicionadas no crânio fotoelástico, e cargas axiais, uniformemente distribuídas de 2,3 e 4 bars foram aplicadas. Dos cinco implantes utilizados, o BL e o AK apresentam plataforma reduzida e formato cilíndrico, o TE apresenta o formato cônico , RNSP e MKIII formato cilíndrico, sendo que estes apresentam plataforma regulares. Os resultados obtidos mostram que ambos os implantes, apresentaram tensões na região onde se localizam as roscas dos implantes. Os implantes BL e AK, ficaram livres de tensões na região cervical. O implante MKIII foi o que apresentou maiores tensões na região apical, e ao longo do implante não foram observadas tensões dissipadas. O implante RNSP apresentou maiores tensões na região do pescoço do implante. O TE apresentou tensões bem distribuídas ao longo do implante, mas não houve isenção de tensões na região do pescoço. Concluímos que implantes que apresentam plataformas reduzidas (AK e BL) geram tensões distantes da região cervical. Apesar dos implantes TE e RNSP apresentarem plataformas de mesma dimensão, o RNSP apresentou maiores tensões na região da plataforma, podendo concluir que implantes de formatos cônicos distribuem de maneira favorável as tensões. O MKIII apresentou maiores tensões na região apical. / The design of the implant is a highly relevant factor in the distribution of stresses generated in the peri-implant tissues. The proposition of this study was to evaluate the stress distribution of five different designs of implants, when subjected to axial loads uniformly distributed. Were prepared five photoelastic jaws, in which the implants used in this research were inserted: Tappered Effect (TE-4.1X12mm Straumann Dental Implant System), Bone Level (BL-4.1X12mm Straumann Dental Implant System), Regular Neck Standard Plus (RNSP 4.1X12mm- Straumann Dental Implant System) Ankylos (AK-4.5X11mm Dentsply Ind e Com Ltda), Branemark MKIII (3.75mmX11.5mm MKIII, Nobel Biocare AB). The mandibles were positioned on the photoelastic skull, and axial loads, uniformly distributed in 2.3 and 4 bars were applied. Among the five implants used, the BL and AK have reduced platform and cylindrical, the TE has conical shape, and MKIII RNSP cylindrical shape, and these have regular platform. The results show that both implants showed tensions in the region where we find the threads of the implants. Implants BL and AK, were free of cervical tension. The MKIII implant showed the highest stresses in the apical region and along the implant there were no tensions dissipated. The implant RNSP showed greater tension in the neck of the implant. The TE showed tensions well distributed over the implant, but there was no relief of tension in the neck. We conclude that implants that have reduced platform (AK and BL) create tension distant from the cervical region. Despite RNSP TE implants have the same dimension platforms, the RNSP showed higher stress in the region of the platform, and may conclude that implants conical distribute favorably tensions. The MKIII showed higher stress in the apical region.

O desenho do implante é um fator de grande relevância na distribuição das tensões geradas nos tecidos perimplantares. A proposição deste estudo foi avaliar a distribuição das tensões de cinco diferentes desenhos de implantes, quando submetidos a carregamentos axiais uniformemente distribuídos. Foram confeccionadas cinco mandíbulas fotoelásticas, nas quais estavam inseridas os implantes utilizados nesta pesquisa Tappered Effect (TE 4.1X12mm- Straumann Dental Implant System), Bone Level (BL 4.1X12mm- Straumann Dental Implant System), Regular Neck Standard Plus (RNSP 4.1X12mm- Straumann Dental Implant System), Ankylos (AK 4.5X11mm- Dentsply Ind e Com Ltda) , Branemark MKIII (MKIII 3.75mmX11.5mm- Nobel Biocare AB). Estas mandíbulas foram posicionadas no crânio fotoelástico, e cargas axiais, uniformemente distribuídas de 2,3 e 4 bars foram aplicadas. Dos cinco implantes utilizados, o BL e o AK apresentam plataforma reduzida e formato cilíndrico, o TE apresenta o formato cônico , RNSP e MKIII formato cilíndrico, sendo que estes apresentam plataforma regulares. Os resultados obtidos mostram que ambos os implantes, apresentaram tensões na região onde se localizam as roscas dos implantes. Os implantes BL e AK, ficaram livres de tensões na região cervical. O implante MKIII foi o que apresentou maiores tensões na região apical, e ao longo do implante não foram observadas tensões dissipadas. O implante RNSP apresentou maiores tensões na região do pescoço do implante. O TE apresentou tensões bem distribuídas ao longo do implante, mas não houve isenção de tensões na região do pescoço. Concluímos que implantes que apresentam plataformas reduzidas (AK e BL) geram tensões distantes da região cervical. Apesar dos implantes TE e RNSP apresentarem plataformas de mesma dimensão, o RNSP apresentou maiores tensões na região da plataforma, podendo concluir que implantes de formatos cônicos distribuem de maneira favorável as tensões. O MKIII apresentou maiores tensões na região apical. / The design of the implant is a highly relevant factor in the distribution of stresses generated in the peri-implant tissues. The proposition of this study was to evaluate the stress distribution of five different designs of implants, when subjected to axial loads uniformly distributed. Were prepared five photoelastic jaws, in which the implants used in this research were inserted: Tappered Effect (TE-4.1X12mm Straumann Dental Implant System), Bone Level (BL-4.1X12mm Straumann Dental Implant System), Regular Neck Standard Plus (RNSP 4.1X12mm- Straumann Dental Implant System) Ankylos (AK-4.5X11mm Dentsply Ind e Com Ltda), Branemark MKIII (3.75mmX11.5mm MKIII, Nobel Biocare AB). The mandibles were positioned on the photoelastic skull, and axial loads, uniformly distributed in 2.3 and 4 bars were applied. Among the five implants used, the BL and AK have reduced platform and cylindrical, the TE has conical shape, and MKIII RNSP cylindrical shape, and these have regular platform. The results show that both implants showed tensions in the region where we find the threads of the implants. Implants BL and AK, were free of cervical tension. The MKIII implant showed the highest stresses in the apical region and along the implant there were no tensions dissipated. The implant RNSP showed greater tension in the neck of the implant. The TE showed tensions well distributed over the implant, but there was no relief of tension in the neck. We conclude that implants that have reduced platform (AK and BL) create tension distant from the cervical region. Despite RNSP TE implants have the same dimension platforms, the RNSP showed higher stress in the region of the platform, and may conclude that implants conical distribute favorably tensions. The MKIII showed higher stress in the apical region.

Mechanical trauma to the brain, both big and small, and the method to protect the brain in its presence is a crucial field of research given the large population exposed to neuronal trauma daily and the benefit available through better understanding and injury prevention. A population of particular interest and risk are youth athletes in contact sports due to large accelerations they expose themselves to and their developing brains. To better monitor the risk these athletes are exposed to, their accumulation of head acceleration events (HAEs), a measure correlated with harmful neurological changes, was tracked over sport seasons. It was observed that few significant differences in HAEs accumulated existed between players of ages from middle school to high school, but there did exist a difference between sports with girls' soccer players accumulating fewer HAEs than football players. This highlights to risk youth athletes are exposed to and the importance of improved technique and individual player size. To better monitor HAEs for each individual, a novel head segmentation program was developed that extracts player specific geometries from a single T1 MRI scan that can improve the accuracy of HAE monitoring. Acceleration measures processed with individualized head model versus those using a standardized head model typically displayed higher accelerations, highlighting the need for individualized measure for accurate monitoring of HAEs and risk of neurological changes. In addition to the large accelerations present in contact sports, the small but constant strains produced by neural implants embedded in the brain is also an important field of neuro-mechanical research as the physical properties of neural implants have been found to contribute to the chronic immune response, a major factor preventing the widespread implementation of neural implants. To reduce the severity of the immune response and provide improved chronic functionality, researchers have varied neural implant design and materials, finding general trends but not precise relationships between the design factors and how they contribute the mechanical strain in the brain. Performing a large series of mechanical simulations and Cotter's sensitivity analyses, the relationships between neural design factors and the stain they produce in the brain was examined. It was found that the direction which neural implants are loaded contributes the most to the strain produced in the brain followed by the degree of bonding between the brain and the electrode. Directly related to the design of electrodes themselves, it was found that in most cases reducing the cross-sectional area of the probe resulted in a larger decrease of mechanical strain compared to softening the implant. Finally, a study was performed quantifying the resting micromotion of the brain utilizing a novel method of soft tissue micromotion measurement via microCT, applicable within the skull and the throughout the rest of the body.

Resumo: O objetivo do presente trabalho de pesquisa foi avaliar a influencia do tipo de conexao protetica, do platform-switching, e do design do implante no ambiente biomec.nico de implantes imediatos com carga imediata. Para tanto, um modelo de alveolo de extraçao de um incisivo central superior foi constru.do baseado em tomografia computadorizada. Implantes inseridos no alveolo de extra..o foram avaliados por meio de analises em elementos finitos. Uma Analise de Variancia (α=0.05) foi utilizada para interpretar os dados do pico de deformaçao equivalente no osso, do pico de tens.es equivalentes no parafuso do abutment, do deslocamento relativo osso-implante e do gap do abutment. A maior influ.ncia do tipo de conexao protetica e do platform-switching foi observado na tensao do parafuso e no gap do abutment. Por sua vez, o design do implante afetou consideravelmente as deformaçoes no osso e o deslocamento relativo entre o osso e o implante. Nao obstante, evitar a sobrecarga do implante e garantir uma alta estabilidade inicial sao os fatores mais importantes na previsibilidade de implantes imediatos com carga imediata / Abstract: The aim of the present research work was to evaluate the influence of different connection type, platform switching and implant designs on the biomechanical environment of immediately placed implants. A CT-based model of an upper central incisor extraction socket was constructed. The immediately placed implants were evaluated by finite element analysis. An Analysis of Variance was used to interpret the data for the peak equivalent strain in the bone, peak Von Mises stress in the abutment screw, bone-to-implant relative displacement and abutment gap. The largest influence of the connection type and platformswitching was seen on the peak equivalent stress in the abutment screw and implant-abutment gap. On contrary, the implant design considerably affects the biomechanical environment of immediately placed implants. However, avoiding implant overloading and ensuring a high implant initial stability are the most important factors for the predictability of implants in this protocol / Orientador: Luis Geraldo Vaz / Coorientador: Elcio Marcantonio Junior / Coorientador: Sonia Aparecia Goulart de Oliveira / Banca: José Maurício dos Santos Reis Nunes / Banca: Rogério Margonar / Banca: Pedro Yoshito Noritomi / Banca: Flávio Domingues das Neves / Doutor

Made available in DSpace on 2014-06-11T19:32:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-03-25Bitstream added on 2014-06-13T19:43:55Z : No. of bitstreams: 1 pessoa_rs_dr_arafo.pdf: 1780565 bytes, checksum: 78498002897f7571851e27403dd44a72 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O objetivo do presente trabalho de pesquisa foi avaliar a influencia do tipo de conexao protetica, do platform-switching, e do design do implante no ambiente biomec.nico de implantes imediatos com carga imediata. Para tanto, um modelo de alveolo de extraçao de um incisivo central superior foi constru.do baseado em tomografia computadorizada. Implantes inseridos no alveolo de extra..o foram avaliados por meio de analises em elementos finitos. Uma Analise de Variancia (α=0.05) foi utilizada para interpretar os dados do pico de deformaçao equivalente no osso, do pico de tens.es equivalentes no parafuso do abutment, do deslocamento relativo osso-implante e do gap do abutment. A maior influ.ncia do tipo de conexao protetica e do platform-switching foi observado na tensao do parafuso e no gap do abutment. Por sua vez, o design do implante afetou consideravelmente as deformaçoes no osso e o deslocamento relativo entre o osso e o implante. Nao obstante, evitar a sobrecarga do implante e garantir uma alta estabilidade inicial sao os fatores mais importantes na previsibilidade de implantes imediatos com carga imediata / The aim of the present research work was to evaluate the influence of different connection type, platform switching and implant designs on the biomechanical environment of immediately placed implants. A CT-based model of an upper central incisor extraction socket was constructed. The immediately placed implants were evaluated by finite element analysis. An Analysis of Variance was used to interpret the data for the peak equivalent strain in the bone, peak Von Mises stress in the abutment screw, bone-to-implant relative displacement and abutment gap. The largest influence of the connection type and platformswitching was seen on the peak equivalent stress in the abutment screw and implant-abutment gap. On contrary, the implant design considerably affects the biomechanical environment of immediately placed implants. However, avoiding implant overloading and ensuring a high implant initial stability are the most important factors for the predictability of implants in this protocol

Endosseous implants have notably high success rates, yet a small percentage of implants still fail for unidentified reasons. Recent literature points to hyperglycemia, resulting from untreated or undiagnosed diabetes, as a possible contraindication in an otherwise apparently healthy population. To investigate the effect of surface design on peri-implant healing in the presence of hyperglycemia, STZ-treated rats were implanted with custom rectangular implants of two surface topographies: grit blasted (GB) and grit-blast with a calcium phosphate nanotopography (GB-DCD). Tensile testing was conducted at 5, 7, and 9 days post-operative. Results demonstrated hyperglycemia to delay early stages of the peri-implant healing. Contact osteogenesis was increased along the GB-DCD surface, even in an environment of uncontrolled hyperglycemia, and the GB-DCD surface outperformed the GB surface in both healthy and hyperglycemic animals, showing peri-implant bone matured more rapidly on nanotopographically complex surfaces, even in the presence of uncontrolled hyperglycemia.

La pose d’une prothèse totale de genou (PTG) se fait selon la technique d’alignement mécanique (AM) qui corrige les déformations constitutionnelles du membre pour créer un membre rectiligne. La survie à long terme des implants est excellente mais les résultats fonctionnels sont décevants avec notamment de nombreux symptômes résiduels. Une nouvelle technique chirurgicale, l’alignement cinématique (AC), vise à rétablir l’anatomie constitutionnelle pré-arthrosique du genou, et permet une amélioration des résultats fonctionnels des PTG. Cette technique est actuellement réalisée avec des implants destinés à un positionnement mécanique, et qui ont un design trochléen ne reproduisant pas l'anatomie trochléaire native. Ceci pourrait affecter la biomécanique de l’articulation patello-fémorale et donc rendre les résultats fonctionnels des PTG cinématiques non optimal. Ce travail vise à démontrer 1) les limitations de la technique mécanique, 2) la fiabilité de la technique cinématique pour le positionnement de l’implant fémoral, et 3) que les implants actuels ne permettent pas une restauration de l’anatomie trochléenne des patients. / The conventional technique for TKA, namely mechanical alignment (MA), does not preserve the constitutional limb anatomy but systematically creates a straight limb. Excellent long-term implant survivorship has been reported, but functional outcomes are disappointing. To solve this problem, an alternative technique for TKA, namely kinematic alignment (KA), has recently been promoted and aims at restoring the constitutional (pre-arthritic) knee anatomy and laxity. Mid-term outcomes have shown excellent functional outcomes with this new KA technique. However, KA technique is currently done with TKA implants designed to be mechanically inserted. Their trochlea design does not reproduce the native trochlear anatomy, which could lead to increased rate of patellar complications with KA TKA. This work aims at demonstrating technical limitations of MA technique, good reproducibility of KA technique, and inappropriateness of current implant to restore patient trochlea anatomy.

Es erfolgt eine Knochenstrukturanalyse der proximalen Tibia unter Berücksichtigung verschiedenster radiologischer, biomechanischer und histomorphometrischer Aspekte. Die regionen-, alters- und geschlechtsspezifischen Aspekte dieser Problemregion werden herausgearbeitet. Der eindeutige Nachweis einer regionen-abhängigen Verteilung der Knochendichte und der biomechanischen Eigenschaften in der proximalen Tibia ist eines der Hauptergebnisse der vorliegenden Studie. In der proximalen Tibia besteht eine signifikante Abnahme der Knochendichte von proximal nach distal. Im zentralen Bereich der proximalen Tibia besteht in allen Sektionen im Vergleich zu den anterior/posterior und medial/lateral liegenden Gebieten die niedrigste Knochendichte. In der vorliegenden Studie wurde die proximale Tibia in 3 Etagen (von proximal nach distal) unterteilt. Beim Vergleich der auf diesen Etagen aufgebrachten ROIs (region of interest,jeweils 5 in den beiden proximalen Etagen und 4 im distalen Abschnitt) zeigte sich in den beiden proximalen Etagen lateral (Ebene I anterolateral/ Ebene II posterolateral) die höchste Knochendichte. Im Gegensatz dazu zeigte sich in der distalen Etage anteromedial die höchste Knochendichte. Weiterhin wurden die 3 gängigen Stabilisierungsverfahren für diese Region einer umfangreichen biomechanischen Testung unterzogen. Es zeigte sich, dass der Ilizarov Fixateur bei den verschiedensten Lastfällen meist das instabilste Implantat war. Trotz der biomechanischen Defizite konnten die in der klinischen Studie mit Composite Fixateur versorgten Frakturen trotz erheblichem Weichteilschaden und instabiler Fraktursituation zur Ausheilung gebracht werden. Das LIS-System erwies sich gegenüber der konventionellen Abstützplatte hinsichtlich der biomechanischen Steifigkeit sowohl in der statischen als auch in der zyklischen Testung als gleichwertiges oder sogar biomechanisch günstigeres Implantat. Diese positiven klinischen wie biomechanischen Erfahrungen führen auch zur Förderung der Entwicklung anderer winkelstabiler Fixateur interne-Systeme in den verschiedensten Problemregionen (Pilon tibiale, proximaler und distaler Humerus, distaler Radius). Als wesentliche neue Therapieansätze für das operative Vorgehen in der Problemregion der proximalen Tibia lassen sich die folgenden Gesichtspunkte herausarbeiten: 1) Knochendichteadaptierte Implantat- und Schraubenpositionierung bei der konventionellen Osteosynthese, 2) Knochendichteadaptierte Pin- und Olivendrahtpositionierung bei externen Fixationsverfahren (Ilizarovringfixateur, Fixateur externe) im Bereich der proximalen Tibia, 3) Implantatverbesserungen (LISS-Schraubenkonfiguration und -positionierung, Plattendesign, Umstellungsplatte, Verriegelungsbolzen bei Marknägeln wie UTN, PTN), 4) Prothesenverbesserung (knochendichteadaptiertes Zapfendesign mit 3 Zapfen für die tibiale Komponente). / In this study an analysis of the bone structure of the proximal tibia was performed with special attention paid to the different radiological, biomechanical and histomorphometrical aspects. Region-, age- and gender-specific attributes of the localised bone were also examined. Evidence of a region related variation of bone density and biomechanical behaviour is one of the main results of this study. In the proximal tibia, a significant reduction in the bone density exists from proximal to distal. In comparison to the anterior/posterior or medial/lateral areas, the lowest bone mineral densities were found in the central region. In this study the proximal tibia was divided into 3 different levels (from proximal to distal). When comparing the different regions of interest (ROIs) 5 each in the two proximal levels and 4 in the most distal level), the lateral regions (level 1 anterolateral/ level 2 posterolateral) presented the highest bone mineral density. In contrast, the highest bone density in the distal- level was detected in the anteromedial region. Furthermore, complex biomechanical testing of- 3 common fixation techniques for fracture situations of the proximal tibia was performed. It was shown that the Ilizarov fixator was the most unstable implant in several load tests. Despite this biomechanical deficit fractures treated by composite- fixators in different clinical trails healed uneventfully, even with severe soft tissue damage or an unstable fracture situation. In comparison to the conventional buttress plate, the LIS-System was an equal or superior implant, both in static and cyclic stiffness testing. These clinical and biomechanical experiences lead to the development of other angle stable internal fixator systems for different problematic regions (tibial plafond, proximal and distal humerus, distal radius). The following new therapeutic aspects were developed for the surgical treatment of the proximal tibia: 1) Bone mineral density adapted implant-and screw placement in conventional plating. 2) Bone density adapted pin- and olive wire placement during external fixation (ilizarov ring fixator, external fixator) techniques of the proximal tibia. 3) Improvement of implant design (LISS screw configuration and- placement, plate design, locking bolt configuration in nails). 4) Improvement of prosthetic design (bone density adapted design of the tibial components)