Theses and Dissertations (Oral Pathology and Oral Biology)

Permanent URI for this collectionhttp://hdl.handle.net/2263/32496

Browse

Now showing 1 - 11 of 11

The anterior loop of the inferior alveolar nerve : prevalence and measurement using reformatted medical computed tomographic imaging
(University of Pretoria, 2014) Van Zyl, Andre W.; Patterson, Geoffrey O.
Background: Implant placement in the anterior mandible has historically been considered a relatively safe procedure. It is now known that multiple anatomically important structures are frequently violated following implant placement in the anterior mandible. Damage to the third division of the trigeminal nerve may have dire consequences for the patient. Purpose: This paper aimed to determine the prevalence and measurement of the length of the anterior loop of the inferior alveolar nerve in a South African population and to make recommendations for the safe distance from the mental foramen for implant placement in the anterior mandible. Materials and methods: The sample population consisted of 200 patients,129 female and 71 male who were sent for CT examination for the purposes of implant planning.Using the cababilties of the software, the prevalence as well as the actual measurement of the anterior loop length was evaluated. Results: The anterior loop was present in 286 out of 400 sides (71%), with a mean length of 1.054mm and a range from 0mm to 5.29mm. Conclusions: When placing implants in close proximity to the mental foramen, caution is recommended to avoid injury to the inferior alveolar nerve, or one of its branches. The anterior loop of the inferior alveolar nerve becomes a critically important surgical reference point during treatment planning. Because of the wide range of the anterior loop lengths observed in our study, no fixed distance mesially or anteriorly from the mental foramen should be considered to be a “safe” distance without the use of 3 dimensional imaging.
The molecular profile of oral plasmablastic lymphomas in a South African population sample
(University of Pretoria, 2011-10-21) Van Heerden, W.F.P. (Willem Francois Petrus), 1958-; Willem, Pascale; sonja.boy@up.ac.za; Boy, Sonja Catharina
Plasmablastic lymphoma (PBL) was originally described in 1997 as an AIDS associated tumour although cases have been described in individuals not infected with HIV. Due to the high number of people living with HIV in South Africa, a substantial number of cases are diagnosed annually and 45 cases were included in this study. This represented the largest cohort of PBL affecting the oral mucosa published to date. Three main aspects of PBL were investigated: pathological features, viral status and certain genetic characteristics. The results from the genetic studies were the most important and interesting. These included rearrangements of the IGH gene in 63% and MYC- rearrangements in 62% of PBL’s. Seven of 43 cases (16%) showed rearrangement of both the IGH gene alleles, a finding never described before. New genetic findings also included increased CCND1 gene copy numbers in 17/41 (42%) and increased IGH gene copy numbers in 6/41 (15%) of cases. The exact role of MYC-rearrangements in the development of PBL is unclear. Many factors may be responsible for MYC deregulation but in the case of PBL of the oral cavity the possible role of Epstein Barr Virus (EBV) infection was considered. All but one of the patients with known HIV-status (32/45) was HIV positive and I supported the proposal that the diagnosis of PBL should serve as a sign of immunodeficiency, either as diagnostic thereof or as a predictor of a progressive state of immunodeficiency in patients with known HIV/AIDS status. The HIV-negative patient in this study was the only one that presented with an EBV-negative PBL on in situ hybridisation. The clinico-pathological features of the current study therefore strongly suggested an association between EBV, PBL and HIV/AIDS although the exact nature thereof remains uncertain. Routine genetic evaluation of tumours diagnosed as PBL should be introduced, as this may have prognostic and eventually treatment implications in the future. The exact panel of genes to be evaluated with a possible diagnosis of PBL should still be determined but examination of IGH and MYC for rearrangements should be included. This study proved the histomorphological features including the degree of plasmacytic differentiation not to have any diagnostic role although its prognostic value should be determined. The results of the immunohistochemical investigations performed in this study confirmed PBL always to be negative for CD20 but proved PBL not to be a morphological or immunohistochemical diagnosis by any means. In conclusion, it became clear that PBL should never be diagnosed without thorough clinical, systemic, pathological and genetic investigations, especially in the backdrop of HIV/AIDS. No pathologist should make the diagnosis of PBL and no clinician should accept such a diagnosis or decide on the treatment modality for the patient involved unless all other possibilities of systemic plasma cell disease have been excluded.
Immunohistochemical profile of odontogenic epithelium of developing dog teeth (Canis Familiaris)
(University of Pretoria, 2008) Boy, Sonja Catharina; sulette.nel@up.ac.za; Nel, Sulette
Similarities between the acanthomatous epulis and ameloblastomas resulted in debate regarding the nature and origin of the acanthomatous epulis found in dogs. In an attempt to elucidate the origin and character of the acanthomatous epulides, this study aimed to find suitable cell markers to identify odontogenic epithelium versus oral epithelium in developing dog teeth in order to use in future research on the pathogenesis and pathology of odontogenic neoplasms in dogs. As specific markers for odontogenic epithelium have not been described in dog tissue, proposed markers of odontogenic epithelium of human and rat tissues were tested on developing dog teeth. Keratin 14, keratin 19, amelogenin, p75 neurotrophin receptor and calretinin have been proposed as markers for inner enamel epithelium and/or ameloblasts in human and rat tissue and was therefore included in this study. Keratin 14 and keratin 19 can not be regarded as specific markers of odontogenic epithelium as various other types of epithelium also stained positive with these markers. Amelogenin could be a promising marker to distinguish between odontogenic tumours and non-odontogenic tumours as it was only detected in odontogenic tissues in this study. However, amelogenin has also been observed in other tissues in dogs and rats, and therefore further studies on this protein will be needed to elucidate the expression profile of amelogenin in odontogenic versus non-odontogenic tissues in dogs. p75 Neurotrophin receptor expression was restricted to certain regions of the inner enamel epithelium and no staining was observed in other epithelial cells. It therefore seems to be a promising marker to differentiate between odontogenic and non-odontogenic epithelium, but the widespread staining observed in the mesenchymal tissue makes differentiation between odontogenic and non-odontogenic stromal elements impossible. Calretinin staining was observed in the alveolar epithelial cells directly overlying the developing tooth germ, proposed as the oral epithelium where the dental lamina takes origin from, as well as the dental laminae and Serres rests. No staining was observed in the rest of the oral epithelium and it can therefore be proposed that calretinin could be a useful marker to distinguish between odontogenic and non-odontogenic epithelial cells. In light of the results found in this study on foetal tissue, the expression profile may be different in adult tissue. Odontogenic tumours in adult dogs may originate from remnants of odontogenic tissue like Serres rests and Malassez rests. It is therefore proposed that this study be repeated on adult dog tissue with specific reference to Serres rests, Malassez rests and the associated gingiva Copyright
A pilot study to assess dental age estimation in black South African children using Demirjian's method
(University of Pretoria, 2011) Bernitz, Herman; andre.uys@up.ac.za; Uys, Andre
The age estimation method as described by Demirjian is the most frequently used tool to estimate the sub-adult dental age in forensic dentistry. This technique has been shown to over or under estimate the chronological age of sub-adults when applied to specific population groups. The aim of this study was to compare a black South African population sample with the original French-Canadian model to determine if Demirjian’s method accurately reflects the true chronological age of this population group. A sample of panoramic radiographs from 279 boys and 325 girls between the ages of 6 and 16 was obtained from the School of Dentistry University of Pretoria, and from orthodontists in private practice in the Pretoria region. The panoramic radiographs were used to score the seven left mandibular teeth. The calculated maturity score was used to determine the Demirjian dental age. All panoramic radiographs were scored by one examiner. A subset of 20 panoramic radiographs was scored by a second examiner and reliability tested using a Wilcoxon Matched Pairs Test. This research showed that black South African children have a more advanced dental age compared to French-Canadian children. Demirjian overestimated the age for boys by 0.8 years and for girls by 0.5 years. The dental age assessment provided by Demirjian is not suitable for black South African children. As a result, new standards of dental age assessment should be established for this population. Copyright
Correlation between histological grade and ploidy status in potentially malignant disorders of the oral mucosa
(University of Pretoria, 2010-08-11) Van Zyl, Andre W.; email@mmdafrica.co.za; Langenegger, Eric Emil
No abstract available. Copyright
Minimum cytocidal effect of different minocycline and doxycycline concentrations to human periodontal ligament fibroblasts in vitro
(University of Pretoria, 2010-07-27) Botha, Stephanus Johannes; upetd@up.ac.za; De Wet, Tanya
Minocycline (MC) and Doxycycline (DC) are used worldwide as locally applied adjuncts in the treatment of periodontal diseases. As a group the tetracyclines are well known for their advantageous properties. There is however possible cytotoxicity towards cells in the area of application. This study determined the minimum cytocidal concentration of MC and DC on the growth and proliferation of Human Periodontal Ligament Fibroblasts (HPLF) in vitro. This was facilitated by growing cells (PDL1 and PDL2) in the presence of MC and DC in media in 96 tissue wells starting at a concentration of 1400 µg.ml-1 (100%). Serial dilutions of the MC and DC at 10% increments were investigated in order to detect significant HPLF cell growth inhibition. The significant LD50 was further determined at one percent increments in order to arrive at a specific percentage value. The results were read as LD50 values from growth concentration curves. The LD50 of MC on PDL1 and PDL2 after one hour exposure was 686 µg.ml-1 and 896 µg.ml-1 respectively while for DC it was 252 µg.ml-1 and 546 µg.ml-1. The LD50 of MC on PDL1 and PDL2 after 24 hour exposure was 196 µg.ml-1 and 266 µg.ml-1 respectively while for DC it was 252 µg.ml-1 for both. The LD50 of MC on PDL1 and PDL2 after 48 hour exposure was 252 µg.ml-1 and 182 µg.ml-1 respectively while for DC it was 154 µg.ml-1 and 168 µg.ml-1. Based upon the LD50 values this study found that DC is more cytotoxic than MC and linked to this, the two cell lines reacted slightly differently. The concentrations MC and DC tested in this study did however not influence growth of HPLF significantly.
Osteo-inductive potential of different doses of recombinant human osteogenic protein-1
(University of Pretoria, 2007-01-05) Pettitt, James; upetd@up.ac.za; Odendaal, Petrus Johannes
Please read the abstract in the section 00front of this document
A protocol to study tissue regeneration in alveolar bony defects
(University of Pretoria, 2007-01-05) Pettitt, James; upetd@up.ac.za; Hattingh, Andre Christiaan
Please read the abstract in the front section of this document
Comparative study of heterotopic bone induction using porcine bone morphogenetic proteins delivered into the rodent subcutaneous space with allogeneic and xenogeneic collagen carriers
(University of Pretoria, 2009-06-15) Duneas, Nicolaas; Van Zyl, Andre W.; govindrau.mohangi@up.ac.za; Mohangi, Govindrau Udaibhan
Please read the abstract in die section front of this document.
The incidence of oral and oropharyngeal cancer in South Africa for the five year period 1997-2001
(University of Pretoria, 2013) Van Heerden, W.F.P. (Willem Francois Petrus), 1958-; mabram@sahcp.com; Abram, Muhammed Hanif
The National Cancer Registry (NCR) of South Africa publishes pathology-based cancer incidence in the country and is the main cancer data source. The data published by the NCR have been used extensively in the development of the draft national guidelines for cancer prevention and control as well as for cancer research. The list of contributing pathology laboratories is fairly inclusive. As far as Oral Cancer is concerned, the Department of Oral Pathology, University of Limpopo, has however not submitted data to the NCR. It is therefore reasonable to assume that because of this, a large proportion of histologically diagnosed oral cancers are not reflected in the NCR. Materials and methods: Data from the National Cancer Registry and the University of Limpopo, Department of Oral Pathology for the five years 1997-2001 were combined and then filtered for sites in the oral and oropharyngeal region. Age- Standardised Incidence Rates (ASIR) and the Cumulative Lifetime Risk (LR) for males and females in the different population groups were determined. Conclusion: It is possible that the total ASIR for oral and oropharyngeal cancer has increased in South Africa. The incidence of oral and oropharyngeal cancer in individuals below the age of 45 years in South Africa is higher than the global average.
The histopathology of lions (Panthera leo) suffering from chronic debility in the Kruger National Park
(University of Pretoria, 2006-03-09) Kriek, N.P.J.; Ide, Annalize
Studies on the health status of lions (Panthera leo) in the Kruger National Park (KNP) have revealed certain lions suffering from chronic debility (“poor doers”). Clinical signs include chronic emaciation, renal failure and chronic bacterial infections. The diagnosis of Mycobacterium bovis in KNP lions in 1995 raised the question of whether these “poor doer” lions were suffering from tuberculosis. Tests confirmed tuberculosis in some cases, but no aetiology for the poor condition was found in a large percentage of the animals tested. Extensive literature review failed to reveal reports of similar findings of chronic debility in free living lion populations, although various disease outbreaks and infectious diseases of lions are described. These are briefly reviewed. Surveys have confirmed that the majority of the KNP lions are serologically positive for feline immunodeficiency virus (FIV), the clinical importance of which is questioned as a possible cause of immunosuppression in lions. Tissue samples from eleven lions suffering from chronic debility and six clinically healthy lions were studied by light microscopy. Changes in the various organ systems were reported and tabulated with reference to degree and relevance. Frozen lymph node samples from some animals in both groups were collected for immunohistochemical staining for T and B lymphocytes and CD4 and CD8 subsets. In some cases serology was done for FIV using a Puma Lentivirus ELISA and a Puma Lentivirus Western Blot technique. Mycobacterial culture results were available for some animals. The histopathological features varied, but notable changes were seen in the lymph nodes. These included generalized lymphoid hyperplasia (predominantly affecting clinically healthy lions), progressing through combined hyperplasia and atrophy in different nodes to lymphoid atrophy affecting most of the lions suffering from chronic debility. These are non-specific findings seen in various systemic diseases, including canine distemper virus infection and toxoplasmosis, but they have also been described in domestic cats suffering from FIV infection and humans with HIV. Further findings in lymph node sections included mineral deposition and multifocal cystic spaces. Other important histopathological changes included chronic interstitial pneumonia, renal amyloidosis, chronic interstitial nephritis, Wallerian degeneration of the spinal cord, encephalomalacia and anterior uveitis. Two animals suffered from multifocal, multisystemic granulomatous inflammation. Mycobacterium bovis was cultured from one of these cases, but no apparent aetiology could be found in the other. Eosinophilia was a consistent finding in many tissues and most likely related to the high parasite load in many of the animals. Parasites found included Hepatozoon spp., microfilaria, cestodes, nematodes and trematodes and Sarcocystis spp. and Trichinella spp. Immunohistochemical staining for B and T lymphocytes and CD4 and CD8 subsets showed a normal distribution of the staining pattern within the lymph node sections, although the samples were all from FIV positive lions. The histopathology in both study groups was of a non-specific nature and not indicative of any particular disease syndrome, although many of the changes are similar to those described in domestic cats infected with FIV. There are indications of possible immunocompromise in the “poor doer” lions, which warrants further investigation.

Browse

Recent Submissions