Orientador: Altair Antoninha Del Bel Cury / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-21T17:30:39Z (GMT). No. of bitstreams: 1 Andrade_CamilaLimade_M.pdf: 1540257 bytes, checksum: bda7c72558234d710525932300d299a1 (MD5) Previous issue date: 2012 / Resumo: Este estudo avaliou a influência da ancoragem apical de implantes sub-cristais com plataforma switching em região posterior de maxila quanto a estabilidade primária e comportamento biomecânico. Quatro modelos de ancoragem óssea foram utilizados nas avaliações: implante de 4,0 x 13 mm de comprimento fixado bicorticalmente (A), implante de 4,0 × 11 mm de comprimento ancorado apenas na cortical da crista (B) ou 2 milímetros posicionados sub-cristal com (C) ou sem (D) o ápice ancorado no osso cortical do assoalho do seio maxilar. A estabilidade primária foi verificada pelo torque de inserção e medida de frequência de ressonância (ISQ) de implantes inseridos em blocos de poliuretano (n=5). O comportamento biomecânico foi obtido através de análise por elementos finitos (AEF), em que os modelos virtuais foram construídos para representar as diferentes ancoragens ósseas. O tecido ósseo foi considerado anisotrópico e um coeficiente de fricção de 0,3 foi utilizado na interface osso-implante para simular carregamento imediato. Todos os modelos foram carregados com 200 N de força distribuída em três pontos oclusais na coroa cerâmica do pré-molar para simular contato cêntrico ou um contato na cúspide vestibular para simular contato excêntrico. A ancoragem do ápice na cortical óssea aumentou a estabilidade primária dos implantes sub-cristais (torque de inserção 43.2±4.1; ISQ 77.2±2.4), entretanto, também aumentou os valores de tensão / deformação quando comparado com o implante sub-cristal ancorado apenas em osso trabecular. O osso trabecular é capaz de dissipar as tensões pelo aumento da micromovimentação, especialmente sob carga excêntrica. A ancoragem do ápice dos implantes sub-cristais na cortical do seio maxilar é benéfica do ponto de vista biomecânico, por direcionar as forças tanto cêntricas quanto excêntricas para a região cortical e contribuir para diminuir a micromovimentação do implante / Abstract: This study evaluated the influence of apical anchorage of implants with platform switching at posterior maxilla on primary stability and biomechanical behavior of subcristal implants. Four anchorage designs were used in evaluations: one 4.0×13 mm length implant was fixed bicortically (A), and one 4.0×11 mm length implant was anchored only in crystal cortical (B) or positioned 2 mm subcrestally with (C) or without (D) its apex anchored in cortical bone. Primary stability was accessed by insertion torque and resonance frequency measurements (ISQ) of implants inserted in polyurethane blocks (n=5). The biomechanical behavior was accessed by finite element analysis (FEA), in which virtual models were constructed to representing one of the anchorage designs. The bone tissue was considered anisotropic and a 0.3 frictional coefficient was used at the implant-bone interface to simulate immediate placement. All models were loaded with 200 N force distributed over three occlusal points on the premolar ceramic crown to simulate centric contacting or over one contact at buccal cusp to simulate eccentric contacting. The anchorage of apex into cortical bone testing material improved the primary stability of subcrestal implants (insertion torque 43.2 ± 4.1; ISQ 77.2 ± 2.4); however, the stress/strain values also increased when compared to the subcristal implant anchored only into trabecular bone. The trabecular bone is able to dissipate the stresses by increasing micromotion, especially at eccentric loading. The anchorage of subcristal implant apex into sinus floor cortical bone is biomechanically beneficial, for directing the centric and eccentric forces to cortical region and reduces the micromotion implant / Mestrado / Protese Dental / Mestra em Clínica Odontológica

Le remplacement des tissus mous du système ostéo-articulaire par des implants synthétiques en hydrogels est souvent limité par un faible ancrage avec le tissu osseux. Une approche pour renforcer l’interface os/implant consiste à fonctionnaliser la surface de l’implant par un revêtement biocéramiques. Dans cette thèse, nous étudions deux approches pour revêtir des hydrogels d’alcool polyvinylique (APV) avec des particules biocéramiques d’hydroxyapatite (HA). Dans une première approche, basée sur le procédé d’enduction, des substrats d’hydrogel ont été revêtus par des particules d’HA enchâssées dans une matrice d’hydrogel d’APV non-dégradable. Dans ce procédé, le contrôle de la composition de la solution de trempage permet d’ajuster finement l’épaisseur, la cohésion et l’adhérence du revêtement, ainsi que le taux d’exposition d’HA à la surface du revêtement. La biocompatibilité avec la pratique chirurgicale et l’ostéointégration de ces revêtements ont été évaluées par une étude in vivo sur un modèle de cicatrisation de tunnel osseux chez le lapin. Ces premiers travaux nous ont menés à la découverte d’une nouvelle approche pour gélifier des films d’hydrogel par un procédé auto-entretenu, qui consiste à utiliser la déplétion de solvant créée à la surface d’un substrat gonflant dans une solution de polymère pour induire la gélification sans action extérieure. Dans ce procédé, la croissance de ces films dépend de la concentration de la solution, du temps de trempage et de la cinétique de gonflement du substrat. Le caractère doux de ce procédé de gélification a été vérifié en encapsulant des fibroblastes, qui restent viables durant 48h. Avec un second procédé plus énergétique, des substrats d’hydrogels d’APV ont été revêtus de couches denses de particules d’HA submicroniques par cold spray. Les paramètres de projection (température, pression, distance de projection) ont été variés systématiquement pour déterminer des conditions de projection appropriées. Un schéma de formation du revêtement est proposé, basé sur les observations microscopiques. Chacun de ces procédés et leur combinaison ouvrent de nouvelles voies dans la conception de système hydrogel-céramique ayant des propriétés microstructurales, mécaniques et biologique contrôlées. / The replacement of soft osteoarticular tissues by synthetic hydrogel implants is often limited by a weak anchorage to bone tissues. One approach to strengthen the bone-implant interface consists in functionalizing the surface of the implant by a coating of bioceramics. In this thesis, we investigate two approaches to coat hydrogels of poly(vinyl alcohol) (PVA) with ceramic particles of hydroxyapatite (HA). In a first “soft” process, based on dip-coating, hydrogel substrates were coated with hydroxyapatite particles embedded in a non-degradable PVA hydrogel matrix. In this process, the control of the soaking solution composition allows to finely tune the thickness, the cohesion and the adhesion of the coating, as well as the HA exposure at the coating surface. The biocompatibility with surgical handling and the osteointegration of these systems were assessed by an in vivo study in a rabbit model of bone tunnel healing. This first approach led to the discovery of a new approach to grow physical hydrogel films by a self-sustained process, consisting in using the solvent depletion created at the surface of a swelling polymer substrate immersed in a PVA solution to induce the gelation of hydrogel films without external action. In this process, the growth of these hydrogel films depends on the solution concentration, the soaking time and the swelling kinetics of the substrate. We verified the gentle character of this process by encapsulating fibroblasts, which remain viable for 48h. In a second more “energetic” process, dense coatings of submicronic HA particles were produced on PVA hydrogel by cold spray. Spraying parameters (temperature, pressure and stand-off distance) were varied systematically to determine efficient spraying condition. Based on microscopic observations, a picture explaining the formation of the coating is proposed. Both processes and their combination open new routes for the design of ceramic-hydrogel systems having controlled microstructural, mechanical and biological properties.