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Orientador: Prof. Dr. Nelson Luis Barbosa Rebellato / Coorientador: Prof. Dr. Delson João da Costa / Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências da Saúde, Programa de Pós-Graduação em Odontologia. Defesa: Curitiba, 2016 / Inclui referências : f. 37-44;56-58 / Área de concentração / Resumo: Este estudo analisou através do método de elemento finito tridimensional (MEF) a distribuição de tensões mastigatórias sobre implantes curtos com coroas alongadas, na região do elemento 36. Os modelos de implantes utilizados foram: M1- Neodent Titamax WS® 4x5mm e M2 - Neodent Titamax WS® 5x5mm. A análise verificou a distribuição das tensões nos implantes e no tecido ósseo, sob cargas de incidência axial e oblíqua e avaliou a influência da diferença no diâmetro dos implantes sobre a distribuição das tensões mastigatórias. Os resultados mostraram que sob incidência de forças axiais, os modelos analisados obtiveram resultados satisfatórios, sem exceder os limites de resistência do tecido ósseo e os limites de escoamento dos implantes e componentes protéticos envolvidos. Porém, sob incidência de forças oblíquas, os modelos apresentaram picos de tensão que ultrapassaram os limites de resistência do osso, indicando uma possível reabsorção óssea, de maior evidência no modelo M1. Verificamos um excesso de tensão incidindo sobre o terço cervical dos implantes analisados sob força oblíqua, porém de maior intensidade no modelo M1, podendo levar a uma falha estrutural deste implante. Observamos que o fato de aumentar o diâmetro do implante favoreceu a distribuição das tensões mastigatórias, tanto nos implantes como no tecido ósseo. Conclui-se que o uso de implantes de maior diâmetro possuem um melhor desempenho para dissipar as forças e reduzir a tensão no implante e no osso circunjacente, e que forças oblíquas são potencialmente prejudiciais ao sistema implante/osso, principalmente em implantes curtos com coroas superdimensionadas. A indicação no uso de implantes curtos unitários deve ser cautelosa e o planejamento protético deve ser rigoroso, favorecendo as cargas oclusais ou axiais e minimizando as cargas oblíquas. Palavras-chave: Análise de elementos finitos, implantes dentários, força de mordida. / Abstract: This study analyzed through 3-D finite element method (FEM) simulation of the distribution of masticatory tension on short implants with long length crowns, in 36 region. The CAD SolidWorks® 2015 (Dassault Systemes, Solidworks Corps, USA) and the Ansys Workbench® V16. (Ansys Inc., Canonsburg, PA, USA) softwares were used. The selected implant models were: M1- Neodent Titamax WS® 4x5mm and M2 - Neodent Titamax WS® 5x5mm. The files with the models of implants and abutments were provided by Neodent® company, Curitiba, Brazil. The analysis showed the stress distribution in the bone tissue and implants under axial and oblique forces incidence and evaluated the influence of the difference in diameter of the implants on the distribution of masticatory tensions. The results showed that under effect of axial forces, the models achieve satisfactory results, without reaching or exceeding the strength limits in bone tissue, implants and prosthetic components involved. However, under oblique forces, the models showed maximum tension values exceeding the bone strength limits, indicating a possible bone resorption, more evident in M1. An excess of tension was found on the cervical third of implants analyzed under oblique incidence, but a greater intensity in the M1 led to structural failure of the implant. We note that the fact of increasing the diameter of the short implants favored the distribution of masticatory stress both the implants and the bone tissue. We conclude that the use of larger diameter implants have a better performance to dissipate the forces, and reduce the tension in the walls of the implant and the surrounding bone, and oblique forces are potentially harmful to the implant / bone system, especially for short implants with oversized crown. The indication on the use of single short implants should be cautious and prosthetic planning should be strict, favoring the occlusal or axial loads and minimizing the oblique loads. Keywords: Finite element analysis, dental implants, bite force

Cette recherche est basée sur l’étude de deux niveaux d’endommagements de la connexion implantaire : en premier lieu, l’usure liée aux différents cycles d’insertion/désinsertion nécessaire à l’élaboration d’une prothèse sur des échantillons implantaires ; et d’autre part, les endommagements au cours du temps, réalisés à l’aide d’une étude par fretting-corrosion en salive humaine. Lors des différents cycles de serrage/desserrage, des endommagements sur l’ensemble des composants sont présents. La vis implantaire, qui concentre la majorité des complications thérapeutiques, doit être renouvelée après 20 cycles de serrage maximum. L’utilisation de vis de laboratoire permet ainsi de limiter les dégradations sur cette dernière et d’optimiser la valeur de précontrainte lors du serrage d’usage. Lorsque la prothèse est mise en service, les endommagements sont principalement liés à des usures par tribocorrosion. Ce phénomène est à l’origine d’usure synergique et engendre une modification de la microstructure en regard des surfaces frottée / This research based on the study of two levels of damage focused on the implant connection: firstly, the wear associated with the opening/closing cycle dedicated to the manufacturing process; secondly, the damage over the time, that is a fretting-corrosion study of dental implants in human saliva. During the tightening/loosening cycles, damage to all the components is present. The screws that include the majority of the complications have to be changed after 20 tightening cycles. The use of laboratory screws limits the damage and optimizes the preload value. When the prosthesis and the implant are assemblies, the damage appears thanks to fretting/corrosion (tribocorrosion) behavior. This phenomenon does involve synergistic wear and a modification of the microstructure on the fretting surfaces

Ce travail de thèse porte sur l’analyse de la tenue mécanique d’un type particulier de prothèse dentaire, la prothèse transvissée sur quatre implants communément appelée «All-on-Four», destinée au traitement des patients totalement édentés. Il est nécessaire de tenter de mieux connaître les indications et la pérennité de ce type de prothèse, car elle a montré de nombreux cas de défaillances précoces. Dans un premier temps, le travail a porté sur l'élaboration d'un capteur occlusal quantifiant les forces fournies par le patient. Ce capteur, facile d'utilisation et peu onéreux, peut devenir un outil commun des cabinets dentaires et permettre au praticien de personnaliser le design de la prothèse et de détecter les patients à risques. Dans un deuxième temps, la recherche a porté sur l'étude proprement dite de la prothèse transvissée sur quatre implants. Le but est d’observer les conséquences d'une solution complète prothétique fixe sur les mouvements du corps mandibulaire lors des trois phases principales de la mastication que sont l'intercuspidie maximale, le bout à bout incisif et la latéralité travaillante. L’influence de plusieurs paramètres a été étudiée (matériaux de la prothèse, design de la prothèse, qualité de l’os mandibulaire, angulation des implants postérieurs). L’étude a été conduite, d’abord par voie numérique, grâce à un modèle par éléments finis paramétré, puis par voie expérimentale, par la création d'un banc test mécanique novateur qui tente de respecter au mieux la physiologie humaine. Il ressort que le biomimétisme est l'une des meilleures réponses mécaniques aux solutions prothétiques en odontologie : l'optimisation et la pérennité des soins doivent tenir compte des propriétés mécaniques des tissus naturels et respecter la physiologie du patient. A terme, l’étude vise à permettre d’optimiser le rôle de prescripteur du chirurgien-dentiste dans le choix de la solution prothétique. Cette démarche s’inscrit dans la dentisterie moderne et actuelle dénommée «e-dentisterie», dont le principe est d’automatiser le processus de création d’une solution prothétique individualisée pour chaque patient, depuis le cabinet du praticien dentaire jusqu’au centre d’usinage / This thesis deals with the analysis of the mechanical behavior of a particular dental prosthesis, named “All-on-Four”, specifically dedicated to totally edentulous patients. Because several complications have been reported, it is necessary to understand the precise behavior of these prostheses. Initially, a new device has been developed, in order to quantify the intensity of the occlusal forces developed by the patient during mastication. Because it is very simple to use and not expensive, this device could help the dental surgeon in choosing the prosthesis’ design and in identifying the high-risk patients. Then the research focused on the prosthesis itself. The aim was to understand how the fixed implant rehabilitation can interact with the mandibular bone deformation during the three main steps of mastication which are incisal clenching, maximum intercuspation and unilateral molar clench. The influence of several parameters was investigated, including the prosthesis’ materials, the prosthesis’ design, the quality of the mandibular bone, and the angulation of posterior implants. The study was conducted in two ways: the first one is numerical, with a complete finite element model of the rehabilitated mandible; the second was experimental and was performed thanks to an innovative test bench specifically developed in order to respect the mandibular physiology. The results showed that biomimetics is one of the best solutions for prosthodontics in dentistry: the optimization and reliability of dental cares have to take into account the mechanical properties of natural tissues and respect the physiology of the patient. In perspective, this study aims to help the dental surgeon in deciding which prosthetic solution should be prescribed to his patient. This approach comes within the scope of the modern dentistry named “e- dentistry”, which consists of designing an individual prosthetic device for each patient through a complete automated processing between the dental surgeon’s office and the fabrication laboratory

Cette thèse aborde une étude biomécanique de l’appareil stomatognathique en vue d’analyser les conséquences sur les articulations temporo-mandibulaires (ATM) de la mise en place d’une prothèse complète implanto-portée. Cette étude est réalisée à l’aide de la méthode des éléments finis. Dans ce travail, deux modèles ont été créés. Un premier est basé sur la géométrie d’un sujet sain volontaire sans problèmes articulaires ni dentaires. Un deuxième, avec une restauration de la dentition par une prothèse dentaire complète sur implants, repose sur la géométrie des structures osseuses du cas sain. Une méthodologie a été mise en place pour la construction du modèle éléments finis, basé sur celle développée dans la thèse d’Alvarez. Une comparaison des résultats est effectuée entre les modèles du cas sain d’Alvarez et celui exposé dans ce travail afin d’évaluer l’influence des modifications apportées et de valider ce dernier. Puis une comparaison est effectuée entre le cas sain et restauré pour une ouverture/fermeture modérée de la mâchoire ainsi que lors de la morsure d’aliments au niveau des incisives. Une autre problématique abordée dans cette thèse est l’analyse du risque d’échec de l’implantation dans l’os dont la qualité est dégradée par la perte des dents. Deux géométries d’implants ont été testées pour différentes qualités osseuses, un implant classique et un implant nouvellement breveté / This study deals with a biomechanical analysis of the stomatognathic system in order to understand the consequences of complete fixed dental prosthesis on temporomandibular joint (TMJ). The finite element method is used to achieve this goal. Two models have been created, a healthy and restored by prosthesis ones. The first model is based on a healthy volunteer subject morphology, without dental or articular troubles. The restored model is based on the bony structures of the healthy individual. Mandibular teeth have been removed numerically and a complete fixed overdenture has been settled on the mandible. The construction of the finite element model has been set up following the method developed by Alvarez. A comparison between results obtained by both approaches on the healthy case has been done to validate our model and to evaluate the impact of the improvements proposed in this work on mandible behavior. Then a comparison between the healthy and restored cases is done for a moderate opening /closing motion of the jaw and for a foodstuff bite between the incisors. Another problematic is treated in this thesis, the risk of peri-implant bone damage. Teeth lose induce a bone quality degradation that could cause the implantation failure. Two implant geometries have been tested for different bone qualities during clenching. In the first case, the classical implants, frequently employed by dentists, have been used. In the second case, the advantages of the newly patented implant, composed of a vertical and horizontal screws, have been tested