Thesis (M.S.)--University of Michigan, 1986.

Thesis (M.S.)--University of Michigan, 1986.

In spite of burgeoning of new technologies in the field of maxillofacial surgery, such as novel methods for osteosynthesis, bone substitution and bone regeneration, the reconstruction of the craniofacial skeleton (CFS) remains a challenge. Complications and failure in existing technologies and treatments for the CFS may be attributed in part to an incomplete understanding of the biomechanical environment in which these technologies are expected to perform. Characterizing the morphology and biomechanical behaviour of this complex and unique structure is important to understanding its global response to mechanical demands. This thesis aims to characterize the biomechanical behaviour of thin bone regions and sutures in the CFS. We investigated the impact of image degradation in CT scans on the ability to develop accurate specimen-specific FE models. Image degradation resulted in large increases in cortical thickness and decreases in scan intensity, which corresponded to significant changes in maximum principal strains in the FE models. A new semi-automated connectivity technique was developed to quantify the degree of fusion in sutures and revealed varying degrees of connectivity and interdigitation depending on the suture location. Morphological features characterized using this technique were incorporated into idealized suture FE models and analysed under multiple loading directions. The idealized FE models revealed that the impact of the number of interdigitations on the strain energy absorption in the suture/bone complex is dependent on the loading direction (inversely related under pressure and directly related under perpendicular and pressure loading); similar behaviour was seen in a μCT based specimen-specific FE model. Three-point bending tests on bone samples containing sutures revealed a positive correlation between the number of interdigitations and bending strength. Finally, experimental testing of full cadaveric heads demonstrated inter-specimen consistency in strain magnitude and direction under muscle loading in spite of morphological differences. Overall, these findings provide new insight into the complex morphology of the CFS, limitations of current clinical imaging and the biomechanical behaviour of thin bone structures and their articulations. This work forms a solid foundation for future development of image analysis, modeling and experimental investigations focused on characterizing the global behaviour of the CFS.

In spite of burgeoning of new technologies in the field of maxillofacial surgery, such as novel methods for osteosynthesis, bone substitution and bone regeneration, the reconstruction of the craniofacial skeleton (CFS) remains a challenge. Complications and failure in existing technologies and treatments for the CFS may be attributed in part to an incomplete understanding of the biomechanical environment in which these technologies are expected to perform. Characterizing the morphology and biomechanical behaviour of this complex and unique structure is important to understanding its global response to mechanical demands. This thesis aims to characterize the biomechanical behaviour of thin bone regions and sutures in the CFS. We investigated the impact of image degradation in CT scans on the ability to develop accurate specimen-specific FE models. Image degradation resulted in large increases in cortical thickness and decreases in scan intensity, which corresponded to significant changes in maximum principal strains in the FE models. A new semi-automated connectivity technique was developed to quantify the degree of fusion in sutures and revealed varying degrees of connectivity and interdigitation depending on the suture location. Morphological features characterized using this technique were incorporated into idealized suture FE models and analysed under multiple loading directions. The idealized FE models revealed that the impact of the number of interdigitations on the strain energy absorption in the suture/bone complex is dependent on the loading direction (inversely related under pressure and directly related under perpendicular and pressure loading); similar behaviour was seen in a μCT based specimen-specific FE model. Three-point bending tests on bone samples containing sutures revealed a positive correlation between the number of interdigitations and bending strength. Finally, experimental testing of full cadaveric heads demonstrated inter-specimen consistency in strain magnitude and direction under muscle loading in spite of morphological differences. Overall, these findings provide new insight into the complex morphology of the CFS, limitations of current clinical imaging and the biomechanical behaviour of thin bone structures and their articulations. This work forms a solid foundation for future development of image analysis, modeling and experimental investigations focused on characterizing the global behaviour of the CFS.

Videonasendoscopy and videofluoroscopy are two instruments used by craniofacial teams for assessing velopharyngeal function. Various methods have been proposed throughout the literature for collecting and reporting data from these two types of imaging studies. The purpose of this investigation is to survey craniofacial teams regarding current use of videonasendoscopy and videofluoroscopy in the clinical setting. The results show the videonasendoscopy is more frequently used than videofluoroscopy and that estimations are a more common data collection/reporting method than objective measurements. The data also show that a wide variety of methods are currently in use and only a small number of teams use the standardizing method proposed by the international working group (Golding-Kushner, et al., 1990).

Skeletal superstructure characteristics such as thick cranial vaults and well-developed supraorbital, infraorbital, zygomatic, temporal, and nuchal regions in hominins are collectively referred to as aspects of craniofacial robusticity. A better understanding of craniofacial robusticity is important because these features are regularly employed as individual traits in circumscribing fossil hominins as a means to separate other taxonomic groups from modern Homo sapiens even though the developmental and functional underpinnings of such traits are incompletely understood. The work of some researchers suggests that these features may be tied to a broader "robusticity complex", in which the expression of all the classically "robust" characteristics of the hominin cranium are intercorrelated and intrinsically linked. If true, then previous studies that have focused on characteristics of craniofacial robusticity as individual characters could be flawed. This study tests for the presence of an intercorrelated craniofacial robusticity complex in a geographically diverse sample of recent Homo sapiens using a morphological integration framework. Within this framework, significant levels of correlation between features of craniofacial robusticity are demonstrative of integration and thus a "robusticity complex", while non-significant levels of correlation provide evidence for modularity and therefore an independent expression of these traits. Craniofacial robusticity is examined among four anatomical areas of the human cranium including the frontal, zygomaxillary, temporal, and occipital regions. The expression of robusticity among these anatomical regions is quantified using three-dimensional coordinate landmark data in addition to classical discrete measures and is analyzed via two-block partial least squares regression analysis. The results show that levels of interaction between these major anatomical units are characterized by a range of correlation values with most obtaining statistical significance. These results frequently provide evidence for integration between subunits demonstrating at least partial evidence for a "robusticity complex" in the craniofacial skeleton of extant humans.

Craniofacial development requires orchestrated and complex interactions between multiple tissues of different origins. Cranial neural crest stem cells migrate from the dorsal neural tube into the frontonasal process and branchial arches where they ultimately form most of the skeletal structures and connective tissue of the craniofacial complex, as well as contributing neurons and glia to cranial ganglia. The timing and mechanism by which cranial neural crest cells progressively differentiate from multipotent stem cells into lineage restricted and terminally differentiating cell types has previously not been investigated. In addition, there are many deficits in our knowledge of the molecular controls regulating early development of neural crest cells within the branchial arches. Spatial and temporal changes in migratory and lineage potential in neural crest populations contributing to the developing first branchial arch and trigeminal ganglia were examined by back-transplanting cells from quail into chick embryos. Neural crest cells that had barely entered the first branchial arch had largely lost both the ability to localise to the trigeminal ganglia and neurogenic differentiation capacity but were still capable of long-distance migration. However, after a further 12 hours residence in the branchial arch, neural crest cells had lost long-distance migratory ability.

Thesis (Ph. D.)--Virginia Commonwealth University, 2006. / Prepared for: Dept. of Human Genetics. Bibliography: leaves 111-135.

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Saúde, 2010. / Submitted by Allan Wanick Motta (allan_wanick@hotmail.com) on 2011-01-17T18:05:09Z No. of bitstreams: 1 2010_SamanthadoPradoSobral.pdf: 2023135 bytes, checksum: 42729d9c2282753d45a51e400a0bb19d (MD5) / Rejected by Luanna Maia(luanna@bce.unb.br), reason: on 2011-01-17T18:32:19Z (GMT) / Submitted by Allan Wanick Motta (allan_wanick@hotmail.com) on 2011-01-17T19:12:25Z No. of bitstreams: 1 2010_SamanthadoPradoSobral.pdf: 2023135 bytes, checksum: 42729d9c2282753d45a51e400a0bb19d (MD5) / Approved for entry into archive by Daniel Ribeiro(daniel@bce.unb.br) on 2011-01-28T01:17:41Z (GMT) No. of bitstreams: 1 2010_SamanthadoPradoSobral.pdf: 2023135 bytes, checksum: 42729d9c2282753d45a51e400a0bb19d (MD5) / Made available in DSpace on 2011-01-28T01:17:41Z (GMT). No. of bitstreams: 1 2010_SamanthadoPradoSobral.pdf: 2023135 bytes, checksum: 42729d9c2282753d45a51e400a0bb19d (MD5) / A Síndrome de Kabuki (KS, Síndrome da maquiagem de Kabuki, Síndrome de Niikawa-Kuroki) é uma desordem genética rara caracterizada por múltiplas anomalias congênitas e deficiência cognitiva. O diagnóstico é clínico e baseado nos achados descritos simultaneamente em estudos independentes de dois grupos no Japão. A amostra foi composta por 16 indivíduos com KS, diagnosticados pelo Serviço de Genética Clínica do Hospital Universitário de Brasília, Brasília, Brasil, com idades compreendidas entre oito e 24 anos de ambos os gêneros. Cada indivíduo foi submetido a exames clínico, radiográfico e a fotografias intra e extrabucais. Anomalias craniofaciais e dentárias foram observadas em todos os indivíduos examinados. Sete dos 16 indivíduos tinham maloclusão classe III de Angle, provavelmente devido à recessão maxilar e hipoplasia do terço médio da face. Palato profundo foi observado em doze indivíduos e aplainamento condilar em dois pacientes. Dentre as anomalias dentárias a mais observada foi a anomalia de forma, principalmente incisivos em chave de fenda. Forma atípica da coroa de premolares e molares e dilaceração radicular também foram relatadas. Hipodontia e microdontia foram diagnosticados em nove e quatro indivíduos, respectivamente. Opacidades difusas foram verificadas na dentição permanente (n=10). Grande heterogeneidade das manifestações clínicas foi observada nos indivíduos com KS examinados em concordância com a literatura. Anomalias não descritas previamente foram observadas nesta amostra, tais como anomalias de forma de coroa dentária, anomalias de forma da raiz, aplainamento condilar e fibrose da rafe palatina. Mais estudos clínicos e moleculares são necessários para melhor compreender as anomalias craniofaciais e dentárias descritas nesta síndrome. _________________________________________________________________________________ ABSTRACT / Kabuki syndrome (KS, Kabuki make-up syndrome, Niikawa-Kuroki syndrome) is a rare genetic disorder characterized by multiple congenital anomalies and mental retardation. The diagnosis is clinical and based on the findings described simultaneously in independent studies of two groups in Japan. The sample comprised sixteen KS individuals diagnosed by Department of Clinical Genetics, University Hospital of Brasilia, Brasilia, Brazil with ages between 8 to 24 years of both genders. Each individual underwent complete physical examination, as well as intra-oral and radiographic examinations. Extra-oral and intra-oral photographs were also performed. Craniofacial and dental anomalies were observed in all KS patients examined. Seven of the 16 individuals had class III malocclusion, probably due to maxillary recession and mid-face hypoplasia. Also, high arched palate was observed in twelve individuals. Flattening of the condyle was revealed in two individuals. The most common dental anomaly observed was teeth shape abnormalities, mainly screwdriver incisors. Moreover, atypical shape of the premolar's and molar's crowns and root dilaceration were also observed. Hypodontia and microdontia were present in 9 and 4 individuals, respectively. Enamel diffuse opacities were reported in permanent dentition (n=10). A great clinical heterogeneity was observed in KS individuals in line with other previous studies in the literature. Some non previously reported anomalies were also observed in this sample, such as crown anomalies, root shape, flattening of the condyle and fibrosis of raphe palate. Further clinical and molecular studies are necessary in order to better understand the presence of dental anomalies in this syndrome.

Orientador: Vera Lucia Gil da Silva Lopes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-10T12:58:59Z (GMT). No. of bitstreams: 1 Simioni_Milena_M.pdf: 1760732 bytes, checksum: daa025a27c5eb01a26a41f7ac8dc50ba (MD5) Previous issue date: 2008 / Resumo: Os Defeitos de Linha Média Facial com Hipertelorismo (DLMFH) constituem um grupo de anomalias craniofaciais raras e heterogêneas caracterizado por hipertelorismo ocular e fenda nasal mediana e (ou) lateral. Esses defeitos podem ocorrer isoladamente ou associados a dismorfismos com ou sem padrão definido, motivo pelo qual sua incidência não foi estabelecida até o momento. Dentre os fatores que podem participar da sua gênese encontra-se a perda de controle de genes de desenvolvimento envolvidos no processo de formação facial. A microdeleção 22q11.2, região dos genes HIRA/TUPLE1 e TBX1, causa a Síndrome Velocardiofacial e a Seqüência de DiGeorge. Essa deleção também foi descrita em casos esporádicos de anomalias congênitas múltiplas e DLMFH. Esses fatos, corroborados por extensa revisão da literatura, sugerem que os DLMFH possam fazer parte do espectro dessas condições clínicas e estarem associados a alterações na região 22q11.2. Para estudar essa hipótese, 10 indivíduos com DLMFH foram analisados por meio da técnica de FISH, utilizando a sonda comercial 22q11.2 DiGeorge ¿ HIRA/TUPLE1 locus (VysisTM). Não foi encontrada perda de fragmento cromossômico nessa região em nenhum dos indivíduos analisados. Os genes HIRA/TUPLE1 e TBX1 foram estudados por meio de técnicas moleculares. Não foi possível realizar a padronização da amplificação dos exons do gene HIRA/TUPLE1. Alterações de seqüência no gene TBX1, descritas como polimorfismos de nucleotídeo único e uma alteração inédita no exon 9C, 1132G ? A, foram encontradas. Em vista do tamanho amostral e da heterogeneidade clínica e etiológica, o presente trabalho não pode relacionar o envolvimento da região 22q11.2 na patogenia dos DLMFH / Abstract: Midline Facial Defects with Hipertelorism (MFDH) is a rare and heterogeneous group of craniofacial disorders characterized by ocular hypertelorism and bifid nose. This group of craniofacial defects occurs isolated or as part of a syndrome. For these reasons, its prevalence is still unknown. Alterations in developmental genes involved in facial process could be implicated in the genesis of this condition. The 22q11.2 microdeletion, localization of the HIRA/TUPLE1 and TBX1 genes, causes Velocardiofacial Syndrome and DiGeorge Syndrome. This deletion was also described in few cases of multiple congenital anomalies and MFDH. These facts suggested that some cases of MFDH may be part of the spectrum of these conditions and associated to alterations in the 22q11.2 region. In order to verify this hypothesis, fluorescent in situ hybridization (FISH) for 22q11.2 region (DiGeorge ¿ HIRA/TUPLE1 locus probe, VysisTM) was performed on metaphase chromosomes and nuclei of 10 individuals with MFDH. The 22q11.2 deletion was not found in any patient. Molecular techniques were applied in the study of HIRA/TUPLE1 and TBX1 genes. The amplification of HIRA/TUPLE1 exons was not possible to be realized. Alterations in the sequence of TBX1 gene, classified as single nucleotide polymorphism and a new alteration in exon 9C, 1132G ? A, were found. In view of the size of the sample and the clinical-genetic heterogeneity, we could not associate the involvement of 22q11.2 region in the genesis of MFDH / Mestrado / Ciencias Biomedicas / Mestre em Ciências Médicas