This study deals with the mechanical aspects of human mandible in physiological state during the occlusion. The work is focused on evaluation of stress-strain conditions of bone tissue. The emphasis is paid to the interaction of teeth with the bone. In addition, contact pres-sures in temporomandibular joints during various loading conditions were determined. The analysis of material model of some parts of the system regarding their modelling-level is pre-sented as well. The problem concerning the evaluation of stress-strain states is solved by computational simulation using the finite element method. The presented work is a detailed analysis of the parts of the masticatory system and a thorough description of their modelling is presented. Special focus is paid to modelling of cancellous bone as well as of periodontal tissue which mediates the interaction between a tooth and the alveolar bone. Three-dimensional geometry of the mandible and all its teeth has been obtained by using the digitizing of real objects, namely by using of three-dimensional optical scanner. Three various modelling levels of the material of periodontium are assessed: Linear iso-tropic model, bilinear isotropic model and linear orthotropic model. Characteristics of these models are analyzed and especially nine new constants describing orthotropic model (which is almost absent in the literature) are proposed. Two-dimensional models are used for analysis of differencies in mechanical response of cancellous bone to the tooth loading. Two cases are considered: Cancellous bone as a ho-mogenous continuous model on one hand and with detailed trabeculous architecture model on the other. Computational model is divided into four basic cases varying in level of masticatory appa-ratus geometry: A – 2D geometry of bone; B – 3D geometry of bone segment with one tooth through three teeth; C – 3D geometry of whole mandible with the only tooth; D – 3D geome-try of whole mandible with all teeth. All basic cases are further researched in different varia-tions for different material models etc.

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Orientador: Guilherme de Paula Nogueira / Banca: Yuri Tani Utsunomiya / Banca: Marco Antonio Rodrigues Fernandes / Resumo: O objetivo desse estudo foi inferir a Densidade Mineral óssea (DMO) a partir da imagem radiográfica (Raios-X) usando como referência a DMO de uma escada de alumínio mensurada por Absorciometria por de Duas-Energias (DXA). Para isso foram utilizadas 30 amostras de tecido ósseo cortical e 30 amostras de tecido ósseo trabecular de osso bovino "in vitro". Foram mensurados neste estudo a Densidade Mineral Óssea (DMO), o Conteúdo Mineral Ósseo (CMO) ambos obtidos pelo densitômetro LUNAR®-DPX ALPHA; a Quantidade Mineral Óssea (QMO) massa das cinzas após a calcinação das amostras; a densidade real das amostras (dReal=massa/volume). Foram feitas 10 tomadas de RX com as 60 amostras, entremeadas pela escada de alumínio (referencial densitométrico). A correlação entre as técnicas (DR-tons de cinza e DXA g/cm2) gerou equações de regressão para cada uma das dez radiografias e permitiu inferir a densidade mineral óssea (DMODR), obtida através da conversão dos tons de cinza em densidade radiográfica pelo software ImageJ® para cada uma das 10 tomadas radiográficas; calculou-se então a média da densidade mineral óssea calculada pela densitometria radiográfica (XDMODR) de todas as dez radiografias. Foi observado que a média da densidade real das amostras foi de 2,2±0,23g/cm2 e 1,05±0,09g/cm2 enquanto que a média da densidade mensurada pelo DXA foi de 0,73±0,11g/cm2 e 0,22±0,11g/cm2, observou que a media da DMODR ficou em 0,93±0,11g/cm2 e 0,34±0,14 g/cm2 para o osso cortical e trabecular respect... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to infer the bone mineral density (BMD) from the radiographic image (X-X) with reference to the BMD of an aluminum step wedge measured by absorptiometry Dual-energy (DXA). For this we used 30 samples of cortical bone 30 and cancellous bone tissue samples of bovine bone "in vitro". Were measured in this study Bone Mineral Density (BMD), bone mineral content (BMC) both obtained by densitometer LUNAR® DPX-ALPHA; Volume Bone Mineral (QMO) mass of ash after calcination of the samples; the real density of the samples (dReal = mass / volume). 10 taken RX were made with the samples 60, interspersed by aluminum step wedge (densitometric reference). The correlation between the techniques (gray DR-tones and DXA g / cm 2) generated regression equations for each of the ten X-rays and allowed to infer bone mineral density (DMODR) obtained by converting grayscale radiographic density by ImageJ® for each of the 10 radiographic taken. It was then calculated average bone mineral density calculated by X-ray densitometry (XDMODR) radiographs of all ten. Was observed that the average true density of the samples was 2.2±0.23g/cm2 and 1.05±0.09g/cm2 while the average density measured by DXA was 0.73±0.11g/cm2 and 0.22±0.11g/cm2 interesting that the average DMODR was 0.93±0.11g/cm2 and 0.34±0.14g/cm2 for cortical and cancellous bone respectively. The average of the BMC was 0.19±0.08g and 0.9±0.02g, and the average QMO 0.14±0.04g and 0.05±0 03g for cortical and cancellous bo... (Complete abstract click electronic access below) / Mestre

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Atenciosamente Ederson Vasconcelos Pereira on 2019-01-29T12:46:31Z (GMT) / Submitted by Rodrigo Antonio Fernandes (rodrigoantoniofernandes@yahoo.com.br) on 2019-01-29T13:37:47Z No. of bitstreams: 2 Fernandes_RA dissert.pdf: 2677985 bytes, checksum: 59bf1c4dbeabd618fa2d4e2bfe9922fa (MD5) ata e aprovação.pdf: 653292 bytes, checksum: bcfcb8279087f3106d7831c31b686782 (MD5) / Approved for entry into archive by Ederson Vasconcelos Pereira null (edersonpereira@fmva.unesp.br) on 2019-01-29T18:18:15Z (GMT) No. of bitstreams: 1 fernandes_ra_me_araca_int.pdf: 2718642 bytes, checksum: 4dea3e0dc607519bbdbdb41a172e9277 (MD5) / Made available in DSpace on 2019-01-29T18:18:15Z (GMT). No. of bitstreams: 1 fernandes_ra_me_araca_int.pdf: 2718642 bytes, checksum: 4dea3e0dc607519bbdbdb41a172e9277 (MD5) Previous issue date: 2019-01-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo desse estudo foi inferir a Densidade Mineral óssea (DMO) a partir da imagem radiográfica (Raios-X) usando como referência a DMO de uma escada de alumínio mensurada por Absorciometria por de Duas-Energias (DXA). Para isso foram utilizadas 30 amostras de tecido ósseo cortical e 30 amostras de tecido ósseo trabecular de osso bovino “in vitro”. Foram mensurados neste estudo a Densidade Mineral Óssea (DMO), o Conteúdo Mineral Ósseo (CMO) ambos obtidos pelo densitômetro LUNAR®–DPX ALPHA; a Quantidade Mineral Óssea (QMO) massa das cinzas após a calcinação das amostras; a densidade real das amostras (dReal=massa/volume). Foram feitas 10 tomadas de RX com as 60 amostras, entremeadas pela escada de alumínio (referencial densitométrico). A correlação entre as técnicas (DR-tons de cinza e DXA g/cm2) gerou equações de regressão para cada uma das dez radiografias e permitiu inferir a densidade mineral óssea (DMODR), obtida através da conversão dos tons de cinza em densidade radiográfica pelo software ImageJ® para cada uma das 10 tomadas radiográficas; calculou-se então a média da densidade mineral óssea calculada pela densitometria radiográfica (XDMODR) de todas as dez radiografias. Foi observado que a média da densidade real das amostras foi de 2,2±0,23g/cm2 e 1,05±0,09g/cm2 enquanto que a média da densidade mensurada pelo DXA foi de 0,73±0,11g/cm2 e 0,22±0,11g/cm2, observou que a media da DMODR ficou em 0,93±0,11g/cm2 e 0,34±0,14 g/cm2 para o osso cortical e trabecular respectivamente. A média da CMO foi de 0,19±0,9g e 0,08±0,02g e a media da QMO 0,14±0,04g e 0,05±0,03g para o osso cortical e trabecular respectivamente. Foi possível obter bons coeficientes de determinação entre todas as variáveis estudadas: CMO e QMO, R2 =0,747; DMO e dReal com R2 = 0,765; dReal e DMODR; DMO e XDMODR, respectivamente 0,764 e 0,856. Para as correlações foram usadas amostras de dois tecidos ósseos cortical e trabecular, o que sugere distinção entre as amostras com as metodologias utilizadas / The aim of this study was to infer the bone mineral density (BMD) from the radiographic image (X-X) with reference to the BMD of an aluminum step wedge measured by absorptiometry Dual-energy (DXA). For this we used 30 samples of cortical bone 30 and cancellous bone tissue samples of bovine bone "in vitro". Were measured in this study Bone Mineral Density (BMD), bone mineral content (BMC) both obtained by densitometer LUNAR® DPX-ALPHA; Volume Bone Mineral (QMO) mass of ash after calcination of the samples; the real density of the samples (dReal = mass / volume). 10 taken RX were made with the samples 60, interspersed by aluminum step wedge (densitometric reference). The correlation between the techniques (gray DR-tones and DXA g / cm 2) generated regression equations for each of the ten X-rays and allowed to infer bone mineral density (DMODR) obtained by converting grayscale radiographic density by ImageJ® for each of the 10 radiographic taken. It was then calculated average bone mineral density calculated by X-ray densitometry (XDMODR) radiographs of all ten. Was observed that the average true density of the samples was 2.2±0.23g/cm2 and 1.05±0.09g/cm2 while the average density measured by DXA was 0.73±0.11g/cm2 and 0.22±0.11g/cm2 interesting that the average DMODR was 0.93±0.11g/cm2 and 0.34±0.14g/cm2 for cortical and cancellous bone respectively. The average of the BMC was 0.19±0.08g and 0.9±0.02g, and the average QMO 0.14±0.04g and 0.05±0 03g for cortical and cancellous bone respectively. It was possible to obtain good determination coefficients between all variables: BMC and QMO, R2 = 0.747; BMD and dReal with R2 = 0.765; dReal and DMODR; BMD and XDMODR respectively 0.764 and 0.856. For correlations were used two samples of cortical and cancellous bone tissues, suggesting a difference between the samples with the methodologies used.

This work deals with problem of dental implant area, where there are many problems at the dental implants application. The essential issue is the bone tissue quality at implant application, which sig-nificantly influences its deformation, tension and the possibility of subsequent implant failure. The knowledge of bone tissue mechanical properties of mandible and mandible with applied implant can significantly affect prediction of dental implant failure. The mechanical interaction can be described by variable determining deformation and tension of solved system. For this reason the computational modeling by using Finite Element Method was used for solving given problem. The computational model creation of solved system on the high resolution level is necessary for biomechanical assessment of implant failure, including bone tissue quality. For this purpose the biomechanical study was performed, which significantly spreads range of solved problem in this work afterwards. In this work the methodology, which describes assessment of bone tissue quality where the implant should be applied as well as mutual interaction, is presented. The results confirm necessity of bone tissue computational models creation on high resolution level including complex trabecular architecture. In this work the creation of trabecular structure computational model from data gained on micro-CT device is described. Further, the trabecular structure computational model was created on the 3D level with dental implant and the stress strain analysis was performed consequently. The last part of this work deals with introductory study of bone tissue modeling and remodeling.

INTRODUÇÃO: O surgimento da tomografia computadorizada quantitativa periférica de alta resolução (HR-pQCT) tornou possível medir a densidade mineral óssea (DMO) volumétrica e a microarquitetura óssea tridimensional in vivo, bem como avaliar a resistência óssea através da análise de elemento finito (FE). Como não há na literatura um banco de dados para a população masculina brasileira, o objetivo principal deste estudo transversal e estabelecer valores de referência para os parâmetros ósseos obtidos por HR-pQCT em homens, categorizados por décadas e ajustados por peso e altura, na região distal do rádio e da tíbia. Como objetivo secundário, correlacionar o parâmetro de resistência óssea - rigidez do tecido ósseo (S), com os demais parâmetros medidos por HR-pQCT, e com parâmetros obtidos por absorciometria de raios- X de dupla energia (DXA), incluindo escore de osso trabecular (TBS). METODOS: Homens brasileiros saudáveis (n = 340) entre as idades de 20 e 92 anos foram incluídos neste estudo. O antebraço não dominante e a perna esquerda foram imobilizados, e foram realizados métodos de segmentação padrão e avançado para as análises da região distal do rádio e da tíbia por HRpQCT. A partir das imagens HR-pQCT, a DMO volumétrica e microestrutura do osso trabecular e cortical foram avaliadas, e a resistência óssea foi estimada usando analise de FE. Também foi realizada medição da coluna lombar e fêmur por DXA para obtenção dos valores de DMO e TBS. Os dados foram descritos em mediana e quartis (IQR). Modelos de regressão linear múltipla em função da idade, peso e altura foram desenvolvidos e ilustrados por diagramas de dispersão com intervalos de 95% de normalidade. Foram calculadas as correlações de Pearson entre alguns parâmetros de interesse. RESULTADOS: Tanto na região distal do rádio como na tíbia, os parâmetros de DMO volumétrica, estrutura e de resistência óssea apresentaram relação estatisticamente significativa com a idade (p < 0,05). As correlações entre S com os demais parâmetros de DMO volumétrica e microarquitetura, bem como com DMO areal e TBS, foram mais fortes na região da tíbia, exceto com espessura trabecular, que foi melhor na região do rádio. As correlações entre TBS com os parâmetros de densidade (trabecular e cortical), número e espessura trabecular, e espessura cortical nas regiões periféricas, foram significativas (p < 0,05), exceto com espessura cortical na tíbia. Quando o TBS foi avaliado de acordo com a categoria de risco, e correlacionado com a rigidez do tecido na região distal do rádio e da tíbia, e com DMO da coluna lombar, apenas o grupo de baixo risco (TBS ³ 1.310) apresentou correlações significativas (p < 0,05). CONCLUSOES: Este trabalho estabeleceu valores de referência para os parâmetros ósseos obtidos por HR-pQCT, com base em uma população saudável miscigenada do sexo masculino. As correlações entre os parâmetros ajudam a compreender o papel de cada variável em relação ao risco de fratura. Pesquisadores e clínicos poderão utilizar esses dados como uma ferramenta adicional para avaliar a saúde óssea e alterações na qualidade óssea / INTRODUCTION: The availability of high resolution peripheral quantitative computed tomography (HR-pQCT) has made it possible to measure volumetric bone mineral density (BMD) and three-dimensional bone microarchitecture in vivo, as well as to evaluate bone strength through finite element (FE) analysis. As there is no database for Brazilian male population, the main objective of this cross-sectional study was to establish reference values for the bone parameters obtained by HR-pQCT in men, categorized for decades and adjusted for weight and height, of the distal radius and tibia. As a secondary objective, to correlate the bone strength parameter - stiffness (S) and other parameters measured by HR-pQCT and parameters obtained by dual-energy X-ray absorptiometry (DXA), including trabecular bone score (TBS). METHODS: Healthy Brazilian men (n = 340) including ages of 20 to 92 years were included in this study. The non-dominant forearm and left leg were immobilized, and standard and advanced segmentation methods were performed for the distal radius and tibia analyzes by HR-pQCT. From HR-pQCT images, volumetric BMD and bone microstructure of trabecular and cortical were evaluated, and bone strength was estimated using FE analysis. Measurements of the lumbar spine and femur by DXA were also performed to obtain BMD and TBS values. The data were described as median and quartiles (IQR). Multiple linear regression models according to age, weight and height were developed and illustrated by dispersion diagrams with 95% normality intervals. Pearson correlations were calculated between some parameters of interest. RESULTS: Parameters of volumetric BMD, structure and bone strength, at distal radius and tibia, showed a significant association with age (p < 0.05). The correlations between S with the other parameters of volumetric BMD and microarchitecture, as well as with areal BMD and TBS, were stronger in the tibia except for trabecular thickness, which was better in the distal radius. The correlations between TBS and density parameters (trabecular and cortical), number and trabecular thickness, and cortical thickness in the peripheral sites were significant (p < 0.05), except with cortical thickness in the tibia. When TBS was evaluated according to risk category, and correlated with S in the distal radius and tibia, and lumbar spine BMD, only the low risk group (TBS ³ 1.310) had significant correlations (p < 0.05). CONCLUSION: This work developed reference values for the bone parameters obtained by HR-pQCT, based on a healthy population for males. Correlations between the parameters support to understand the role of each variable and the relationship with fracture risk. Researchers and clinicians can use these data as an additional tool to assess male bone health and changes in bone quality

This thesis deals with the fixation of lower jaw with bone tissue defect using commercially produced fixator. Large defects of bone tissue are mainly caused due to the removal of bone tissue affected by tumor. These topics have been researched on the basis of the literature. Subsequently, stress strain analysis of the lower jaw with the applied fixation plate was performed. This analysis was solved by using computational modeling with variational approach, ie the finite element method. The work also describes in detail the procedure of creating model of geometry, model of material, model of boundary conditions and loads with subsequent solution of several computational models. The stress strain analysis was done for lower jaw with varying size of the removed bone tissue with applied reconstruction plate made of CP-Ti Grade 4 and for the lower jaw with the plate, which is made of -Ti-Mo. Finally, the influence of the mechanical properties of the callus during formation of new bone tissue (callus healing) on the stress and deformation of the solved system was evaluated.

Presented work deals with Biomechanical study of the facial skeleton. This work is focused on the fixation of the mandible after removal of a tumor from affected bone tissue. The aim of the work is to perform biomechanical study of the facial skeleton with subsequent detailed stress strain analysis of two mandible implants designed and manufactured for specific patients. The geometry model of mandible used for design of mandible implants and used for computational modelling has been obtained on the basis of CT data of two patients. A Theoretical-Clinical sub-study that deals with the comparison the CT data processing which is necessary for creating the model of geometry is a part of the thesis. Two models of mandible with applied mandible implant have been created for two specific patients with tumorous mandible bone tissue. Stress strain analysis has been performed for these two models. Results of the stress strain analysis of two models of mandibles with mandible implants are presented in the final chapters of the thesis. Findings of the biomechanical study have been published and applied in clinical practice.

Presented work deals with Biomechanical study of the facial skeleton. This work is focused on the fixation of the mandible after removal of a tumor from affected bone tissue. The aim of the work is to perform biomechanical study of the facial skeleton with subsequent detailed stress strain analysis of two mandible implants designed and manufactured for specific patients. The geometry model of mandible used for design of mandible implants and used for computational modelling has been obtained on the basis of CT data of two patients. A Theoretical-Clinical sub-study that deals with the comparison the CT data processing which is necessary for creating the model of geometry is a part of the thesis. Two models of mandible with applied mandible implant have been created for two specific patients with tumorous mandible bone tissue. Stress strain analysis has been performed for these two models. Results of the stress strain analysis of two models of mandibles with mandible implants are presented in the final chapters of the thesis. Findings of the biomechanical study have been published and applied in clinical practice.