Magister Scientiae - MSc / Palatal Rugae Patterns in a Sudanese Population Sample Palatal rugae are ridges resulted from symmetrical and irregular mucosal folds of tissue and located in the alveolar third of the palate. Palatal rugae identification can have a significant role in forensic identification where it is difficult to use the normal identification methods. The aim of this study is to identify and compare the palatal rugal morphological patterns in a sample of adult males and females of Sudanese population. Maxillary impression models obtained from 100 subjects (50 males and 50 females) of age group 21 – 23 years, of the dental students of University of Science and Technology, Sudan. The data were assessed based on the Thomas and Kotze classification (1983) for the length, shape and prevalence. The Independent - t - Test was used for the statistical analysis. Ethical approvals declared from the University of Science and Technology, Sudan and University of the Western Cape South, South Africa to conduct the study. Statistical analysis showed that females had significantly more number of total rugae on the right side of the palate than in males. The prevalence of the palatine rugae numbers was significantly more in females than in males. Primary rugae were distributed more significantly in females more than males. On the right side of the palate, the straight type of rugae was significantly predominant in females than in males whilst the wavy shape was more in males than in females. On the left side of the palate, the curved type of rugae was significantly more presented in males than in females whilst the diverging unification type was more in females than in males. The distribution of number of rugae shapes in both males and females were seen as straight followed by wavy and least was the circular. The total number of straight rugae was significantly more in females than in males, as well as circular rugae and diverging rugae. In contrast, curved rugae were significantly more in males than in females. There were 11 individuals who did not comply with the Thomas and Kotze classification thus was recorded as unspecified. Page iv This Sudanese study showed significant differences between males and females in the number, length and shapes of rugae. Hence, the individuality and uniqueness of palatine rugae can be used as a tool for forensic dental identification, and possibly distinction between males and females. There is also a possibility that there are ethnic differences in rugal patterns.

Philosophiae Doctor - PhD / Histological observations revealed that oral epithelium originated from a single ectodermal layer. As the ectoderm grew so it differentiated into squamous epithelium. The first features of squamous differentiation were noticed at 8 weeks in utero in areas where keratinized mucosae were developing, and these were the changing of cuboidal to cylindrical basal cells and the subsequent growth of prickle cells from these cylindrical basal cells. The prickle cells merged with the existing primitive cells and at no stage could a separate squamous epithelial layer I such as the stratum tritermedium of the epidermis I be observed inside the mouth. At 12 weeks in utero squamous differentiation had reached a stage where acidophilic layers appeared in certain regions on the epithelial layer. The time of appearance of these layers varied from case to case. At this stage most of the primitive characteristics had disappeared from the keratinizing epithelium. Unlike the periderm of the skin which was shed into the amniotic fluid, shedding of primitive epithelial cells from the keratinizing squamous epithelium was not noticeable. Thence, the growth of keratinizing epithelium was followed by an increase of acidophilic layers, the appearance of keratohyaline granules in cells and, in some instances, full keratinization. The latter I however I was almost exclusively confined to the vermilion border of the lip. The squamous epithelium of the lining mucosa, which is unkeratinized I developed at a much slower tempo. It retained its cuboidal-shaped basal cells and the primitive features of the overlying cells were lost only at about 4- 5 months in utero I when squamous differentiation set in. At no stage was the squamous differentiation a prominent feature. At junctions between keratinized and unkeratinized epithelia and epidermis the epithelium exhibited features of both types of epithelia that were being joined. This was especially noticeable at the junction between vermilion epithelium and epidermis, where part of the vermilion epithelium displayed a prominent intermediate type of layer. Similarly, acidophilic layers of keratinizing epithelium merged imperceptibly with the walls of cells of unkeratinizing epithelium, creating a small region of an unkeratinizing type of epithelium with keratinized cells. Thus the development of the oral epithelium is through differentiation and renewal of epithelial cells: the ectodermal layer developes into an epithelial layer which is recognised by its squamous appearance. The subsequent growth is by constant renewal of this differentiated epithelium. The pattern of epithelial development I the appearance of the junctional epithelia and the manner in which acidophilic layers merge with unkeratinized epithelial cells I indicate a unity between these epithelia. According to these developmental features, the epithelium of the mouth and epidermis can be classified into less differentiated and better differentiated, but with a commonbackground for these epithelia. When the formation and the established appearance of keratin in the mouth and on the skin was compared histologically I ultrastructurally and histochemically I a unity between these features became apparent. Ultrastructurally it appeared that keratin consisted basically of 2 cytoplasmic constituents: tonofilaments and a fine granular substance. The tonofilaments were gathered at first into bundles and then broken up into finer tonofibrils. These finer fibrils mixed with a granular ground substance to form a homogenous granular filamentous material. This product can be regarded as a pre-keratin. With the addition of a keratohyaline layer to the process I keratin was formed, Apart from the keratohyaline granules several additional changes took place in cells concerned in this process I whether keratin was formed or not. These changes were flattening of cells, extensive interdigitation between cell walls, disappearance of micro-villi I loss of structure in desmosomes I thickening of cell walls and the disappearance of glycogen from cells. Some of these features were displayed in each of the types of epithelium examined here.

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