No description available.

Thesis for Master of Science in Medicine at the School of Anatomical Sciences 5/11/2015 / In forensic anthropology, the estimation of sex is important for eliminating half of the possible identities the skeletal remains may have, as a result, sexing standards were set from fully dentate mandibles. Edentulous mandibles were excluded from studies that set these standards. Thus, this study intended to determine the effect of tooth loss on accurately estimating sex from the mandibular morphology of black South Africans. The mandibles sampled included 79 (31 males and 48 females) full dentition and 117 (57 males and 60 females) variable degrees of tooth loss mandibles from the Raymond A. Dart Collection of Human Skeletons. Outlines of the non-alveolar regions of the mandibles were digitised. The alveolar regions were rated according to the level of resorption that had occurred. A two block partial least square was performed to determine the effect of tooth loss on the mandibular morphology and a two sample permutation test was conducted to determine the sexing accuracies from all sampled mandibles. Tooth loss had a significant effect on the mandibular morphology. The overall accuracies determined were 85.5% from mandibles with tooth loss and 63.3% from full dentition mandibles. The overall mandible morphology is sexually dimorphic irrespective of the presence of tooth loss. The main factor that may affect the outcome was the mandibular mechanics in males and females. The results suggest that mandibles with high levels of tooth loss could be used in studies of identification. Further studies may want to set sexing standards from both dentate and edentate mandibles.

No description available.

Thesis (Ph. D.)--Pennsylvania State University, 1996. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Pennsylvania State University, 1996. / Includes bibliographical references.

Thesis--Rijksuniversiteit te Leiden, 1951.

Thesis--Rijksuniversiteit te Leiden, 1951.

No description available.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2015. / It is recognised that tooth loss as a consequence of oral diseases affects quality of life in humans. This has directed studies towards biological tooth replacement in vivo. In humans and other mammals, tooth replacement occurs only once (diphyodonty) as opposed to non-mammalian vertebrates where tooth replacement continues throughout life (polyphyodonty). Detailed knowledge of tooth initiation, development and morphology amongst vertebrates and especially amniotes, is necessary to understand the tooth replacement process. Crocodilians provide an interesting model for tooth replacement studies as they also exhibit thecodonty. Regulation of polyphyodonty has not been genetically defined, and it is uncertain whether the molecular mechanisms of continuous tooth replacement are similar to those involved in the primary dentition. The aim of this study was therefore to analyse crocodilian odontogenesis in detail, with the aid of light microscopy and CT scans, in order to provide a structural framework for molecular processes regulating polyphyodonty. Crocodile probes to bmp4 and pitx2 were designed, generated and labelled for use in in situ hybridisation. The expression patterns of pitx2 and bmp4 in embryos and hatchlings of the polyphyodont Nile crocodile (Crocodylus niloticus) were examined at different stages of tooth development. Histologically crocodilian tooth development appears similar to mammals. Interesting variations include the initiation of odontogenesis in the ectomesenchyme, the presence of dental placodes, the ‘null generation teeth’, the two different bell-stage tooth germs and the tooth-family organisation. A direct 1:1 relationship between the status of the erupted tooth and the developmental phase of the replacement tooth was not seen. However in more mature teeth, the replacement tooth germs were at a more advanced developmental stage than those associated with less mature teeth. Molecular data revealed that pitx2 was expressed in the oral epithelium and the dental placode. Bmp4 expression was not evident in the dental placode, but was localised in the odontoblasts of early bell stage tooth germs. Pitx2 and bmp4 were expressed in both the odontoblast and ameloblast layers in late bell stage tooth germs. Expression of pitx2 and bmp4 is conserved across vertebrates and pitx2 may play a role in initiation of primary and successional teeth.

No description available.