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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Two Stage Repair of Composite Craniofacial Defects with Antibiotic Releasing Porous Poly(methyl methacrylate) Space Maintainers and Bone Regeneration

Spicer, Patrick 16 September 2013 (has links)
Craniofacial defects resulting from trauma and resection present many challenges to reconstruction due to the complex structure, combinations of tissues, and environment, with exposure to the oral, skin and nasal mucosal pathogens. Tissue engineering seeks to regenerate the tissues lost in these defects; however, the composite nature and proximity to colonizing bacteria remain difficult to overcome. Additionally, many tissue engineering approaches have further hurdles to overcome in the regulatory process to clinical translation. As such these studies investigated a two stage strategy employing an antibiotic-releasing porous polymethylmethacrylate space maintainer fabricated with materials currently part of products approved or cleared by the United States Food and Drug Administration, expediting the translation to the clinic. This porous space maintainer holds the bone defect open allowing soft tissue to heal around the defect. The space maintainer can then be removed and one regenerated in the defect. These studies investigated the individual components of this strategy. The porous space maintainer showed similar soft tissue healing and response to non-porous space maintainers in a rabbit composite tissue defect. In humans, the porous space maintainers were well tolerated and maintained a soft tissue envelope for closure after implantation of a bone regeneration technology. The antibiotic-releasing space maintainers showed release of antibiotics from 1-5 weeks, which could be controlled by loading and fabrication parameters. In vivo, space maintainers releasing a high dose of antibiotics for an extended period of time increased soft tissue healing over burst release space maintainers in an infected composite tissue defect model in a rabbit mandible. Finally, stabilization of bone defects and regeneration could be improved through scaffold structures and delivery of a bone forming growth factor. These studies illustrate the possibility of the two stage strategy for repair of composite tissue defects of the craniofacial complex.
2

A morphological and biometric study of the facial characteristics of two South African childhood populations at different age levels

Briers, N. January 2015 (has links)
Positive identification can be problematic if fingerprinting, DNA, dental history, etc. are no longer available. This may be possible through techniques such as facial approximation, but any form of craniofacial identification requires intimate knowledge of human craniofacial anatomy. Where children are involved, craniofacial changes due to facial growth further complicate matters and require knowledge of tissue thickness and variation in facial shapes. These have hardly been studied in children of African descent. The aims of this study were to provide data on tissue thickness and craniofacial proportions of South African Black and Coloured children and to document the lateral profile shape changes between the ages of 6 and 13 years. Tissue thickness was measured using cephalograms of South African children (n = 388). After digitizing the images, tissue thickness measurements were taken at 11 mid-facial landmarks from each image using the iTEM measuring program. Craniofacial proportions were assessed through assessing standardized anterior and lateral facial photographs of 1749 children. Measurements of facial features were taken using iTEM, from which 28 standard facial indices were calculated. For both tissue thickness and craniofacial indices comparisons between groups per age, sex and ancestry were statistically analyzed. In addition, geometric morphometrics were used to describe lateral facial shape changes and differences age, sex and ancestry (n = 800). The results showed that tissue thickness differences at lower face landmarks are more pronounced in age groups per ancestry as opposed to differences per age and sex. Facial profile per facial shape, class and ancestry showed differences at all landmarks. Craniofacial indices indicated that Coloured children have wider heads, foreheads and faces compared to Black children. The height of the nose and lower lip is longer in Coloured children compared to Black children. In Coloured children, mandibular height and lower face height is shorter in relation to total face height. Males have wider heads, foreheads, mandibles and faces compared to females. The degree of prognathism is dictated by ancestry and to a lesser extent by age and sex as findings showed that maxillary prognathism was more prominent in Black children, while mandibular prognathism were more pronounced in male children. South Africans have a relative concave lateral facial profile due to the maxilla and mandible being more prognathic than in North American children. Differences in lateral face shape between children of various ages, sexes and ancestral groups were visualized through the relative displacement of landmarks related to the forehead and lower face. The resultant differences in lateral facial profile can assist in more accurate estimation of age and ancestry of unknown children. This research created reference datasets for tissue thickness and craniofacial indices of South African children of Black and Coloured ancestry per age and sex that will be useful in the diagnosis of facial dysmorphology and for facial reconstruction / approximation of juvenile remains. It also shed more light on facial growth patterns in the various groups. / Thesis (PhD)--University of Pretoria, 2015. / tm2015 / Anatomy / PhD / Unrestricted
3

Rekonstrukce obličeje na základě lebky: analýza CT snímků hlavy dospělé populace / Reconstruction of the face using skull:analysis of CT images of the head of adult Czech population

Drgáčová, Anna January 2014 (has links)
AJ Knowledge of the soft facial tissues is the basis of any craniofacial reconstruction. It is of a great importance mainly for forensic practice, but it plays an important role in other fields, for example aesthetic surgery. Defining the thickness of facial tissues for different sexes, age and ethnic groups is an important aspect of forensic anthropology. The thesis specialises in finding out the thickness of soft facial tissues in modern czech population, it takes into consideration the sex, age and assymetry. The main source of information are the CT scans of the heads of 46 adult women and 56 adult men of czech nationality ranging between ages 21 to 83. 80 landmarks are defined in each scan, therefore 40 linear measurements between corresponding points have been evaluated. Data were analysed using the PCA, Hotelling test, linear discrimination analysis, Kolmogorov-Smirnov test, MANOVA, Kruskal-Wallis test and Wilcoxon paired test. Retrieved thicknesses of soft tissues will serve as the standards for the current czech population. Sexual dimorphism has been proven regarding the whole face, as well as both upper and lower parts of the face. The success of classification on the upper part of the face decresases significantly. Aging has been proven to have strong effect on the thickness of soft...
4

Avaliação da acurácia e da semelhança da reconstrução facial forense computadorizada tridimensional e variação facial fotoantropométrica intraindivíduo / Assessment of accuracy and recognition of three-dimensional computerized forensic craniofacial reconstruction and intraindividual photoanthropometric facial variation

Miranda, Geraldo Elias 31 August 2018 (has links)
Esta tese é composta por três capítulos. O primeiro teve o objetivo de avaliar a acurácia e a semelhança da reconstrução facial forense computadorizada (RFFC) tridimensional realizada com softwares livres. As RFFC foram realizadas no programa Blender® a partir de tomografias do crânio, utilizando templates do MakeHuman®. A avaliação da acurácia foi feita no CloudCompare® que comparou a RFFC com a pele na tomografia, enquanto a avaliação da semelhança foi realizada no Picasa® utilizando fotografias dos participantes. Os resultados mostraram que do total de pontos que formam cada reconstrução, 63.20% a 73.67% apresentaram uma distância de -2,5 <= x <= 2,5mm entre a RFFC e a superfície da pele, enquanto a distância média variou entre -1,66 a 0,33mm. Duas das quatro reconstruções foram reconhecidas objetivamente pelo Picasa®. As RFFC realizadas utilizando esses softwares apresentam plausíveis níveis de acurácia e semelhança, portanto indicam valor para uso no campo forense. Os outros dois capítulos tiveram como objetivo avaliar a estabilidade métrica facial do mesmo indivíduo por meio da análise de fotografias tomadas em um intervalo de tempo de cinco anos. Trata-se de um estudo longitudinal realizado com fotografias frontais padronizadas de 666 indivíduos adultos divididos por faixa etária e sexo. Com o programa SAFF 2D foram marcados 32 pontos, cujas coordenadas foram utilizadas para calcular 40 medidas, sendo 20 horizontais e 20 verticais. Cada uma dessas medidas foi dividida pelo diâmetro da íris e assim foram obtidas razões iridianas. Os resultados mostraram que a maioria das razões não sofreu variação estatisticamente significante. As razões que tiveram maior variação foram aquelas da região do nariz e da boca. Quando se compara as faixas etárias entre si observa-se que a grande maioria das razões é diferente, mostrando a influência da idade nas dimensões faciais. Quando se compara a estabilidade dentro mesmo sexo observa-se que houve razões que diminuíram e outras aumentaram tanto no sexo feminino quanto no sexo masculino, enquanto outras variaram apenas em um dos sexos. Quando se compara a variação entre os sexos observa-se que a maioria das razões é diferente, mostrando o dimorfismo sexual das medidas faciais. A face passa por alterações métricas ao longo da vida em todas as faixas etárias, principalmente na região do nariz e boca, com maiores diferenças após os 60 anos. Além disso, algumas medidas faciais são mais influenciadas pelo sexo do que outras. Entretanto, a maioria das medidas levantadas se mantem relativamente estáveis dentro de um período de 5 anos tanto em relação ao sexo quanto a idade. / This thesis contains three chapters. The aim of the first chapter was to evaluate the accuracy and recognition level of three-dimensional (3D) computerized forensic craniofacial reconstruction (CCFR) performed in a blind test on open-source software using computed tomography data from live subjects. The CCFRs were completed using Blender® with 3D models obtained from the computed tomography data and templates from the MakeHuman® program. The evaluation of accuracy was carried out in CloudCompare®, by geometric comparison of the CCFR to the subject 3D face model (obtained from the CT data). A recognition level was performed using the Picasa® with a frontal standardized photography. The results were presented from all the points that form the CCFR model, with an average for each comparison between 63.20% and 73.67% with a distance -2.5 <= x <= 2.5 mm from the skin surface and the average distances were 1.66 to 0.33 mm. Two of the four CCFRs were correctly matched by the Picasa® tool. Free software programs are capable of producing 3D CCFRs with plausible levels of accuracy and recognition and therefore indicate their value for use in forensic applications. The other two chapters study the facial comparison and aimed to evaluate the facial metrical stability of an individual through photographs taken in a time interval of five years. It is a longitudinal study composed of standard frontal photographs of 666 adults divided by sex and age groups. By using the SAFF 2D® software, 32 landmarks were positioned, whose coordinates were used to calculate 40 measurements, 20 horizontal and 20 vertical. Each of these measurements was divided by iris diameter and thus iridian ratios were obtained. The results showed that most of the ratios did not suffer statistically significant variations. The ratios that had the greatest variation in the different age groups were those of the nose and mouth regions. When comparing the age groups with each other it is observed that the great majority of the reasons are different, showing the influence of age on the facial dimensions. When comparing stability with respect to sex, it was observed that there were ratios that decreased and others that increased in both sexes, while other ratios varied only in females or in males. When the sexes were compared, it was observed that the majority of the ratios were different, showing sexual dimorphism of the facial measures. The face undergoes metrical alterations throughout the life, mainly in the region of the nose and mouth, with the greatest differences seen in those who are aged 60 years and older. In addition, some facial measures are more influenced by sex than others. However, most of the measures raised have remained relatively stable within a period of five years in both sex and age groups.
5

Avaliação da acurácia e da semelhança da reconstrução facial forense computadorizada tridimensional e variação facial fotoantropométrica intraindivíduo / Assessment of accuracy and recognition of three-dimensional computerized forensic craniofacial reconstruction and intraindividual photoanthropometric facial variation

Geraldo Elias Miranda 31 August 2018 (has links)
Esta tese é composta por três capítulos. O primeiro teve o objetivo de avaliar a acurácia e a semelhança da reconstrução facial forense computadorizada (RFFC) tridimensional realizada com softwares livres. As RFFC foram realizadas no programa Blender® a partir de tomografias do crânio, utilizando templates do MakeHuman®. A avaliação da acurácia foi feita no CloudCompare® que comparou a RFFC com a pele na tomografia, enquanto a avaliação da semelhança foi realizada no Picasa® utilizando fotografias dos participantes. Os resultados mostraram que do total de pontos que formam cada reconstrução, 63.20% a 73.67% apresentaram uma distância de -2,5 <= x <= 2,5mm entre a RFFC e a superfície da pele, enquanto a distância média variou entre -1,66 a 0,33mm. Duas das quatro reconstruções foram reconhecidas objetivamente pelo Picasa®. As RFFC realizadas utilizando esses softwares apresentam plausíveis níveis de acurácia e semelhança, portanto indicam valor para uso no campo forense. Os outros dois capítulos tiveram como objetivo avaliar a estabilidade métrica facial do mesmo indivíduo por meio da análise de fotografias tomadas em um intervalo de tempo de cinco anos. Trata-se de um estudo longitudinal realizado com fotografias frontais padronizadas de 666 indivíduos adultos divididos por faixa etária e sexo. Com o programa SAFF 2D foram marcados 32 pontos, cujas coordenadas foram utilizadas para calcular 40 medidas, sendo 20 horizontais e 20 verticais. Cada uma dessas medidas foi dividida pelo diâmetro da íris e assim foram obtidas razões iridianas. Os resultados mostraram que a maioria das razões não sofreu variação estatisticamente significante. As razões que tiveram maior variação foram aquelas da região do nariz e da boca. Quando se compara as faixas etárias entre si observa-se que a grande maioria das razões é diferente, mostrando a influência da idade nas dimensões faciais. Quando se compara a estabilidade dentro mesmo sexo observa-se que houve razões que diminuíram e outras aumentaram tanto no sexo feminino quanto no sexo masculino, enquanto outras variaram apenas em um dos sexos. Quando se compara a variação entre os sexos observa-se que a maioria das razões é diferente, mostrando o dimorfismo sexual das medidas faciais. A face passa por alterações métricas ao longo da vida em todas as faixas etárias, principalmente na região do nariz e boca, com maiores diferenças após os 60 anos. Além disso, algumas medidas faciais são mais influenciadas pelo sexo do que outras. Entretanto, a maioria das medidas levantadas se mantem relativamente estáveis dentro de um período de 5 anos tanto em relação ao sexo quanto a idade. / This thesis contains three chapters. The aim of the first chapter was to evaluate the accuracy and recognition level of three-dimensional (3D) computerized forensic craniofacial reconstruction (CCFR) performed in a blind test on open-source software using computed tomography data from live subjects. The CCFRs were completed using Blender® with 3D models obtained from the computed tomography data and templates from the MakeHuman® program. The evaluation of accuracy was carried out in CloudCompare®, by geometric comparison of the CCFR to the subject 3D face model (obtained from the CT data). A recognition level was performed using the Picasa® with a frontal standardized photography. The results were presented from all the points that form the CCFR model, with an average for each comparison between 63.20% and 73.67% with a distance -2.5 <= x <= 2.5 mm from the skin surface and the average distances were 1.66 to 0.33 mm. Two of the four CCFRs were correctly matched by the Picasa® tool. Free software programs are capable of producing 3D CCFRs with plausible levels of accuracy and recognition and therefore indicate their value for use in forensic applications. The other two chapters study the facial comparison and aimed to evaluate the facial metrical stability of an individual through photographs taken in a time interval of five years. It is a longitudinal study composed of standard frontal photographs of 666 adults divided by sex and age groups. By using the SAFF 2D® software, 32 landmarks were positioned, whose coordinates were used to calculate 40 measurements, 20 horizontal and 20 vertical. Each of these measurements was divided by iris diameter and thus iridian ratios were obtained. The results showed that most of the ratios did not suffer statistically significant variations. The ratios that had the greatest variation in the different age groups were those of the nose and mouth regions. When comparing the age groups with each other it is observed that the great majority of the reasons are different, showing the influence of age on the facial dimensions. When comparing stability with respect to sex, it was observed that there were ratios that decreased and others that increased in both sexes, while other ratios varied only in females or in males. When the sexes were compared, it was observed that the majority of the ratios were different, showing sexual dimorphism of the facial measures. The face undergoes metrical alterations throughout the life, mainly in the region of the nose and mouth, with the greatest differences seen in those who are aged 60 years and older. In addition, some facial measures are more influenced by sex than others. However, most of the measures raised have remained relatively stable within a period of five years in both sex and age groups.

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